Stoneflies - Plecoptera: Capniidae of Gunnison County, Colorado
Isocapnia grandis - Giant Snowfly (Banks) 1907
Updated 23 Dec 2023
TSN 102747
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On this website:
Isocapnia Introduction
References
Banks,N 1907 A list of Perlidae from British Columbia and Alberta. The Canadian Entomologist 39(10) 325-330.
Description from page 329:Arsapnia grandis, n. sp. -
Black; antennae brownish; legs brownish; wings brownish, sometimes darker on the anastomosis; venation dark brown. Posterior ocelli about twice as far apart as from the eyes; pronotum about as long as broad, narrowed behind, slightly rugose each side; abdomen elongate, setas nearly as long as the abdomen, their joints (beyond basal ones) very long and slender; hind tibiae scarcely reaching to tip of abdomen. Wings large and elongate, three to seven costal cross-veins, also one beyond end of subcosta, apical cells longer than discal cell; in the median and cubital areas there is but one cross-vein, which is continuous.
Expanse, 22-26 mm.
Specimens from Wellington, February; Vancouver, April; and Banff, Alberta, 17th June.
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 80: "This species is common in rivers throughout the Pacific Northwest but is rare in more southern latitudes. The adults emerge from March to June. "
DelVecchia,AG; Stanford,JA and Xu,X 2016 Ancient and methane-derived carbon subsidizes contemporary food webs. Nature communications, 7 PDF
Hanson,JF 1946 Comparative morphology and taxonomy of the Capniidae (Plecoptera). The American Midland Naturalist, 35(1)193-249.
The author synonymized I. fumosa and C. fumigata Claassen (1937) with I. grandis.
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 family Capniidae of western North America (Plecoptera). Journal of the Kansas Entomological Society 40(3)415-421 Abstract and first page
Nelson,CH 2009 Surface ultrastructure and evolution of tarsal attachment structures in Plecoptera (Arthropoda: Hexapoda). Aquatic Insects, (31)523-545. Html
The author used scanning electron microscopy (SEM) to image the plantar surfaces of the stonefly tarsomeres and pretarsus of Isocapnia grandis and a number of other species.
Quote from page 527 "Tarsus and pretarsus of this species are shown in Figure 9 and are very similar to those of the Nemouridae and Leuctrinae described previously, except that tarsomere 1 is slightly shorter than tarsomere 3 and tarsomere 2 is very short, approximately one-third the length of tarsomere 3. Moreover, the setae of tarsomeres 1-3 surfaces are more numerous on the plantar surfaces."
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"
Radford,DS and Hartland-Rowe,R 1971 Emergence patterns of some Plecoptera in two mountain streams in Alberta. Canadian Journal of Zoology, 49(5), 657-662.
Ricker,WE 1959 The species of Isocapnia Banks (Insecta, Plecoptera, Nemouridae). Canadian Journal of Zoology, 37(5), 639-653.
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.
Stewart,KW and Stark,BP 2002 Nymphs of North American Stonefly Genera. 2nd edition The Caddis Press, Columbus, Ohio. 510 pages. Illustration of nymph on pages 133-134 figure 7.11-7.12
Stewart,KW and Zeigler,DD 1984 Drumming behavior of twelve North American stonefly (Plecoptera) species: First descriptions in Peltoperlidae, Taeniopterygidae and Chloroperlidae. Aquatic Insects. 6(1) 49 - 61. Abstract
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
Quote: "Species in the genus Isocapnia can be divided into 5 groups based on the phylogeny of the genus: the Grandis Group: I. grandis and I. rickeri n. sp., [are] characterized by the lack of micropterous males and by an S-shaped epiproct. --snip-- The distribution of the Grandis Group demonstrates the 2 extremes in Isocapnia distribution. Isocapnia grandis is found from the North Slope of Alaska south to Utah and west to the northern Sierra Nevada. Isocapnia rickeri n. sp., on the other hand, is limited to an isolated area, one in which it likely evolved, south of the Snake River in southeastern Washington and northeastern Oregon."
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