Stonefly Species Megarcys signata (Larimide Springflies)

Source: Larvae Of The Nearctic Species Of The Stonefly Genus Megarcys Klapálek (Plecoptera: Perlodidae)

(Figs. 2 - 11, 13, 18, 19, 25, 31, 37, 43, 50, 61, 71, 80, 85 a-b, Table 1)Source: Larvae Of The Nearctic Species Of The Stonefly Genus Megarcys Klapálek (Plecoptera: Perlodidae)

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