Polycaoninae Lesne, 1896

Liu, Lan-Yu & Beaver, Roger A., 2023, The first Asian species of Polycaon Castelnau, and a new montane species of Melalgus Dejean from China (Coleoptera: Bostrichidae: Polycaoninae), Zootaxa 5315 (3), pp. 271-281 : 272

Subfamily Polycaoninae Lesne, 1896

Diagnosis: The extant species in this subfamily are characterised within the Bostrichidae by the prognathous head, the antennae with 9–11 antennomeres, including a club with three antennomeres, the unmargined pronotum, the globular procoxae separated by a prosternal process constricted in the middle and extending to the mesoventrite (usually known as the mesoscutum), and the protibiae with a large outwardly curved tooth at the apex ( Fisher 1950, Ivie 2002, Borowski & Węgrzynowicz 2012). Sexual differences are evident in the sculpture, puncturation and vestiture of the body.

In the fossil genus, Cretalgus, there are important differences from the extant genera. The elytra are striate, the procoxae contiguous, the prosternal process short, not extending to the mesoventrite, and the tarsi four-segmented ( Legalov & Háva 2020).

The subfamily has been included in the Psoinae Blanchard, 1851, by most anglophone authors (e.g. Fisher 1950), but Lesne (1938) and Vrydagh (1960a, b) treated polycaonines at the same taxonomic level as the psoines. Ivie (2002) and Borowski & Węgrzynowicz (2007, 2012) also treat the polycaonines as a separate subfamily from the psoines. Liu & Scĥnitzer (2011) in their phylogenetic analysis, showed the subfamily is the sister-group of the large tribe Bostrichinae Latreille, 1802 .