Megarcys watertoni ( Ricker 1952 )

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 : 28-33

publication ID	https://doi.org/ 10.5281/zenodo.4760667
DOI	https://doi.org/10.5281/zenodo.4762543
persistent identifier	https://treatment.plazi.org/id/C250BC3D-FFB4-FF8A-FE89-3D9BFE0443D8
treatment provided by	Felipe
scientific name	Megarcys watertoni ( Ricker 1952 )
status

Treatment

Megarcys watertoni ( Ricker 1952) View in CoL

( Figs. 17 View Figs , 23 View Figs , 29 View Figs , 35 View Figs , 41 View Figs , 47 View Figs , 53 View Figs , 65-68 View Figs , 73 View Figs , 75-77, 82 View Figs , 87 View Figs , Table 1 View Table 1 )

Distribution. Northern Rocky Mountains; Idaho, Montana, Alberta, British Columbia.

Material examined. British Columbia: Kooteny National Park, 8-VII-1985, 2♂, 2♀, many exuviae. Montana: Carbon Co., Baring Falls , 28-VII-1989, B. Stark et al., 1♀ larva; Rock Creek , 0.8 km below Glacier Lake Trailhead, 22-VII-1989, B. Stark, 1 brachypterous ♂ (to Ab9), 1 brachypterous ♂ (to Ab 5), 4♀, 1♀ larva; Glacier Co. , Baring Creek , Sunrift Gorge , Glacier National Park , 22-VII-1979, K. Stewart, R. Baumann, B. Stark, 4♂ larvae, 5♀ larvae; Iceberg Creek at Iceberg Lake , Glacier National Park , 29-VII-1969, R. Haick, 2 brachypterous ♂, 1♀; 3-VII- 1972, J. Stanford, 3♂ larvae, 1♀ larva; 21-VII-1979, K. Stewart, R. Baumann, B. Stark, 1♂ larva, 1♀ larva; Roes Creek , Rising Sun Campground, Glacier National Park , 6-VII-1963, coll.?, 3♂, 3♀; Flathead Co. , Bear Creek / jct. Middle Fork Flathead River , Hwy. 2, 7-VI-1996, R. Hansen, B. Ward (C. Nelson # 6347), 1♂ larva, 1♀ larva; Juliet Creek , Bob Marshall Wilderness, 19-VII-1981, J. Stanford, 1♀; Lion Creek , 14-VII-1985, K. Stewart, 4♂ larvae, 4♀ larvae; Logan Creek at Logan Pass, Glacier National Park , 11-VII- 1987, K. Stewart, 1♂ larva; 2100 m, 10-X-1991, J. Giersch, 5 small larvae; Logan Creek /confluence McDonald Creek , Glacier National Park , 29-VI-1995, J. Giersch, 2♂, 1♀; Spotted Bear River at Pentagon, Bob Marshall Wilderness, 21-VII-1981, J. Stanford, 1♂ larva.

Characters. Bear Creek, Montana, macropterous population: Head capsule width ♂ 3.72mm, ♀ 4.32- 4.38mm; pronotal width ♂ 3.00mm, ♀ 3.90mm; body length ♂ 20.4, ♀ 24.3mm ( Table 1 View Table 1 ). Color and pigmentation, lacinia, and dorsomesal band of erect white hairs similar to Iceberg Creek , Montana, population (described below) ( Figs. 17 View Figs , 23 View Figs , 29 View Figs , 35 View Figs , 41 View Figs , 47 View Figs , 53 View Figs ). Wingpads of ♂ ( Fig. 76 View Figs ) and ♀ macropterous. Gill number and arrangement typical of genus. Submental gill ( Fig. 66 View Figs ) length ♂ 0.54-0.57mm, ♀ 0.66-0.72mm; anterior supracoxal gill ( Fig. 67 View Figs ) length ♂ 0.36mm, ♀ ( Fig. 68 View Figs ) 0.60-0.66mm ( Table 1 View Table 1 ). Legs with typical setation of genus as described by Stewart & Stark (2002). Y-arms of mesosternum typical of genus. Cercal segments ♂ 26 ( Table 1 View Table 1 ), with setation typical of genus. Developing membranous windsock-like process of male epiproct evident in late instar individuals, and pointed posteroventrally in lateral view like the Iceberg Creek, Montana, population below ( Figs. 73 View Figs , 82 View Figs ). Developing female subgenital plate of 8 th sternum shallowly notched mesally like Glacier Creek population below ( Fig. 87 View Figs ).

Iceberg Creek, Montana, male brachypterous (female macropterous) population: Head capsule width ♂ 2.76-3.00mm, ♀ 3.48-3.84mm; pronotal width ♂ 2.58-2.64mm, ♀ 3.36mm; body length ♂ 16.08-17.28mm, ♀ 20.9-22.2mm ( Table 1 View Table 1 ). Color and pigmentation (Figs, 17, 29, 35, 41, 47, 53), lacinia, ( Fig. 23 View Figs ), and dorsomesal band of erect silky white hairs typical of genus. Wingpads ♂ ( Fig. 75 View Figs ) brachypterous, ♀ ( Fig. 29 View Figs ) macropterous. Gill number and arrangement ( Fig. 65 View Figs ) typical of genus. Submental gill length ♂ 0.24-0.27mm, ♀ 0.36- 0.39mm; anterior supracoxal gill length ♂ 0.24- 0.27mm, ♀ 0.33-0.42mm ( Table 1 View Table 1 . Legs ( Fig. 35 View Figs ) with typical setation of genus. Y-arms of mesosternum ( Fig. 41 View Figs ) typical of genus. Cercal segments ♂ 26 ( Table 1 View Table 1 ), with setation typical of genus. Developing membranous windsock-like process of male epiproct ( Fig. 73 View Figs ) evident in late instar individuals, and pointed posteroventrally in lateral view ( Fig. 82 View Figs ). Developing female subgenital plate of 8 th sternum ( Fig. 87 View Figs ) shallowly notched mesally.

Comments. The high elevation Iceberg Creek population was similar in color and pigmentation, and other generic characters, to the lower elevation Bear Creek population, except for male brachyptery and smaller body and gill sizes. Head capsule widths of males and females were on average 21.4% and 17.8%, respectively, smaller; pronotal widths of males and females were on average 13.0% and 13.8% smaller, and body lengths were on average 10.0% and 11.4% smaller ( Table 1 View Table 1 ). Gill lengths were substantially smaller; submental gills of males and females were on average 54.1% and 45.7% shorter; anterior supracoxal gills of males and females were on average 29.2% and 40.5% shorter, respectively ( Table 1 View Table 1 ).