Isoperla obscura (Zetterstedt, 1840)

Judson, Sarah W. & Nelson, C. Riley, 2012, 3541, Zootaxa 3541, pp. 1-118 : 49

Isoperla obscura (Zetterstedt, 1840)

SYNONYMY

Perla obscura Zetterstedt, 1840

Perla grisepennis Pictet, 1841

Perla tenella Rambur, 1842

Chloroperla limbata Bengtsson, 1933

Isoperla obscura Brinck, 1952

TYPE LOCALITY: Sweden: Lappland .

DIAGNOSIS: Adult head coloration is generally infuscate with dark pigmentation connecting the ocelli and an interocellar pale oval closed posteriorly by dark pigmentation ( Fig. 341). A nearly continuous pale line is present from the clypeus through the mesoscutum, Isoperla obscura lacks golden markings on the anterior lobes of the mesoscutum above the wing insertion points ( Fig. 341), which is distinct from the mesonotum coloration of Kaszabia nigricauda and I. kozlovi ( Fig. 350, 326) which otherwise have vaguely similar head coloration. Males have dark, heavily sclerotized paraprocts, the tips of which are pointed and arch over the 10th tergum, but are not diagnostic. The male penis, if extruded as illustrated in Zwick and Surenkholoo (2005), has a V-shaped row of sharp teeth and lacks large sclerites. The female subgenital plate is triangular with a rounded apex ( Fig. 343), resembling K. nigricauda and I. kozlovi ( Fig. 353, 329). Also like K. nigricauda , the plate is long, and completely covers segments 8 and 9, whereas the plate of I. kozlovi only extends over half of segment 9. Female specimens more readily distinguished by head and other coloration. Nymph head coloration ( Fig. 308) is similar to I. mongolica with a pale oval in the ocellar region in line with two other ovals located anterior and poster to the ocellar oval, though I. obscura is lighter overall especially without dark pigmentation on the posterior margin of the head. The nymph is also distinct from I. mongolica based on abdominal coloration, specifically the placement of pale heart shaped marks of which I. obscura has one medial marking on each of the anterior segments, but none on the terminal segment as in I. mongolica . Nymph also noted to have similar coloration to K. nigricauda (Teslenko 2008) .

DISTRIBUTION—Global: TransPalearctic— Regional: AOB, IDB— Aimag: BO, BU, DA*, KhD*, KhG, SE, TO^.

DISCUSSION: We primarily collected I. obscura near larger rivers like the Selenge and Eroo, but this species was also collected historically near a lake in western Mongolia. ENM range predictions indictate that this species may occur in eastern Mongolia (Fig. 394).