3541 Author Judson, Sarah W. Author Nelson, C. Riley text Zootaxa 2012 2012-11-06 3541 1 118 journal article 1175­5334 505937B0-9F57-4068-82E6-8553826DD5AA Isoperla potanini (Klapalek, 1923) SYNONYMY Mesoperlina potanini Klapálek, 1923 Isoperla chasaudina Navás, 1923 Isoperla potanini Zwick and Surenkhorloo, 2005 TYPE LOCALITY: Mongolia : Khangai Mountains . DIAGNOSIS: The head of the adult is generally infuscate and dark ( Fig. 345 ) with pale, diamond-shaped central mark between the ocelli ( Fig. 345 ). Most other Mongolian Isoperla have a more rounded pale oval in the interocellar region. Cercal segments have a whorl of long hairs on each segment, useful for distinguishing it from I. asiaitca which has a single hair per segment. The male paraprocts are poorly sclerotized and pointed. This species entirely lacks a ventral lobe on sternum 8 ( Fig. 347 ), leaving this segment smooth along the posterior edge whereas all other Isoperla have distinct lobes ( Fig. 328 ), even in the case of I. asiatica , which is broadly joined but clearly protrudes past the posterior edge ( Fig. 318 ). The female has a short, broadly bilobed plate with a shallow median notch ( Fig. 348 ). Nymphal head coloration reminiscent of the adult pigmentation ( Fig. 309 ). DISTRIBUTION—Global: Endemic to Mongolia — Regional: AOB, IDB— Aimag: AR, BO, BR*, BU*, GA, KhD, KhG, OV, UB*, UV*, ZA. DISCUSSION: This species was originally described from Mongolian material and continues to be recorded only from northern and western Mongolia . The nymph was originally described by Raušer (1968). The nymphs we documented were collected concurrently with adults on multiple occasions, but were not formally reared to confirm association with adults. The species was recently moved from the genus Mesoperlina (Zwick & Surenkhorloo 2005) after having been noted as atypical for that genus by Zhiltzova (1970).