Bagous nodulosus

ROBERTO CALDARA, CHARLES W. O’BRIEN & MASSIMO MEREGALLI, 2017, A phylogenetic analysis of the aquatic weevil tribe Bagoini (Coleoptera: Curculionidae) based on morphological characters of adults, Zootaxa 4287 (1), pp. 1-63 : 45-46

16. B. nodulosus group

Diagnosis. Penis body elongate with sides convergent from base to apex, with ventrobasal margin truncate; dorsal process very high and composed of a pair of very elongate sclerotized pieces, in dorsal view sinuate and joined at base with two small V-shaped vertical orificial sclerites (char. 83.1) and with membrane from dorsal process to proximal margin of orifice.

Remarks. This group is characterized by a very peculiar shape of the penis, especially due to the high dorsal process, and the sclerites. This group was also supported in the phylogenetic analysis (BI: 95% pp; ML: 75% bs; MP: 59% sr). Moreover, the two taxa included in this group, which are largely widespread in the western Palaearctic region, are apparently the only two species living on Butomus umbellatus L. ( Butomaceae ). However, they differ from each other in several external characters. Apart from the general habitus which is distinctly thinner, B. nodulosus has a very well-developed declivital callus of interval 5, long and distinctly apically curved tibiae, with distinct denticles, elongate and linear tarsi. In contrast, B. validus has a rostrum with numerous scale-like setae along the ventro-lateral margins (char. 12.1) and penis body with sclerotized subtriangular plate behind the dorsal process, (char. 95.1). Due to these differences these species were placed in two separated monotypic groups by Caldara & O’Brien (1998).

Species included. PAL: §*¹ Bagous nodulosus Gyllenhal, 1836 ; *² Bagous validus Rosenhauer, 1847 .