Tetraodontiform fishes are distributed in tropical to temperate seas and freshwaters of the world. They show a remarkable diversity in shape, size, and way of life (Fig. 1). A small filefish of the genusRudarius Jordan and Fowler1902 and a small pufferfish of the genusCarinotetraodon Benl1957 mature at about 2 cm in total length (TL) (Lim and Kottelat1995; Tyler1970), whereas ocean sunfishes of the genusMola Koelreuter1766 attain over 300 cm TL (Yoshita et al.2009). Tetraodontiform fishes are characterized by a small mouth with either relatively few teeth that are often enlarged or massive beak-like tooth plates, a small gill opening restricted to the side of the body, scales usually modified as spines, enlarged plates, or a carapace, and pelvic fins that are reduced or absent (Tyler1980; Nelson2006). In addition, many pufferfishes are characterized by having a strong toxin in the viscera and skin, and even in the musculature of some species ofLagocephalus Swainson1839 (Matsuura1984). Because of their peculiar morphological characters, tetraodontiforms have long attracted the attention of ichthyologists and biologists.

Representatives of the 10 extant families of Tetraodontiformes.a Triacanthodidae,Triacanthodes anomalus;b Triacanthidae,Triacanthus biaculeatus;c Balistidae,Abalistes filamentosus;d Monacanthidae,Thamnaconus hypargyreus;e Aracanidae,Kentrocapros aculeatus;f Ostraciidae,Ostracion immaculatus;g TriodontidaeTriodon macropterus;h Tetraodonitidae,Arothron mappa;i Diodontidae,Diodon liturosus;j Molidae,Masturus lanceolatus. Photographs ofa ande provided by BSKU;b,d,f,h, andi by KAUM;c andg by NSMT;j by Hideki Sugiyama

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Since Cuvier (1816) classified tetraodontiforms in the order Plectognathi, tetraodontiforms were usually considered to form a monophyletic group among the advanced percomorph fishes (Nelson2006). Although the taxonomy of tetraodontiform fishes progressed greatly in the nineteenth century (see Tyler1980, for a history of the classification of the order), information about tetraodontiform taxonomy was scattered in many articles, making it difficult to understand the taxonomic relationships of tetraodontiforms overall. Alec Fraser-Brunner published an important series of articles on various groups of tetraodontiforms as reviews of genera and families during the mid-1930s to early 1950s: however, many parts of his publications were based on cursory examinations of relatively few specimens. There were no comprehensive phylogenetic studies until Winterbottom (1974) and Tyler (1980) provided their interpretations of the phylogenetic relationships of tetraodontiforms based on myology and osteology, respectively.

When the first Indo-Pacific Fish Conference (IPFC1) was held in Sydney in 1981, many problems remained in the generic- and species-level taxonomy of all tetraodontiform families, except for the Triacanthodidae and Triacanthidae for which Tyler (1968) had provided a monographic revision. The period from IPFC1 to IPFC9 (1981−2013) was a time of great progress in the taxonomy and systematics of tetraodontiforms. Many review and revisional papers have been published for various genera and species, with descriptions of new taxa found mainly in coral reefs and tropical freshwaters; and cladistic analyses of morphological characters have clarified phylogenetic relationships of a number of families and molecular analyses greatly assisted our understanding of the detailed phylogenetic relationships of families, genera, and even species. The purpose of this paper is to present a review of the developments in the taxonomy and systematics of the Tetraodontiformes, focusing primarily on contributions from 1980 (when James C. Tyler’s monumental work was published) through the period of IPFCs, but including pertinent publications before 1980. This paper is composed of two parts, the first reviewing taxonomic studies and the second focusing of studies on systematics. Institutional abbreviations follow Fricke and Eschmeyer (2014).

Spikefishes of the family Triacanthodidae are usually found in depths of 100−600 m on continental shelves and slopes (Tyler1968; Matsuura and Tyler1997). They are easily distinguished externally from other families of the order Tetraodontiformes by the following combination of characters: body deep and slightly compressed, covered by moderately thick skin with numerous small scales not readily distinguishable to the unaided eye, with each scale bearing upright spinules and having a roughly shagreen-like appearance; two separate dorsal fins, six spines in the first dorsal fin and 12−18 soft rays in the second dorsal fin; caudal fin rounded to almost truncate, not forked; most dorsal-, anal-, and pectoral-fin rays branched; pelvic fins with a large spine and one or two inconspicuous and rudimentary soft rays; mouth small and usually terminal; teeth of moderate size, usually conical, 10 or more in an outer series in each jaw; caudal peduncle compressed, deeper than wide, not distinctly tapered (Matsuura2001).

Spikefishes are still relatively poorly known in terms of taxonomy and biology among tetraodontiform families, although Tyler (1968) published an excellent monograph on the superfamily Triacanthoidea including the Triacanthodidae and Triacanthidae. He recognized 19 triacanthodid species in 11 genera (Table 1):Atrophacanthus Fraser-Brunner1950 (one species),Bathyphylax Myers1934 (two species),Halimochirurgus Alcock1899 (two species),Hollardia Poey1861 (three species),Johnsonina Myers1934 (one species),Macrorhamphosodes Fowler1934 (two species),Mephisto Tyler1966b (one species),Parahollardia Fraser-Brunner1941b (two species),Paratriacanthodes Fowler1934 (two species),Triacanthodes Bleeker1857 (two species), andTydemania Weber1913 (one species). Because all these genera and species were described in detail by Tyler (1968), their taxonomic features are not repeated here, except for new information that provides a better understanding of taxa.

Many species of the Triacanthodidae are known from the tropical and warm regions of the Indo-Pacific. However, five species are distributed in the western Atlantic:Hollardia hollardi Poey1861,Hollardia meadi Tyler1966a,Johnsonina eriomma Myers1934,Parahollardia lineata (Longley1935), andParahollardia schmidti Woods1959.Hollardia goslinei Tyler1968 are known only from nine specimens collected from the Hawaiian Islands.

Little information about the Atlantic and Hawaiian spikefishes has been published since Tyler’s (1968) monograph. Matsuura (1983) provided a brief morphological account ofHollardia hollardi with a color photograph based on specimens collected from off Surinam. McEachran and Fechhelm (2005) also provided a brief account and line drawing ofHollardia hollardi andHollardia meadi from the Gulf of Mexico. McEachran and Fechhelm (2005) and Hartel et al. (2008) reported brieflyParahollardia lineata from the Gulf of Mexico and off greater New England, respectively. Tyler et al. (2013) documented a large northern range extension forHollardia hollardi to the northeast coast of the USA off Massachusetts, whereas this species had previously only been known from the Florida Keys, Bahamas, Bermuda, Gulf of Mexico, Caribbean, and south to Brazil, with the new northern occurence perhaps associated with warming currents along the east coast of North America.

In contrast to the Atlantic spikefishes, many papers on Indo-Pacific spikefishes were published after 1980. Matsuura (1982) describedTriacanthodes indicus based on 13 specimens collected from the western Indian Ocean. This species is characterized by relatively large nasal organs compared to other species ofTriacanthodes. Matsuura and Fourmanoir (1984) describedTriacanthodes intermedius based on two specimens collected from New Caledonia.Triacanthodesintermedius is unique among spikefishes in having several intermediate characters betweenParatriacanthodes andTriacanthodes. Tyler (1997) describedParatriacanthodes abei based on a single specimen collected in the South China Sea. Santini (2006) describedBathyphylax pruvosti based on 25 specimens collected from the Marquesas Islands. In addition to these contributions, papers and books on taxonomic and zoogeographical studies of spikefishes were published by authors from various countries including Australia, China, Japan, Korea, Russia, Taiwan, Ukraine, and the USA.

Amaoka (1982) reportedHalimochirurgus alcocki Weber1913,Macrorhamphosodes uradoi (Kamohara1933), andParatriacanthodes retrospinis Fowler1934 with detailed descriptions and color photographs of fresh specimens collected from the Kyushu-Palau Ridge. Matsuura (1984) provided brief accounts and color photographs of tetraodontiform fishes found in the Japanese Archipelago, includingAtrophacanthus japonicus Kamohara1941,Halimochirurgus alcocki,Macrorhamphosodes uradoi,Triacanthodes anomalus (Temminck and Schlegel1850), andTriacanthodes ethiops Alcock1894. In the following year, Matsuura (1985) provided detailed accounts and a color photograph ofTriacanthodes anomalus collected from the Okinawa Trough. Matsuura (1987) and Stewart and Clark (1988) recordedMacrorhamphosodes uradoi from New Zealand, a species previously known only from Japan (Kamohara1933; Tyler1968; Matsuura1984), Kenya (Tyler1983) and South Africa (Hulley1972). Matsuura and Tyler (1997) reportedBathyphylax bombifrons Myers1934,Halimochirurgus alcocki,Macrorhamphosodes uradoi,Paratriacanthodes retrospinis,Triacanthodes ethiops, andTriacanthodes intermedius based on many specimens collected from New Caledonia. Except forTriacanthodes intermedius, these are the first records for the species from New Caledonia. Chen et al. (1997) recordedTriacanthodes anomalus from the South China Sea. Matsuura (2000) compiled a checklist of Tetraodontiformes from the South China Sea including eight species of spikefishes:A. japonicus,B. bombifrons,Halimochirurgus alcocki,Macrorhamphosodes platycheilus Fowler1934,Paratriacanthodes retrospinis,Triacanthodes anomalus,Triacanthodes ethiops, andTydemania navigatoris Weber1913.

Myers and Donaldson (2003) published a checklist of fishes from the Mariana Islands including a record ofHalimochirurgus alcocki. Kim et al. (2005) provided brief accounts and color photographs ofTriacanthodes anomalus andMacrorhamphosodes uradoi from Korea. Hoese et al. (2006) recorded eight species of spikefishes for the first time from Australia:B. bombifrons (New South Wales and Queensland),Halimochirurgus alcocki (New South Wales, Queensland and Western Australia),Halimochirurgus centriscoides (Western Australia),Macrorhamphosodes platycheilus (Northern Territory and Western Australia),Macrorhamphosodes uradoi (New South Wales and Queensland),Paratriacanthodes retrospinis (New South Wales and Western Australia),Triacanthodes ethiops (Northern Territory, Queensland, Western Australia), andTydemania navigatoris (Western Australia). Shao et al. (2008) recorded seven species of spikefishes from off southern Taiwan in the South China Sea:B. bombifrons,Halimochirurgus alcocki,Halimochirurgus centriscoides,Macrorhamphosodes uradoi (first record from the South China Sea),Paratriacanthodes retrospinis,Triacanthodes anomalus, andTydemania navigatoris. All species records of Shao et al. (2008) were based on specimens deposited at museums and institutions in Taiwan and the USA. Larson et al. (2013) published an annotated checklist of the fishes of the Northern Territory, Australia, in which they recordedHalimochirurgus centriscoides,Macrorhamphosodes platycheilus,Triacanthodes ethiops, andTydemania navigatoris.

Tyler (1983) reported four spikefishes from off Kenya in the western Indian Ocean:B. bombifrons,Bathyphylax omen Tyler1966c,Macrorhamphosodes uradoi, andMacrorhamphosodes platycheilus. When Tyler (1968) comparedB. bombifrons andB. omen, the main differences were thatB. bombifrons has a narrower pelvis, a shorter postorbital length, a less distinctly supraterminal mouth, and a more concave snout profile. Because the holotype ofB. omen (37.5 mm in standard length, SL) from the western Indian Ocean is much smaller than that ofB. bombifrons (77.6 mm SL) from off Hong Kong in the South China Sea, some of these differences were considered to be due in part to the size differences of the holotypes (Tyler1968). Based on four additional, newly collected specimens ofB. bombifrons (80.9−84.0 mm SL) and two specimens ofB. omen (67.0−93.5 mm SL), Tyler (1983) concluded that the most reliable character separating the two species is the degree of concavity of the snout. The depth of the snout in the middle of its length is 10.8−13.4 % SL (average 12.0) inB. bombifrons and 12.5−15.5 % SL (average 13.9) inB. omen. Matsuura and Tyler (1997) confirmed this difference in three specimens (86.2−93.0 mm SL) ofB. bombifrons collected off New Caledonia.

Tyler (1986) provided keys to the genera and species of spikefishes known from South and East Africa. He recognized 11 species in this region:A. japonicus,B. bombifrons,B. omen,Halimochirurgus alcocki,Halimochirurgus centriscoides,Macrorhamphosodes platycheilus,Macrorhamphosodes uradoi,Mephisto fraserbrunneri,Paratriacanthodes retrospinis,Triacanthodes ethiops, andTydemania navigatoris. Adam et al. (1998) recordedA. japonicus andTriacanthodes ethiops for the first time from the Maldive Islands in the central Indian Ocean.Atrophacanthus japonicus had previously been recorded only from southern Japan, the Celebes Sea, and off Tanzania (Kamohara1941; Fraser-Brunner1950; Tyler1968; Matsuura1984). AlthoughT. ethiops is relatively common in the West Pacific and New Caledonia (Tyler1968; Matsuura and Tyler1997), it had previously been known only from East Africa in the Indian Ocean (Tyler1968,1986). Manilo and Bogorodsky (2003) studied coastal fishes of the Arabian Sea based on specimens collected by research vessels of Russia and Ukraine from 1967 to 1991. They also examined specimens collected by the GermanRV Meteor, which are deposited at the Zoological Museum of Hamburg University. The two authors recordedHalimochirurgus centriscoides andMephisto fraserbrunneri Tyler1966b (previously known only from the holotype, 52.2 mm SL from the Andaman Sea and a non-type specimen, 66.0 mm SL from off Somalia in the western Indian Ocean), but did not provide descriptions of the two species. The specimens they studied are deposited at the National Museum of Natural History, National Academy of Sciences, Ukraine, the Zoological Museum of the Russian Academy of Sciences, and the Zoological Museum of Moscow State University. In addition to these, Venkataramanujam et al. (1993) erroneously described a new solenostomid species,Solenostomus tuticoriensis based on a specimen ofMacrorhamphosodes platycheilus from southern India (see Orr and Fritzsche1997).

This brief historical review clearly shows that there are many collection lacunae with respect to the distribution and diversity of spikefishes in the world oceans. New Caledonia is one example of how collection efforts could provide us with better understanding of spikefish diversity. When Matsuura and Fourmanoir (1984) describedTriacanthodes intermedius from New Caledonia, only two type specimens were available for their study. Long-term deep-water surveys by ORSTOM around New Caledonia added six species of spikefishes including 16 specimens ofTriacanthodes intermedius to a taxonomic study on tetraodontiform fishes of this region by Matsuura and Tyler (1997). Many regions of the world oceans need to be surveyed, but the most promising areas would be waters in French Polynesia and the Indian Ocean coast of Sumatra and Java in Indonesia. Japanese and Indonesian fisheries agencies have recently implemented a joint survey along the Indian Ocean coast of Sumatra and Java. Their surveys have resulted in many interesting spikefishes, including two undescribed species and several rarely collected species, which will be published elsewhere (Matsuura and Kawai in preparation).

Triplespines of the family Triacanthidae are found on continental shelves in the Indo-West Pacific, usually just below the sea surface to 60 m depth (Tyler1968). They clearly differ from other families of the order Tetraodontiformes in having the following combination of characters: moderately elongate, strongly compressed body; skin moderately thick with numerous scales not easily discernible to the unaided eye, with each scale bearing upright spinules and having a rough, shagreen-like appearance; two separate dorsal fins, six spines (usually only five spines visible, the sixth rudimentary) in the first dorsal fin and 20−26 soft rays in the second dorsal fin; pelvic fin with a large spine and no visible soft rays; mouth small and usually terminal; teeth in jaws with an outer series of about 10 heavy incisors and an internal series of several molars, usually four in the upper jaw and two in the lower jaw; caudal fin deeply forked; caudal peduncle distinctly tapering to a narrow transversely indented region just in front of the caudal-fin base where the peduncle is wider than deep (Matsuura2001).

In his monograph of the superfamily Triacanthoidea, Tyler (1968) recognized seven species (Table 2):Pseudotriacanthus strigilifer (Cantor1849),Triacanthus biaculeatus (Bloch1786),Triacanthus nieuhofii Bleeker1852b,Tripodichthys blochii (Bleeker1852a),Tripodichthys angustifrons (Hollard1854),Tripodichthys oxycephalus (Bleeker1851c), andTrixiphichthys weberi (Chaudhuri1910). He appeared to have resolved all taxonomic problems in the Triacanthidae, except for two unusual specimens ofTriacanthus biaculeatus collected from the Gulf of Thailand. Tyler (1968) reported that four specimens from the Gulf of Thailand near Paknam have differences in eye size and the width of the interorbital space. Two of these specimens (111.5 mm SL and 113.9 mm SL) have exceptionally large eyes (10.4 % SL) and the other two (105.6 mm SL and 107.9 mm SL) have a normal eye size (7.8 and 8.5 % SL). The two large-eye specimens have eyes that are also larger than those of any other specimens of equivalent size. The large-eye specimens have a wider interorbital space (10.2−10.5 % SL vs. 6.3−10.0 % SL in many other specimens). Tyler (1968) stated that they could be an undescribed species, but tentatively considered them as abnormalTiracanthus biaculeatus. Although I have been to the Gulf of Thailand many times and examined local collections in Thailand, I have not seen specimens ofTriacanthus with such large eyes.

Tyler (1968) provided color descriptions ofP. strigilifer,Triacanthus biaculeatus, andTrixiphichthys weberi based on color notes or color photographs of fresh specimens, but neither was available for the other species. Matsuura (2009) included a color photograph of a juvenile specimen (50 mm SL) ofTriacanthus nieuhofii collected from Phuket in the Andaman Sea: body silvery white with light brown tinge on dorsal half of body; first dorsal spine silvery white with a black membrane between the first and third dorsal spines; second dorsal, anal, and pectoral fins with light yellowish rays; caudal fin dark yellow. Matsuura (2013) provided brief accounts and a color photograph ofTripodichthys blochii collected from the northern Gulf of Thailand: body silvery white with several irregular golden brownish markings on head and body; basal half of first dorsal spine silvery white and proximal half black with yellowish orange first dorsal fin membrane; second dorsal, anal, and pectoral fins with light yellowish rays; caudal fin dusky yellow.

Distribution ranges of triplespines were well documented by Tyler (1968). After his monograph appeared, many publications on fish faunas, field guides and checklists have provided additional information on triplespine distributions (e.g., Matsuura1984,2003a,2009,2011,2013; Allen and Swainston1988; Talwar and Jhingran1991; Kottelat et al.1993; Randall1995; Allen1997; Chen et al.1997; Fricke1999; Johnson1999; Matsuura and Peristiwady2000; Hutchins2001b; Hoese et al.2006; Kottelat2013; Larson et al2013). Although most of these publications did not greatly extend the previously reported distributions of triplespines, Fricke (1999) recordedTriacanthus biaculeatus from the Mascarene Islands and Kottelat et al. (1993) reported a 60-mm SL specimen of this species from freshwater in Indonesia.

Triggerfishes of the family Balistidae occur in shallow waters, mainly on coral reefs around the world usually from just below the sea surface to 50 m depth. They differ externally from other families of the order Tetraodontiformes by the following combination of characters: body deep, moderately compressed, encased in very thick, tough skin with large scales easily discernible as individual units; scales above pectoral-fin base in many species enlarged, forming a flexible tympanum; mouth small and terminal, or almost terminal; teeth strong, eight in the outer series of both jaws; gill opening, a moderately short, vertical to oblique slit in front of pectoral-fin base; two dorsal fins, first dorsal fin with three visible spines, the second spine more than 1/2 length of first spine; first spine capable of being locked in an erect position by second spine; second dorsal and anal fin similar in shape; most dorsal-, anal-, and pectoral-fin rays branched; pelvic fins rudimentary, represented by a series of four pairs of enlarged scales encasing posterior end of pelvis (Matsuura2001).

Triggerfishes of the Balistidae have not yet been comprehensively reviewed, but Matsuura (1979) described the osteology of family and its generic relationships, and Matsuura (1980) diagnosed and illustrated the 20 species of 10 genera found in Japanese waters. His latter paper covered many of the 25 species that were known from the Indo-Pacific before 1980. Prior to this publication two papers reviewed triggerfishes in the eastern Pacific (Berry and Baldwin1966) and those of the western Atlantic (Moore1967a). In addition, Randall and Klausewitz (1973) reviewedMelichthys Swainson1839, with a description ofMelichthys indicus, and Randall et al. (1978) revisedXanthichthys Kaupin Richardson1856 with a description ofXanthichthys caeruleolineatus. These were important contributions about the taxonomy of triggerfishes up to and including 1980. A brief historical review of triggerfish taxonomy follows.

Fraser-Brunner (1935a) published a review of the Balistidae, one of his series of taxonomic studies of tetraodontiform fishes. He recognized 13 genera in the Balistidae and provided a platform for triggerfish taxonomy. Although de Beaufort and Briggs (1962) lumped Fraser-Brunner’s 11 genera into the single genusBalistes Linnaeus1758, they relegated all 11 genera to subgenera. Berry and Baldwin (1966) reviewed triggerfishes of the eastern Pacific with comments on Fraser-Brunner’s classification. They pointed out that Fraser-Brunner (1935a) recognizedNematobalistes Fraser-Brunner1935a andVerrunculus Jordan1924 on trivial differences of squamation and the anterior few soft rays of the dorsal fin. Berry and Baldwin (1966) examined many individuals of the eastern Pacific triggerfishes, which diminished differences amongBalistes,Nematobalistes, andVerrunculus. It led Berry and Baldwin (1966) to conclude that the latter two are junior synonyms ofBalistes. They partially accepted Fraser-Brunner’s system by recognizing six genera:Balistes,Canthidermis Swainson1839,Melichthys,Pseudobalistes Bleeker1865–1869,Sufflamen Jordan1916, andXanthichthys, but they left the other five genera,Abalistes Jordan and Seale1906,Balistapus Tilesius1820,Balistoides Fraser-Brunner1935a,Odonus Gistel1848, andRhinecanthus Swainson1839 to the deliberations of subsequent authors. Just after Berry and Baldwin’s (1966) paper appeared, Moore (1967a) published a review of the triggerfishes of the western Atlantic and recognized four genera,Balistes,Canthidermis,Melichthys, andXanthichthys (i.e., triggerfishes of other genera not occurring in the western Atlantic). Just after his review of the western Atlantic triggerfishes, Moore (1967b) clarified the taxonomic status ofBalistes punctatus Gmelin1789, stating that it occurs only in the eastern Atlantic.

Matsuura (1980) provided keys to genera and species, and taxonomic accounts of 20 Japanese species that he classified in 10 genera,Abalistes,Balistapus,Balistoides,Canthidermis,Melichthys,Odonus,Pseudobalistes,Rhinecanthus,Sufflamen, andXanthichthys. He also addressed a taxonomic problem in the genusHemibalistes.Hemibalistes as proposed by Fraser-Brunner (1935a) was not an available name because two species,Sufflamen bursa (Bloch and Schneider1801) andSufflamen chrysopterum (Bloch and Schneider1801), were included and neither was designated type species. Smith (1949b) subsequently designatedBalistes bursa Bloch and Schneider1801 as the type species of the genusHemibalistes. However, the diagnostic character ofHemibalistes, all scales on cheek smaller than those on body, is not adequate to differentiate it from other triggerfish genera because squamation on the cheek ofSufflamen andHemibalistes is variable (Matsuura1980). As stated above, the papers of Berry and Baldwin (1966), Moore (1967a), Randall and Klausewitz (1973), Randall et al. (1978), and Matsuura (1980) contributed to the proper recognition of 11 genera,Abalistes,Balistapus,Balistes, Balistoides,Canthidermis,Melichthys,Odonus,Pseudobalistes,Rhinecanthus,Sufflamen, andXanthichthys. Tyler (1980) also accepted these 11 genera in his phylogenetic study on tetraodontiform fishes. The osteologically based phylogenies of balistoids given by Matsuura (1979) and Tyler (1980) were largely in agreement, as were the majority of their morphological description; the few conflicts between their respective accounts were clarified by Tyler and Matsuura (1981) as an aid to subsequent workers.

Matsuura (1981) describedXenobalistes tumidipectoris as a new genus and species based on a small juvenile collected from stomach contents of a marlinfish,Makaira mazara (Jordan and Snyder1901), captured in the Mariana Islands. Although the holotype ofXenobalistes tumidipectoris was partially damaged by digestion, it differs clearly from other triggerfishes by its possession of a number of unique characters, such as there is a large lateral expansion protruding laterally just below the pectoral fin, the supraorbital ridge is well developed and convex dorsolaterally, and the mid-lateral portion of the coracoid is greatly expanded to form a disk-like bone. Two years later, Heemstra and Smith (1983) describedXenobalistes punctatus as a new species, based on a small juvenile washed up on a beach at the mouth of the Van Stadens River, South Africa.

Randall and Steene (1983) describedRhinecanthus lunula and provided brief comments about the other five species,Rhinecanthus aculeatus (Linnaeus1758),Rhinecanthus assasi (Forsskål1775),Rhinecanthus cinereus (Bonnaterre1788),Rhinecanthus rectangulus (Bloch and Schneider1801), andRhinecanthus verrucosus (Linnaeus1758). Matsuura and Shiobara (1989) describedRhinecanthus abyssus on the basis of two specimens collected off the northeast coast of Kume-jima in the Ryukyu Islands, at depths of 120−150 m, which is quite deep for triggerfishes. Matsuura and Yoshino (2004) studied the monotypic genusAbalistes and recognized two species,Abalistes stellatus (Anonymous1798) and a new species,Abalistes filamentosus.

Taxonomic studies of triggerfishes continued during the period from Berry and Baldwin (1966) to Matsuura and Yoshino (2004), resulting in the classification shown in Table 3, which recognizes 37 species of triggerfishes in 11 genera. In addition to the above contributions, many checklists and illustrated books on shallow-water fishes also provided taxonomic and zoogeographical information of the Balistidae and other tetraodontiforms (Böhlke and Chaplin1968; Jones and Kumaran1980; Kyushin et al.1982; Gloerfelt-Tarp and Kailola1984; Matsuura1984,2000,2001,2002,2003a,2009,2011,2013; Sainsbury et al.1984; Smith and Heemstra1986; Tortonese1986; Allen and Swainston1988; Winterbottom et al.1989; Kuiter1993; Allen and Robertson1994; Randall1995,1996,2005,2010; Kyushin et al.1977; Randall et al.1997,2004; Fricke1999; Myers1999; Manilo and Bogorodsky2003; Munday2005; Shao et al.2008; Fricke et al.2009; Allen and Erdman2012). Still, taxonomic challenges remain.Sufflamen verres (Gilbert and Starks1904) in the eastern Pacific is said to be different from the Indo-West Pacific species,Sufflamen fraenatum (Latreille1804), in having higher counts of fin rays of the second dorsal and anal fins (Berry and Baldwin1966). According to their study,S. verres has 30−33 dorsal rays and 27−30 anal rays, whileS. fraenatum has 28−30 dorsal rays and 24−26 anal rays. However, Berry and Baldwin (1966) also noted that a specimen ofS. fraenatum from South Africa with 31 dorsal rays and 27 anal rays, overlapping the counts ofS. verres. Matsuura (1980) showed on the basis of 22 specimens ofS. fraenatum from Japan that dorsal rays range from 27 to 30 and anal rays from 24 to 27. Randall (2010) stated that the Hawaiian population ofS. fraenatum has 27−31 dorsal rays and 24−28 anal rays. These data strongly suggest thatS. verres is a junior synonym ofS. fraenatum. Molecular comparisons ofS. verres andS. fraenatum may help clarify their relationships. Fricke (1999) stated thatXanthichthys lineopunctatus (Hollard1854) is a synonym ofXanthichthys lima (Bennett1832). However, the original description ofBalistes lima by Bennett (1832) comprised only 50 words with fin ray counts “D. 1?, A. 26, P. 13.” Because the poor original description fits several species of the Balistidae, it is impossible to verify thatBalistes lima is conspecific withXanthichthys lineopunctatus. As no type specimens are known forBalistes lima, I conclude thatBalistes lima should be treated as a nomen dubium.

Santini et al. (2013a) showedXenobalistes tumidipectoris to be deeply nested among five species ofXanthichthys in a phylogenetic tree of the Balistidae based on molecular analysis. Their molecular analysis suggests thatXenobalistes is a junior synonym ofXanthichthys. I am currently comparing larger specimens ofXenobalistes tumidipectoris andXenobalistes punctatus with those ofXanthichthys to clarify the relationships of the two species ofXenobalistes with the five species ofXanthichthys. This study will be published elsewhere to resolve the taxonomic status ofXenobalistes. Santini et al. (2013a) also mentioned thatBalistoides andPseudobalistes are not monophyletic:Balistoides conspicillum (Bloch and Schneider1801) is sister toMelichthys, andPseudobalistes flavimarginatus (Rüppell1829) forms a clade withBalistoides viridescens (Bloch and Schneider1801), whereasPseudobalistes fuscus (Bloch and Schneider1801) andPseudobalistes naufragium (Jordan and Starksin Jordan1895) represent a single clade. These species should be revisited with detailed morphological examinations.

Filefishes of the family Monacanthidae occur on coral and rocky reefs and in sea grass beds, shallower than 200 m, but some species are found at depths reaching almost 300 m (Matsuura and Tyler1997; Hutchins2001b). They differ externally from other families of the order Tetraodontiformes by the following combination of characters: body usually deep, strongly compressed, body shape varying from oblong to almost circular; skin smooth to rough, shagreen-like, with minute to small scales armed with one to many fine spinules, spinules enlarged in some species forming bristles or spines on the posterior portion of the body; scales on head of some species with strong flattened spinules; mouth small, generally terminal, non-protractile; teeth pointed and not fused together, central pair usually the largest in each jaw; gill opening, a short vertical to oblique slit in front of, or above, pectoral-fin base; two dorsal fins, first dorsal fin consisting of a prominent spine, which can be locked upright by a second very small spine, second dorsal fin with 22 to 52 simple (unbranched) soft rays; anal fin with 20 to 62 simple soft rays; pelvic fin and spines rudimentary or absent, represented by a series of three or fewer pairs of enlarged scales encasing the pelvic terminus, or segments of indeterminate number, or entirely absent; pelvis usually capable of vertical movement giving rise to a ventral flap (Hutchins2001b; Matsuura2003b).

There are no comprehensive reviews of the Monacanthidae, although in 1988 Barry Hutchins provided taxonomic, morphological, and phylogenetic data for all monacanthid species in the world in his doctoral dissertation. Some parts of his dissertation were published, however, the taxonomic accounts of many species and genera and the phylogenetic analysis of the genera remain unpublished. Hutchins published a series of articles on the Monacanthidae between 1977 and 2002. His first article on Australian filefishes recognized 28 genera in Australia (Hutchins1977) where the greatest diversity of filefishes is found (Hutchins2001a).

Before Hutchins’ (1977) review of Australian filefishes appeared, Fraser-Brunner (1941a) published a review paper on the Monacanthidae (his Aluteridae), recognizing 22 genera. Although de Beaufort and Briggs (1962) lumpedAmanses Gray1835,Chaetodermis Swainson1839,Paramonacanthus Bleeker1865–1869,Pervagor Whitley1930a, andPseudomonacanthus Bleeker1865 into a single genus,Monacanthus Linnaeus1758, they recognizedAluterus Cloquet1816,Anacanthus Gray1830 (theirPsilocephalus Swainson1839),Paraluteres Bleeker1865, andPseudalutarius Bleeker1865 as distinctive genera. Berry and Vogele (1961) reviewed nine species of the Monacanthidae of the western North Atlantic with detailed accounts ofAmanses pullus (Ranzani1842),Aluterus monoceros (Linnaeus1758),Aluterus heudelotii Hollard1855,Aluterus schoepfi (Walbaum1792),Aluterus scriptus (Osbeck1765),Monacanthus ciliatus (Mitchill1818),Monacanthus tuckeri Bean1906,Stephanolepis hispidus (Linnaeus1758), andStephanolepis setifer (Bennett1831). Although Berry and Vogele (1961) placedMonacanthus pullus in the genusAmanses, they also pointed out thatM.pullus should be classified in the subgenusCantherhines Swainson1839 becauseM.pullus does not have a patch of long spines on the mid-side of the body between the dorsal and anal fins, which is a diagnostic character ofAmanses. When Randall (1964) reviewed the filefish generaAmanses (monotypic) andCantherhines, he recognized 11 species ofCantherhines in the tropical seas of the world. He showed thatAmanses possesses a patch of long stout spines (male) or a dense brushlike mass of long setae (female) on the mid-side of the body, whereas all species ofCantherhines lack long spines or long setae on the mid-side of the body. Randall (1964) describedCantherhines tiki as a new species based on a single specimen collected from Easter Island.Cantherhinestiki was said to be distinguishable from other species ofCantherhines by its strongly produced snout (Randall1964). However, Caldwell and Randall (1967) showedCantherhines tiki to be a junior synonym ofCantherhines rapanui (de Buen1963) because of the considerable variation in the snout shape ofCantherhines rapanui.

Hutchins (1977) described three new genera,Bigener,Cantheschenia andColurodontis, and eight new species from Australia. However, Hutchins (1994a) subsequently placedAleuterius brownii Richardson1848, the type species ofBigener, inAcanthaluteres Bleeker1865, makingBigener a junior synonym ofAcanthaluteres. Hutchins and Randall (1982) reviewed theCantherhines fronticinctus complex and describedCantherhines longicaudus as a new species from Tahiti and Rarotonga. Matsuura (1984) provided brief accounts and color photographs of 26 monacanthids found in Japanese waters. Hutchins and Matsuura (1984) describedThamnaconus fijiensis from Fiji. In the following year, Hutchins (1985) reviewed the genusBrachaluteres Bleeker1865 and recognized four species with comments on their ability to inflate the abdomen. Hutchins (1986a) published a revision of the genusPervagor and recognized eight species including two new species,Pervagor randalli andPervagormarginalis. Hutchins (1986b) provided a key and brief taxonomic accounts for 16 species of filefishes found along South Africa. Hutchins (1987) publishedEubalichthys cyanoura as a new species from South Australia. Hutchins (1994b) described and illustratedLalmohania velutina from India as a new genus and species. Hutchins (2002) reported another new genus and species,Enigmacanthus filamentosus, from the Seychelles and Marshall Islands.Enigmacanthus filamentosus is a very small filefish, 27−36 mm SL, resembling in size species of the genusRudarius. Randall (2011) again reviewed the genusCantherhines, recognizing 11 species, including two new species,Cantherhines cerinus from the Philippines andCantherhines nukuhiva from the Marquesas Islands.

Based on the contributions shown above, I recognize 102 species in 27 genera worldwide (Table 4). I provisionally placePseudomonacanthus multilineatus Tanaka1918 in the genusCantherhines following previous authors (Matsuura1984; Kyushin et al.1977; Lindberg et al.1997). Although Randall (1964) placedPseudomonacanthus multilineatus inCantherhines, Hutchins and Randall (1982) said thatCantherhines multilineatus should be classified in the genusThamnaconus Smith1949b. However, they did not provide characters to justify the transfer fromCantherhines toThamnaconus. To resolve the taxonomic status ofCantherhines multilineatus, a detailed study of diagnostic characters, including encasing scales of the posterior end of the pelvis, is needed. Hutchins suggested in his dissertation thatThamnaconus melanoproctes (Boulenger1889) is a senior synonym ofPseudomonacanthus multilineatus. However, an examination of specimens from various localities in the Indo-West Pacific is necessary to properly access the relationships of the two nominal species. Although Barry Hutchins made great contributions to the better understanding of taxonomy and diversity of filefishes, in particular Australian filefishes, taxonomic problems in several genera such asAcreichthys Fraser-Brunner1941c,Pseudomonacanthus, andThamnaconus remain. As in the case of triggerfishes, many checklists and illustrated guidebooks have provided much useful information on the taxonomy, distribution, and biology of filefishes (see the section on the Balistidae).

Trunkfishes of the family Aracanidae occur in shallow to relatively deep waters in depths from 5 m to 300 m. The species ofAracana Gray1833,Anoplocapros Kaup1855,Caprichthys McCulloch and Waite1915,Capropygia Kaup1855 andPolyplacapros Fuji and Uyeno 1979 are found in temperate seas of southern Australia, whereas species ofKentrocapros Kaup1855 are known from deep waters in the warm, tropical regions of the Indo-Pacific (Matsuura and Yamakawa1982; Matsuura and Tyler1997; Matsuura2006,2008).

Trunkfishes differ externally from other families of Tetraodontiformes by the following combination of characters: body almost completely encased in a bony shell or carapace formed of enlarged, thickened scale plates, usually hexagonal in shape and firmly sutured to one another; isolated bony plates on caudal peduncle; carapace triangular or hexagonal in cross section, with openings for mouth, eyes, gill slit, pectoral, dorsal, and anal fins, and for the flexible caudal peduncle; scale plates often with surface granulations and prolonged in some species into prominent carapace spines over the eyes or along ventrolateral or dorsolateral angles of the body; mouth small, terminal, with fleshy lips; teeth of moderate size, conical, usually fewer than 15 in each jaw; gill opening moderately short, a vertical to oblique slit in front of pectoral-fin base; spinous dorsal fin absent; most dorsal-, anal-, and pectoral-fin rays branched; caudal fin with nine branched rays; pelvic fins absent (Matsuura2001).

The Aracanidae and Ostraciidae have been placed in separate families by some authors (e.g., Winterbottom1974; Tyler1980; Matsuura1984,2001), but they have also been treated as two subfamilies of the family Ostraciidae by others (e.g., Winterbottom and Tyler1983; Klassen1995; Allen et al.2006; Nelson2006; Matsuura2008). All the above authors recognized the two groups as closely related phylogenetic clades (sister groups), but placed them at different taxonomic ranks. Santini and Tyler (2003) studied fossils and extant members of the Tetraodontiformes extensively and recognized familial groupings for the Aracanidae and Ostraciidae. Recently, Santini et al. (2013a) investigated the phylogenetic relationships of the Aracanidae and Ostraciidae based on molecular analysis of many taxa (nine species of five genera of Aracanidae and 17 species of six genera of Ostraciidae). They demonstrated that the species examined in their studies (Santini and Tyler2003; Santini et al.2013a) have adequate characteristics to recognize two separate groups at the family level.

A problem exists with the spelling of the genusAracana. When Gray (1833) published his article on Indian zoology, he used two different spellings for a species of trunkfish. At the beginning of the article, a section titled “Directions for arranging the plates” provided the name of animals in the plates where he presented the name of the trunkfish as “Many Spined Coffin Fish.Ostracion (Acerana)auritus”; however, the legend of plate 98 spelled the name as “Ostracion (Acarana)auritus.” Plate 98 provided a good illustration of the species showing appropriate characters to identify the species. It is the type species of the subgenus by monotypy. However, in 1838 John E. Gray published another paper in which he described three species,Ostracion (Aracana)ornata,Ostracion (Aracana)flavigaster, andOstracion (Aracana)lineata. The second species is a junior synonym ofAracana ornata and the thirdAracana aurita (Shawin Shaw and Nodder1798). Gray (1838) stated for his three species that “I have formed a subgenus under the name ofAracana” indicating his intention to establish the group at the subgeneric level. Although the nameAracana has long been used for the trunkfish genus, the two namesAcerana andAcarana were published earlier thanAracana, thus creating a nomenclatural problem. If one follows the priority rule of the Code (ICZN1999), the family name should be Aceranidae or Acaranidae. AsAracana has been used almost universally in the literature, withAcerana orAcarana virtually ignored by taxonomists,Aracana should be preserved under Article 33.3.1 of the Code, making the spelling of the family group name Aracanidae preserved under Article 35.4.1.

Trunkfishes have not yet been comprehensively reviewed. Although Fraser-Brunner (1935b,1941d) provided brief reviews of the family, his accounts of genera and species were cursory as they were based on few specimens and did not provide adequate characteristics for the species treated. Kuiter (1994) and Matsuura (2008) diagnosed and illustrated seven species in four genera of Australian aracanids, covering many representatives of the family except for the generaKentrocapros andPolyplacapros.Polyplacapros tyleri Fujii and Uyeno1979 is unique in having a fusiform body and the caudal peduncle nearly completely covered by discrete bony plates. In addition to Australian genera of Aracanidae, detailed descriptions and illustrations of all four known species ofKentrocapros were provided by Matsuura and Yamakawa (1982), Matsuura and Tyler (1997), and Matsuura (2006). Matsuura (1990) provided brief accounts and a color photograph of a species ofKentrocapros collected from the Tasman Sea (32°43′S, 167°30′E) under the nameKentrocapros eco (Phillipps1932). However, an examination of the holotype (102 mm TL) ofOstracion eco (NMNZ P. 903) revealed Matsuura’s (1990) Tasman Sea material to be an undescribed species (Fig. 2). This undescribed species has a spine on the dorsolateral ridge midway between the eye and the dorsal-fin origin, whereas the holotype ofO. eco lacks this spine. This new species will be described and published elsewhere.

Kentrocapros eco (NMNZ P.903, 102 mm TL, from Pahia, Bay of Islands, New Zealand;a lateral view;b dorsal view) and an undescribed species ofKentrocapros (c NSMT-P 43344, 104 mm SL) collected from New Zealand

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As discussed above, no major taxonomic problems remain in the Aracanidae. However, there still remains a need to clarify the nomenclature of some species ofAnoplocapros as well as the intraspecific variation of morphological characters related to ontogenetic development ofKentrocapros.

Boxfishes of the family Ostraciidae occur in shallow tropical and warm seas of the world. Boxfishes differ externally from other families of Tetraodontiformes by the following combination of characters: body almost completely encased in a bony shell or carapace formed of enlarged, thickened scale plates, usually hexagonal in shape and firmly sutured to one another; no isolated bony plates on caudal peduncle; carapace triangular, rectangular, or pentangular in cross section, with openings for mouth, eyes, gill slits, pectoral, dorsal, and anal fins, and for the flexible caudal peduncle; scale-plates often with surface granulations, which are prolonged in some species into prominent carapace spines over the eye or along the ventrolateral or dorsal angles of the body; mouth small, terminal, with fleshy lips; teeth moderate, conical, usually fewer than 15 in each jaw; gill opening, a moderately short, vertical to oblique slit in front of pectoral-fin base; spinous dorsal fin absent; most dorsal-, anal-, and pectoral-fin rays branched; caudal fin with eight branched rays; pelvic fins absent (Matsuura2001).

Fraser-Brunner (1935b) published a brief review of the Aracanidae and Ostraciidae, recognizing six genera in the Ostraciidae:Acanthostracion Bleeker1865,Lactophrys Swainson1839,Lactoria Jordan and Fowler1902,Ostracion Linnaeus1758,Rhinesomus Swainson1839, andRhynchostracion Fraser-Brunner1935b. Boxfishes found in the Indo-Australian Archipelago were studied by de Beaufort and Briggs (1962) who lumped Fraser-Brunner’s (1935b) Indo-Pacific genera into the genusOstracion. However, they recognized five subgenera inOstracion:Lactoria,Ostracion,Rhynchostracion,Tetrosomus Swainson1839, andTriorus Jordan and Hubbs1925.Triorus is a junior synonym ofTetrosomus because the type species of the former,Lactophrys tritropis Snyder1911, is a junior synonym ofTetrosomusconcatenatus (Bloch1786) (see Randall et al.1997). AlthoughOstracion nasus Bloch1785 andOstracion rhinorhynchos Bleeker1851a have been placed in the genusRhynchostracion by some authors (Kyushin et al.1982; Gloerfelt-Tarp and Kailola1984; Sainsbury et al.1984; Mohsin and Ambak1996; Randall et al.1997; Allen et al.2006), they were classified in the genusOstracion by other authors (Klassen1995; Matsuura2001; Hayashi and Hagiwara2013). When Fraser-Brunner (1935b) establishedRhynchostracion, he differentiated it from other ostraciid genera by the degree of the development of the dorsal ridge, the convexity of the dorsal surface of the carapace, and the projection of the snout anterior to the mouth. However, the two characters involving the carapace do not clearly differentiateRhynchostracion from other ostraciids and the snout ofOstracion nasus, the type species ofRhynchostracion, protrudes anteriorly beyond the mouth in adults but not juveniles. In addition, large adults ofOstracion cubicus Linnaeus1758 have a snout protruding to some extent beyond the mouth. These factors led Matsuura (2001) to placeO. nasus andO. rhinorhynchos in their own genus in his key and brief accounts of ostraciids found in the western central Pacific. Klassen (1995) studied osteological characters of many species of the Ostraciidae extensively and provided evidence thatRhynchostracion is a junior synonym ofOstracion. Klassen (1995) also regardedTetrosomus as a junior synonym ofLactoria because all species ofLactoria andTetrosomus examined by him formed a single clade. If Klassen’s (1995) proposal is accepted,Lactoria should be a junior synonym ofTetrosomus because the latter has priority over the former. However, it seems premature to accept his proposal because there are species-level taxonomic problems in several species ofTetrosomus (Allen and Erdman2012).

Tyler (1965) revised the genusAcanthostracion in the Atlantic and recognized four species,Acanthostracion guineensis Bleeker1865,Acanthostracion notacanthus (Bleeker1863),Acanthostracion polygonus Poey1876, andAcanthostracionquadricornis (Linnaeus1758). Böhlke and Chaplin (1968) provided keys and accounts accompanied by illustrations to boxfishes found in the western Atlantic. They recognized five species,A. polygonus,A. quadricornis,Lactophrysbicaudalis (Linnaeus1758),Lactophrys trigonus (Linnaeus1758),Lactophrys triqueter (Linnaeus1758).Lactophrysbicaudalis andL. triqueter were placed in the genusRhinesomus by Matsuura (2003b) and McEachran and Fechhelm (2005). However, Klassen (1995) argued thatL. bicaudalis,L. triqueter, andL. trigonus are nested in a single clade on the basis of his extensive osteological analysis; I agree with this.Acanthostracion quadricornis is common in the western Atlantic, but strays were recorded from waters off South Africa (Tyler1965). Whitley (1965) describedAcanthostracion bucephalus on the basis of a specimen from Queensland, Australia. However, there seems little doubt that it is actuallyA. quadricornis (Fig. 3). The record ofA. quadricornis from Australia may suggest that the specimen was transferred by ballast water from a ship or released from an aquarium. As with the Balistidae, many checklists and illustrated guidebooks have provided a great deal of information on the taxonomy, distribution, and biology of boxfishes (see the section on the Balistidae). On the basis of the above overview, I recognize 22 species in the Ostraciidae (Table 6). However the relationships ofT. concatenatus andT. reipublicae need to be examined in detail based on a comparison of a large selection of specimens including the types from various localities of the Indo-West Pacific to better understand the morphological variations observed inT. reipublicae (Fig. 4).

Holotype ofAcanthostracion bucephalus (AMS IB.6355) collected from Queensland, Australia. Photograph provided by Mark McGrouther

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Two forms ofTetrosomus reipublicae collected from the Ryukyu Islands (a,b) and Kochi, Japan (c).a Deep body with no blue lines (BSKU 29663);b,c slender body with wavy blue lines (b BSKU 29697;c BSKU 59588)

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The family Triodontidae is represented by a single extant species,Triodon macropterus Lesson1831, but several fossil taxa referred to this genus date back to the Eocene (see Tyler and Patterson1991). The family differs externally from others of the order Tetraodontiformes by the following combination of characters: body moderately elongate and moderately compressed, with a very large ventral flap that may be extended downward by a rotation of the long, shaft-like pelvis; jaws modified to form a beak of three heavy, massive teeth, two on the upper jaw and one on the lower jaw; two rudimentary dorsal-fin spines present or absent; and caudal fin deeply forked (Matsuura2001).

Triodon macropterus is rare in museum collections and poorly known. It is a deep-water species collected at depths of 50−377 m (Kyushin et al.1977; Matsuura and Tyler1997). When Tyler (1967) redescribedT. macropterus in detail, only 20 specimens were available for his study: five from the Indian Ocean (Mauritius, Reunion and India) and 15 from the West Pacific (Indonesia, Philippines and Japan). Due to the poor condition of two specimens, Tyler (1967) used 18 specimens to determine whether the first dorsal fin, composed of one or two spines, is present or absent. His examination revealed 12 specimens from the West Pacific to have a first dorsal fin, and five Indian Ocean specimens and a specimen from the West Pacific to lack a first dorsal fin (Table 7). However, he did not find other differences between the Indian Ocean specimens and those from the West Pacific. This led him to recognize the two groups as being conspecific. I have recently had the opportunity of examining 28 specimens ofT. macropterus, nine from the Indian Ocean and 19 from the West Pacific (seeAppendix). My examination revealed that the first dorsal fin to be absent in the nine specimens from the Indian Ocean, and present in the 19 specimens from the West Pacific (Table 7). Tyler (1967) also provided frequency distributions of fin-ray counts. My examination of 28 specimens produced almost the same frequency distributions of fin-ray counts as those of Tyler (1967), except for a count of 17 fin rays on the right side pectoral fin in a single specimen (Table 8).

Since Tyler’s (1967) redescription was published,T. macropterus was reported (with color photographs) from several areas in the Indo-West Pacific: the Chagos Archipelago (Kyushin et al.1977), the South China Sea (Kyushin et al.1982), the Kyushu-Palau Ridge (Okamura et al.1985), the Timor Sea (Gloerfelt-Tarp and Kailola1984), and the Japanese Archipelago (Matsuura1984). Color photographs taken by research staff of the National Museum of Nature and Science showT. macropterus to have the following coloration: body yellowish brown dorsally, becoming white ventrally; ventral flap yellow in the ventral four-fifths and white in the proximal one-fifth; a large black ocellus with a narrow white edge in the proximal part of the ventral flap; second dorsal, anal, pectoral, and caudal fins yellow or yellowish brown; when present, membrane of first dorsal fin black (Fig. 1g). In addition to the above reports,T. macropterus has been recorded in checklists of fishes from several areas in the West Pacific: the Mariana Islands (Myers and Donaldson2003), Tonga (Randall et al.2004), off southern Taiwan (Shao et al.2008), Northern Territory of Australia (Larson et al.2013), and northern half of Australia (Hoese et al.2006). Kim et al. (2005) provided a brief account and a color illustration ofT. macropterus from Korea.

Johnson and Britz (2005b) reported the smallest knownT. macropterus (20 mm SL), collected at Wallis and Futuna at a depth of 245−440 m. They provided detailed characters and the visceral anatomy of the early juvenile that differs from adults in having a huge head (45 % SL vs 28.5−32.7 % SL in adults), no ventral flap, and different scale structure. Juveniles also differ from adults in having a very large distended stomach.

Pufferfishes of the family Tetraodontidae usually occur in shallow warm, tropical seas, and freshwaters of the world, although some species may be found at depths over 350 m (Matsuura1982; Tyler and Matsuura1997). They differ externally from other families of the order Tetraodontiformes by the following combination of characters: head large and blunt; jaws modified to form a beak of four heavy, powerful teeth, two above and two below; eyes high on head; gill opening, a simple slit in front of pectoral fins; dorsal and anal fins located far posteriorly, containing seven to 15 soft rays; caudal fin truncate, rounded, or emarginate to somewhat lunate; pelvic fins absent; lateral line (when present) often indistinct, forming an interconnected pattern on sides of the head and body, but quite distinct in some genera (e.g.,Lagocephalus andTorquigener Whitley1930c); typical scales absent, but many spinules often present on back and/or belly, and sometimes on sides (Matsuura2001).

The Tetraodontidae is the most speciose family in the Tetraodontiformes, including 184 species (Table 9). Because pufferfishes possess very few external characters useful for taxonomy and specimens are easily distorted when they are fixed in formalin and preserved in ethanol, it is often not easy for ichthyologists to recognize species limits and classify them into natural groups. Consequently, they have been poorly studied and taxonomic confusion remains. Although the Tetraodontidae has never been comprehensively reviewed, the taxonomy of pufferfishes has progressed since Fraser-Brunner’s (1943) brief review of tetraodontid genera. He classified pufferfishes into 11 genera,Canthigaster Swainson1839,Lagocephalus,Sphoeroides Anonymous1798,Amblyrhynchote Bibron in Duméril1855,Torquigener,Colomesus Gill1884,Ephippion Bibronin Duméril1855,Tetraodon Linnaeus1758,Arothron Müller1841,Chonerhinos Bleeker1854,Xenoptere Bibronin Duméril1855, based on osteological characters of the skull, the lateral-line system on the head and body, a skin fold on the ventrolateral side of the body, and spinule distributions on the body. Although Fraser-Brunner (1943) used the spellingsAmblyrhynchotes andXenopterus, I follow Kottelat’s (2001,2013)Amblyrhynchote andXenoptere because Kottelat (2001) showed thatAmblyrhynchotes andXenopterus of Troschel (1856) are incorrect spellings.

When Alec Fraser-Brunner studied pufferfishes during World War II, Abe (1939,1942,1944,1949a,b,c,1950,1952,1954) independently studied pufferfishes found in Japan and adjacent regions. Abe (1949c) provided keys and accounts of pufferfishes in the seas around Japan. Subsequently, Abe (1952) proposedFugu as a new genus to include five subgeneraAkamefugu,Higanfugu,Shosaifugu,Takifugu, andTorafugu, which had been previously proposed and made available by Abe (1949c,1950). However, the genusFugu is an objective synonym of the subgenusTorafugu Abe1950, because the type species of these genus group names isTetraodon rubripes Temminck and Schlegel1850. Matsuura (1990) clarified the nomenclatural problems concerning the genus group names proposed by Abe (1949c,1950,1952) and showed thatTakifugu Abe1949c is the appropriate generic name for warmwater pufferfishes found mainly around Japan, Korea, and China. As with other tetraodontiform families, de Beaufort and Briggs (1962) lumped Fraser-Brunner’s (1943) Indo-Pacific genera,Amblyrhynchote,Lagocephalus, andTorquigener into the genusSphoeroides although they recognizedCanthigaster,Chelonodon Müller1841,Chonerhinos, andTetraodon. As shown by subsequent authors,Amblyrhynchote,Lagocephalus, andTorquigener are distinctive genera.

Marine pufferfishes occurring in warm and tropical regions of the world were studied by many authors from the 1970s to present. Allen and Randall (1977) reviewedCanthigaster and described seven new species, bringing the total number of species to 22. Since Allen and Randall’s (1977) revisionary study was published, six Indo-Pacific species have been described as new as follows:Canthigaster leoparda Lubbock and Allen1979 from the Indo-West Pacific,Canthigaster flavoreticulata Matsuura1986 from the Tonga Submarine Ridge, South Pacific,Canthigastercyanetron Randall and Cea-Egaña1989 from Easter Island,Canthigaster punctata Matsuura1992 from the Mascarene Submarine Ridge in the western Indian Ocean,Canthigastercyanospilota Randall, Williams and Rocha2008 from the Red Sea, andCanthigaster criobe Williams, Delrieu-Trottin, Planes2012 from the Gambier Archipelago in French Polynesia. In addition, Randall et al. (2008) reviewedCanthigaster coronata (Vaillant and Sauvage1875) and recognizedCanthigaster axiologa Whitley1931 as a separate species. Although Allen and Randall (1977) synonymizedCanthigaster papua (Bleeker1848) withCanthigaster solandri (Richardson1845), Randall (1995) and Allen and Erdman (2012) recognized it as a distinctive species. Moura and Castro (2002) reviewedCanthigaster in the Atlantic where many authors recognized only a single speciesCanthigaster rostrata (Bloch1786). Moura and Castro (2002) extensively studied specimens collected from various localities from both sides of the Atlantic and recognized six species, three of which they described as new:Canthigaster figueiredoi from the east coast of South America,Canthigaster jamestyleri from the southeast coast of the United States and the Gulf of Mexico, andCanthigaster supramacula from the west coast of Africa. The above studies bring the total number of species ofCanthigaster to 36, making it the largest genus in the Tetraodontidae.

Shipp (1974) reviewed pufferfishes of the Atlantic belonging toCanthigaster,Colomesus Gill1884,Ephippion Bibron in Duméril1855,Lagocephalus, andSphoeroide. Prior to Shipp’s (1974) publication, Tyler (1964) reviewed two species ofColomesus,Colomesus asellus (Müller and Troschel1848), andColomesus psittacus (Bloch and Schnedier 1801) in detail. Amaral et al. (2013) describedColomesus tocantinensis from the Tocantins River, Brazil. Shipp (1974) recognized 13 species ofSphoeroides in the Atlantic and provided a key to the species, along with detailed accounts of all Atlantic species. Walker and Bussing (1996) described the eastern PacificSphoeroides lispus Walkerin Walker and Bussing1996 andSphoeroides rosenblatti Bussingin Walker and Bussing1996 as new species. Prior to Shipp (1974) and Walker and Bussing (1996), five species ofSphoeroides had already been reported from the eastern Pacific. With 20 species,Sphoeroides is the third largest genus in the Tetraodontidae. Most species ofSphoeroides occur in shallow waters of the Atlantic and the eastern Pacific, butSphoeroides pachygaster (Müller and Troschelin Schomburgk1848) is found in deep waters exceeding 350 m in all oceans.

Shipp (1974) also provided detailed accounts and photographs ofLagocephalus laevigatus (Linnaeus1766) andLagocephalus lagocephalus (Linnaeus1758). The former is endemic to the Atlantic and the latter is distributed in tropical and other warm seas of the world. Abe and Tabeta (1983) describedLagocephalus gloveri as a new species from Japan. Abe et al. (1984) described another new species,Lagocephalus wheeleri, from Japan, but Matsuura (2010) showed it to be a junior synonym ofLagocephalus spadiceus (Richardson1845). Matsuura et al. (2011) redescribedLagocephalus guentheri (Miranda Ribeiro1915) based on an examination of the holotype and many specimens from the Red Sea. Although the genusLagocephalus has not been comprehensively reviewed, an ongoing study by the author has revealed 11 valid species in the genus. This study will be published elsewhere.

Although Abe (1949a,b,c,1950,1952,1954) made progress on the taxonomy ofTakifugu, many species found along the coast of China were not included in his articles. Cheng et al. (1975) reviewed pufferfishes found in Chinese waters and describedTakifugu flavidus (Li, Wang and Wangin Cheng et al.1975) andTakifugu reticularis (Tian, Cheng and Wangin Cheng et al.1975). Subsequently, Chinese authors described four species ofTakifugu from China:Takifugu orbimaculatus Kuang, Li and Liang1984 from a creek in Lianhuashan, Guangdong;Takifugu coronoides Ni and Li1992 from an estuary of Chang Jiang;Takifuguplagiocellatus Liin Su and Li2002 from the coast of Hainan Island; andTakifugu variomaculatus Liin Su and Li2002 from brackish waters of Modaomen Zhuhai, Guangdong. These Chinese and Japanese authors increased the number ofTakifugu species making it the second largest genus in the Tetraodontidae, with 25 species. However, taxonomic problems still remain inTakifugu, such asTakifugu basilevskianus (Basilewsky1855) andTakifugu pseudommus (Chu1935), which show significant variation in morphological features including ontogenetic color changes.

Benl (1957) describedCarinotetraodon chlupatyi as a new genus and species from Thailand. However, Dekkers (1975) synonymizedCarinotetraodon chlupatyi withCarinotetraodon lorteti (Tirant1885), making that species the type of the genus.Carinotetraodon is similar toCanthigaster in having a laterally compressed body and several derived osteological features, as well as a shared derived behavioral peculiarity in their skin ridge-lifting along the midline of the body (Tyler1978,1980). Additional new species ofCarinotetraodon were described:Carinotetraodon salivator Lim and Kottelat1995 from Sarawak,Carinotetraodon irrubesco Tan1999 from Sumatra, andCarinotetraodon imitator Britz and Kottelat1999 from India.

Tyler and Paxton (1979) describedPelagocephalus coheni as a new genus and species based on a single specimen collected at Norfolk Island.Pelagocephalus is externally distinguished from other pufferfishes by its nasal apparatus in the form of an open, flat, and relatively unornamented disk. Heemstra and Smith (1981) described a second species ofPelagocephalus,Pelagocephalus marki from South Africa. Hardy (1982b) recordedP.marki from New Zealand.

In the period from 1980 to 1989, Graham S. Hardy published a series of papers on the taxonomy of pufferfishes that are distributed mainly in the Southern Hemisphere. Hardy (1980) reviewed the antitropical speciesArothron firmamentum (Temminck and Schlegel1850) indicating that it should be classified inArothron, whereas it had previously been classified inBoesemanichthys by Abe (1952). The monotypic genusContusus Whitley1947 was reviewed by Hardy (1981), who described a second speciesContusus brevicaudus restricted to southern Australia. Hardy and Hutchins (1981) recognized the validity ofOmegophora Whitley1934 with the description ofOmegophora cyanopunctata from the southwestern part of Australia. Hardy (1982a) erected two new genera,Marilyna andReicheltia, based on detailed morphological comparisons including skull osteology. Hardy (1983a) reviewed the Australian species ofTorquigener and established two new generic names,Polyspina with one species andTetractenos with two species. He recognized 12 species ofTorquigener, including five new species from Australia. Hardy and Randall (1983) describedTorquigener flavomaculosus as a new species from the Red Sea. Hardy describedTorquigener randalli Hardy1983b from the Hawaiian Islands andTorquigener gloerfelti Hardy1984b from Indonesia. Hardy (1989) describedTorquigener balteus as a new species from South Africa and provided a key to 19 species ofTorquigener, although he overlookedSphoeroides marleyi Fowler1929, which is a member ofTorquigener. My examination of the holotypes ofTorquigener balteus andS. marleyi from South Africa revealed them to be conspecific, making the former a junior synonym of the latter. Matsuura (2014) recently describedTorquigener albomaculosus as a new species from Amami-oshima Island, Ryukyu Islands.Torquigener albomaculosus is unique in building large spawning nests, called “mystery circles” by local SCUBA divers. Thus, the above studies ofTorquigener bring the total number of species ofTorquigener to 20, the co-equal third largest genus in the Tetraodontidae along withSphoeroides. Hardy (1984a) recognizedSphoeroides spinosissimus Regan1908 as being distinctive from other genera of the Tetraodontidae and established a new genusTylerius for it. Hardy (1985) describedJavichthys kailolae as a new genus and species from Indonesia. Su et al. (1986) established a new genus,Feroxodon, forAnchisomus multistriatus Richardson1854 from Australia.

The taxonomy of freshwater pufferfishes in Asia was in a confused state until Dekkers (1975) reviewed the genusTetraodon. Subsequently, Sontirat and Soonthornsatit (1985) describedTetraodon suvattii as a new species from Thailand, and Roberts (1988) describedTetraodon abei as a new species from Laos. Roberts (1982) reviewed the genusChonerhinos Bleeker1854 and described three species from Borneo,Chonerhinos amabilis,Chonerhinos nefastus, andChonerhinos silus. Still, complex nomenclatural problems involvingChonerhinos andXenoptere remained until Kottelat (1999) proposed the new genus,Auriglobus, to rectify these problems. Kottelat (2013) discussed nomenclatural issues of the Tetraodontidae found in Southeast Asia in detail. He established the new genusPao (type species,Tetraodon leiurus Bleeker1850a) that includes 13 species previously placed inTetraodon andMonotrete, but differentiated from other pufferfishes by their unique color pattern and a very elongate premaxillary pedicel that creates a greatly enlarged open space between their dorsomedial edges. Thus, the generic nameTetraodon is now applied to only six species of African freshwater pufferfishes. Kottelat (2013) also recognizedLeiodon Swainson1839 as a valid genus that includesTetrodon cutcutia Hamilton1822 distributed in freshwaters of southern Asia. Kottelat (2013) recognizedDichotomyctere Duméril1855 for six species:Dichotomyctere erythrotaenia (Bleeker1853),Dichotomyctere fluviatilis (Hamilton1822),Dichotomyctere kretamensis (Inger1953),Dichotomyctere nigroviridis (Marion de Procé1822),Dichotomyctere ocellatus (Steindachner1870), andDichotomyctere sabahensis (Dekkers1975). Saenjudaeng et al. (2013) describedTetraodon palustris as a new species from the Mekong basin of Thailand. Because of its publication date, July 2013, the authors were unaware of Kottelat’s (2013) article proposing the genusPao. However, it is clear from the original description ofTetraodon palustris, that it is a species ofPao, bringing the total number of species in that genus to 14.

Kottelat (2013) also commented on genera of marine pufferfishes. AlthoughTetrodon patoca Hamilton1822 has long been placed inChelonodon Müller1841, Kottelat (2013) pointed out thatTetrodon cutcutia Hamilton1822, the type species ofChelonodon, had been placed in the same genus asTetraodon fluviatilis Hamilton1822 and related species by Tyler (1980). Tyler (1980) called this groupChelonodon but Kottelat (2013) stated that the oldest available name for a genus includingTetraodon fluviatilis isDichotomyctere.Tetrodon patoca andTetraodon fluviatilis have a sufficient number of character differences to warrant being placed in separate genera. The type species ofChelonodontops Smith1958 isChelonodontops pulchellus Smith1958, a junior synonym ofChelonodon pleurospilus (Regan1919) and congeneric withTetraodon patoca (see Smith1986). Thus,Tetraodon patoca is a species ofChelonodontops (Kottelat2013). Matsuura (2002) reviewed two species ofChelonodon,Chelonodon laticeps Smith1948, andChelonodon patoca, both of which belong inChelonodontops. Kottelat (2013) showed thatGastrophysus Müller1843 is an objective synonym ofTakifugu Abe 1949, as the type species of both genus group names isTetrodon oblongus Bloch1786. However, this is likely to cause confusion not only in pufferfish taxonomy, but also in the fisheries of East Asia where pufferfishes are treated as important and expensive fishes (e.g., several species ofTakifugu cost about US$100 per kilogram at fish markets). In addition, because pufferfishes have fatal poison in their viscera, scientific names are very important for food security management in East Asia. As suggested by Kottelat (2013),Gastrophysus can be suppressed under the International Code of Zoological Nomenclature (ICZN1999). I will ask the International Commission on Zoological Nomenclature to suppressGastrophysus.

Matsuura and Okuno (1991) redescribed a rare pufferfish,Arothron carduus (Cantor1849), on the basis of the holotype from Penang and two additional specimens from the West Pacific. Matsuura (1994) describedArothron caeruleopunctatus as a new species from the tropical region of the Indo-West Pacific. Matsuura (1999) briefly reviewedArothron with a key to species and accounts of all members of the genus including two undescribed species.

As indicated above, there has been a great deal of progress in taxonomy of the Tetraodontidae during the past several decades, especially in the period from the mid-1970s to the present. However, there remain taxonomic problems in genera such asArothron,Chelonodontops,Lagocephalus,Pao,Takifugu, andTorquigener where many species await description and detailed morphological and molecular comparisons to classify them into appropriate groups. The taxonomy of pufferfishes in Southeast Asia is important not only for the understanding of fish diversity of the region, but also for the welfare and food management for humans. Dao et al. (2012) reported that the number of victims of food poisoning by eating pufferfishes reached 737, with 127 mortalities from 1999 to 2003. Due to the lack of knowledge about pufferfishes and their toxicity, pufferfishes are still found in Southeast Asian fish markets (Fig. 5), although local and state governments in countries around the South China Sea have prohibited the sale of pufferfishes for food.

Pufferfishes found in a fish landing place 60 km north of Nha Trang in southern Vietnam (a) and a fish market in Sabah, Malaysia (b):a many small pufferfishes ofLagocephalus and a large specimen ofL. inermis in the center;b large specimens ofArothron hispidus,A. reticularis, andA. stellatus

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Many species of the family Diodontidae are benthic inhabitants around coral or rocky reefs, but some occur frequently in seagrass beds and on sand or mud bottom to depths of 150 m, with one species being found in pelagic waters. They differ externally from other families of the order Tetraodontiformes by the following combination of characters: body wide and capable of great inflation, covered with massive spines, which may be quite long; spines with large bases or roots, which are beneath the skin; long spines that are usually erectile and double-rooted, or short spines fixed in an erect position by their triple-rooted bases; head broad and blunt; nasal organ usually appearing as small tentacles located in front of the large eyes; mouth large, wide, and terminal, teeth fused to form a strong, beak-like crushing structure without a median suture dividing the upper and lower jaws into left and right halves; gill opening, a relatively small, vertical slit immediately preceding the pectoral-fin base; short-based dorsal and anal fins with soft rays, set far back on body, and like caudal fin, generally rounded; most fin rays branched; bases of fins often thick and fleshy; no pelvic fins (Leis2001).

Porcupinefishes were well studied by Leis (1978,1986,2001,2003,2006). Leis (1978) reviewedDiodon Linnaeus1758 and provided detailed accounts of five species:Diodon eydouxii Brisout de Barneville1846,Diodon holocanthus Linnaeus1758,Diodon hystrix Linnaeus1758,Diodon liturosus Shaw1804, andDiodon nicthemerus Cuvier1818. Leis (2006) provided a list of synonyms and keys for all species of the Diodontidae. Keys to regional species were also provided by Leis (1986, western Indian Ocean; 2001, eastern Indian Ocean and western central Pacific; 2003, western Atlantic). Accounts and color photographs for species of the eastern Pacific were provided by Allen and Robertson (1994). Australian species were diagnosed and illustrated by Gomon (2008). As pointed out by Leis (2006), taxonomic problems remain for some species, such asChilomycterus reticulatus (Linnaeus1758) and species of “AtlanticChilomycterus.”

Ocean sunfishes of the family Molidae occur in tropical and other warm seas of the world. They are usually pelagic, descending to a depth of over 200 m. The ocean sunfishes differ externally from other families of Tetraodontiformes by the following combination of characters: body short and deep or oblong, prominently compressed; caudal peduncle and typical caudal fin absent; eyes small; mouth terminal, small; teeth united and beak-like in each jaw without a median suture; no palatine teeth; gill opening small, pore-like, located in front of pectoral-fin base; dorsal and anal fins of similar shape, generally triangular, dorsal fin located opposite anal fin; dorsal and anal fins spineless, each with 15 to 21 soft rays; pectoral fins of small to moderate size, located midlaterally, fitting into a shallow concavity in side of body in some; pelvic fins absent; caudal fin replaced by a leathery, rudder-like lobe known as a pseudocaudal fin or clavus (supported mostly by fin-ray elements originally belonging to dorsal and anal fins); skin leathery, with many small scales (small juveniles may also have some larger scattered spiny scales) (Hutchins2001b).

Fraser-Brunner (1951) reviewed ocean sunfishes and recognized five species in the Molidae:Masturus lanceolatus (Liénard1840),Masturus oxyuropterus (Bleeker1873),Mola mola (Linnaeus1758),Mola ramsayi (Giglioli1883), andRanzania laevis (Pennant1776). Because species ofMola andMasturus reach more than 3 m in length and two tons in weight, it is difficult to preserve specimens of adults in museums. It is also difficult for ichthyologists to obtain measurements and counts on large adult ocean sunfishes in the field, and specimens ofMola andMasturus are not frequently collected and returned to museum collections.Ranzania laevis is relatively small, reaching around 80 cm TL, but specimens ofRanzania have also been rarely collected. Since ichthyologists have few opportunities to study an adequate number of adult specimens of ocean sunfishes, authors have been unable to agree how many species in the family, some believing a single species exists in each genus, and others recognizing two species each inMola andMasturus and one species inRanzania (Bray2008).

Parenti (2003) published a list of nominal species in the Molidae. Bass et al (2005) published a molecular analysis of ocean sunfishes and recognized two clades inMola,M. mola andM. ramsayi. They demonstrated thatM. ramsayi occurs in South Africa and Australia, whereasM. mola is found in all oceans. However, they were unable to differentiate among specimens ofMasturus from the West Pacific (Taiwan) and the western Atlantic (Florida). Yoshita et al. (2009) studied ocean sunfishes within the genusMola around Japan. They took measurements and counted 99 specimens of young and adults (maximum size 332 cm TL, Fig. 6). They showed convincingly that there are two species with clear morphological differences: a well-developed head bump (head bump height 12.1 % TL) in group A vs. with no distinct head bump (head bump height 7.8 % TL) in group B, number of clavus fin rays 14−17 in group A vs 10−13 in group B, number of clavus ossicles 8−15 in group A vs. 8−9 in group B, and edge of clavus not wavy in group A vs. wavy in group B. Yoshita et al. (2009) suggested strongly that their group A wasM. ramsayi and group B wasM. mola. However, a clearer view of intra- and interspecific relationships ofMola must await the availability of more specimens from other regions of the world’s oceans for study by both morphological and molecular methods.

A large specimen ofMola ramsayi (330 cm TL) captured with a set net along the Pacific coast of northern Honshu, Japan

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Cuvier (1816) pioneered the classification of tetraodontiform fishes by placing them in the order Plectognathi based on his detailed anatomical studies. Since Cuvier’s (1816) work was published, there have been various arrangements of tetraodontiform classification (see Tyler1980 for a history of tetraodontiform classification), but the Plectognathi or Tetraodontiformes has nearly always been considered a monophyletic group, except for Le Danois (1955,1959,1961). As appropriately criticized by Tyler (1963), Yseult Le Danois tried to destroy the order Tetraodontiformes. She stated that the triacanthoids and balisoitds are of acanthurid origin and that the other plectognaths (her Orbiculati) are not even of percoid derivation, being related to the isospondylous fishes, and thatCanthigaster is related to the ostracioids rather than the tetraodontids. However, her statements were based on erroneous observations and interpretations of the osteological and myological characters of tetraodontiforms (Tyler1963; Winterbottom1974). No comprehensive phylogenetic studies of tetraodontiforms appeared prior to studies by Winterbottom (1974) and Tyler (1980). Morphological synapomorphies of tetraodontiforms have been provided by Winterbottom (1974), Tyler (1980), Rosen (1984), Tyler and Sorbini (1996), and Santini and Tyler (2003). In their review of the interrelationships of actinopterygian fishes, Lauder and Liem (1983) supported the monophyly of Tetraodontiformes by adding to the already substantial list of synapomorphies. In addition, Wiley and Johnson (2010) provided a list of 10 synapomorphies for fossil and extant tetraodontiforms.

On the basis of a comprehensive myological study, Winterbottom (1974) analyzed relationships of Tetraodontiformes using cladistic methods. He recognized three major clades: (1) Triacanthodidae + Triacanthidae, (2) (Balistidae + Monacanthidae) + (Aracanidae + Ostraciidae), and (3) Triodontidae + [(Tetraodontidae + Diodontidae) + Molidae] (Fig. 7). The first clade, including the Triacanthodidae and Triacanthidae, was considered to be the sister group of all other tetraodontiforms. Tyler (1980) studied tetraodontiforms extensively and provided a huge number of osteological descriptions, comparative diagnoses, and illustrations for all extant families, major representatives of extant genera, and most of the known fossil taxa of the Tetraodontiformes. Tyler (1980) analyzed phylogenetic relationships of the Tetraodontiformes by an evolutionary (traditional) method and his systematic arrangements of families are similar to those of Winterbottom (1974), except for placing the superfamily Triacanthoidea (Triacanthodidae + Triacanthidae) as the basal sister group to the two superfamilies, the Balistoidea (Balistidae and Monacanthidae) and the Ostracioidea (Aracanidae and Ostraciidae).

Phylogenetic relationships of the extant families of Tetraodontiformes inferred from cladistic analyses of morphological characters.a Winterbottom1974;b Leis1984 (larvae of the Aracanidae and Triodontidae not available for Leis);c Santini and Tyler2003

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Winterbottom (1974) and Tyler (1980) stated that tetraodontiforms were probably related to acanthuroid fishes of the Perciformes, although Winterbottom (1974) suggested that some zeiforms might also be related to tetraodontiforms. Rosen (1984) proposed on the basis of his osteological analysis that zeoids have a sister-group relationship with tetraodontiforms and the two groups are sister to the caproids. Leis (1984) used characters of eggs and larvae to investigate tetraodontiform relationships. Although no aracanid and triodontid larvae were available for his study, Leis (1984) showed relationships of tetraodontiform families that were similar to those of Winterbottom (1974) and Tyler (1980), except for the phylogenetic position of the Ostraciidae. Leis (1984) placed the Ostraciidae in an unresolved trichotomy, Ostraciidae + Diodontidae + Molidae, and placed the three families as a sister clade to the Tetraodontidae (Fig. 7b). This was the first time that the Ostraciidae was placed in the gymnodonts (Triodontidae, Tetraodontidae, Diodontidae, and Molidae). Winterbottom and Tyler (1983) also provided many synapomorphies involving osteological and myological characters that supported a sister-group relationship of balistoids and ostracioids. Klassen (1995) similarly supported the relationship of the two groups.

James C. Tyler and other authors published many papers on fossil tetraodontiforms (e.g., Tyler and Patterson1991; Tyler and Banikov1992,1994,2011,2012; Tyler et al.1992,1993,2000,2003,2006; Tyler and Sorbini1996,1998; Tyler and Winterbottom1999; Tyler and Santini2001,2002; Sorbini and Tyler2004; Bannikov and Tyler2008a,b; Gregorova et al.2009; Carnevale and Tyler2010; Tyler and Kriznar2013; Miyajima et al.2014).

Santini and Tyler (2003) used osteological data on fossil and extant tetraodontiform fishes accumulated by previous contributions to generate a new classification of all known families represented by fossil and extant forms. For extant families, Santini and Tyler (2003) placed the Triacanthodidae as a sister group to all other families of the Tetraodontiformes (Fig. 7). They arranged the other families into two suborders, the Balistoidei and Tetraodontoidei. The former is composed of the Triacanthidae + [(Balistidae + Monacanthidae) + (Aracanidae + Ostraciidae)]. The latter suborder is composed of the Triodontidae + [(Tetraodontidae + Diodontidae) + Molidae]. This classification is similar to those of Winterbottom (1974) and Tyler (1980).

Miya et al. (2003) analyzed molecular data for 100 species of higher teleosteans. Their study was the first to hypothesize close relationships among lophiiforms, tetraodontiforms, and caproids. They retrieved phylogenetic topologies placing caproids as a sister group with tetraodontiforms and the two groups as sister to lophiiforms. However, they used few taxa: one species of Caproidae, two species of Tetraodontiformes, and six species of Lophiiformes. Yamanoue et al. (2007) analyzed more species of the three groups and provided a robust phylogenetic topology that placed the Caproidei as sister to the Lophiiformes, and the two groups as a clade that is sister to the Tetraodontiformes.

Nakae and Sasaki (2010) studied the lateral-line system and its innervations of nine species of tetraodontiforms (representing all families examined except for the Molidae) and a single species each from the Lophiidae, Zeidae, Caproidae, and Siganidae. Their analysis supported a close relationship of the Tetraodontiformes with the Lophiidae, but not with the Zeidae, Caproidae, or Siganidae. Recently, Chanet et al. (2013) presented synapomorphies of tetraodontiforms and lophiiforms involving soft anatomical characters: rounded and anteriorly disposed kidneys, a compact thyroid included in a blood sinus, an abbreviated spinal cord, an asymmetric liver, and clusters of supramedullary neurons in the rostral part of the spinal cord. Baldwin (2013) also provided a putative synapomorphy of some tetraodontiforms and lophiiforms: they are strikingly similar in having the trunk enclosed in an inflated sac covered with xanthophores. Although Nakae and Sasaki (2010), Chanet et al. (2013), and Baldwin (2013) did not study many species of tetraodontiform and outgroup fishes, and the relationship between the Tetraodontiformes and Lophiiformes is now supported both by molecular and morphological characters.

Molecular studies by various authors have generally supported the monophyly of tetraodontiform families (Holcroft2005; Alfaro et al.2007; Yamanoue et al.2007,2008), although conflicts exist between the constructed topologies of familial relationships by morphological and molecular analyses (Figs. 7,8). In the morphological studies by Winterbottom (1974), Tyler (1980), and Santini and Tyler (2003), the Triodontidae, Tetraodontidae, Diodontidae, and Molidae form a monophyletic group, whereas Holcroft (2005) placed the Molidae with Aracanidae + Ostraciidae, treating them as subfamilies. Alfaro et al. (2007) placed the Molidae as the basal sister group to Triodontidae + (Aracanidae + Ostraciidae). Britz and Johnson (2005) and Johnson and Britz (2005a) found the fusion of anterior vertebral centra in the occipital region and a thick band of cartilage on the side of the pterygiophores of the vertical fins in an ostraciid and molids suggestive of a close relationship between the Ostraciidae and Molidae. However, because they studied only one species of Ostraciidae and two species of Molidae, it seems premature to hypothesize a close relationship of the two families until further support for it may be forthcoming. In contrast, the Molidae was recovered as the sister group to a clade comprising the Tetraodontidae and Diodontidae by Santini et al. (2013c) as previously indicated by morphological studies. The Triodontidae was considered to be close to the Tetraodontidae, Diodontidae, and Molidae by morphological studies (Winterbottom1974; Tyler1980; Santini and Tyler2003), whereas molecular studies recovered close relationship of the Triodontidae with the Aracanidae and Ostraciidae (Alfaro et al.2007; Yamanoue et al.2008; Santini et al.2013c).

Phylogenetic relationships of the Tetraodontiformes inferred from molecular analyses.a Holcroft2005;b Alfaro et al.2007;c Yamanoue et al.2007;d Santini et al.2013c. The Triodontidae was not included in Holcroft (2005), and the Ostraciidae of Holcroft (2005) and Yamanoue et al. (2007) included two subfamilies the Aracaninae and Ostraciinae, which were classified as families in the other papers

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Despite differences in molecular trees of familial relationships among authors, several sister group relationships are generally supported by molecular studies (Holcroft2005; Alfaro et al.2007; Yamanoue et al.2007; Santini et al.2013c) as follows: Triacanthodidae + Triacanthidae, Balistidae + Monacanthidae, Aracanidae + Ostraciidae, and Tetraodontidae + Diodontidae, as previously seen in morphological studies. On the basis of whole mitochondrial genome sequences, Yamanoue et al. (2008) documented different phylogenetic relationships from those of other authors. Whereas the Triacanthidae was usually placed close to the Triacanthodidae, Balistidae, and Monacanthidae in other studies (Winterbottom1974; Tyler1980; Leis1984; Santini and Tyler2003; Holcroft2005; Alfaro et al.2007; Santini et al.2013c), Yamanoue et al. (2008) recovered a relationship of the Triacanthidae with the Tetraodontidae and Diodontidae.

Phylogenetic relationships of genera and species were studied by various authors in the Triacanthidae, Balistidae, Monacanthidae, Aracanidae, Ostraciidae, Tetraodontidae, and Molidae, but the numbers of taxa studied differed greatly and resulted in different resolutions of phylogenetic analyses. Santini and Tyler (2002b) analyzed phylogenetic relationships of species and genera of the Triacanthidae using morphological characters. They found two clades, one composed of two species ofTriacanthus Oken1817, and the other composed of three species ofTripodichthys Tyler1968 and one species each ofPseudotriacanthus Fraser-Brunner1941b andTrixiphichthys Fraser-Brunner1941b. Matsuura (1979,1981) analyzed cladistic relationships of all extant genera of the Balistidae and 22 genera of the Monacanthidae using osteological characters. Although many balistid genera showed no significant differences in osteological characters, Matsuura (1979) found that a derived condition of the interhyal was shared byRhinecanthus andSufflamen. He also recoveredCanthidermis as sister to all other balistid genera based on a scale bone in the posterior part of the skull. However, Tyler and Matsuura (1981) revealed Matsuura’s (1979) “scale bone” to be the posterior part of the sphenotic that appears separated from the major portion of the sphenotic. Matsuura (1981) found derived conditions of the pectoral girdle and the skull inXenobalistes, making it a sister group to all other balistid genera. Matsuura (1979) recognized two clades in the Monacanthidae: the first composed ofArotrolepis Fraser-Brunner1941c,Paramonacanthus,Monacanthus,Stephanolepis Gill1861,Chaetodermis,Acreichthys, andPervagor; the secondCantherhines,Eubalichthys Whitley1930b,Thamnaconus (=Navodon Whitley1930b of Matsuura1979),Pseudomonacanthus,Scobinichthys Whitley1931,Nelusetta Whitley1939,Meuschenia Whitley1929,Rudarius,Aluterus,Oxymonacanthus Bleeker1865,Pseudalutarius,Brachaluteres,Paraluteres, andAnacanthus. The second clade possesses more advanced characters than the first clade and is composed of three subclades: (1)Amanses andCantherhines, (2)Eubalichthys,Thamnaconus,Pseudomonacanthus,Scobinichthys,Nelusetta,Meuschenia andRudarius, and (3)Aluterus,Oxymonacanthus,Pseudalutarius,Brachaluteres,Paraluteres, andAnacanthus.

In her molecular analyses of tetraodontiforms, Holcroft (2005) also recovered the close relationship ofRhinecanthus andSufflamen found by Matsuura (1979). She further showed that three species ofBalistes form a sister group toPseudobalistes fuscus (Bloch and Schneider1801) and thatXanthichthys auromarginatus (Bennett1832) is sister toBalistoides viridescens. Her analysis revealed thatBalistoides conspicillum is sister to other balistids, includingBalistes,Pseudobalistes,Rhinecanthus,Sufflamen,Abalistes,Canthidermis,Xanthichthys, andBalistoides viridescens. In addition, she foundMelichthys niger (Bloch1786) to be the first lineage to diverge in the Balistidae. Although Holcroft (2005) studied phylogenetic relationships of nine genera of Monacanthidae, her study covered relatively small numbers of monacanthid genera making it difficult to compare her phylogenetic tree with that constructed by Matsuura (1979). Yamanoue et al. (2009) studied the phylogenetic relationships of 12 species of Balistidae and 21 genera of Monacanthidae, involving one species each from 33 genera of the two families. The molecular analysis placedBalistes as sister to all other balistid genera that were separated into two clades, the first comprisingCanthidermis,Abalistes,Rhinecanthus, andSufflamen, and the secondPseudobalistes,Xanthichthys,Xenobalistes,Odonus,Balistapus,Balistoides, andMelichthys. In the Monacanthidae they found the clade that included two genera,Oxymonacanthus andPseudalutarius, form a sister group to other genera that are divisible into two major clades, the first composed ofRudarius,Brachaluteres,Paraluteres,Pervagor,Stephanolepis,Acreichthys,Chaetodermis,Monacanthus, andParamonacanthus, and the secondAluterus,Pseudomonacanthus,Amanses,Cantherhines,Eubalichthys,Thamnaconus,Nelusetta,Scobinichthys,Meuschenia, andAcanthaluteres.

Santini et al. (2013a) provided the largest molecular dataset for the Balistidae and Monacanthidae based on two mitochondrial and three nuclear loci of 33 species of Balistidae and 53 species of Monacanthidae. The molecular analysis supported monophylies of the following genera:Odonus,Balistapus,Melichthys,Xanthichthys,Canthidermis,Balistes,Abalistes,Rhinecanthus, andSufflamen. Species ofBalistoides andPseudobalistes were recovered in separate clades withBalistoides conspicillum sister toMelichthys, andB. viridescens forming a clade withP. flavimarginatus. The latter two species share at least two morphological characters, a small naked area on the cheek just behind the mouth, and a large maximum size, reaching over 60 cm TL. In the balistid treeXenobalistes tumidipectoris was deeply nested in a clade composed of five species ofXanthichthys, strongly supportingXenobalistes as a junior synonym ofXanthichthys (see Santini et al.2013b). Santini et al. (2013b) recovered virtually all of the subclades of Yamanoue et al. (2009), except forChaetodermis andAcreichthys relationships. In the phylogenetic topology of Santini et al. (2013b),Chaetodermis andAcreichthys are sequential sister taxa to the clade composed of three species ofParamonacanthus andMonacanthus chinensis, whereas Yamanoue et al. (2009) presented sister-group relationships ofChaetodermis andAcreichthys. Santini et al. (2013b) supported monophylies or close relationships of most genera, but species ofMonacanthus andParamonacanthus were separated into different clades suggesting strongly that these genera require revision.

A cladistic analysis of the external characters, osteology, and myology of all genera of Aracanidae led Winterbottom and Tyler (1983) to recognize two clades in the Aracanidae, the first composed ofKentrocapros andPolyplacapros, and the secondAracana,Strophiurichthys Fraser-Brunner1935b,Anoplocapros,Caprichthys, andCapropygia. In the second cladeAracana was sister to the remaining genera,Strophiurichthys andAnoplocapros diverged sequentially, andCaprichthys andCapropygia were placed in a small terminal clade. Santini et al. (2013a) studied the phylogenetic relationships ofKentrocapros (two species),Caprichthys (monotypic),Capropygia (monotypic),Aracana (two species), andAnoplocapros (three species), withPolyplacapros (monotypic). The two monotypic generaCaprichthys andCapropygia were found to represent a clade to other genera.Kentrocapros was placed as sister to the subclade composed ofAracana andAnoplocapros.

Klassen (1995) studied the osteological characters of 19 species of the Ostraciidae extensively. His phylogenetic analysis found two clades in the Ostraciidae, the first composed ofAcanthostracion andLactophrys Swainson1839, and the secondOstracion andLactoria, having synonymizedRhynchostracion withOstracion andTetrosomus withLactoria. Santini et al. (2013a) studied the phylogenetic relationships of 17 species of Ostraciidae by molecular analysis. The resultant phylogenetic tree closely resembled that of Klassen (1995), but where Klassen (1995) foundRhynchostracion nasus (Bloch1785) deeply nested withinOstracion, Santini et al. (2013a) presented it as sister toOstracion.

On the basis of many osteological characters, nasal organ, and lateral-line system, Tyler (1980) inferred three groups of pufferfish genera: (1)Lagocephalus,Colomesus,Guentheridia Gilbert and Starks1904, andSphoeroides; (2)Amblyrhynchote,Torquigener, andFugu (=Takifugu); and (3) all other genera. Holcroft (2005) and Alfaro et al. (2007) analyzed the phylogenetic relationships of 19 species of 10 genera (Arothron,Canthigaster,Lagocephalus,Marilyna,Monotreta,Sphoeroides,Takifugu,Tetractenos,Tetraodon, andTorquigener). Their results are similar, placingLagocephalus at the base of the topologies. Yamanoue et al. (2011) studied the phylogenetic relationships of 50 species of Tetraodontidae by molecular analysis. The study found four major clades, the first composed of species ofLagocephalus, the secondColomesus and three species ofSphoeroides, the thirdMarilyna,Tetractenos,Tylerirus,Polyspina,Torquigener, andTakifugu, and the fourth and the largest cladeCarinotetraodon,Tetraodon,Auriglobus,Pelagocephalus,Canthigaster,Chelonodon,Omegophora, andArothron. The phylogenetic tree of Yamanoue et al. (2011) recognized many monophyletic lineages, butColomesus and species ofTetraodon fell into distantly related clades. A relaxed molecular-clock Bayesian divergence time estimation calculated three invasions to freshwater by pufferfishes during their evolution: the first 48−78 million years ago in Southeast Asia, the second 17−38 million years ago in Africa, and the third 0−10 million years ago in South America.

Igarashi et al. (2013) studied the phylogenetic relationships of 17 species ofTetraodon by molecular analysis. The study clearly showed that they did not form a monophyletic group. Except forT. cutcutia, 16 species were placed into three major clades: an Asian freshwater group composed ofT. leiurus,Tetraodon palembangensis Bleeker1850b,T. abei,Tetraodon baileyi Sontirat1985,Tetraodon cochinchinensis Steindachner1866,T. suvattii, andTetraodon turgidus Mitchill1815; an Asian brackish water group ofTetraodon erythrotaenia Bleeker1853,Tetraodon biocellatus Tirant1885,T. fluviatilis, andTetraodon nigroviridis Marion de Procé1822; and an African freshwater group ofTetraodon lineatus Linnaeus1758,Tetraodon pustulatus Murray1857,Tetraodon mbu Boulenger1899,Tetraodon miurus Boulenger1902, andTetraodon duboisi Poll1959. Two molecular studies by Yamanoue et al. (2011) and Igarashi et al. (2013) produced essentially the same phylogenetic tree for freshwater pufferfishes.

In his review of ocean sunfishes, Fraser-Brunner (1951) foundMasturus Gill1884 andMola to be more closely related to each other than toRanzania. Tyler’s (1980) extensive surveys of osteological characters supported the phylogenetic tree of Fraser-Brunner (1951). Santini and Tyler (2002a) performed the first cladistic analysis of the phylogenetic relationships of ocean sunfishes, using 48 morphological characters. Their study supported the results of the previous studies. Yamanoue et al. (2004) used mitochondrial genomes to analyze the phylogenetic relationships of ocean sunfishes. Their study resulted in the same phylogenetic tree as recovered by previous morphological studies. Molecular studies on tetraodontiform relationships by Alfaro et al. (2007) also produced the same result. Bass et al. (2005) examined many specimens of ocean sunfishes captured from various localities worldwide. The molecular analysis found thatM. ramsayi is distributed in the Southern Hemisphere andM. mola in both the Northern and Southern hemispheres. Yoshita et al. (2009) studied ocean sunfishes ofMola around Japan employing both morphological and molecular characters. As discussed in the section of Molidae, the study clearly showed two species ofMola around Japan, probably identifiable asM. mola andM. ramsayi.

The taxonomy of tetraodontiforms has progressed greatly since the mid-1960s. On the basis of contributions to date, this paper identifies 412 extant species in the 10 living families of Tetraodontiformes, with an allocation of species and genera as follows: Triacanthodidae including 23 species in 11 genera, Triacanthidae with seven species in four genera, Balistidae with 37 species in 12 genera, Monacanthidae with 102 species in 27 genera, Aracanidae with 13 species in six genera, Ostraciidae with 22 species in five genera, monotypic Triodontidae, Tetraodontidae with 184 species in 27 genera, Diodontidae with 18 species in seven genera, and Molidae with five species in three genera. However, many taxonomic problems involving species and genera of various families still remain. In particular, taxonomic anomalies exist in the Monacanthidae and Tetraodontidae, which have the greatest number of species and diversity within the order. Studies of spikefishes of the Triacanthodidae reveal clarity on the number of genera and species, but poorly surveyed deep areas of the world’s oceans exist where new species may occur. Several genera of Balistidae, Aracanidae, and Ostraciidae require study both by morphological and molecular analyses to clarify generic and species limits. The large size attained by ocean sunfishes has made it difficult for us to have a clear understanding of species limits, although a combination of molecular and morphological approaches have clarified that the presence of several populations probably represent species ofMola (see Bass et al.2005; Yoshita et al.2009). When the taxonomic levels of these populations are established, difficult nomenclatural challenges still remain: many nominal species of ocean sunfishes were published in the old days without type specimens.

With regard to the systematics of the Tetraodontiformes overall, familial relationships have been clarified by morphological and molecular analyses, providing us with a firm understanding of the sister relationships of the following family groups: Triacanthodidae and Triacanthidae, Balistidae and Monacanthidae, and Tetraodontidae and Diodontidae. However, the phylogenetic positions of the Triodontidae and Molidae remain unclear because of conflicts about their positions in morphological and molecular studies (the position of Molidae differs even among molecular studies). More taxon sampling is needed for molecular analyses to produce more robust phylogenetic topologies. Although generic and specific phylogenetic relationships for the families Triacanthidae, Balistidae, Monacanthidae, Aracanidae, Ostraciidae, and Molidae have been studied using morphological and/or molecular analyses, the genera and species of the Triacanthodidae and Diodontidae have never been studied cladistically and await future studies.