To be biased or to be Neotropical: systematic reassessment of a megadiverse lineage of rove-beetles (Philonthina, Staphylinini, Staphylininae)

Abstract

Classifications in the world's tropics often involve an early and sustained adoption of Holarctic-based patterns. Such is the case of the megadiverse subtribe Philonthina and its Neotropical (NT) members, for which generic limits are ill-defined due to an alleged high level of homoplasy. Although a recent total-evidence study confirmed the monophyly of a NT lineage, most of its species are assigned to the speciose genera Belonuchus Nordmann and Paederomimus Sharp, neither of them monophyletic. Here, we aim to reveal internal relationships within the NT lineage by the reassessment of characters from traditional morphology-based systematics. Specific objectives are to test the monophyly of Belonuchus with regards to its only junior synonym, Musicoderus Sharp, as well as the placement of the six South American species of Hesperus Fauvel, a genus of Holarctic origin. We performed a phylogenetic analysis of the subtribe with focus on its NT lineage based on 132 morphological characters (50 of them novel) including 79 taxa from genera and/or species groups relevant to our study. Most novel characters assessed herein supported clades across Philonthina and its NT lineage. We found that the NT lineage diversified into at least seven clades, each of which provides a framework for future taxonomic studies. Among them, three clades containing the type species of Belonuchus, Paederomimus and Musicoderus (respectively) appear to be well supported and not closely related. The currently known South American species of Hesperus, however, are recovered within the NT lineage. We propose to resurrect Musicoderus from synonymy with Belonuchus and to transfer Hesperus novoteutonicus to Paederomimus as a new combination: Paederomimus novoteutonicus (Wendeler), comb.n.