What is "aceros"

Aceros is a genus of large south-east Asian hornbills ( Bucerotidae family). This genus sometimes includes all species generally placed in the genus Rhyticeros. Alternatively, Aceros has been considered monotypic, only including the rufous-necked hornbill, in which case all of the remaining are moved to the Rhyticeros. Additionally, the white-crowned hornbill is sometimes placed in this genus, but most now place it in Berenicornis instead.

Among the species generally included in Aceros, the rufous-necked hornbill is unique in that it lacks a conspicuous casque, and its bill is mainly dull yellowish. In fact, the genus, which means "no horn/hornless," is named really for the rufous-necked hornbill. All other species generally placed in Aceros have a relatively high casque and brightly coloured bills.