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Stoneflies - Plecoptera: Perlodidae of Gunnison County, Colorado

Introduction to Isogenoides

Klapálek, 1912
Updated 5 August 2017
TSN 103124

Provisional Species List

Isogenoides colubrinus
Isogenoides elongatus
Isogenoides zionensis

Good Links

On this website:
Key to Perlodidae Nymphs

Other Websites:
John Sandberg has many Isogenoides papers, drumming recordings and other things http://www.ias.unt.edu/~StoneflyHome/Home/


Baumann,RW, Gaufin,AR and Surdick,RF 1977 The stoneflies (Plecoptera) of the Rocky Mountains. Memoirs of the American Entomological Society 31, 1-208.
     Quote from page 126 "The large dark stoneflies of the genus Isogenoides are distinguished from all other perlodids by their mesosternal ridge pattern. Both adults and nymphs have a median ridge connecting the transverse ridge to the fork of the y-ridge (figs. 23, 29). The tenth tergum of the male is completely cleft and the epiproct is slender with a terminal or subterminal backwardly directed sclerotized or membranous hook or hooks (figs. 376, 377). Ventral lobes are well developed on the seventh segment. The epiproct and subgenital plate are used to differentiate the three Rocky Mountain species. Nymphs are similar but vary in the serration of the mandibles.
This genus is usually found in large rivers but does occur in large creeks at the headwaters of rivers. Nymphs of Isogenoides seem to be well adapted to life in large silty rivers because they are the only large perlodids found in the lower reaches. "
     Also see (Sandberg, 2005).

DeWalt,RE and Stewart,KW 1995 Life histories of stoneflies (Plecoptera) in the Rio Conejos of southern Colorado. Great Basin Naturalist 55, 1-18.

Hanson,JF 1949 Studies on the Plecoptera of North America: V. Notes on Isogenoides. Bulletin of the Brooklyn Entomological Society 44:109-116.

Klapálek, Frantisek 1912 Plécoptères. I. Fam. Perlodidae; [monographische Revision. II. Fam. Perlidae; Subfam. Perlinae, Subfam. Neoperlinae; mongraphische Revision] Series Sélys-Longchamps, Edmond de, baron, 1813-1900. Collections zoologiques; catalogue systematique et descriptif, fasc. 4, pt. 1-2.
     Original description of the genus Isogenoides split out as a subgenus.

Kreutzweiser DP, Holmes SB, Behmer DJ. 1992 Effects of the herbicides hexazinone and triclopyr ester on aquatic insects. Ecotoxicology Environmental Safety 23(3):364-74. Abstract
     They tested the effects of the herbicides (Velpar L) and triclopyr ester (Garlon 4) on a number of aquatic insects in indoor and outdoor artifical streams. As with all 13 species of aquatic insects tested, Isogenoides suffered no mortality at the maximum concentration of 80 mg/liter of hexazinone. Significant drift and mortality of Isogenoides sp. occurred at 32 mg/liter of Triclopyr ester. The LC50 of Triclopyr ester was 61.7 mg/liter for Isogenoides sp.

Richardson,JW; Gaufin,AR 1971 Food habits of some western stonefly nymphs. Transactions of American Entomological Society 97, 91-121.

Sandberg,JB 2005 The stonefly genus Isogenoides Klapálek (Plecoptera: Perlodidae) of North America: Systematics, behavior and ecology. Ph.D. dissertation. University of North Texas, Denton. Available as a 60MB pdf on Sandberg's website

Sandberg,JB; Stewart,KW 2003 Continued studies of drumming in North American Plecoptera; Evolutionary implications. In: Research Update on Ephemeroptera and Plecoptera. Ed: Gaino,E University of Perugia, Perugia, Italy, 73-81.

Sandberg,JB and Stewart,KW 2004 Capacity for extended egg diapause in six Isogenoides Klapálek species (Plecoptera: Perlodidae). Transactions of the American Entomological Society 130(4): 411-423. PDF
     Abstract: "The eggs of six Isogenoides species have been incubated at a single, approximately simulated, San Miguel River, Colorado, seasonal temperature regime for 2-5 years. Eggs were collected from reared, laboratory-mated females of I. colubrinus, I. doratus, I. elongatus, I. frontalis, I. varians, and I. zionensis. Eggs were held in 8 ml containers and visually examined usually weekly for development and hatch. Only some I. zionensis eggs from a combined first and second mass of a Leopard Creek, Colorado population hatched directly within two weeks, continuing until late September, and resuming mainly May-June the following year; one and two eggs hatched in 2002 and 2004, respectively. I. doratus and I. varians experienced hatch only after an over-summer, 3-4 month diapause, and I. varians again in late August-September during the second year. Populations of I. colubrinus, I. elongatus, I. frontalis and a San Miguel River, Colorado population of I. zionensis began hatching only in the year following deposition, after a 10-12 month diapause. Some hatching of these four species occurred at spring-summer temperatures in subsequent years (2nd, 3rd, 3rd, and 4th years, respectively), with no intervening hatch at winter temperatures. The study confirms extended, usually asynchronous diapause and hatching for from 3 months to 4 years, probably genetically controlled, in the six species, and a great degree of adaptive capacity for diapause in the genus Isogenoides."

Sandberg,JB and Stewart,KW 2005 Life History of the stonefly Isogenoides zionensis (Plecoptera: Perlodidae) from the San Miguel River, Colorado. Illiesia 1(4)21-32.     http://www2.pms-lj.si/illiesia/Illiesia01-04.pdf

Sandberg,JB and Stewart,KW 2005a Vibrational communication (Drumming) of the nearctic stonefly genus Isogenoides (Plecoptera: Perlodidae). Transactions of American Entomological Society 131 1+2, 111-130. PDF

Sandberg,JB and Stewart,KW 2005b Holomorphology and systematics of the stonefly genus Isogenoides (Plecoptera: Perlodidae). Transactions of American Entomological Society 131 3+4, 269-345.

Stanford,JA and Ward,JV 1989 Serial discontinuities in a Rocky Mountain river. I. Distribution and abundance of Plecoptera. Regulated Rivers: Research and Management 3, 169-175.

Stewart,KW and Stark,BP 2002 Nymphs of North American Stonefly Genera. 2nd edition The Caddis Press, Columbus, Ohio. 510 pages. Illustrations of Isogenoides zionensis on page 404-405, figures 14.27-14.28

Mesosternal Y-arms.
Only visible easily on mature nymphs.
Look at the nymph's belly on the middle segment with legs.
This one is different from other stoneflies because there's so many lines and connections between the arms. See Pictetiella expansa for an example of a simpler mesosternal y arm.

Brown,WS 2005 Plecoptera of Gunnison County, Colorado, USA