Heteroptera
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 Gerris najas, a pondskater
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Cimicomorpha |
Heteroptera is a group of about 40,000 species of insects in the Hemiptera. Sometimes called "true bugs"[1], that name more commonly refers to Hemiptera as a whole, and "typical bugs" might be used as a more unequivocal alternative since among the Hemiptera the heteropterans are most consistently and universally termed "bugs". "Heteroptera" is Greek for "different wings": most species have forewings with both membranous and hardened portions (called hemelytra); members of the primitive Enicocephalomorpha have wings that are completely membranous.
The name "Heteroptera" is used in two very different ways in modern classifications; in Linnean nomenclature it commonly appears as a suborder within the order Hemiptera, where it can be paraphyletic or monophyletic depending on its delimitation. In phylogenetic nomenclature it is used as an unranked clade within the Prosorrhyncha clade which in turn is in the Hemiptera clade. This results from the realization that the Coleorrhyncha are actually just a "living fossil" relative of the traditional Heteroptera, close enough to them to be actually united with that group.
The Gerromorpha and Nepomorpha contain most of the aquatic and semi-aquatic members of the Heteroptera, while nearly all of the remaining groups that are common and familiar are in the Cimicomorpha and Pentatomomorpha.
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Classification
The use of the name "Heteroptera" has a long history at the rank of order, dating back to Latreille, 1810, and it is only recently that it has 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 be used at all, though three basic approaches ranging from abolishing it entirely to maintaining the taxonomy with a slight change in systematics are proposed, two of which (but not the traditional one) agree with the phylogeny. The competing classifications basically boil down to preference for two suborders versus one when the "living fossil" family Peloridiidae is taken into consideration:
- In the traditional classification[2], the Peloridiidae are retained as its own suborder, called Coleorrhyncha, and "Heteroptera" is treated as a suborder as well. 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 the paraphyletic Heteroptera plus the monophyletic Coleorrhyncha: Many believe is preferable to use one name only, because they feel that the two traditional suborders are too closely related to be treated as separate and should instead be one suborder only.
- In one revised classification proposed in 1995[3], the name of the suborder is Prosorrhyncha, and Heteroptera is a rankless subgroup within it. The only difference between Heteroptera and Prosorrhyncha is that the latter includes the family Peloridiidae, which is a tiny relictual group that is in its own monotypic superfamily and infraorder (if these totally rediundant ranks are used at all). In other words, the Heteroptera and Prosorrhyncha sensu Sorensen et al. are identical except that Prosorrhyncha contains one additional infraorder, called Peloridiomorpha (comprising only 13 small genera). The ongoing conflict between traditional, Linnaean classifications and non-traditional 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 wins out, then the "Heteroptera" grouping may be discarded in the near future, but in that case it is likely that no ranks are used at all according to the standards of phylogenetic nomenclature.
- Alternatively[4], 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 good monophyletic group, it seems preferable to the paraphyletic "Heteroptera" used in older works. In that case, the "core" Heteroptera could be considered a section – as of yet unnamed, mainly because the Prosorrhyncha were proposed earlier – within the "expanded" Heteroptera, or the latter could simply be described as consisting of a basal "living fossil" lineage and a more apomorphic 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 a mandatory 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".
Selected families of Heteroptera
- assassin bugs (Reduviidae)
- bedbugs and flower bugs (Cimicidae)
- leaf bugs (c.6,000 species of Miridae)
- leaf-footed bugs and squash bugs (Coreidae)
- seed bugs (mainly Lygaeidae and Rhyparochromidae)
- stink bugs or shield bugs (Pentatomidae and related families)
"Waterbugs"
"Waterbugs" is a common name for a number of aquatic insects, most of which are classified in the infraorders Gerromorpha and Nepomorpha of the order Hemiptera. The latter infraorder contains those taxa that were once known as the "Gymnocerata". Note that the term "water bug" is very often applied to some cockroaches, which are not true bugs and as Dictyoptera not even close to them (true bugs are Paraneoptera).
Selected families of water bugs
- back swimmers (Notonectidae)
- giant water bugs (Belostomatidae)
- water scorpions (Nepidae)
- water boatmen (Corixidae)
- pond skaters (Gerridae)
- Smaller water strider (Veliidae)
Footnotes
References
- Cassis, Gerasimos & Gross, Gordon (1995): Australian Biological Resources Study - Hemiptera: Heteroptera (Coleorrhyncha to Cimicomorpha). Gerrids, Reduviids, Water-striders. Version of 1995-JUN-30. Retrieved 2008-JUL-28.
- Maddison, David R. (1995): Tree of Life Web Project - Hemiptera. True bugs, cicadas, leafhoppers, aphids, etc.. Version of 2005-JAN-01. Retrieved 2008-JUL-28.
- Sorensen, J.T.; Campbell, B.C.; Gill, R.J. & Steffen-Campbell, J.D. (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 Entomologist 71(1): 31-60.
- Tree of Life Web Project (ToL) (2005): Heteroptera. True bugs. Version of 2005-JAN-01. Retrieved 2008-JUL-28.
External links
- List of species in Heteroptera (1998)
- Heteropteran Systematics Lab at University of California, Riverside http://heteroptera.ucr.edu