Bolbochromus (Metabolbochromus) catenatus (Lansberge, 1886)

Li, Chun-Lin, Krikken, Jan & Wang, Chuan-Chan, 2019, Review of the genus Bolbochromus (Coleoptera, Scarabaeoidea, Geotrupidae, Bolboceratinae) in the Philippines, ZooKeys 842, pp. 135-152 : 135

Bolbochromus (Metabolbochromus) catenatus (Lansberge, 1886) Figs 1, 2, 13, 19, 20, 25, 26, 33

Material examined.

PHILIPPINES: Luzon, Quezon Province, Real, Brgy Cawayan, nr stream, 80m asl, 14°39'56"N, 121°35'35"E, 08-10.IV.2017, by FITs, ML Jeng, H Cahilo (3 females in the collections of Chun-lin Li, CCLI); PHILIPPINES: Palawan Province, Balabac Is., Brgy Malaking Ilog, E coast, 1 km SE to Balabac, near stream, 50m asl, 07°58'45"N, 117°04'23"E, 13-16.VI. 2017, by FITs, ML Jeng, H Cahilog (1 male and 1 female at CCLI); PHILIPPINES. Sibuyan Isl., S-coast, Mabini, Barangay, II-3-III-1999, 0-100 m (Howden collection, the Canadian Museum of Nature, Ottawa).

Diagnosis.

Body length 9.4-10.5 mm. Dorsum black to brownish dark with yellowish orange markings along lateral sides of pronotum (markings separated or contiguous, except for fovea) (Figs 1, 2) and across intervals 2-3 at sides of scutellum (Fig. 13); eyes small, canthus wide and simple; horn at middle of anterior margin of clypeus and middle of base of frons well developed; frons glossy, distinctly concave, with 4-5 setigerous punctures, setae long and robust, transversally aligned (Fig. 19, 20); clypeofrontal suture invisible; coarse punctures concentrated on disc of sides of pronotal midline and along lateral margins, anterior side of pronotum behind head upright (female) to sharply declivous (male), face concave, midline deeply indented; each elytron with 7 coarsely punctate striae between suture and humeral umbone, stria 2 interrupted by stria 1 not reaching base, stria 5 terminated in length subequal to stria 2; intervals 1, 3 and 4 more convex and wider than others, interval 2 less convex than others; parameres strongly swollen, ovoid capsule-like in shape, fused with a large opening at base (Figs 25, 26, 33).

Distribution.

Philippines (Fig. 39), Borneo, Sumatra.

Remarks.

This species is the only representative of the subgenus Metabolbochromus in the Philippines and is also widely distributed from Borneo to Sumatra. Adults are variable in size and the shape of dorsal markings and it was considered by Krikken and Li (2013) that a potential subspecies complex existed. In fact, the pair of specimens collected from Palawan that we treat in this paper have 4 or 5 long, robust setae (Figs 25, 26) on their frons, a feature that has not been observed in other specimens discussed in this paper, which may be due to them having been worn off. For the stability of name usage, we refrain from erecting a new species or subspecies herein and await additional material being available in future.