TheHeteroptera are a group of about 40,000 species of insects in the orderHemiptera. They are sometimes called "true bugs",[1] though that name more commonly refers to the Hemiptera as a whole. "Typical bugs" might be used as a more unequivocal alternative, since theheteropterans are most consistently and universally termed "bugs" among the Hemiptera. "Heteroptera" is Greek for "different wings": most species haveforewings with both membranous and hardened portions (calledhemelytra); members of the primitive sub-groupEnicocephalomorpha have completely membranous wings.
The name "Heteroptera" is used in two very different ways in modern classifications. InLinnean nomenclature, it commonly appears as asuborder within theorder Hemiptera, where it can beparaphyletic ormonophyletic depending on its delimitation. Inphylogenetic nomenclature, it is used as an unrankedclade within theProsorrhyncha clade, which in turn is in the Hemiptera clade. This results from the realization that theColeorrhyncha are just "living fossil" relatives of the traditional Heteroptera, close enough to them to be united with that group.
The infraordersLeptopodomorpha,Gerromorpha, andNepomorpha, comprise a significant component of the world's aquatic and semiaquatic insects. There are 23 families, 343 genera and 4,810 species group taxa within these three infraorders.[2] Most of the remaining groups that are common and familiar are in theCimicomorpha andPentatomomorpha.
The use of the name "Heteroptera" has had the rank oforder, dating back to 1810 byPierre André Latreille. Only recently has it been relegated to a subsidiary rank within a larger definition of Hemiptera, so many reference works still include it as an order. Whether to continue treating it as a suborder is still a subject of some controversy, as is whether the name itself should ever be used, although three basic approaches ranging from abolishing it entirely to maintaining thetaxonomy with a slight change insystematics is proposed, two of which (but not the traditional one) agree with thephylogeny. The competing classifications call for a preference for two suborders versus one when the "living fossil" familyPeloridiidae is taken into consideration:
In one revised classification proposed in 1995,[3] the name of the suborder isProsorrhyncha, and Heteroptera is a rankless subgroup within it. The only difference between Heteroptera and Prosorrhyncha is that the latter includes the familyPeloridiidae, which is a tinyrelictual group that is in its ownmonotypic superfamily and infraorder. In other words, the Heteroptera and Prosorrhynchasensu Sorensen et al. are identical except that Prosorrhyncha contains one additional infraorder, calledPeloridiomorpha (comprising only 13 small genera). The ongoing conflict between traditional, Linnaean classifications and nontraditional classifications is exemplified by the problem inherent in continued usage of the name Heteroptera when it no longer can be matched to any standard Linnaean rank (as it falls below suborder but above infraorder). If this classification succeeds, then the "Heteroptera" grouping may be discarded, but in that case it is likely that no ranks will be used at all according to the standards ofphylogenetic nomenclature.
In the traditional classification,[4] the Peloridiidae are retained as their own suborder, calledColeorrhyncha; "Heteroptera" is treated the same. Functionally, the only difference between this classification and the preceding is that the former uses the name Prosorrhyncha to refer to a particular clade, while the traditional approach divides this into theparaphyletic Heteroptera and themonophyletic Coleorrhyncha. Many believe it is preferable to use only one name because the characteristics of the two traditional suborders are too closely related to be treated as separate.
Alternatively,[5] the modified approach of placing Coleorrhyncha 'within' the Heteroptera can be used. Indeed, as that solution preserves the well-known Heteroptera at the taxonomic rank they traditionally hold while making them a goodmonophyletic group, it seems preferable to the paraphyletic "Heteroptera" used in older works. In that case, the "core" Heteroptera could be considered asection – as yet unnamed, mainly because the Prosorrhyncha were proposed earlier – within the "expanded" Heteroptera, or the latter could simply be described as consisting of abasal "living fossil" lineage and a moreapomorphic main radiation. Whether the name "Coleorrhyncha" is to be retained for the basal lineage or whether the more consistent "Peloridiomorpha" is used instead is a matter of taste, as described below.
Separate from the question of the actual "closeness" of Heteroptera and Coleorrhyncha is the potential disruption to traditional construction of names; there seems to be reluctance among hemipterists to abandon the use of "Heteroptera". This can be seen by the name itself, as it is a violation of convention to use the ending "-ptera" for any rank above genus other than an order – though since it is a convention rather than amandatory rule of Linnean nomenclature, taxonomists are technically free to violate it (which is why, for example, not all insect orders end in "-ptera", e.g.,Odonata). However, in most cases when such conventions are violated, it does not create an internal conflict as in the present case (that is, the order Hemiptera has a suborder named Heteroptera, which is an internal conflict). At least some hemipterists argue that the name Heteroptera should be dropped entirely to eliminate this internal conflict, though the third possibility offers a workaround. In that case, to achieve full consistency of names "Coleorrhyncha" would probably be dropped in favor of "Peloridiomorpha".
^Sorensen, J. T., B. C. Campbell, R. J. Gill & J. D. Steffen-Campbell (1995): Non-monophyly of Auchenorrhyncha ("Homoptera"), based upon 18S rDNA phylogeny: eco-evolutionary and cladistic implications with pre-Heteropteroidea Hemiptera (s.l.) and a proposal for new monophyletic suborders.Pan-Pacific Entomologist71 (1): 31–60.
