New Genus and Two New Species of Railroad-Worm Beetles from Brazil, with a Discussion on Asymmetry of Aedeagus in the Family (Coleoptera: Phengodidae)

Abstract

Here we describe a new genus, Microphrixothrixgen. nov., and two new species, Michrophrixothrix gandarelasp. nov. and Michrophrixothrix kumagaiaesp. nov., both from Minas Gerais, Brazil. This new genus is distinguished by the following character combination: interantennal distance larger than scape length, antenna with eleven antennomeres, IV to X with two long symmetrical branches; mandible long, pointed forward; maxillary palpi 4-segmented, last segment digitiform; labial palpi 3-segmented: posterior tentorial pit consisting of a single small fossa; elytron medium, surpassing the fourth abdominal segment, 4× longer than wide; first and second tarsomere of protarsus, and first tarsomere of mesotarsus with a ventral comb as long as the tarsomere length; wing with radial cell closed and transverse, vein r4 interrupted; aedeagus with paramere asymmetrical, apex toothed, with a patch of bristles. We provide a key to Mastinocerinae genera with 11-segmented antennae as well as illustrations for the diagnostic features for this new genus and a key to its species. We discuss the asymmetry in the aedeagus of Phengodidae, recorded for three previously described genera (Brasilocerus Wittmer, 1963, Mastinocerus Solier, 1849 and Taximastinocerus Wittmer, 1963) and Microphrixothrixgen. nov. We advocate that this feature is caused either by a change in mating position or by a one-sided reduction to save space and resources.