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 Diura bicaudata (Linnaeus, 1758) SYNONYMY Phryganea bicaudata Linneaus, 1758 Perla bicaudata Newman, 1839 Diura bicaudata Ricker, 1952 TYPE LOCALITY: Sweden : Lappland . DIAGNOSIS: The adult males of this species are brachypterous, with wing tips always terminating at or prior to tergum 2 ( Fig. 263 ), whereas in D. majuscula , they typically extend past tergum 2. Both sexes have a pale subtriangular mark in the interocellar region that is open posteriorly ( Fig. 263 ), as opposed to D. majuscula whose mark is rounded anteriorly and closed posteriorly ( Fig. 268 ). The pronotum has a pale median stripe, slightly thinner than that of D. majuscula . The subanal lobes of the male are smooth ( Fig. 264, 265 ) and completely lack setation, whereas the lobes of D. majuscula are noticeable pilous ( Fig. 269 ). The female subgenital plate is truncate on the posterior margin and sometimes with a slight depression ( Fig. 266 ), in contrast to D. majuscula which is broadly rounded ( Fig. 270 ). Nymph has been extensively collected in Europe and Canada , but is indistinguishable from other species of Diura unless in final instars with apparent adult genitalic structures. DISTRIBUTION—Global: Circumpolar— Regional: AOB, IDB— Aimag: AR, BO, KhG^. DISCUSSION: In Mongolia , D. bicaudata was typically found in moderately sized rivers located in higher elevation mountain valleys. Many European species of Dictyopterygella , Dictyopteryx , Isogenus , and Perla were placed in D. bicaudata over the course of is synonymic history (DeWalt, Neu-Becker & Steuber 2010). These species are not treated in this synonmy due to lack of relevance for Mongolia .