Vaquerister Caterino and Tishechkin, 2022

Caterino, Michael S. & Tishechkin, Alexey K., 2022, A New Genus and Species of Histerid Beetle from Western Mexico Showing a Remarkable Sexual Mesotibial Dimorphism (Coleoptera: Histeridae: Histerinae: Exosternini), The Coleopterists Bulletin 76 (3), pp. 357-363 : 358

Vaquerister Caterino and Tishechkin , new genus

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Type Species. Vaquerister cantador Caterino and Tishechkin , new species.

Diagnosis. This genus has the general appearance of a large (~3.5-mm) Phelister , black, rounded and convex, lacking a frontal stria and lateral pronotal striae, having spinose but not strongly dentate tibiae, only a single complete, subapical antennal club annulus, and numerous lateral punctures on the pronotal disc. However, the projecting anterior mesoventral margin, characteristic of Exosternini , is only weakly developed in females, and the mesoventrite is deeply emarginate in males. Males of Vaquerister are highly distinctive in the large, circular excavations of their mesotibiae ( Figs. 1B, C, E , 2E ), the weakly depressed and setose metaventral disc ( Fig. 1B ), the presence of small, trichome-like foveae on the posterior corners of the prosternal keel ( Fig. 2D ), and large, flattened ventral setae on the protarsomeres ( Fig. 2B ). Several characters of the male genitalia are also unusual or unique, including the short, apically truncate and densely setose sternite VIII ( Fig. 3B ), the laterally carinate tergite IX ( Fig. 3C ), and the subdivided aedeagal tip with thin distal processes ( Fig. 3E ). Another unique character, pertinent to females as well, is a conspicuous structure on the vertex of the head ( Fig. 2D ), which we hypothesize to be a stridulatory file. Both sexes have a weakly produced pronotal margin above the head, a broad, weakly emarginate labrum, complete, deeply impressed prosternal keel striae, and ventrally plurisetose meso- and metatarsomeres.

Remarks. This new genus is highly distinct from any other New World Histerinae , and, at least where the male mesotibia can be observed, cannot be mistaken for anything else.

Etymology. The name vaquero, Spanish for cowboy, was suggested by the “spurred” middle legs, in combination with the typical “-ister” ending in this beetle family.

Figures

Fig. 1. Vaquerister cantador, new species, habitus photos of male. A) Dorsal view, B) Ventral view, C) Anterior view of head and prothorax, D) Lateral view, E) Posterior view of propygidium and pygidium.

Fig. 2. Vaquerister cantador, new species, scanning electron micrographs of male. A) Ventral view of mouthparts, B) Protarsus, C) Lateral view of prosternum, D) Anterior view of head, with white arrows pointing to stridulatory files, E) Mesotibia, F) Metafemur and metatibia.

Fig. 3. Vaquerister cantador, new species, male genitalia. A) Dorsal view of tergite VIII, B) Dorsal view of sternite VIII, C) Dorsal view of tergites IX and X, D) Dorsal view of sternite IX (spiculum gastrale), E) Dorsal view of aedeagus, F) Lateral view of aedeagus.