Bolbochromus (Bolbochromus) nigriceps (Wiedemann, 1823)

(Figs. 1–2, 37, 52–53)

Bolboceras sumatranus Lansberge, 1886 (synonym)

Identification. Common on Java, and there usually recognisable from infuscated elytral striae on a generally yellow to ochreous interstrial background; sides of pronotum usually with pair of contiguous yellow markings. However, elytra (and pronotum) of B. nigriceps may vary from completely (rufous) yellow to virtually completely black—possibly a populational phenomenon. On Sumatra the species may be more variable than on Java and appears much less common, inducing Lansberge (1886) to describe his B. sumatranus, with an entirely rufous pronotum (synonymy correct judged from external characters, type seen; other colour forms were seen from Peninsular Malaysia). The only tubercle on the head of B. nigriceps is always the small cone between the eye canthi; the clypeal apex may be slightly raised. Other congeners on Java and Sumatra have two medial protrusions, one on the clypeal apex and one on the postfrons ( B. niger, B. catenatus, B. ludekingi, B. walshi), B. sulcicollis having also a clypeogenal tubercle on either side. Anterior declivity of pronotum of B. nigriceps usually more or less deplanate (any protrusions hardly distinct); anterolateral angle of pronotum (full-face view) distinct. Aedeagus very small, with pair of relatively simple, short, convex, apically blunt parameres. Elytra with 7 striae between suture and humeral umbone. Body length usually 8.0– 11.5 mm.

Distribution. Indonesia: Java, Sumatra, possibly Malay Peninsula.