Kaszabia nigricauda (Navás, 1923)

Judson, Sarah W. & Nelson, C. Riley, 2012, 3541, Zootaxa 3541, pp. 1-118 : 50

Kaszabia nigricauda (Navás, 1923)

SYNONYMY

Isoperla nigricauda Navás, 1923

Kaszabia spinulosa Raušer, 1968

Kaszabia nigricauda Zhiltzova, 1979

TYPE LOCALITY: Mongolia .

DIAGNOSIS: Kaszabia nigricauda adults have a dark central U-shaped marking connecting the ocelli on an otherwise pale head. The mesoscutum has anterior golden-yellow coloration above the wing insertions ( Fig. 350). The similarly colored I. kozlovi ( Fig. 326) shares these golden mesoscutum markings, but not the head coloration, whereas I. obscura lacks the golden markings but has a similar infuscate head including a pale oval mark in the ocellar region which is closed posteriorly ( Fig. 341) whereas the pale central mark of K. nigricauda is open posteriorly. Males have stout paraprocts that curve dorsally over the 10th tergum. The male also has unique dorsally-directed lateral processes on abdominal segments 3 and 4 ( Fig. 352). The male is otherwise externally indistinct from Isoperla species. The female subgenital plate triangular with a rounded apex ( Fig. 353), similar in shape to I. obscura and I. kozlovi . Also like I. obscura ( Fig. 343), the plate is long and completely covers segments 8 and 9, whereas the plate of I. kozlovi only extends over half of segment 9 ( Fig. 329). Female specimens are more readily distinguished by coloration. Nymphal coloration mimics the adult pattern and is similar to I. obscura nymphs ( Fig. 310, Teslenko 2008). Nymph otherwise highly similar to Isoperla species.

DISTRIBUTION—Global: East Palearctic— Regional: AOB, POB*— Aimag: AR, DO*, KhE*, KhG, SE*, TO, UB*, ZA^.

DISCUSSION: In Mongolia, K. nigricauda most often occurs in larger streams. The species appears to be restricted to the Selenge River basin ( Fig. 354), but historical collections are noted from eastern Mongolia and the predicted range shows moderate probability of encounter in the east.