Trichillum Harold, 1868

Vaz-De-Mello, Fernando Z., 2008, Synopsis of the new subtribe Scatimina (Coleoptera: Scarabaeidae: Scarabaeinae: Ateuchini), with descriptions of twelve new genera and review of Genieridium, new genus, Zootaxa 1955, pp. 1-75 : 47-48

17. Trichillum Harold, 1868

Diagnosis: Body form oval ( Figs. 37–38); color grey to black, shiny or not, always lacking metallic sheen. Clypeal teeth variable in shape, but always two (or indicated by anterior sinuosity) and always continuing clypeal border (Figs. 98, 100, 102). Pseudoepipleura strongly sinuate on anterior half and strongly angled near metacoxa; basal half with longitudinal carina parallel to pseudoepipleural-epipleural division ( Fig. 5). Aedeagus with short subrectangular parameres (Figs. 99, 101) and phallobase very short (about twice as long as wide); spermatheca particularly spiral shaped, spermathecal duct sclerotized and feebly differentiated from spermatheca itself ( Fig. 13).

Description: Size 2.2–5.0 mm, body oval ( Figs. 37–38), color grey or brown to black, always lacking metallic sheen. Clypeus with two strong teeth separated by U- or V-shaped emargination. Clypeogenal and frontoclypeal sutures indistinct. Clypeal margin lateral to clypeal teeth strongly curved or angled, becoming straight nearing clypeogenal border, which is straight or slightly sinuate. Gena straight or slightly curved mesally to lateral angle (Figs. 98, 100, 102). Pronotum lacking anterior or posterior beads (Fig. 102); disc with indistinct lateral callosity. Hypomeron posteriorly with longitudinal lateral carina; mesoepimera with transverse anterior carina. Metasternal disc glabrous. Elytral interstriae with uniseriate setose punctures, mesal striae slightly widened and deepened at apical declivity. Pseudoepipleura strongly narrowed to apex, angled near metacoxa, anterior half sinuous; glabrous, with longitudinal carina on anterior half, ending in shallow medial concavity ( Fig. 5). Protibiae with three strong lateral teeth, distributed along apical four fifths of tibial length; with scale-like setae ventrally to teeth base. Parameres shorter than half of phallobase length; rectangular, apically flattened (Figs. 99, 101); phallobase only twice as long as its width. Coxites large, laminar, asymmetrical or centrally fused. Spermatheca spiral shaped, spermathecal duct sclertotized and difficult to differentiate from spermatheca itself ( Fig. 13).

Sexual dimorphism: Males with ventrally directed apicomesal tooth on protibiae and concave metasternal disc (convex in females).

Type species: Trichillum heydeni Harold, 1868 (monotypy)

Distribution: Brazil, French Guyana, Argentina, Bolivia, Paraguay and Uruguay, always eastern of the Andes. Comprises the Humid Guyana, Amapa, Para, Pantanal, Tapajos-Xingu and Roraima provinces of the Amazonian subregion, and the entire Chacoan and Parana subregions.

Remarks: Trichillum in its present definition is undoubtedly sister to Besourenga (see remarks under that genus), and is supported by the following apomorphies: presence of a pseudoepipleural carina parallel to the pseudoepipleuron-epipleuron delimitation on anterior half; mesotibiae and metatibiae strongly widened apically, with apical width less than third of tibial length; coxites large and asymmetrical, or if symmetrical, centrally fused as single piece; spermathecal duct uniformly sclerotized, not differentiated from the spermatheca itself. The strong sinuosity of the anterior half of pseudoepipleura is shared with Silvinha , however it is probably a symplesiomorphy.

Composition: Trichillum in the present sense is almost equivalent to the subgenus Trichillum as defined by Martínez, except for the inclusion of T. pauliani , which Martínez placed (1969) in Eutrichillum . Trichillum adjunctum and T. pauliani form a somewhat isolated group within the genus, distinguished by the dull grey color and the uniquely centrally fused coxites; that form a large vaginal plaque continuously sclerotized with the spermathecal duct and spermatheca. Besides the type species, this genus contains T. externepunctatum Preudhomme de Borre, 1880 ; T. arrowi Saylor, 1935 ; T. pauliani Balthasar, 1939 ; T. depilatum Balthasar, 1942 ; T. adjunctum Martínez, 1969 ; T. halffteri Martínez, 1969 ; T. morellii Verdú & Galante, 1998 ; T. tischechkini Vaz-de-Mello & Génier, 2005; T. pseudoarrowi Vaz-de-Mello & Génier, 2005; T. cordobense Vazde-Mello & Génier, 2005 ; and at least 30 new species currently under description.

Material examined: