Odontocorynus Schönherr

Prena, Jens, 2008, Review ofOdontocorynusSchönherr (Coleoptera: Curculionidae: Baridinae) with Descriptions of Four New Species, The Coleopterists Bulletin 62 (2), pp. 243-277 : 243-277

Odontocorynus Schönherr

Odontocorynus Schönherr 1844: 271 .

Centrinus , subgenus IX. Casey (1892).

Centrinus , subgenus Odontocorynus . Casey (1892).

Odontocorynus . Champion (1908).

Odontocrynus. Manee (1924), misspelling.

Odontocerinus . Jacob (1936), misspelling.

Type species. Odontocorynus creperus Boheman (in Schönherr 1844), by original designation.

Recognition. The name Odontocorynus generally has been applied to baridine weevils with the scutellum notched and the male antenna modified as shown in figs. 6–9. The primitive condition, a simple ovate club, is preserved in O. tectus ( Fig. 5 ), O. townsendi , and to some extent in O. salebrosus ( Fig. 6 ). Odontocorynus is closely related to Platyonyx Schönherr 1826 and Leptoschoinus Dejean 1836 , species of which usually have an elongate club. Except for some common species, the latter genera are not represented well in collections, and their phylogenetic relationships have not been explored. These genera include some species with derived, often sexually dimorphic character states, such as anterolaterally tuberculate pronotum and specialized tarsal setae, and exhibit the same range of shapes of body, elytral apices, and mandibles. A derived character state that is shared universally by all of them is an internal sac with anvil-shaped denticles.

Asymmetrical antennomeres also occur in male Loboderes , a genus with a quite different scutellum. For the purpose of this study, I maintain Odontocorynus as a distinct genus based on the following diagnostic characters: (1) mandibles prominent, triangular, cutting edge straight, with or without minute secondary tooth, (2) modification of distal desmomeres and club of male within range shown in figs. 5–9, (3) scape compressed and micro-reticulate at least in male ( Figs. 10– 18 ), (4) scutellum with distal margin notched ( Figs. 1–2 ), (5) prosternal spines absent, (6) derm with setiform to ovate scales set in large, shallow pits, (7) total length 2.2–6.5 mm, standard length 2.0– 6.1 mm. All species exhibit remarkable morphological variability, particularly in size (up to 250%), body proportion, color, vestiture, and details of the tegmen. Intraspecific variation often may mask interspecific differences between two species in one sex, but usually not in the other. Representative series of both sexes facilitate the identification of material particularly from the southeastern United States. The dichotomous key provided here assists in the identification of typical specimens. In addition, Table 1 summarizes diagnostic character states of species of the O. umbellae complex that occur in the central and southeastern United States.

Distribution. The extant species occur from southern Canada to Costa Rica. Most collecting records cluster in two subregions in North America, which are separated from each other by arid climatic conditions. One subregion covers most eastern and central parts of the United States and southern Canada ( Figs. 33–36 ), the other covers the central part of Mexico ( Figs. 37–39 ). Outside of these subregions Odontocorynus specimens are scarce. One collection of O. salebrosus 246 from El Salvador (USNM) is doubtful. Casey’s (1922) records from Brazil could not be substantiated and are dismissed here as being erroneous.

Plant association. Species of Odontocorynus were collected frequently from Asteraceae and occasionally from Annonaceae , Asclepiadaceae , Clusiaceae , Convolvulaceae , Cyperaceae , Droseraceae , Euphorbiaceae , Fabaceae , Fagaceae , Lamiaceae , Malvaceae , Onagraceae , Papaveraceae , Poaceae , Rhizophoraceae , Rubiaceae , and Solanaceae . The recorded plant associations are documented under each species. Several specimens have labels ‘‘ex [plant species]’’ or ‘‘ex flower’’, but I am not confident that they were reared. In Maryland, I monitored O. salebrosus over approximately four months in a patch of Chrysanthemum vulgare , where they swarmed very actively and fed on pollen. I found no immature stages or signs of oviposition and speculate that adults visited this plant only for feeding and reproduce elsewhere. Kissinger (1964) suspected that the larvae may develop in monocotyledonous plants.

Economic importance. Numerous species of related genera develop in the stolon, culm, root, or seeds of Poaceae , among them several cereal crops. Casey (1892) initially lumped many of these in Centrinus Schönherr and later ( Casey 1920) assigned them to separate genera, such as Geraeus Pascoe , Linogeraeus Casey , Nicentrus Casey , and Odontocorynus Schönherr. At least one lineage of Geraeus (K. Nishida, in litt.) develops in Asteraceae , and flowering plants of this family seem to be an important diet of Odontocorynus species though not likely the larval host. Apart from sunflowers and one isolated record from artichoke, they appear to frequent predominantly uncultivated plants and cannot be considered detrimental to agriculture at present.

Systematic relationships. The dimorphic rostrum and antenna, prominent mandibles with reduced secondary tooth, distally notched scutellum, variably exposed pygidium, and denticulate internal sac are morphological character states of Odontocorynus and various other genera, among which Leptoschoinus Dejean is the type genus of the most senior applicable family-group taxon. Here I transfer Odontocorynus Schönherr from Madopterini, Zygobaridina to Madarini, Leptoschoinina (new placement). The geographic distribution of the species with a denticulate internal sac suggests that Odontocorynus evolved from a hypothetical South American ancestor that may have invaded via an earlier, now submerged land-bridge or otherwise. Donnelly (1985) discusses geological evidence for how such a connection could have formed at the end of the Cretaceous, during an episode of tectonic compression of the Caribbean ‘‘plate’’. At about the same time, a long episode of oceanic transgression into today’s Great Plains ended ( Trimble 1980). The current distribution of O. calcarifer and O. pulverulentus seems to be related to habitats that were formed during this time. However, transient characters between Odontocorynus and Central American Leptoschoinus (which will be treated in a separate paper), their generally low degree of diversification, and their absence in the West Indies favor a concept of more recent invasion, via the Panamerican Isthmus. Episodes of cooling and aridification are suggested here as a possible mechanism that led to habitat fragmentation and the prevailing geographic restriction of Odontocorynus to North America.

Figures

Figs. 1–18. Odontocorynus spp., 1–2, body shapes, male, dorsal. 1) O. creperus; 2) O. salebrosus; 3) mesotibia, O. umbellae, female; 4) metatibia, O. calcarifer, male; 5–9, antenna, club and distal desmomeres, male. 5) O. tectus; 6) O. salebrosus; 7) O. umbellae; 8) O. nunume; 9) O. creperus; 10–14, antennal scape, dorsal, male. 10) O. latiscapus; 11) O. salebrosus; 12) O. pulverulentus; 13) O. calcarifer; 14) O. umbellae. 15–18, antennal scape, female. 15) O. salebrosus; 16) O. pulverulentus; 17) O. calcarifer; 18) O. umbellae.

Figs. 33–34. Map of central and eastern United States showing distributions of O. calcarifer, O. falsus, O. pulverulentus, and O. umbellae.

Figs. 35–36. 35) Map of Florida showing distribution of O. larvatus; 36) Map of United States (without northwest) and bordering regions showing distributions of O. salebrosus and O. townsendi.

Figs. 37–39. Map of central Mexico (top) and northern Central America and Mexico (bottom) showing distributions of O. creperus, O. histriculus, O. latiscapus, O. luteogramma, O. nunume, O. procerus, O. subvittatus, O. suturaflava, and O. tectus.