Taenionema japonicum (Okamoto, 1922)

Judson, Sarah W. & Nelson, C. Riley, 2012, 3541, Zootaxa 3541, pp. 1-118 : 52

Taenionema japonicum (Okamoto, 1922)

SYNONYMY

Rhabdiopteryx japonica Okamoto, 1922

Taeniopteryx japonica Ueno, 1935

Rhabdiopteryx japonicum Illies, 1966

Taenionema japonicum Ricker and Ross, 1975

TYPE LOCALITY: Japan .

DIAGNOSIS: Adult is coloration highly contrasting ( Fig. 368), especially when preserved. The head has a light interocellar mark and light markings near the eyes. The pronotum has light reticulations, especially at the lateral margins. The male genitalia is demarcated by a sclerotized triangle ( Fig. 369) with processes emerging at each corner of the triangle, including the epiproct which emerges from the posterior apex of the triangle. Sternum 9 of male lacks a vesicle and extends dorsally, forming a cup-like shape around the genitalia and cerci ( Fig. 369). In comparison, Taeniopteryx nebulosa has a ventral vesicle ( Fig. 375) and sternum 10 is less pronounced ( Fig. 374). The cerci of T. japonicum males have five segments ( Fig. 369), whereas those of Taeniopteryx nebulosa have only one stout segment ( Fig. 374). The female subgenital plate gradually tapers to a rounded tip ( Fig. 370), terminating just short of the abdominal apex. The nymph has a ventral triangular plate extending to the tip of the abdomen ( Fig. 365), which Taeniopteryx nebulosa lacks.

DISTRIBUTION—Global: East Palaearctic— Regional: AOB, IDB— Aimag: AR^, BO, KhG^, SE.

DISCUSSION: This species was originally reported from Mongolia by Zhiltzova (1982). Although T. japonicum is commonly encountered in rivers of various size, we also documented it in springs and marshes in Mongolia. The high predicted probability of encounter in the northwest Uvs region ( Fig. 372) warrants sampling in this area which the scope of our study did not target.