Monday, December 10, 2007 - 8:17 AM

Phylogenetic analysis of Euaesthetinae (Coleoptera: Staphylinidae) based on adult morphology

David Clarke,, The Field Museum/University of Ilinois, at Chicago, 1400 S Lake Shore Drive, Chicago, IL

This study aims to test the monophyly of the highly enigmatic rove beetle subfamily Euaesthetinae and to present a preliminary phylogenetic analysis of the genera. Euaesthetinae is distributed worldwide and includes 29 genera with 866 described species, all of which live in forest leaf litter habitats and are presumed predators. No synapomorphies were previously known for Euaesthetinae and recent phylogenetic work suggested Euaesthetinae is paraphyletic with respect to the megadiverse subfamily Steninae. Scanning electron and light microscopy were employed to compile a data matrix of 122 characters from the adult exoskeleton, endoskeleton, and genitalia of 34 ingroup and 5 outgroup terminal taxa. Phylogenetic analysis of equally weighted (and unordered multistate) characters using parsimony recovered strong support for the monophyly of 1) Euaesthetinae (11 synapomorphies), 2) Steninae (15 synapomorphies), and Euaesthetinae + Steninae (21 synapomorphies). Five novel adult synapomorphies for Euaesthetinae include: 1) a denticulate labrum, 2) modified setae on antennomeres 9 and 10, 3) anteriorly projecting mesendosternites, 4) absence of the mesothoracic pleural suture, and 5) males with acutely produced ninth sternite. Relationships among genera of Euaesthetinae were obscured by homoplasy and missing data, causing some taxa to behave as “wildcards”. One monophyletic group within Euaesthetinae comprised four of the five genera of the tribe Stenaesthetini, which may be nested within a larger clade uniting 10 genera sharing unique labial structures. However, the existing suprageneric classification of 6 tribes, based on tarsal formula and abdominal margination, was not supported by character data, suggesting a new classification is needed.