Oncopsis tristis Zetterstedt 1840

10. Oncopsis tristis (Zetterstedt, 1840)

Figs. 101–107, 116–120

Description. Coloration typical, females similar to males or lighter, brown with dark spots to yellowish brown without dark pattern (as in O. ochotensis, Fig. 30).

Penis of typical shape, with ventral margin convex in side view (Figs. 101–102). Lower appendage of dorsal connective bifurcated, usually with rather short widely separated branches; upper branch is somewhat longer than the lower one. Inner margins of branches finely serrated (Figs. 102–105). Style narrow, finely tapering apically, with narrow hook-like tip (Figs. 106–107).

Body length (including tegmina): ♂, 3.7–4.1 mm; ♀, 3.9–4.3 mm.

Differs from all species from Russia and adjacent countries by combination of very narrow style with hooklike tip and penis with convex ventral margin in side view. Two species with similar shape of style were described from Japan have penis with strongly concave ventral margin, as in O. flavicollis species group (Okudera, 2008).

Host. Betula alba and B. pendula in Europe and European Russia, B. platyphylla in the Southern Sakhalin.

Distribution. From Western Europe to the Russian Far East including Sakhalin and Kurile Islands; Japan, Honshu (Hayashi & Higashikawa, 1997); China, “Sze-chuan” (evidently Sichuan Province; Lauterer & Anufriev, 1969).

Remark. Comparison of calling signals of males from the Southern Sakhalin (environs of Sokol Town, recording at 27o C; Figs. 116, 118), Altai Mts. (Northern shore of Teletskoe Lake, recording at 29o C; Fig. 119), and Moscow Area (environs of Pushkino Town, recording at 22–23o C; Figs. 117, 120) supports the conspecificity of specimens from Europe, Siberia and the Far East.