Arnaudius Grossi and Bartolozzi

Grossi, Paschoal Coelho & Bartolozzi, Luca, 2011, Description Of A New Genus And Species Of Stag Beetle (Coleoptera: Lucanidae: Lucaninae) From The Peruvian Andes, The Coleopterists Bulletin 65 (4), pp. 387-392 : 387-388

Arnaudius Grossi and Bartolozzi , new genus

Type species: Sclerostomus koikei Arnaud, Noguchi, and Bomans 2007 . Here designated.

Diagnosis. Fully-winged species. Body short, subparallel, slightly convex. Male mandibles short, as long as or a little longer than head length; ventral face lacking distinct furrow; dorsal surface of female mandibles lacking longitudinal furrow and with a dorsal basal tooth. Temporal process absent behind eyes in both sexes. Male pronotum with one anterior tubercle or projection; females with two tubercles; surface finely punctate; elytra apparently glabrous.

Description. Size (according to the known species): Length 9.6–12.3 mm; width 4.0–5.5 mm. Color: Body predominantly black with sides of elytra reddish black; integument shiny. Head: Shape transverse; surface moderately punctuate, punctures denser in females. Ocular canthi expanded externally, more so in males; temporal process absent in both sexes. Male mandibles symmetrical, bifurcated apex with an internal basal or median tooth; ventral face lacking longitudinal furrow, setose; setae concentrated in more punctate areas. Female mandibles asymmetrical with right inner tooth smaller; dorsal longitudinal furrow absent. Mentum in males with sides flattened, not elevated; disc flat, moderately punctate; punctures coarse, coalescent. Antennal club with sensorial area confined to anterior border. Pronotum: Shape convex with slight discal furrow; anterior margin in males with one tubercle or acute median projection; in females with two tubercles; surface punctate; punctures fine, becoming moderate at discal furrow. Anterior angles strongly produced with rounded apex; posterior angles acute to obtuse. Elytra: Shape elongate, longer than head and pronotum together; striae distinct, disc with 5–6 striae; interstriae subcostate and finely punctate. Humeri toothed. Legs: Anterior tibial spur glabrous. Meso- and metatibiae with more than one external tooth; posterior tibial apex with acute internal tooth in males, truncate in females. Venter: Mesosternum slightly convex. Male genitalia: Genital capsule with dorsal plate rounded; posteriorly with internal margin of bifurcation sinuous, apex convergent; disc with two subtriangular symmetrical sclerites. Ventral plate with posterior margin concave; disc sclerotized, darkened and setose. Parameres with narrowed apices; laterally lobed.

Etymology. We are glad to name this genus in homage to our friend and colleague Mr. Patrick Arnaud (Saintry sur Seine, France) who described two of the three species included in this genus. Arnaudius is masculine in gender.

Remarks. Arnaudius contains three species, two recently described, Arnaudius koikei (Arnaud, Noguchi, and Bomans, 2007) and Arnaudius digennaroi (Arnaud, Noguchi, and Bomans, 2008) , and a new species described here. The genus is currently known to occur only in the Peruvian Andes ( Fig. 18 ). Arnaudius species are the smallest in size among genera possessing a complex male genital capsule.

Arnaudius can be easily distinguished from Metadorcinus by the absence of the temporal process that is present in both sexes of the genus; the absence of a ventral mandibular furrow on the male mandibles; female pronotum finely punctate in Arnaudius (not strongly as in Metadorcinus species ); male genitalia lacking the ventral internal tooth-like projection found in Metadorcinus (e.g. Grossi and Vaz-de-Mello 2007, figs. 15–19). Sclerostomus can be separated from Arnaudius by the following combination of characteristics: temporal process present in males; presence of a ventral mandibular depression in males; pronotum in both sexes with four strongly punctate depressions; strong longitudinal, median pronotal furrow; elytra with interstriae costate; male genitalia with internal distal margin of paramera with a densely setose area (e.g. Grossi and Paulsen 2009, fig. 3).

Nothing is known about the biology or life history of the species of Arnaudius .

The three known species of Arnaudius can be distinguished using the following key (the female of A. bomansi is unknown).

Figures

Fig. 18. Map of the known distributions for the species of Arnaudius.