Coptoborus Hopkins, 1915

Smith, Sarah M. & Cognato, Anthony I., 2021, A revision of the Neotropical genus Coptoborus Hopkins (Coleoptera, Curculionidae, Scolytinae, Xyleborini), ZooKeys 1044, pp. 609-720 : 609

Coptoborus Hopkins, 1915

Type species.

Xyleborus vespatorius Schedl, 1931; original designation.

Diagnosis.

Coptoborus is distinguished from all other Xyleborini genera by the following combination of characters: antennal funicle four-segmented, antennal club type 3, 4 or 2 (typically type 3) with two (rarely three) arcuate sutures visible on the posterior face, club round or longer than wide, posterior face of the protibiae flat and unarmed, both elytral discal striae and interstriae uniseriate punctate, anterior margin of pronotum typically weakly produced with a row of serrations, pronotal disc alutaceous, procoxae contiguous, scutellum small, flush with elytral surface and mycangial tufts absent.

Coptoborus is very similar to Euwallacea Hopkins, 1915, and like Euwallacea , is diagnosed by a combination of homoplastic characters ( Smith et al. 2019a, 2020). Both genera have the posterior face of the antennal club with 2 or 3 arcuate sutures near the apex. Euwallacea species typically have a subquadrate or quadrate pronotum (types 3, 4, 8) but some species do have rounded anterior margins like Coptoborus (types 2, 7). All Coptoborus have rounded anterior margins of the pronotum (types 7, 2, 1 or 9) (except C. obtusicornis (type b) which is conspicuously elongate and acuminate frontally), and most have the median area of the pronotum weakly produced and bearing a row of serrations, usually 2-6. Euwallacea species with rounded anterior margins of the pronotum always lack serrations, have semi-circular protibiae with evenly rounded outer edge (except obliquely triangular in E. luctuosus (Eggers, 1939)) and a posterolateral costa that extends to at interstriae 7 (except inconspicuous, short in E. luctuous ).

Revised description.

Female. Length 1.4-3.6 mm and 2.1-4.3 × as long as wide. Body nearly glabrous to densely setose; color variable, light to dark brown, red brown to nearly black; legs and antennae yellow brown to red brown. Appearing very stout to slender, elytra rather variable, appearing round, attenuate, or acuminate. Mycangial tufts absent.

Head: Epistoma entire, transverse, lined with a row of hair-like setae. Frons slightly convex from epistoma to upper level of eyes; surface shagreened, dull, reticulate; punctures small, fine, shallow. Eyes broadly or narrowly emarginate above level of antennal insertion, upper portion of eyes smaller than lower part. Submentum slightly or deeply impressed below genae, narrowly or broadly triangular. Scape short and thick or long and thick, about as long as club. Antennal funicle four-segmented, segments equal in size. Pedicle shorter than funicle or as long as funicle. Club variable, either obliquely truncate, type 2, approximately circular, segment 1 corneous, transverse or weakly convex on anterior face, nearly covering all of posterior face; segment 2 slightly procurved, corneous, visible on anterior and posterior faces of club or club flattened, types 3 or 4 (rarely obliquely truncate and type 2), approximately circular or longer than wide, segment 1 corneous, transverse or sinuate on anterior face, with segments 1, 2, and rarely 3 visible on posterior face. Pronotum: 0.8-1.75 × as long as wide. Pronotum from lateral view typically elongate with disc as long or slightly longer than anterior slope (type 7), taller than basic (type 2), or round (type 1), rarely basic (type 0) or elongate with disc much longer than anterior slope (type 8). In dorsal view typically rounded frontally and long (type 7), basic and parallel-sided (type 2), rarely rounded (type 1) or rounded frontally and very long (type 9) or conspicuously elongate and angulate frontally (type b), anterior margin of pronotum typically weakly produced with a row of 2-6 serrations. Surface alutaceous, anterior slope finely asperate, asperities close, arranged in concentric rings from midpoint of pronotum to anterior and anterolateral areas; disc finely and evenly punctate. Lateral margins variable, obliquely costate, carinate on basal third or along entire length. Posterior angles acutely rounded. Base transverse. Elytra: 1.2-2.5 × as long as wide. Elytral base transverse, margin oblique; humeral angles rounded. Scutellum small to minute, triangular or linguiform, flat, flush with elytra. Elytral shape quite variable, sides straight between basal 42-88%. Disc convex, longer than declivity, rarely as long as declivity. Disc smooth, shiny, finely punctate; striae not impressed, interstrial punctures seriate, or confused (rare). Declivity variable. Posterolateral margin of declivity typically with interstriae 3 and 9 joining, forming a carina and continuing submarginally to apex, but may also be costa, or carinate from suture to interstriae 2, 7, or 8. Legs: Procoxae contiguous. Protibiae obliquely triangular, broadest at apical third, or distinctly triangular, or with evenly rounded outer margin, posterior face flat, unarmed; 5-8 denticles present on outer margin. Meso- and metatibiae obliquely triangular, flattened, posterior face unarmed with 6-12 and 6-11 denticles, respectively.