- Capniidae
__NOTOC__Taxobox
name = Small winter stoneflies
image_width = 240px
image_caption = "Eocapnia nivalis " on the snow inNagano (Japan )
regnum =Animal ia
phylum =Arthropod a
subphylum =Hexapoda
classis =Insect a
subclassis =Pterygota
infraclassis =Neoptera
superordo =Exopterygota
ordo =Plecoptera
subordo =Arctoperlaria
infraordo =Euholognatha
familia = Capniidae
familia_authority =
subdivision_ranks =Genera
subdivision = 17-20, see textCapniidae, the small winter stoneflies, are a family of
insect s in thestonefly order (Plecoptera). They constitute one of the largest stonefly families, containing some 300species distributed throughout theHolarctic . Their closest relatives are therolled-winged stoneflies (Leuctridae ). [Nelson (1996a,b)]Many species are endemic to small ranges, perhaps due to the family's tendency to evolve tolerance for cold (isolating populations in mountain valleys) and winglessness (inhibiting dispersal)Nelson (1996b)] . Indeed, some wingelss Capniidae, e.g. the
Lake Tahoe Benthic Stonefly (""Capnia" lacustra" ["Capnia " is not monophyletic and this species is suspected to belong elsewhere (see "Systematics and taxonomy" section)] ) or "Baikaloperla ", spend their entire lives underwater and do not disperse from their native lakes at all [Holst (2000)] .Description and ecology
Adult Capniidae are, as their commnon name implies, usually small Plecoptera; while most are less than 1 cm long with some measuring just 4 mm as adults, a few can get as large as 25 mm (1 inch) however. The adults emerge form the water in winter and are often found walking around on the snow. Characteristic are the wings with at most one cubital crossvein, and the
paraproct s (anal lobes) whose inner lobes form a tube closed on the underside by the outer lobes.Nymphs of small winter stoneflies typically have a very elongated and slender body, similar to those of
rolled-winged stoneflies (Leuctridae ). However, the groove along theabdomen , from segment 1 to 9, is generally very pronounced.The nymphs dwell in the
hyporheic zone , the interface between stream water andgroundwater . Only immediately before moulting into the adult form will the nymphs move out of the substrate and appear on thestream bed . Thus, although they may be plentiful in clean rivers and streams, they are seldom encountered in standard samples ofbenthos .ystematics and taxonomy
Often, the family Capniidae is considered
monotypic as tosubfamily , with the Capniinae being inserted at that rank. However, this is rather pointless; in any case thephylogeny ,systematics andtaxonomy of the small winter stoneflies are highly confused. There appear to be two very basal genera and presumably two largerclade s which conceivably could be considered subfamilies. However, the phylogeny of the Capniidae is by no means robustly resolved, with about one-third of the named genera of uncertain position. Hence, any subdivision beyond the generic level is premature.Furthermore, the
type genus "Capnia" is probably notmonophyletic and in serious need of splitting up. Thetype species "Capnia nigra " and its closest relatives would retain their genus name; they are closely related to "Capnura ". TheNorth America n species at least for the largest part are closer to "Mesocapnia "; other "Capnia" are closest to "Bolshecapnia " as it seems. Finally, there is a fourth group of rather uncertain position in the main assemblage of Capniidae.A rough layout of the suspected phylogeny can be given as follows:
Basal genera
* "Isocapnia "
* "Paracapnia "Suspected clade/subfamily 1
* "Nemocapnia "
* "Capnioneura "
* "Eucapnopsis "Suspected clade 2/subfamily Capniinae "sensu stricto"
* "Bolshecapnia "
* "Allocapnia "
* "Baikaloperla "
* "Capnia " (paraphyletic )
* "Capnura "
* "Utacapnia "
* "Mesocapnia ""
Incertae sedis " as to clade 1 or 2
* "Allocapniella "
* "Capniella "
* "Capnopsis "
* "Eocapnia "
* "Takagripopteryx "Footnotes
References
* (19961): [http://tolweb.org/Plecoptera/8245/1996.01.01 Plecoptera. Stoneflies] . Version of 1996-JAN-01. Retrieved 2008-JUL-31.
* (1996b): [http://tolweb.org/Capniidae/13943/1996.01.01 Capniidae. Winter Stoneflies] . Version of 1996-JAN-01. Retrieved 2008-JUL-31.
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