Key to species from the subgenus Coprochara in Japan

1. Body (Figs. 3–4) gray, thick, spindle shaped; dorsal surface covered with granular microstructures and forebody not glossy at all. Intercoxal process of metaventrite (Figs. 12–13) narrow and long, pointed apically. Elytra (Fig. 11) with posterior margins deeply notched laterally; surface rough, densely covered with short but robust setae. Tergite VIII (Figs. 34–35) with numerous large oval projections on surface. Collected from decaying seaweed on seashore beach. [Male]: median lobe of aedeagus as in Figs. 38–39; sclerite Z large, without attachment at apex; flagellum longer than median lobe of aedeagus. [Female]: proximal portion of spermatheca (Fig. 41) with extremely numerous coils........ Aleochara (Coprochara) squalithorax Sharp, 1888

- Body black to blackish brown, slender, parallel or subparallel sided; dorsal surface not covered with granular microstructures, and clearly glossy. Intercoxal process of metaventrite wide and rounded apically. Elytra with posterior margins rounded, usually with yellowish portion. Tergite VIII without large oval spines on surface, with serrate or truncate posterior margin. Spermatheca proximally with 20 coils at most.................................................................. 2

2. Dorsal surface smooth and apparently glossy (Fig. 1). Pronotum with shallow and inconspicuous punctures and with thin setae. Two rows of punctures along midline fine. Elytra (Fig. 5) with a pair of small reddish to yellowish spots near posterior margin and suture, bearing with numerous thin and inconspicuous setae. Common species in Japan. [Male]: sternite VIII (Fig. 16) simple and weakly pointed. Median lobe of aedeagus (Figs. 18–19): apex of apical lobe of median lobe blunt in lateral view; flagellum long, slightly longer than median lobe of aedeagus; sclerite Z large, with long and prominent attachment, waving toward apex. [Female]: coiled portion of spermatheca (Fig. 21) not greatly extended laterally........ A. (C.) verna Say, 1833

- Body more slender. Elytra entirely yellow except for anterior margins near pronotum (Japanese specimens).............. 3

3 Dorsal surface with distinct and deep coarse punctures, and with thick yellowish setae (Fig. 2). Pronotum with distinct punctures and rows of deep punctures along midline. [Male]: sternite VIII (Fig. 24) pointed triangularly. Median lobe of aedeagus (Figs. 26–27): apex of apical lobe sharply pointed in lateral view; flagellum short, but basal plate of flagellum long and large; sclerite Z small, with straight attachment pointed toward apex. In Japan known only from Hokkaidô. [Female]: proximal portion of spermatheca (Fig. 29) with thick coils and widely extended laterally................. A. (C.) binotata Kraatz, 1856