Plecoptera

__NOTOC__Taxobox
name = Stoneflies
fossil_range= Permian - Recent


image_caption = Adult of family Pteronarcyidae (Systellognatha)
image_width = 200px
regnum = Animalia
phylum = Arthropoda
subphylum = Hexapoda
classis = Insecta
subclassis = Pterygota
infraclassis = Neoptera
superordo = Exopterygota
ordo = Plecoptera
ordo_authority = Burmeister, 1839
subdivision_ranks = Suborders
subdivision =
Arctoperlaria
and see text

Plecoptera are an order of insects, commonly known as stoneflies. There are some 1,700 recorded species worldwide, and new ones continue to evolve. Stoneflies are believed to be one of the most primitive groups of Neoptera, with close relatives identified from the Carboniferous and Lower Permian geological periods, while true stoneflies are known from fossils only a bit younger. The modern diversity however apparently is of Mesozoic origin. [Zwick (2000]

Plecoptera are found in both the Southern and Northern hemispheres, and the populations are quite distinct although the evolutionary evidence suggests that species may have crossed the equator on a number of occasions before once again becoming geographically isolated [Hynes (1993), Zwick (2000] .

All species of Plecoptera are intolerant of water pollution and their presence in a stream or still water is usually an indicator of good or excellent water quality.

Description and ecology

The name literally means "braided-wings", from the Ancient Greek "plekein" (πλέκειν, "to braid") and "pteryx" (πτέρυξ, "wing") [Woodhouse (1910)] . This refers to the complex venation of their two pairs of wings, which are membranous and fold flat over the back. Both nymphs and adults have long paired cerci projecting from the tip of their abdomens.

The nymphs are aquatic and live in the benthic zone of lakes and streams. Nymphs of this order are hunters of other aquatic arthropods or shredders of large organic particles, such as leaves. Some also graze on benthic algae. They undergo many molts as aquatic nymphs (10 instars?) before emerging and becoming terrestrial as adults.

A few wingless species such as the Lake Tahoe Benthic Stonefly (""Capnia" lacustra" [The genus "Capnia" is not monophyletic and this species is suspected to belong elsewhere: Nelson (1996a)] ) or "Baikaloperla" are the only known insects that are exclusively aquatic from birth to death [Holst (2000)] . Some true water bugs (Nepomorpha) may also be fully aquatic for their entire life, but can leave the water to travel.

ystematics

Traditionally, the stoneflies were divided into two suborders, the "Antarctoperlaria" (or "Archiperlaria") and the Arctoperlaria. However, the former simply unites the two basalmost superfamilies, which do not seem to be each other's closest relatives however. Thus, the "Antarctoperlaria" are not conformed as a natural group (despite some claims to the contrary) and thus are not used here. [Nelson (1996b)]

The Arctoperlaria, meanwhile, have been divided into two infraorders, the Euholognatha (or Filipalpia) and the Systellognatha (aso called Setipalpia or Subulipalpia). This corresponds to the phylogeny, with one exception: the Scopuridae must be considered a basal family in the Arctoperlaria, not assignable to any of the infraorders. Alternatively, the Scopuridae were placed in an unranked clade "Holognatha" together with the Euholognatha (hence the name of the latter, meaning approximately "advanced Holognatha"). But the Scopuridae do not appear significantly closer to the Euholognatha than to the Systellognatha, and therefore the "Holognatha" are also not used here either. In addition, not adopting these two dubious "clades" allows for a systematic layout of the Plecoptera that adequately reproduces phylogeny, while retaining the familiar ranked taxa. [Nelson (1996b), Zwick (2000)]

[
Taeniopterygidae (Euholognatha)]
[
Perlidae (Systellognatha)] Basal lineages ("Antarctoperlaria")
* Superfamily Eusthenioidea
** Family Diamphipnoidae
** Family Eustheniidae
* Superfamily Leptoperloidea
** Family Austroperlidae
** Family Gripopterygidae

Suborder Arctoperlaria
* Basal family Scopuridae
* Infraorder Euholognatha
** Family Capniidae (ca. 300 species) - small winter stoneflies
** Family Leuctridae - rolled-winged stoneflies
** Family Nemouridae (ca. 400 species) - spring stoneflies
** Family Notonemouridae
** Family Taeniopterygidae (ca. 75 species) - winter stoneflies
* Infraorder Systellognatha
** Family Chloroperlidae (100+ species) - green stoneflies
** Family Perlidae (ca. 400 species) - common stoneflies
** Family Perlodidae (250+ species)
** Family Peltoperlidae (ca. 50 species) - roachlike stoneflies
** Family Styloperlidae (ca. 7 species)
** Family Pteronarcyidae (ca. 12 species) - salmonflies, giant stoneflies

Footnotes

References

* (2000): Lake Tahoe benthic stonefly ("Capnia lacustra"). "In:" aut|Murhy, D.D. & Knopp, C.M.: " [http://www.fs.fed.us/psw/publications/documents/gtr-175/ Lake Tahoe Watershed Assessment] ": O-118 – O-120. USDA. [http://www.fs.fed.us/psw/publications/documents/gtr-175/gtr-175-appendixO.pdf PDF fulltext]
* (1993): "Adults and Nymphs of British Stoneflies". Freshwater Biological Association. ISBN 0-900386-28-2
* (1996a): Tree of Life Web Project - [http://tolweb.org/Capniidae/13943/1996.01.01 Capniidae. Winter Stoneflies] . Version of 1996-JAN-01. Retrieved 2008-JUL-31.
* (1996b): Tree of Life Web Project - [http://tolweb.org/Plecoptera/8245/1996.01.01 Plecoptera. Stoneflies] . Version of 1996-JAN-01. Retrieved 2008-JUL-31.
* (1910): English-Greek Dictionary - A Vocabulary of the Attic Language. George Routledge & Sons Ltd., Broadway House, Ludgate Hill, E.C. [http://www.lib.uchicago.edu/efts/Woodhouse/ Searchable JPEG fulltext]
* (2000): Phylogenetic System and Zoogeography of the Plecoptera. "Annu. Rev. Entomol." 45: 709-746. doi|10.1146/annurev.ento.45.1.709 (HTML abstract)