Morphology of the larvae and biology of the adults of Psilorrhynchus bifasciatus do not confirm previous hypotheses about systematics and feeding habits (Coleoptera: Cantharidae)

Abstract

Psilorrhynchus bifasciatus (Blanchard, 1844) is broadly distributed through South America, but its biology, behaviour and life cycle are unknown. The most characteristic feature of the adults is slender rostrum, presumably associated to a specialised feeding habit. However, new observations of P. bifasciatus feeding on nectar in inflorescences of Matayba guianensis Aubl. (Sapindaceae) do not support such a hypothesis. Here, we describe and illustrate their early larval instars in details and compare them with the other Chauliognathini. The larvae are remarkably characterised especially by a long and thick pubescence, conspicuous roughness on the head and thoracic terga, and head with sharp lateral projections. These features are unique amongst the known Cantharidae larvae and do not confirm a previous hypothesis of close affinity between Psilorrhynchus Gemminger & Harold, 1869 and bromeliad-inhabiting Chauliognathini species.