Ditrichocis mussauense Souza-Gonçalves & Lopes-Andrade 2024, comb. nov.

Ditrichocis mussauense (Chûjô, 1966) comb. nov. Fig. 1A–C Ennearthron (Ennearthron) mussauense Chûjô, 1966: 529 (original description). Comments. From the island of Mussau, Bismarck Archipelago, Papua New Guinea. The species is known only from the holotype, from which only the head and the pronotum remain (Fig. 1A–B). It has nine antennomeres and, based on the description, it is a male: “(...) 1st visible sternite of abdomen with a distinct ciliate-pore in the center.” Chûjô (1966). In a strict sense, the genus Ennearthron Mellié, 1847 includes species with single vestiture of bristles, outer protibial angles toothed in both sexes and males with paired anterocephalic plates separated by a distinct notch, and a pair of pronotal horns (Lawrence 2016), characteristics that are not present in E. mussauense. Ditrichocis Lawrence, 2016 also has 9-segmented antennae. Moreover, the dorsal vestiture is dual, consisting of longer and shorter bristles, and males lack secondary sexual characters in the head and pronotum, which justifies the transference of E. mussauense to the genus. It differs from other species of Ditrichocis in the absence of distinct colored marks on the elytra, a conclusion based only on the description by Chûjô (1966), since the holotype no longer has the elytra. Ditrichocis includes two other described species: D. pulchellus (Scott, 1926) and D. bifasciatus (Reitter, 1877), and two undescribed species are known from Palau and Micronesia (Lawrence 2016). The genus occurs in the Malagasy subregion (Ethiopian region), Polynesian subregion (Australian region), Chinese transition zone, and Indo-Malayan transition zone.