Plegaderus (Plegaderus), 1834

Lackner, Tomáš & Vienna, Pierpaolo, 2017, Histeridae of Socotra (Coleoptera: Histeroidea), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 57, pp. 55-76 : 65

Plegaderus (Plegaderus) sp.

(Fig. 23)

Material examined. YEMEN: SOCOTRA: 1 ♀, Al Haghier Mts., Wadi Madar, 12°33.2′N, 54°00.4′E, 1180–1230 m, 12.–14.xi.2010, P. Hlaváč lgt. ( TLCM).

Comments. Genus Plegaderus Erichson, 1834 contains two subgenera: monotypic Hemitrichoderus Reichardt, 1941 with a single species P. (H.) adonis Marseul, 1876 described from Cyprus and also occurring in Turkey, and the nominotypical subgenus, which contains 27 species spread mostly in the Holarctic Region ( MAZUR 2011). The species from Socotra belongs to the group of species with deeply impressed median stria on pronotum, dividing it into two convex parts ( Fig. 8 ). Other species of this group are: P. (P.) caesus (Herbst, 1791) , spread across Europe, Turkey, Azerbaijan and north Iran; P. (P.) dissectus Erichson, 1839 spread across southern England, central and south Europe, Turkey and north Iran; and the extremely rare P. (P.) fortesculptus Reitter, 1897 described from Azerbaijan and occurring also in Iran ( MAZUR 2011). In fact, the type specimen of P. (P.) fortesculptus was discovered only recently (LACKNER, unpublished). SECQ & SECQ (1991) beautifully depicted the two former species in their key to French Plegaderini. Of the three, the species from Socotra most resembles Plegaderus (P.) caesus , which likewise possesses a string of tiny, equally distanced granules along lateral pronotal margins. The Socotran species differs, however, from P. (P.) caesus , in its smaller size, anteriorly narrowed pronotum; less impressed punctation of the elytra, in more dilated apices of protibia, body shape more rounded; the shape of prosternum, as well as in other characters. The herein depicted specimen from Socotra ( Fig. 8 ) most likely belongs to a new species, we are, however, reluctant to describe it based on a single female. This is the first record of the genus Plegaderus from the Afrotropical Region, to which the Socotran Archipelago biogeographically belongs.

Figures

Figs 6–12. Pachycraerus socotrensis sp. nov., male genitalia. 6 – sternite and tergite VIII, ventral view; 7 – ditto, dorsal view; 8 – ditto, lateral view; 9 – tergites IX–X, dorsal view, spiculum gastrale (sternite IX), ventral view; 10 – tergites IX–X and spiculum gastrale (sternite IX), lateral view; 11 – aedeagus, dorsal view; 12 – ditto, lateral view; 13 – female genitalia: gonocoxite and median sclerite, dorsal view.