Phaenostoma Orchymont, 1937

Clarkson, Bruno, Albertoni, Fabiano Fabian & FIKÁýEK, Martin, 2014, Taxonomy and biology of the bromeliad-inhabiting genus Lachnodacnum (Coleoptera: Hydrophilidae: Sphaeridiinae), Acta Entomologica Musei Nationalis Pragae 54 (1), pp. 157-194 : 185

Phaenostoma Orchymont, 1937

Phaenostoma Orchymont 1937: 133 . Type species: Cyclonotum posticatum Sharp, 1887 , by original designation.

= Psilodacnum Orchymont 1937: 134 , syn. nov. Type species: Cyclonotum urichi Scott, 1912 , by original designation.

Comments on Psilodacnum . The detailed examination of Lachnodacnum urichi , which is the type and sole species of the genus Psilodacnum described by ORCHYMONT (1937) and later synonymized with Lachnodacnum by HANSEN (1991), revealed that the species is not congeneric with the two species treated above. Psilodacnum differs from Lachnodacnum e.g. by completely obliterated anapleural sutures of the mesoventrite, aedeagus with largely reduced phallobase and femora without ventral hydrophobic pubescence. In all these characters, it agrees with the remaining coelostomatine genera occurring in the Neotropics. Moreover, Psilodacnum agrees well with Phaenostoma in all characters considered at the moment as diagnostic at the generic level: antennal club is loosely segmented, elytra lack punctural series but bear the sutural stria, prosternum is flat mesally, meso- and metaventrite form a composite structure, mesocoxal cavities are rather widely separated, all femora lack the ventral hydrophobic pubescence, the ¿rst abdominal ventrite lacks the median carina, and the ¿fth abdominal ventrite lacks the apical emargination. The only difference between Psilodacnum and Phaenostoma is the shape of the clypeus, the relative size of the eyes, and the detailed morphology of the aedeagus, plus very likely also the preferred habitat. All these differences are too weak to justify the separate position of Psilodacnum , and it is hence synonymized here with Phaenostoma , and its type species is transferred to Phaenostoma as well. Phaenostoma urichi comb. nov. is redescribed in detail below, to illustrate its differences from Lachnodacnum and to justify the changes at the genus level proposed here.