Gymnocychramus Lea, 1921

Lawrence, John F. & Kirejtshuk, Alexander G., 2019, Review of the Australian Cyllodini (Coleoptera: Nitidulidae: Nitidulinae), with descriptions of new taxa, and notes on the genus Macleayania (Nitidulini), Zootaxa 4544 (3), pp. 301-334 : 324

Gymnocychramus Lea, 1921

Gymnocychramus Lea 1921: 184 . Type species: Gymnocychramus politus Lea, 1921 .

Notes. This genus is the only Australian member of the Oxycnemus complex and as such differs from all other Australian Cyllodini in having 1) a distinctive labrum, which is wider than the clypeus and consists of a pair of diverging, rounded lobes flanking a deep notch widest at its opening, narrowing posteriorly and almost reaching the labral base, 2) a distinct tooth at the outer apical angle of the protibia, and 3) an association with phallaceous fungi. It also differs from Pallodes , Coxollodes and Cyllopallodes gen. nov. in the presence of a vertexal line, from Cyllodes in the presence of a frontoclypeal suture (represented by a transverse shallow depression), from Camptodes in the structure of the mesoventrite, the serrate incisor area of the mandible, the posteriorly narrowing metanepisternum, and the seriate elytral punctation.

Gymnocychramus differs from all other members of the Oxycnemus complex, except Eugoniopus Reitter , in having metatarsomere 1 equal to or shorter than 2. The posteriorly narrowed metanepisternum and conjointly rounded elytral apices exposing only part of the pygidium distinguish it from all members of the group except Oxycnemus Erichson. The relatively short prosternal process terminated by a vertical wall and not extending posteriorly to meet or overlap the metaventrite is shared only with Oxycnemus ; in Psilopyga LeConte , Eugoniopus and Interfaxia Kirejtshuk this process extends to the edge of the metaventrite, while in Triacanus Erichson (including Monafricus Kirejtshuk ) it extends well beyond this, fitting into one or more grooves on the metaventrite. A more or less concealed anal sclerite also occurs in Oxycnemus , Interfaxia , Triacanus and Monafricus , but this sclerite is exposed in Psilopyga and Eugoniopus . In Gymnocychramus and Oxycnemus the body of the penis is about as long as the tegmen, while in all other members of the group it is much shorter than the tegmen.