Diura bicaudata (Linnaeus, 1758)

Judson, Sarah W. & Nelson, C. Riley, 2012, 3541, Zootaxa 3541, pp. 1-118 : 42

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.