On the Identity of Sphenophorus melanocephalus (Fabricius) (Coleoptera: Curculionidae: Dryophthorinae)

Abstract

Weevils of the genus Sphenophorus Schönherr, 1838 (colloquially called billbugs) are comparatively large, conspicuous, and frequently encountered. Horn (1873) and Vaurie (1951) revised the Nearctic species but, although milestones during their times, these works contained a number of speculative interpretations about species identities. The potential magnitude of this problem for diverse, taxonomically difficult taxa already became apparent in a reassessment of Thomas Say’s long overlooked weevil types (Prena 2018). During a recent study of Fabrician types at the Zoological Museum, Kiel, Germany, I noticed a single specimen (Fig. 1) of a familiar-looking species labeled “Calandra melanocephala.” When I later transferred the record to my database, I realized that Calandra melanocephala Fabricius was described from the collection of Louis Bosc d’Antic and that the original material had not been studied since Olivier (1807). Vaurie (1951) suspected the type in a European collection but she could not find it among the Bosc material in Paris and London. It is possible that Bosc’s specimen was misplaced or lost when it was illustrated for the plates in Olivier (1807). Subsequent authors apparently relied on this illustration when they interpreted the name in the sense of Sphenophorus nubilusGyllenhaal, 1838 [for genuine and Latinized spellings of authority, see Palmblad and Wieselgren (1839: 313)]. The specimen in the Fabricius Collection agrees with the admittedly vague descriptions by Fabricius (1801) and Olivier (1807). Fabricius often was allowed to retain vouchers from other entomologists’ collections but did not record them in the descriptions. Sphenophorus melanocephalus (Fabricius, 1801) is a senior subjective synonym of Sphenophorus inaequalis (Say, 1832) and Sphenophorus contractus Gyllenhaal, 1838 (new synonymies). It is a small, merely 6-mm-long species with apically outwardly flared protibiae. Sphenophorus nubilus Gyllenhaal, 1838 (resurrected name) is removed here from synonymy with S. melanocephalus and reinstated as the valid name for S. melanocephalus in the sense of Horn (1873) and Vaurie (1951). This species is larger than the true S. melanocephalus and has a differently shaped rostrum and protibial apex (Vaurie 1951). Schönherr received from Say the type specimen of S. nubilus in 1830 along with the comment “*48 nubilis [sic!] n. (country unknown but at N[ew] Y[ork]),” with the asterisk denoting it as a singleton (Prena 2018). The herein figured specimen is designated as lectotype for S. melanocephalus and the specimen in the