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 Mesocapnia altaica (Zapekina-Dulkeit, 1955) SYNONYMY Capnia vidua altaica Zapekina-Dulkeit, 1955 Mesocapnia altaica Zwick, 1973 TYPE LOCALITY: Siberia : Altai . DIAGNOSIS: Adult males are brachypterous ( Fig. 65 , 67 ) and their average wing length is 1–1.5 mm . Females are also brachypterous but with longer wings than males, approximately 3–4 mm in length. The male epiproct usually extends to the anterior margin of tergite 9. It is relatively uniform in width ( Fig. 68 ) from both the lateral and dorsal views, with a pronounced and abrupt tapering at the apex. Based on historical illustrations (Raušer 1968) ( Fig. 72 ), the epiproct is most similar to that of M. silvatica , in which the epiproct is shorter and wider with more gradual tapering at the apex. The female subgenital plate forms a broad triangle ( Fig. 69 ), whereas the plates of M. silvatica and M. variabilis are rounded at the apex ( Fig. 79 ). Nymphs ( Fig. 70 ) are indeterminable to genus or species. DISTRIBUTION—Global: Sayan & Altai Mountains— Regional: IDB— Aimag: BO^. DISCUSSION: This is the first documented occurence of M. altaica in Mongolia . The species is endemic to the Altai Mountains for which it is named. We collected nymphs ( Fig. 70 ) concurrently with adults, but these were not reared to formally confirm association with adults.