Bolbochromus (Bolbochromus) nigriceps (Wiedemann, 1823)

Krikken, Jan & Li, Chun-Lin, 2013, Taxonomy of the Oriental genus Bolbochromus: a generic overview and descriptions of four new species (Coleoptera: Geotrupidae: Bolboceratinae), Zootaxa 3731 (4), pp. 495-519 : 506

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.

Figures

FIGURES 1 – 8. Habitus of male Bolbochromus (oblique and lateral views). 1 – 2, B. nigriceps; 3 – 4, B. mindanaicus; 5 – 6, B. celebensis; 7 – 8, B. dumogensis. Scale lines 1 mm.