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Stoneflies - Plecoptera: Capniidae of Gunnison County, Colorado

Isocapnia crinita - Hooked Snowfly

(Needham and Claassen) 1925
Updated 22 Dec 2023
TSN 102749


Rare, two of the three records of I. crinita are from Gunnison County (Nelson and Baumann, 1989). The genus Isocapnia was previously included in Capnia. Older publications may refer to this species as Capnia crinita.

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Isocapnia grandis
Introduction to Isocapnia


Banks,N 1938 New native neuropteroid insects. Psyche, 45(1) 72-79 PDF
      Isocapnia gen. nov.
Rather large, heavy species; radius not bent at origin of radial sector, an oblique vein beyond end of subcosta, several (five or more) costal cross-veins; setae long, twenty or more joints, four or five or more near base very short; anal area of hind wing not reaching to tip of wing. Much larger species than others of the subNotonectidae. Genotype, Arsapnia grandis Bks. There are at least four species, Capnia crinita Claassen, 74 Psyche [March I. fumosa, herewith described, and a clear winged species in which the radial sector is forked beyond the cross-veins; all are from the northwestern parts of United States and western Canada.

Baumann,RW, Gaufin,AR and Surdick,RF 1977 The stoneflies (Plecoptera) of the Rocky Mountains. Memoirs of the American Entomological Society 31, 1-208. PDF
     Quote from page 78: "This rare species occurrs in both creeks and rivers. The adults emerge from March to May. " Illustrations include Figure 232, male terminalia, lateral view; Figure 233 male terminalia dorsal view on page 79.

DelVecchia,AG; Stanford,JA and Xu,X 2016 Ancient and methane-derived carbon subsidizes contemporary food webs. Nature communications, 7 PDF

Kondratieff,BC and Baumann,RW 2002 A review of the stoneflies of Colorado with description of a new species of Capnia (Plecoptera: Capniidae). Transactions of American Entomological Society 128 3, 385-401.
     Quote from page 390: "This rare species is presently known from only three localities in Colorado: Gunnison Co., Gunnison River, Gunnison, 18 April 1954, W.E. Ricker, 1 male,1 female (CNC); Routt Co., Yampa River, Hwy 40, eat of Hayden, 9 May 1997, R.W. Baumann, 1 micropterous male (BYU); Saguache Co., Tomichi Creek, Hwy 50, west of Sargents, 7 May 1992, R.W. Baumann, B.C. Kondratieff and J.T. Zenger, 3 micropterous male (CSU, BYU). "

Knight,AW and Gaufin,AR 1966 Altitudinal distribution of stoneflies (Plecoptera) in a Rocky Mountain drainage system. Journal of the Kansas Entomological Society 39(4) 668-675.
First page

Knight,AW and Gaufin,AR 1967 Stream type selection and associations of stoneflies (Plecoptera) in a Colorado River drainage system. Journal of the Kansas Entomological Society, 347-352. Abstract and first page

Malison,RL; Ellis,BK; DelVecchia,AG; Jacobson,H; Hand,BK; Luikart,G; Woods,HA; Gamboa,M; Watanabe,K and Stanford,JA 2020 Remarkable anoxia tolerance by stoneflies from a floodplain aquifer. Ecology, 101(10), p.e03127. PDF
     Abstract: "Alluvial aquifers are key components of river floodplains and biodiversity worldwide, but they contain extreme environmental conditions and have limited sources of carbon for sustaining food webs. Despite this, they support abundant populations of aquifer stoneflies that have large proportions of their biomass carbon derived from methane. Methane is typically produced in freshwater ecosystems in anoxic conditions, while stoneflies (Order: Plecoptera) are thought to require highly oxygenated water. The potential importance of methane-derived food resources raises the possibility that stonefly consumers have evolved anoxia-resistant behaviors and physiologies. Here we tested the anoxic and hypoxic responses of 2,445 stonefly individuals in three aquifer species and nine benthic species. We conducted experimental trials in which we reduced oxygen levels, documented locomotor activity, and measured survival rates. Compared to surface-dwelling benthic relatives, stoneflies from the alluvial aquifer on the Flathead River (Montana) performed better in hypoxic and anoxic conditions. Aquifer species sustained the ability to walk after 4-76 h of anoxia vs. 1 h for benthic species and survived on average three times longer than their benthic counterparts. Aquifer stoneflies also sustained aerobic respiration down to much lower levels of ambient oxygen. We show that aquifer taxa have gene sequences for hemocyanin, an oxygen transport respiratory protein, representing a possible mechanism for surviving low oxygen. This remarkable ability to perform well in low-oxygen conditions is unique within the entire order of stoneflies (Plecoptera) and uncommon in other freshwater invertebrates. These results show that aquifer stoneflies can exploit rich carbon resources available in anoxic zones, which may explain their extraordinarily high abundance in gravel-bed floodplain aquifers. These stoneflies are part of a novel food web contributing biodiversity to river floodplains."

Nebeker,AV and Gaufin,AR 1967 Geographic and seasonal distribution of the Notonectidae Capniidae of western North America (Plecoptera). Journal of the Kansas Entomological Society 40(3)415-421 Abstract and first page

Needham,JG and Claassen,PW 1925 A Monograph of the Plecoptera of North America. Entomological Society of America, Lafayette, Indiana. 397 pages.
      Described as Capnia crinita.

Nelson,RC and Baumann,RW 1989 Systematics and distribution of the winter stonefly genus Capnia (Plecoptera: Capniidae) in North America. Great Basin Naturalist 49, 289-363. PDF

Newell,RL; Baumann,RW and Stanford,JA 2008 Stoneflies of Glacier National Park and Flathead River basin, Montana. International Advances in the ecology, zoogeography, and systematics of mayflies and stoneflies. University of California Publications in Entomology, Berkeley and Los Angeles, pp.173-186. PDF
     Quote from page 176: "Stoneflies recorded from hyporheic habitats (pumped wells) included: Alloperla severa, Capnia confusa, Claassenia sabulosa, Diura knowltoni, Hesperoperla pacifica, Isocapnia crinita, I. grandis, I. integra, I. vedderensis, Isoperla fulva, Kathroperla, Paraperla frontalis, and P. wilsoni"

Stanford,JA and Gaufin,AR 1974 Hyporheic communities of two Montana rivers. Science 185:700-702. PDF

Stanford,JA and Ward,JV 1993 An ecosystem perspective of alluvial rivers: connectivity and the hyporheic corridor. Journal of the North American Benthological Society, 48-60.

Zenger,JT and Baumann,RW 2004 The Holarctic winter stonefly genus Isocapnia, with an emphasis on the North American fauna (Plecoptera: Capniidae). Monographs of the Western North American Naturalist, 2(1) 65-95. HTML PDF
      The authors studied a specimen collected from the Gunnison River in April of 1954 by William Ricker. Quote: "Species in the genus Isocapnia can be divided into 5 groups based on the phylogeny of the genus: --snip-- the Crinita Group: I. crinita, I. agassizi, and I. palousa n. sp., characterized by the presence of micropterous males and by forward or upward curving epiproct. --snip-- In the Crinita Group, I. crinita extends from near Fairbanks, Alaska, south along the Rocky Mountains into Utah, Colorado, and northern New Mexico."

Brown, WS 2004 Stoneflies or Plecoptera of Gunnison County, Colorado