Coptonotus Chapuis, 1869

Smith, Sarah M. & Cognato, Anthony I., 1869, A Revision ofCoptonotusChapuis, 1869 (Coleoptera: Curculionidae: Coptonotinae) with Notes on Its Biology, The Coleopterists Bulletin 1869 (3), pp. 409-428 : 409-428

Coptonotus Chapuis, 1869

Redescription. Head rostrate, not concealed by pronotum. Eye elongate, weakly emarginate, coarsely faceted, flush with head, amount of ventral eye separation highly variable in all species (except C. striatus ). Point of antennal insertion at midpoint between mandibular base and upper level of eye, not exposed. Subantennal groove (scrobe) well-developed, deep, apical margin directed toward ventral margin of eye. Funicle 7-segmented, antennal club with 3 visible sutures. Frons flat to convex, male frons with a large median tumescence, tumescence densely minutely punctate, within each puncture 2–10 potential pores are visible at 250X magnification, pores appearing convex, each potential pore filled with red lipid material. Prosternal process with a modified sternellum and often a modified poststernellum that are identical in both sexes. Femur strong, as long as tibia, entirely punctured and shagreened; tibia with terminal uncus on interior margin, uncus mesally curved, mucro at outer margin apex, outer margin with a large premucro at apical third and 2 smaller teeth along basal margin; protibia with distal comb of setae along inner margin. Tarsus with 5 tarsomeres, tarsomere 4 not apparent; tarsomeres 1–3 entire, tarsomere 5 weakly bilobed,1 narrow, 2 and 3 subequal, 5 slightly curved, glossy; posterior face of protibia inflated, appearing triangular, impunctate; posterior face with a groove for reception of tarsi from apex to dorsal margin of distal comb, groove glabrous. Meso- and metatibiae with posterior face not inflated, without a groove for tarsal reception, parallel-sided, bearing spines and teeth along outer margin. Elytra declivous, dimorphic or not, sculpture variable, strial punctures at least twice as large as interstrial punctures. Spiculum gastrale moderately asymmetrical, sickle-shaped, slightly longer than aedeagus. Tegmen a broadly sclerotized ring, open dorsally, with a simple anterior strut.

Sexual Dimorphism. Sexual dimorphism is exhibited on five structures: the length of tarsomere 1; the presence of a frontal tumescence in all species; in some species, the presence of a frontal fovea; strial puncture size; and the elytral declivity. Tarsomere 1 length has not been previously reported as dimorphic, but it does explain inconsistencies regarding the length of 1 to 2+ 3 in the literature ( Hagedorn 1910; Schedl 1962). In females, tarsomere 1 is longer than 2+3 combined and equal in length to 2+ 3 in males. All males possess a frontal tumescence, while the female frons is convex. In most species, the strial punctures are larger in males (except C. striatus ). In some species, only the female has a median frontal fovea.

Discussion. The male frons of each species has a large median tumescence. This tumescence is densely and minutely punctate, and each puncture appears red and convex, resembling eye facets. This lead Chapuis to erroneously conclude that they represented a third eye – hence the specific epithet ‘ cyclopus ’ for the type species ( Hagedorn 1910). The exact composition and function of this structure is unknown. Collection of additional male specimens for examination with scanning electron microscopy should help elucidate the function of these structures.