Phylogenetic systematics of the genera Plochionocerus Dejean and Agrodes Nordmann (Coleoptera: Staphylinidae: Xantholinini)

A systematic revision of Plochionocerus Dejean, 1833 and Agrodes Nordmann, 1837 (Staphylinidae: Xantholinini) is conducted. Based on a phylogenetic analysis, the genus Agrodes, which includes A. conicicollis and A. elegans, and appears as the sister taxon to Plochionocerus, is revalidated. The genus Renda was found to be the sister taxon of Agrodes plus Plochionocerus. Plochionocerus leprieuri is transferred to Renda (comb. nov.). Plochionocerus (sensu stricto) is a monophyletic genus supported by six synapomorphies, but relationships of its species are not resolved because of the high proportion of homoplastic characters. Keys to the genera Renda, Plochionocerus and Agrodes, and to the species of the two latter genera are provided. Plochionocerus and Agrodes stat. rev. are redescribed, and diagnoses for their species are given. Eight new species of Plochionocerus are described: P. ashei, P. gracilis, P. hermani, P. modestus, P. newtonorum, P. pronotalis, P. reticularis and P. transversalis. Based on the study of type specimens, 17 new synonymies are proposed for species of Plochionocerus and Agrodes: Plochionocerus fulgens (Fabricius, 1793) = P. violaceus (Olivier, 1795) syn. n., = P. amazonicus (Sharp, 1876) syn. n., = P. carinatus (Bernhauer, 1916) syn. n., = P. auripennis (Bernhauer, 1927) syn. n.; P. janthinus (Erichson, 1847) = P. peruvianus (Bernhauer, 1907) syn. n.; P. simplicicollis (Waterhouse, 1879) = P. basalis (Sharp, 1885) syn. n., = P. mandibularis (Sharp, 1885) syn. n., = P. pollens (Sharp, 1885) syn. n., = P. nordmanni (Fauvel, 1901) syn. n.; P. discedens (Sharp, 1885) = P. nevermanni (Bernhauer, 1942) syn. n.; P. humeralis (Sharp, 1885) = P. kayseri (Bernhauer, 1927) syn. n.; P. puncticeps (Sharp, 1885) = P. lautus (Casey, 1906) syn. n.; P. impressipennis (Sharp, 1891) = P. punctipennis (Bernhauer, 1916) syn. n.; P. igneus (Fauvel, 1901) = P. magnificus (Bernhauer, 1911) syn. n.; Agrodes elegans Nordmann, 1837 = P. longicornis (Sharp, 1885) syn. n., = P. melancholicus (Schubert, 1911) syn. n.; A. conicicollis Sharp, 1876 = P. longiceps (Sharp, 1876) syn. n. Lectotypes are designated for P. humeralis, P. impressipennis and P. simplicicollis. Biological and distributional information is given, and 24 first country records are reported.