Besuchetostes jaccoudi Paulian, 1977

Alberto Ballerio & Munetoshi Maruyama, 2010, The Ceratocanthinae of Ulu Gombak: high species richness at a single site, with descriptions of three new species and an annotated checklist of the Ceratocanthinae of Western Malaysia and Singapore (Coleoptera, Scarabaeoidea, Hybosoridae), Zookeys 34, pp. 77-104 : 83

Besuchetostes jaccoudi Paulian, 1977

Known distribution: West Malaysia (Pahang) (Paulian 1977).

Remarks. This is another flightless species known up to now by the holotype (in the collection of the Museum National d’Histoire naturelle, Paris) and a few further specimens from the type locality (MHNG, ABCB). Examination of all available material revealed that this species does not belong to Besuchetostes . Paulian placed this species in the genus Besuchetostes mainly because of the lack of genal canthus/ dorsal ocular area, a character to which he gave much importance. However, according to a preliminary analysis carried out by the first author, the presence/absence of a genal canthus seems often the result of the fusion of the genal canthus with the occipital area of the head surface, a character that could be related to an adaptation to live in dark environments (leaf litter, dead logs), so it is highly homoplastic in the group and not particularly reliable for defining genera. Based on the aforesaid analysis the genus Besuchetostes is now characterized by a combination of characters involving mouthparts morphology, pronotum posteriorly swollen and protruding backwards, male genitalia and, above all, the shape of antennal scape and pedicellus. In Besuchetostes the antennal scape is regularly gradually swollen proximad and the pedicellus is very large (about as wide as the apical portion of scape), whereas in B. jaccoudi the scape is securiform, with pedicellus smaller than the apical portion of the scape. The overall morphology of B. jaccoudi would suggest its placement in the Perignamptus genus group, as defined by Ballerio (2009), although currently it is not possible to assign it to any given genus, due to the messy systematics of the genera belonging to the group.