Megarcys signata ( Hagen 1874 )

Stewart, Kenneth W. & Kondratieff, Boris C., 2012, Larvae Of The Nearctic Species Of The Stonefly Genus Megarcys Klapálek (Plecoptera: Perlodidae), Illiesia 8 (3), pp. 16-36 : 20

publication ID	https://doi.org/ 10.5281/zenodo.4760667
DOI	https://doi.org/10.5281/zenodo.4762539
persistent identifier	https://treatment.plazi.org/id/C250BC3D-FFBC-FF9F-FE86-385AFAEF43F5
treatment provided by	Felipe
scientific name	Megarcys signata ( Hagen 1874 )
status

Treatment

Megarcys signata ( Hagen 1874) View in CoL

( Figs. 2-11 View Fig View Figs , 13 View Figs , 18, 19 View Figs , 25 View Figs , 31 View Figs , 37 View Figs , 43 View Figs , 50 View Figs , 61 View Figs , 71 View Figs , 80 View Figs , 85 View Figs a-b, Table 1 View Table 1 )

Distribution. Rocky Mountains, New Mexico- Nevada northward to British Columbia and Alaska. Material examined. Colorado: Boulder Co., South Boulder Creek, 3.2 km west of Tolland, 7-VII-1991, B. Kondratieff, R. Durfee, 11♂ (both macropterous and brachypterous), 6♀, 11♀ larvae, 2♂ exuviae; Middle St. Vrain Creek, FR 14 west of Peaceful Valley, 17- VII-1993, B. Kondratieff, B. Painter, 1♂, 2♀ larvae; Gunnison Co., Mosquito Creek/confluence Quartz Creek, Colorado Rd. 76 north of Pitkin, 9-VII-2008, K. Stewart, reared series: 2 reared ♂ with exuviae, 1 reared ♀ with exuvium, 8♂ larvae, 14♀ larvae; Larimer Co., outlet stream of Chasm Lake, Rocky Mountain National Park, El. 3536m, 16-VII-1994, B. Kondratieff, R. Durfee, 2 brachypterous ♂ larvae, 1♀ brachypterous larva. Montana: Gallatin Co., 5.63 km off Trail Creek Rd., 10-6-1987, B. Kondratieff, 2♂, 2♂ larvae, 3♀ larvae, 3♂ exuviae, 2♀ exuviae. Wyoming: Teton Co., Granite Creek, Granite Falls, 8-VII-2001, B. VanWieren, 1♀, 2♀ larvae. Yukon Territory: Alaska Hwy., stream crossing between Watson Lake and Whitehorse, V-1997, P. Niblett, 4♂ larvae, 3♀ larvae.

Characters. Head capsule width ♂ 3.24-3.48mm, ♀ 4.14-4.20mm; pronotal width ♂ 2.64-2.76mm, ♀ 3.36- 3.90mm; body length ♂ 16.2-18.5mm, ♀ 25-26mm ( Table 1 View Table 1 ). Color and pigmentation ( Figs. 2 View Fig , 3 View Figs , 13 View Figs , 19 View Figs , 25 View Figs , 43 View Figs , 50 View Figs ), lacinia ( Fig. 21 View Figs ), and dorsomesal band of erect silky white hairs ( Figs. 18, 19 View Figs ) typical of genus and as described by Stewart & Stark (1988, 2002). Wingpads of ♂ and ♀ ( Figs. 2 View Fig , 25 View Figs ) macropterous (or brachypterous in high elevation streams). Gill number and arrangement typical of genus ( Fig. 61 View Figs ). Submental gill length ♂ 0.36-0.48mm, ♀ 0.54- 0.60mm; anterior supracoxal gill length ♂ 0.36- 0.42mm, ♀ 0.45-0.0.60mm (shorter in high elevation Chasm Lake outlet stream in Rocky Mountain National Park) ( Table 1 View Table 1 ). Legs ( Figs. 6 View Figs , 31 View Figs ) with setation typical of genus as described by Stewart & Stark (2002).Y-arms of mesosternum meet anterior corners of furcal pits ( Figs. 7, 8 View Figs , 37 View Figs ), typical of genus. Cercal segments ♂ 26 ( Table 1 View Table 1 ), as described by Stewart & Stark (2002) with apical whorl of short setae on cercomeres and dorsal fringe of silky white hairs ( Fig. 11 View Figs ). Developing membranous, windsocklike posterior process of male epiproct ( Fig.71 View Figs ) evident in late instar individuals, and pointed posteroventrally in lateral view ( Fig. 80 View Figs ). Developing female subgenital plate of 8 th sternum ( Figs. 50 View Figs , 85 View Figs ) shallowly notched mesally.

Comments. The generic characters proposed by Stewart & Stark (1988, 2002) were further confirmed in these additional larvae examined. Color and pigmentation ( Figs. 2 View Fig , 3 View Figs , 13 View Figs , 19 View Figs , 25 View Figs , 31 View Figs , 43 View Figs , 50 View Figs ) were of a generic pattern that was similar in the other four species examined. The measured gill lengths, and shapes, were variable between left and right sides, individuals, and populations, therefore difficult to compare with the generalized terms “short” and “long” as used by Teslenko (2009) in her descriptions and keys to Palearctic species. Submental (SM) gills ( Figs. 8 View Figs , 61 View Figs ) are not visible from dorsal view; anterior supracoxal (ASC) gills and anterior mesothoracic and anterior metathoracic (AT2, AT3) gills ( Figs. 8 View Figs , 61 View Figs ) are “long” and usually visible in dorsal view.