Nigidius helleri Boileau 1905: 47

Type material. Holotype female (Fig. 7), MNHN, labeled: a) “Palembang / Sumatra ”; b) “TYPE / [H.B.]”; c) handwritten, “Helleri / type”; d) “ex coll. / Boileau”; e) on red paper, “TYPE”; f) on red paper, “HOLOTYPE”; g) “ HOLOTYPE / Nigidius / helleri Boileau ”; h) “ MNHN / EC4652 ”. Type locality: “ Palembang, Sumatra ”.

Additional material examined. INDONESIA: JAMBI: Tebo/Teluk Kayu Putih (3 SLTC). SUMATERA BARAT: Annai Valley/Lapai (2 SLTC); Mt. Singgalang (2 SLTC); Mt. Talang (9 MJPC); Padang (10 MJPC); Pariaman (1 MJPC).

Diagnosis. The Sumatran member of the obesus group is recognizable by its more homogeneous pronotal punctures that, although variable in size, are regularly distributed and never fine enough to give the appearance of impunctate areas (Fig. 8). In addition, the anterior lateral margin of the pronotum is the least produced in N. helleri, and the seta of the pronotum are most distinct.

Remarks. This name has until now been misapplied to different species in the cornutus group of Nigidius from Java and Sumatra, and this will be addressed fully in a subsequent paper on that group. Specimens examined are from February, April, August, and December, indicating that adults are present year-round.