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Small-dark-stonefly

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Allocapnia rickeri
Midwest Snowfly
Allocapnia rickeri is a small winter stonefly in the family Capniidae, commonly known as the Midwest Snowfly. It is one of numerous small, dark stoneflies in the genus Allocapnia that emerge during cold months when few other insects are active. The species has been documented across the central and eastern United States. Like other capniids, it is associated with clean, cold streams and is an important indicator of water quality.
winter-stonefly bioindicator coldwater Plecoptera Capniidae Allocapnia lotic emergence brachyptery aptery genitalia-identification Frison-1942 Midwest southeastern-US clean-water-indicator January-March small-stonefly wingless-female stream-insect shredder gatherer seasonal-resource water-quality aquatic-insect terrestrial-adult short-lived-adult oviposition submerged-eggs high-dissolved-oxygen low-temperature central-US eastern-US Alabama Arkansas Delaware Georgia Illinois hexapod hemimetabolous Euholognatha Nemouroidea Arctoperlaria Insecta Arthropoda Animalia GBIF Catalogue-of-Life iNaturalist NCBI taxonomy accepted-species 1942 Frison Ricker Midwest-Snowfly snowfly small-dark-stonefly clean-streams rivers well-oxygenated lotic-habitat cold-months winter-activity wing-reduction female-aptery male-flight epiproct paraproct terminalia taxonomic-revision congeners distribution-records observations 9-observations eukaryote metazoan arthropod insect stonefly winter-emerging January February March cold-weather near-freezing below-freezing water-surface submerged-substrates allochthonous-organic-material stream-ecosystems seasonal-food-resource insectivorous-birds predators scarce-prey unpolluted no-economic-importance stream-monitoring water-quality-indicator high-quality-coldwater microscopic-examination taxonomic-keys male-terminalia reliable-separation genitalic-examination overlapping-distribution similar-habitat small-size under-10-mm body-length reduced-wings absent-wings fully-developed-wings specific-identification published-descriptions illustrations subsequent-revisions characteristic family-Capniidae common-name extended-nymphal-period one-to-two-years short-lived does-not-feed aquatic-nymph clean-cold-streams low-temperatures year-round winter-months January-through-March family centered-Midwest extends-southeastern United-States documented appears most-reliably distinguished subtle-differences terminal-abdominal-structures should-be-compared against published subsequent genus-level characterized reduced absent females fully-developed males requires-examination male-genitalia structure paraprocts reliable separation overlaps similar many externally definitive relies microscopic examination comparison keys used biological indicator programs presence indicates cold conditions no-direct economic importance shredders gatherers processing allochthonous organic material stream ecosystems seasonal food resource insectivorous birds other when alternative prey scarce serves high-quality habitats development aquatic nymphal stages terrestrial adult stage nymphs develop streams extended period likely one two years based related species adults do-not feed active during weather air temperatures may near below freezing winged capable flight wingless short-winged remain water surface mating occur winter entering deposit eggs submerged substrates small commonly known numerous dark emerge few insects central eastern associated clean important under mm body length members genus wings possess fully developed specific identification level within requires male genitalia particularly most reliably subtle differences these terminal abdominal structures should compared descriptions taxonomic revisions winter-emerging maintain low high dissolved oxygen levels throughout year United States distribution centered extends southeastern months typically through this activity gives rise common name do not provides quality monitoring no direct habitat morphology size genitalic