Megarcys yosemite ( Needham & Claassen 1925 )

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 : 33

publication ID	https://doi.org/ 10.5281/zenodo.4760667
DOI	https://doi.org/10.5281/zenodo.4762547
persistent identifier	https://treatment.plazi.org/id/C250BC3D-FFA9-FF8A-FF6D-3D63FB4D4172
treatment provided by	Felipe
scientific name	Megarcys yosemite ( Needham & Claassen 1925 )
status

Treatment

Megarcys yosemite ( Needham & Claassen 1925) View in CoL

( Figs. 1 View Fig , 54-59 View Figs , 69 View Figs , 74 View Figs , 78, 83 View Figs , 88 View Figs a-b, Table 1 View Table 1 )

Distribution. California, Washington (high elevation streams).

Material examined. California: Inyo Co., Ruby Creek, about 56.33km from the Mt. Lyell Type Locality, El. 3444m, water temp. 12.2°C, 20-VIII- 2010, L. Serpa, 1 pre-emergent ♂ larva (died in rearing), 4 early instar larvae (on a previous date in 2008, 1♂ determined by R. Baumann, and 1♀ larva, were collected by L. Serpa at this site; personal correspondence); GoogleMaps Mono Co. , Coldwater Creek , 37°34 ’ 27.4 ’’ N 118° 59 ’ 16.7 ’’ W, El. 3063m, water temp. 4.44°C, 19-VIII-2010, L. Serpa, 2 reared brachypterous ♂ (one ♂ determined by R.W. Baumann ), 2 brachypterous ♂ larvae, 4 brachypterous ♀ larvae, 6 early instar larvae with average head capsule width of 1.14mm, and average body length of 5.64mm; GoogleMaps Coldwater Creek , Sky Meadow, 2.7km above Coldwater Creek Campground, El. 3067m, water temp. 4.49°C, 2 reared ♂, 1 reared ♀ ( Fig. 1 View Fig ), 6 larvae (5 died in rearing: 07-IX-2010 collection date, 17-IX- 2010 emergence date) (personal correspondence, J. Sandberg ). GoogleMaps

Characters. Head capsule width ♂ 2.88-3.36mm, ♀ 3.60-3.84mm; pronotal width ♂ 2.76-3.30mm, ♀ 3.54-3.66mm; body length ♂ 17.64-20.2mm, ♀ 22.4- 22.9mm ( Table 1 View Table 1 ). Color and pigmentation ( Figs. 54- 59 View Figs ), lacinia, and dorsomesal band of erect silky white hairs typical of genus. Wingpads of ♂ ( Figs. 55 View Figs , 78 View Figs ) and ♀ brachypterous, reflective of adults. Gill number and arrangement typical of genus ( Fig. 69 View Figs ). Submental gill length ♂ 0.27-0.36mm, ♀ 0.33- 0.45mm; anterior supracoxal gill length ♂ 0.18- 0.30mm, ♀ 0.24-0.33mm ( Table 1 View Table 1 ). Legs ( Fig. 56 View Figs ) with setation typical of genus. Y-arms of mesosternum ( Fig. 57 View Figs ) typical of genus. Cercal segments ♂ 24-26 ( Table 1 View Table 1 ), with setation typical of genus. Developing membranous windsock-like process of male epiproct ( Figs. 59 View Figs , 74 View Figs ) evident in late instar individuals, and pointed posteroventrally in lateral view ( Fig. 83 View Figs ). Developing female subgenital plate of 8 th sternum ( Fig. 88a, b View Figs ) shallowly notched mesally.

Comments. Males and females ( Fig. 1 View Fig ) of this high elevation California population are brachypterous, reflected by the very short wingpads of preemergent larvae. The submental and anterior supracoxal gill lengths of both sexes of larvae, like the brachypterous male larvae of M. subtruncata larvae of Quinn Spring, Oregon, and brachypterous male and macropterous female larvae of M. watertoni from Iceberg Creek, Montana, were substantially shorter than those of the macropterous populations studied ( Table 1 View Table 1 ). Otherwise, coloration and pigmentation, generic, and other specific characters of larvae were not separable from the other four species.