Stenocranus chenzhouensis Ding, 1981

[Japanese name: Hososuji-naga-unka]

(Figs 2, 8–10, 13, 16)

Stenocranus chenzhouensis Ding, 1981: 76 [Type locality: China (Hunan)].

Material examined. [Honshu] 2♂ 3♀ (MH), Inayama, Aomori, Aomori Pref., 31. VIII. 1997, T. Ichita; 6♂ 2♀ (SF), Kamitakamori, Tsukidate, Kurihara, Miyagi Pref., 24. VII. 2022, S. Fujinuma; 5♂ 2♀ (SF), same data except 29. X. 2022, S. Fujinuma; 2♂ (MH), Sugao-numa, Mitsukaido, Ibaraki Pref., 20. IX. 1996, M. Hayashi et al.; 5♂ 5♀ (MH), Yanagiyatsu-numa, Namegawa, Saitama Pref., 18. X. 1996, M. Hayashi et al.; 4♂ 2♀ (MH), Akigase, Saitama-Urawa, Saitama Pref., 20. VI. 1990 (light trap), M. Hayashi et al.; 12♂ 11♀ (SF), Murakuni, Iwatsuki, Saitama Pref. 26. VI. 2016, S. Fujinuma; 5♂ 4♀ (SF), same data except 25. IX. 2016, S. Fujinuma; 54♂ 60♀ (MH), Sugadaira Moor (1,250 m), 25. IX. 1985, M. Hayashi et al.; 98♂ 109♀ (MH), same data except 3. IX. 1996; 2♀ (SF), Ibi Riv., Kaizucho-Fukuoka, Kaizu, Gifu Pref., 20. II. 2011, S. Fujinuma.

Redescription. General coloration stramineous, paler in summer form. Frons with dark stripes. Genae with dark stripes. Mid-dorsal parts of vertex, pronotum, and mesonotum narrowly whitish, fringed with orange and dark stripes (orange stripes usually feeble even in winter form). Forewings as in S. kisimotoi. Male pygofer pale to dark brown.

Vertex about 1.6× as long as wide. Frons about 2.9× as long as wide; median carina forked in apical 1/3. Antennal segment II about 3.1× as long as wide. Forewing venation and hind leg spinulation as in S. niisimai. Post-tibial spur with 23–26 fine teeth.

Body length (mean): ♂ 5.1–5.6 mm (5.4 mm); ♀ 6.1–6.5 mm (6.3 mm).

Male genitalia: Similar to S. kisimotoi except gonostyles much broader; phallotheca broad in lateral view; opening near caudal side; two apical processes: left process long, falcate, slightly angulated; right process long, downcurved at right angle; anal tube with ventral margin bluntly angulated near midlength. Female genitalia: Similar to S. sapporensis except gonapophyses IX with 16–20 teeth, symmetrically diverged mostly. Gonoplacs semicircular in ventral view, broad, wider in apical half.

Distribution. Japan (Honshu), China.

Remarks. This species is similar to S. fallax in coloration and structure but can be distinguished by the following features: face with dark lines from base to apex (paler in basal two-thirds in S. fallax), antennal segment II about 3.1× as long as wide (shorter in S. fallax), and phallotheca with two apical processes subequal in length (right process shorter in S. fallax).

Biological notes. This species is found in lowland to mountainous marshes and feeds on Carex dispalata Boott (Cyperaceae). Adults are usually observed from June to November, and females lay eggs in the host plants in late autumn as in S. sapporensis; thus, this species may overwinter as eggs.