A phylogenetic revision ofSpilodiscusLewis (Coleoptera: Histeridae)

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Abstract
Spilodiscus Lewis, a Nearctic group of Histerini, is polyphyletic as presently constituted. Morphological analyses indicate that the following species should be removed from the taxon to Hister: militaris Horn, lucanus Horn, patagiatus Lewis, sarcinatus Lewis, penulatus Lewis, tunicatus Lewis, humilis Fall, bilobatus Casey, and quadratulus Casey. Based on cladistic character evidence, Spilodiscus contains eight valid species (new junior synonyms in brackets). Morphological data supports exclusive, full-species status for S. arcuatus (Say), S. sellatus (LeConte), S. flohri (Lewis), and S. floridanus Ross. The remaining four taxa are ferespecies, which are putatively reproductively isolated entities whose phylogenetic exclusivity is not well-supported: S. ‘ulkei’ (Horn) [= Hister sculpticauda Casey, H. subcruentus Casey, H. coruscans Casey, H. iowensis Casey], S. ‘gloveri’ (Horn), S. ‘biplagiatus’ (LeConte), and S. ‘instratus’ (LeConte) [= Hister semiruber Casey, H. solaris Carnochan]. Over time the lineage has shifted from largely free-living but facultatively inquilinous habits to obligate rodentophily with a more recent reversal back to facultative inquilinism.