Oxarthrius escharus Park, 1942

Chandler, Donald S., 2013, Further Notes on the New World Pselaphinae (Coleoptera: Staphylinidae) Described by Victor Motschulsky, The Coleopterists Bulletin 67 (3), pp. 321-327 : 323-324

Oxarthrius escharus Park, 1942

Batrisus rivularis Schaufuss 1874: 285 (not Batrisus rivularis Motschulsky, 1855 ). C. Schaufuss 1888: 16. Type locality: Obispo, Panama. Holotype female examined [MNHP], // Panama / Museum Paris 1917 Coll. A. Raffray/ TYPE [red label]/ rivularis A. Raffray det.//. New synonymy.

Batrisus (Oxarthrius) rivularis: Raffray 1898: 438 .

Oxarthrius rivularis (Schaufuss) : Raffray 1904: 77, 1908: 154, 1911: 59; Park 1942: 246; Blackwelder 1944: 92.

Oxarthrius rivularis (Motschulsky) : Chandler 1992: 348.

Oxarthrius (Baroxarthrius) escharus Park 1942: 244 . Type locality: Barro Colorado Island, Gatun Lake, Panama. Chandler 1992: 348. Holotype male examined [FMNH].

Comments. Batrisus rivularis Schaufuss, 1874 is a primary junior homonym of B. rivularis Motschulsky, 1855 . Both names resided in the genus Batrisus until Raffray (1904) treated Oxarthrius at the generic level. This conflict extended past 1900, and a replacement name is needed. There is an available name based on the synonymy established here. Park (1942) described O. escharus from Panama, and designated it as the type species of his new subgenus Baroxarthrius Park. Members of this subgenus lack basal elytral foveae, while members of the nominate subgenus have a single basal fovea on each elytron, and the locations of the male characters are different. The holotype female of B. rivularis Schaufuss is clearly a member of the subgenus Baroxarthrius , and with the exception of the sexual characters it is similar to a male specimen identified as and compared with the holotype male of O. escharus by myself in 2000. The sculpturing of the body, antennal proportions, indistinctness of the antennal club, and elevation and density of the setae are similar, with the antennal proportions being slightly shorter — a common feature when comparing males and females of the same species.

Members of this subgenus are uncommon in the Panama Canal area, with only one species ( O. escharus ) being present in my extensive material from Panama, while this subgenus is diverse in Costa Rica. The two names are here synonymized, and the available name Oxarthrius escharus Park is selected as the replacement name for Batrisus rivularis Motschulsky. A female specimen from Refugio Nacional de Vida Silvestre Gandoca-Manzanillo in Costa Rica, a near sea-level site close to the border with Panama, compares favorably with the female holotype of B. rivularis and has been so labeled.