Chryasus Champion 1908
Creators: name: Prena, Jens
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Curculionidae
Chryasus

description: Chryasus Champion, 1908
Chryasus Champion, 1908: 337; type species Chryasus cavernosus Champion, by original designation
= Aniops Casey, 1922: 274 and 319; type species Aniops sculpturatus Casey, by original designation; new synonymy
= Psiona Casey, 1922: 274 and 319; type species Psiona carinulosa Casey, by original designation; new synonymy
= Preglyptobaris Bondar, 1946: 100; type species Preglyptobaris bicolor Bondar, by original designation; new synonymy
= Prospoliata Hustache, 1950: 90; type species Prospoliata bicolorata, by indication (monotypy); new synonymy
Diagnosis. The species subsumed here under Chryasus have ventrally denticulate femora (Figs. 5–10), premucrones, subconnate claws and the distal abdominal tergite is concealed underneath the elytral apices. Some other Neotropical genera have similar, usually single denticles along the edge(s) of a femoral sulcus which is absent in Chryasus. These denticles may not be lined up perfectly in individual specimens or, in rare cases, may even form a seemingly second, parallel row. Because very few other baridine weevils have denticulate femora without a ventral sulcus, this trait is most diagnostic. Comparable femora occur only in species of Ganymela Pascoe, 1886 and Pteridobaris Morimoto & Yoshihara, 1996. Ganymela (2 species studied) includes large, apparently orchid-associated species with basally inserted antenna, undulate elytra and very small claws. The Southeast Asian Pteridobaris (3 species studied) has the distal tergite partially exposed and does not occur in our study area. Male Chryasus have stridulatory files on the seventh tergite (Fig. 11), pilose patches on ventrites 1, 2 and 5 (appressed or absent in two examined species) and, in the aedeagus, a flagellum with an elongate basal appendage. The metaventrite is tumid with a deeply engraved discrimen in many cases. Large species generally are recognized readily by their conspicuously humped pronotum with vermicular surface, while species in the lower size range tend to blend in with the bulk of miscellaneous other non-descript forms. The genus is known from southern Mexico and Guatemala southward to southern Brazil and from the Antillean islands Dominica (USNM) and Guadeloupe (Chevrolat 1880, ASUCOB) and Trinidad and Tobago (JPPC). The species have been found in open areas as well as in cloud forests, between sea level and 2650 m elevation. Two were obtained from spindle-shaped petiole galls of Miconia Ruiz & Pavón (Melastomataceae) (Figs. 2–4; Almeida-Cortez et al. 2006) and three others were collected from the same plant genus (this paper). Two specimens occurred in flowers of Psychotria micrantha Kunth (Rubiaceae), likely an accidental association.
Redescription. Total length 1.9–6.3 mm, width 0.8–3.2 mm; large species with humped pronotum, salient metaventrite and rhombic-cuneate outline, body more ovate to oblong-linear in lower size range; integument predominantly black, brown or red, occasionally bicolored or with fascia, metallic iridescence absent; large species with inconspicuous appressed setae on appendages and sternites, setae increasingly prevalent and more conspicuous in small species, erect squamulae only on male ventrites. Eyes large, oblong ovate, somewhat encroaching base of rostrum, forehead slightly to distinctly (when rostrum slender) narrower than width of rostrum at base; rostrum moderately thick (most) to slender (elongate species), at most slightly longer than pronotum, dorsal transition to forehead slightly angular and without fovea; antenna inserted almost always at mid-length, antennal sulcus descending to ventral margin of rostrum in front of eye, scape not quite reaching eye, funicle of 7 articles, club oblong-ovate in small species, distal articles increasingly truncated in large species and therefore club shorter than in small species; mandibles clunky and with inner faces fitting into each other in large species, increasingly more delicate and at least partially decussate in lower size range. Pronotum bell-shaped with distinct anterior constriction to almost perfectly conical, basal margin slightly (small species) to moderately (large species) protracted to, but not notched by, scutellar shield; disc slightly (small species) to strongly (large species) vaulted, with confluent or separate punctation, interspaces often forming oblique ridges; anterolateral margin straight or with subtle postocular lobe, some small species with fringe of squamiform setae; scutellar shield with median furrow and pair of distal tubercles; procoxae separated by 0.2–1.5x their own width, width of intercoxal lobe correlating with widths of prothorax and body (even within species and between sexes) and less so with body size, channel subcordate and shallow when coxae widely apart in humped species with contracted prosternum, narrower and deeper when coxae approximated (Figs. 13–15), bordered laterally by ridge ending before coxa; metaventrite slightly (small species) to steeply (large species) sloping toward mesoventrite, male metaventrite often more or less tumid with deeply engraved discrimen; sclerolepidia peg-shaped, distinct, evanescent in large species; elytra conjointly rounded and concealing distal tergite, striae deep, often punctate but without setae, interstriae almost always ridged; hind wings developed. Femora clavate in small species, increasingly subparallel in larger species, ventral margin denticulate, denticles arranged linearly, somewhat irregularly or (rarely) in seemingly 2 rows, distal denticle distinct and present on all legs, proximal denticles increasingly smaller, reduced on middle leg and often absent on front leg, denticles generally reduced in very small species (Figs. 5–10); tibiae increasingly curved in upper size spectrum, premucro generally present but indistinct in small species; claws flat, basally subconnate. Male ventrites 1, 2 and 5 with modified, often erect setae; male tergite 7 with stridulatory files, male tergite 8 gently sloping, not transversely kinked (Fig. 11); basal apodemes of penis generally not much more than 2x longer than body of penis, endophallus with short to moderately long flagellum, flagellum with elongate basal appendage, in at least one species endophalic structures reduced to this basal sclerite, tegmen with long apodeme, parameroidal lobes well-developed (Figs. 16– 25); female tergite 7 without stridulatory files, gently sloping, not transversely kinked (Fig. 12); duct approximately as long as coxites, insertion in bursa subdistal.
Variation. The few species with representative series from several sites indicate that individual specimens can deviate substantially from each other in body proportions, size, color and surface texture. Large specimens tend to be stouter, have darker integument and more distinct femoral denticles. Possible influencing factors are environmental settings, larval substrate, sex and age.
description: Published as part of Prena, Jens, 2024, Consolidation of Aniops Casey, Psiona Casey, Preglyptobaris Bondar and Prospoliata Hustache with Chryasus Champion (Coleoptera, Curculionidae, Baridinae) and descriptions of new species, pp. 1-24 in Zootaxa 5492 (1) on pages 3-4, DOI: 10.11646/zootaxa.5492.1.1, http://zenodo.org/record/13211499