Xanthocomus Guillebeau, 1893

Gimmel, Matthew L., 2011, Review of the species described in Leptostilbus Casey in North America (Coleoptera: Phalacridae: Xanthocomus Guillebeau), Insecta Mundi 2011 (188), pp. 1-8 : 2

Xanthocomus Guillebeau, 1893

Xanthocomus Guillebeau 1893: 291 . Type species: Xanthocomus striatus Guillebeau, 1893 .

Leptostilbus Casey 1916: 71 . Type species: Leptostilbus rutilans Casey, 1916 , here designated. New synonymy.

Diagnosis. Recognized among North American phalacrids by the mandible having a ventral fold; ventral seta-lined ridge behind eye oblique (not transverse); prosternal process with apex arcuate and with row of stiff setae; metaventral postcoxal lines smoothly arcuate; posterior tarsi with tarsomere I short, tarsomere II much longer than I; presence of rows of rounded (not crescentiform) punctures on the elytra; the elongate body form (pronotum more than half as long as wide); reddish coloration; and microsculpture very weak or absent over most of the elytral disc.

Notes. With the addition of species from Leptostilbus , the genus Xanthocomus contains nine described species collectively distributed from the northern United States south to Argentina. They are also widespread in the West Indies. After examining the types of X. striatus (Muséum National d’Histoire Naturelle, Paris), the type species of Xanthocomus , and those of several other species, I have concluded that these genera should be combined. All species share the diagnostic characters presented above with the exception of the species described as Stilbus elongatulus Casey (1890: 136) . Casey (1916: 73) subsequently transferred this species to Leptostilbus based on the structure of the hind tarsi, but neglected to observe the state of the metaventral postcoxal lines, which are distinctly acuminate posteriorly in this species. Additionally, the elytra are microsculptured with dense transverse lines. It actually belongs in the genus Acylomus Sharp , as Acylomus elongatulus (Casey, 1890) , comb. nov. Neither Casey nor any more recent workers have designated a type species for Leptostilbus , so I have rectified this situation.