| Nemadactylus macropterus | |
|---|---|
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Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Centrarchiformes |
| Family: | Cheilodactylidae |
| Genus: | Nemadactylus |
| Species: | N. macropterus |
| Binomial name | |
| Nemadactylus macropterus (J. R. Forster, 1801) | |
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| Range (in blue) | |
| Synonyms[1] | |
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Nemadactylus macropterus, thetarakihi,jackass morwong ordeep sea perch, is a species of marineray-finned fish, traditionally regarded as belonging to thefamilyCheilodactylidae, the members of which are commonly known as morwongs. It is found in the south western Pacific Ocean, in Australia and New Zealand. Although there are records from the southern Indian Ocean and southwestern Atlantic, these may be due to misidentifications of similar species.
Nemadactylus macropterus was first formallydescribed in 1801 asCichla macroptera by the GermannaturalistJohann Reinhold Forster with thetype locality given as New Zealand.[2] In 1839 SirJohn Richardson described a new speciesNemadactylus concinnus from Tasmania he created themonotypicgenusNemadactylus for it,N. concinnus was later considered to be asynonym of Forster'sC. macroptera, making this species thetype species of the genusNemadactylus as Richardson's N. concinnus.[3] The specific namemacropterus means "long-winged", a reference to the very elongated seventh ray of thepectoral fins.[4]Genetic andmorphological analyses strongly support the placement ofNemadactylus in the familyLatridae, alongside almost all of the other species formerly classified in the Cheilodactylidae.[5]
Nemadactylus macropterus has 17 - 18 spines and 25-28 soft rays in its dorsal fin and 3 spines and 14-15 soft rays in itsanal fin. It attains a maximum total length of 70 cm (28 in), although 35 cm (14 in) is more typical, and a maximum published weight of 2.9 kg (6.4 lb).[1] This is a large species with an overall silvery colour with a wide black band or crescentic marking which runs from the nape to the base of the pectoral fin. The seventh pectoral fin ray is elongated.[6] The fins are light to dark-greyish without any clear markings. The juveniles are also silvery but have dark bands or blotches on their upper bodies.[7]
Nemadactylus macropterus is definitely found in Australia and New Zealand. In Australia it occurs along the southern coast from Broken Bay, New South Wales to Rottnest Island, Western Australia, its range encompassing Tasmania too.[6] It is widespread in New Zealand, occurring fromCape Reinga to the seas immediately south of theSnares Islands, on the shallower areas on the Chatham Rise and off theChatham Islands.[7] There are reports of this species from South America and islands in the southern Indian Ocean but it is thought that these may be misidentifications of similar looking congeners.[8] It is found on deep reefs in depths down to 400 m (1,300 ft), although they are known to enter large coastal bays at times.[6]
Nemadactylus macropterus has a maximum lifespan of approximately 35 years, and maturation is obtained at the age of 3-6 years.[9] They spawn from the periods of February to June.[10] The youngN.macropterus are found in high density in the inner and mid shelf, while the adults reside on the outer continental shelf.[11] This species has a diet of benthic invertebrates includingpolychaetes,crustaceans,molluscs andechinoderms.[6] There are known regular spawning aggregations in New Zealand waters and individuals have been known to migrate up to 500 km (310 mi) from their home range to breed.[7]