Megarcys subtruncata Hanson 1942
Creators: name: Stewart, Kenneth W.
name: Kondratieff, Boris C.
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Plecoptera
Perlodidae
Megarcys
Megarcys subtruncata

description: <i>Megarcys subtruncata</i> Hanson 1942 (Figs. 14-16, 20, 22, 26-28, 32-34, 38-40, 44-46, 51, 52, 62-64, 72, 81, 86, Table 1) <b>Distribution.</b> California, Pacific Northwest (Oregon, Washington, British Columbia), and Northern Rocky Mountains (Idaho, Montana). <b>Material examined.</b> California: Butte Co., Butte Creek, Cherry Hill Campground, 12-V-2007, J. Sandberg, 1&amp;male;, 5 &amp;male; larvae, 5&amp;female; larvae. Shasta Co., Hat Creek at Hat Creek Lake, Lassen-Volcanic National Park, 6-VII-1979, K. Stewart, B. Stark, 1 reared &amp;female;, 1 pharate &amp;male; larva (cleared genitalia), 1&amp;female; larva; Hat Creek, Big Pine Camp, 26-IV-1987, B. Stark, R. Baumann, C. Nelson, 1&amp;male; larva. Oregon: Deschutes Co., Quinn River Spring, Quinn River Campground, 10-VI-2004, B. Stark, R. Baumann, 20&amp;male;, 13&amp;female;, 8&amp;male; larvae, 8&amp;female; larvae. Washington: Lewis Co., Ohanapecosh River, Grove of the Patriarchs, Mount Rainier National Park, 28-V-1997, B. Kondratieff, 1 reared &amp;male; with exuvium; Ohanapecosh River, Hwy. 123, North Silver Falls, Mount Rainier National Park, 23-V-2003, B. Kondratieff, J. Schmidt, R. Evans, 2&amp;male; larvae, 4&amp;female; larvae; Ohanapecosh River, Hwy. 123, Paradise River above Narada Falls, Mount Rainier National Park, 16-VIII-1999, B. Kondratieff, R. Lechleitner, 1&amp;female;, 2 reared &amp;female; with exuviae, 5 exuviae; Pierce Co., Fish Creek, Westside Road Bridge, Mount Rainier National Park, 21-VI-2003, B. Kondratieff, R. Zuellig, J. Schmidt, 2&amp;male;, 1&amp;female;, 1&amp;male; exuvium, 2&amp;female; exuviae; Fryingpan Creek, Sunrise Road, Mount Rainier National Park, 16-VIII-1999, B. Kondratieff, 1&amp;male; with exuvium, 1&amp;female; with 2 exuviae; Ipsut Creek at bridge, Mount Rainier National Park, 6-VI-1997, R. Lechleitner, 2&amp;female;, 1 exuvium. Characters. Butte Creek, California, macropterouspopulation: Head capsule width &amp;male; 3.78-3.90mm, &amp;female; 4.68-4.74mm; pronotal width &amp;male; 3.36-4.48mm, &amp;female; 4.20mm; body length &amp;male; 17.9-21.6mm, &amp;female; 22.2-25.5mm (Table 1). Color and pigmentation (Figs. 15, 27, 33, 39, 45, 51), lacinia (like Ohanapecosh River, Washington population Fig. 28), and dorsomesal band of erect silky white hairs typical of genus. Wingpads of &amp;male; (Fig. 27) and &amp;female; macropterous. Gill number and arrangement typical of genus (Fig. 62). Submental gill length &amp;male; 0.39-0.54mm, &amp;female; 0.54- 0.66mm; anterior supracoxal gill length &amp;male; 0.42- 0.54mm, &amp;female; 0.54-0.66mm (Table 1). Legs (Fig. 33) with typical setation of genus as described by Stewart &amp; Stark (2002). Y-arms of mesosternum (Fig. 39) typical of genus. Cercal segments &amp;male; 24-26 (Table 1), with setation typical of genus. Developing membranous windsock-like process of male epiproct (Fig. 72) evident in late instar individuals, and pointed posteroventrally in lateral view (Fig. 81). Developing female subgenital plate of 8 th sternum (Figs. 51, 86) shallowly notched mesally. <b>Quinn Spring, Oregon, brachypterous population</b>: As indicated by Stark &amp; Baumann (2005), larvae of this population, that they did not describe in detail, “agree in most respects” with the generic description in Stewart &amp; Stark (2002). Head capsule width &amp;male; 3.12-3.48mm, &amp;female; 4.20-4.22mm; pronotal width &amp;male; 2.94- 3.12mm, &amp;female; 4.02-4.26mm; body length &amp;male; 15.6-16.0mm, &amp;female; 19.5-21.2mm. Color and pigmentation (Figs. 16, 28, 34, 40, 46), lacinia typical of genus. Dorsomesal band of erect silky white hairs and those along the ecdysial suture of the head absent. Wingpads &amp;male; (Fig. 28) and female brachypterous. Gill number and arrangement typical of genus. Submental gill (Fig. 63) length &amp;male; 0.27-0.30mm, &amp;female; (Fig. 64) 0.34-0.36mm; anterior supracoxal gill length &amp;male; 0.21-0.24mm, &amp;female; 0.30-0.34mm (Table 1). Legs (Fig. 34) with typical setation of genus. Y-arms of mesosternum (Fig. 40) typical of genus. Cercal segments of &amp;male; 22+ (all broken), dorsal silky fringe (typical of the other four species) absent or with a few obscure setae on basal segments. Developing membranous, windsock-like process of male epiproct evident in late instar individuals, and pointed posteroventrally in lateral view like the Butte Creek, California, population (Fig. 81). Developing female subgenital plate of 8 th sternum shallowly notched mesally like the Butte Creek, California, population (Figs. 51, 86). <b>Comments.</b> The Quinn Spring, Oregon, brachypterous population exhibited these substantial character differences from generic and the Butte Creek, California, and Ohanapecosh River, Washington macropterous populations examined: 1) the dorsomesal band of erect silky white hairs and those along the ecdysial suture of the head were absent, 2) the dorsal silky fringe of basal cercal segments was absent or with only a few obscure setae present, 3) the body size (length) of pre-emergent males was on average 20% shorter, and females about 15% shorter (Table 1), 4) submental and anterior supracoxal gills of males (Fig. 63) were on average about 39% and 53% shorter, respectively (Table 1). The gills of the Quinn Spring population could therefore generally be described as “short” in comparison with “long” in the other two populations studied. This suggests that populations of this species in ecotypes may vary in wing length, body and gill size, and setation, but still conform to the diagnostic generic characters of gill arrangement and Y-arms extending to anterior corners of the furcal pits (Stewart &amp; Stark 2002).
description: Published as part of <i>Stewart, Kenneth W. &amp; Kondratieff, Boris C., 2012, Larvae Of The Nearctic Species Of The Stonefly Genus Megarcys Klapálek (Plecoptera: Perlodidae), pp. 16-36 in Illiesia 8 (3)</i> on pages 23-27, DOI: 10.5281/zenodo.4760667
description: {"references": ["Hanson, J. F. 1942. Records and descriptions of North American Plecoptera. Part II. Notes on North American Perlodidae. American Midland Naturalist, 28 (2): 389 - 407.", "Stewart, K. W. &amp; B. P. Stark. 2002. Nymphs of North American stonefly genera (Plecoptera), 2 nd Ed. The Caddis Press, Columbus, Ohio. 510 pp.", "Stark, B. P. &amp; R. W. Baumann. 2005. A micropterous crenon-dwelling population of Megarcys subtruncata Hanson (Plecoptera: Perlodidae). Western North American Naturalist, 65: 131 - 132."]}