Isocapnia guentheri (Joost, 1970)

Judson, Sarah W. & Nelson, C. Riley, 2012, 3541, Zootaxa 3541, pp. 1-118 : 20

Isocapnia guentheri (Joost, 1970)

SYNONYMY

Capnia guentheri Joost, 1970

Isocapnia guentheri Zhiltzova, 1972

TYPE LOCALITY: Mongolia: Archangai [Arkhangai], Tamir River .

DIAGNOSIS: The male of I. guentheri is brachypterous ( Fig. 50), whereas other Isocapnia males in Mongolia are macropterous ( Fig. 55). The male epiproct ( Fig. 51) is narrow and long, approximately the length of 2 abdominal segments. This trait is shared with I. kudia ( Fig. 56), but is longer than the epiproct of I. sibirica (Zapekina-Dulkeit, 1955) ( Fig. 61). The apex of the epiproct forms a beak-like shape, rounded at the tip and curved back to a point creating a subapical hook. In contrast, I. kudia has two points or hooks on the epiproct apex and I. sibirica has a truncate apex lacking additional processes. The vesicle of sternum 9 in males is narrow with prominent hairs at the apex ( Fig. 52). Other Isocapnia have a more rounded vesicle with shorter or less pronounced hairs ( Fig. 62). The female subgenital plate is deeply incised, although the sclerotized portion is flush with the preceding membrane ( Fig. 53). The plate of I. sibirica is similar to I. guentheri in general shape and outline ( Fig. 63), but the plate of I. guentheri is more uniform in color. Nymphs exhibit a central dark mark on the head and light coloring posterior to the eyes, whereas I. kudia is dark behind the eyes. The nymph of I. sibirica is currently unknown and unavailable for comparison.

DISTRIBUTION—Global: East Palaearctic— Regional: AOB, IDB— Aimag: AR, BU^, KhG^, SE^, TO^, UB^, ZA.

DISCUSSION: I. guentheri was originally described from Mongolia by Joost (1970). The species has since been documented throughout the Russian Far East (Zenger & Baumann 2004). It is the most widespread Isocapnia species in Mongolia ( Fig. 54).