Conotrachelus posticatus Boheman in Schoenherr, 1837

Chamorro, Maria Lourdes & Barclay, Maxwell V. L., 2018, On the identity of a U. S. intercepted Conotrachelus Dejean (Coleoptera: Curculionidae) with avocado (Perseaamericana), Biodiversity Data Journal 6, pp. 26362-26362 : 26362

Conotrachelus posticatus Boheman in Schoenherr, 1837

Conotrachelus posticatus Say, 1831 in Say 1831:19 [nomen nudum]; Boh. in Schoenherr 1837: 406 [original description]; Champion 1904: 403 [redescription, variation, distribution]; O'Brien and Wibmer 1982: 131 [annotated checklist].

Diagnosis

One of the salient features of C. posticatus (Figs 7a, 8, 9, 10) is the presence of a costate first elytral interval (interstriae) in both male and females (Figs 9b, 10b, Figs 12b, 13b). In addition, males usually have the second interval costate (Fig. 9b). Conotrachelus posticatus also has subparallel elytral margins beyond midline, then abruptily converging (abruptily constricted in some specimens) to the apex. In other species herein treated, the elytral margins gradually converge towards the apex, hence C. posticatus has a rather pseudo-quadrate gestalt with the elytra roughly 2.5 times the pronotal length (Figs 7, 9b, 10b).

Distribution

Canada, Guatemala, Mexico, Panamá, U.S.A.

Notes

It is not uncommon in collections to find Conotrachelus naso misidentified as C. posticatus . The fore-femora of C. posticatus are distally excavate ventrally and bear a tooth, while in C. naso , the ventral margin of the fore-femora is largely entire. During the course of this study, we came across multiple species that resemble C. posticatus (e.g. elytral maculation, males with metauncus dentiform and first and second striae costate); however, upon dissection of males, differences in the median lobe confirmed these to be different species. Careful examination of the metauncus reveals additional diagnostic characters. While many of these superficially similar C. posticatus males possess a dentiform metauncus, slight differences exist, such as the presence of tufts of setae on the denticles themselves. Other species, in what is here termed the C. posticatus complex, share many characteristics with C. naso ; for example, the ventral margins of the fore-femora are entire with either a small spine or altogether lacking one. In addition, the shape of the apex of the median lobe resembles that of C. naso . A revision of C. posticatus and related species is needed.