Morphology of immature stages, biology, and systematic position of the Violet seed weevil, Orobitis cyanea (Linnaeus, 1758) (Curculionidae, Conoderinae, Orobitiditae, Orobitidini)

Abstract

The mature larva of the weevil species Orobitis cyanea (Linnaeus, 1758), one of only two Palaearctic members of the supertribe Orobitiditae, is re-described, while the pupa is described for the first time. The biology of this species was studied at two sites in Germany. It was reared from seed capsules of Viola canina L. (Violaceae), and feeding holes were observed on V. riviniana Rchb. Adults of Orobitis cyanea and O. nigrina Reitter, 1885, specialists of Viola, show a well-developed escape mechanism, to which contribute a smooth surface, a rounded, nearly spherical body shape, and a seed-imitating thanatosis behaviour. The molytine weevil Leiosoma cribrum (Gyllenhal, 1834), the only other known weevil specialist of Viola in Europe, has a smooth surface, also, and is the most spherical species of the genus. The unique characters of the larva and pupa of Orobitis cyanea are discussed in regard to the systematic position of this taxon.