(Figs 4–6)
Demicryptochironomus chuzequartus Sasa, 1984: 47; Sasa (1985: 111, 1989: 70); Zorina (2004: 225); Makarchenko et al. (2005: 409).
Material examined. Holotype male (NSM No. A 39: 96), JAPAN: Lake Chuzenji, 28.iv.1979, M. Sasa.
Diagnostic characters. The species can be distinguished by the following combination of characters: AR 2.93; LR 1 1.60; frontal tubercles prominent; both superior and inferior volsella tubercle-like, with 1–3 setae, lacking microtrichia.
Male (Figs 4–6). As in Sasa (1984: 47) with the following corrections and additions: Brachiolum with 2 setae, R with 26 setae, R 1 with 22 setae, R 4+5 with 34 setae. Mid ta 1 with 3 sensilla chaetica. Tergite IX with 39 setae. Laterosternite IX with 7 setae. Anal tergite bands V-shaped. Phallapodeme 108 µm long. Transverse sternapodeme 48 µm long. Superior volsella with 1–2 setae, without microtrichia. Inferior volsella with 2–3 setae, without microtrichia. Gonocoxite 183 µm long, inner margin with 5 strong setae. Gonostylus 235 µm long, swollen medially, tapering towards apex, inner margin with 12 setae. HR 0.78; HV 2.63.
Remarks. Without examining type material, Dutta et al. (1996) proposed that D. chuzequartus Sasa is as a synonym of Demicryptochironomus vulneratus (Zetterstedt). However, according to our examination the species should be retained as a valid species.
Zorina (2004) recorded the species from Sakhalin Island, Russia. The Russian specimens have the superior volsella covered with microtrichia, and the inferior volsella can be strongly reduced or absent.
Distribution. The species is recorded from Japan and the Russian Far East.