Coptoborus silviasalasi Atkinson, 2018

Atkinson, Thomas H., 2018, A new species, new synonymy and new records of Mexican and Central American Xyleborini (Coleoptera: Curculionidae: Scolytinae), Zootaxa 4442 (2), pp. 345-350 : 345-346

Coptoborus silviasalasi Atkinson , new species ( Figure 1 )

Diagnosis: This unusual species appears to be somewhat intermediate between the genera Coptoborus and Theoborus . It is placed in Coptoborus because the elytra are narrowed posteriorly and there is a clearly marked sutural emargination at the apex of the declivity. It is distinguished from all other species previously described from either genus by the strongly concave elytral declivity with prominent teeth along the declivital margin that somewhat resembles the declivities of some species of Taurodemus .

Description: Female: Length: 2.7 mm (2.6¯ 2.8 mm, n=5); width 1.1 mm (1.0¯ 1.2 mm); 2.42 times as long as wide; length of elytra 1.5 mm, occupying 56% of the body length. Color uniformly dark brown to black, entire body surface shining.

Head. Frons convex, reticulate; sparsely punctured; each puncture with a stiff seta, more abundant towards epistoma. Antennal club type 4 ( Hulcr et al. 2007), 2 procurved sutures clearly visible on posterior face, strongly displaced towards the apical margin; anterior face with sutures 1 and 2 bisinuate, corneous basal portion occupying approximately 1/4 length of the club.

Pronotum. Pronotum anterior margin slightly produced with 4 serrations, the central pair more prominent; numerous asperities evenly distributed on anterior half, each associated with a hair-like seta, rising to a well-defined summit slightly posterior to mid point; disc smooth, shining, with sparse punctures, these separated by more than 3X their diameters. Vestiture short, sparse, approximately half length of setae on anterior slope.

Scutellum. Scutellum small, triangular, flush with elytral surface.

Elytra. Discal striae clearly marked, not impressed; punctures shallow, spaced within rows by about 2X their diameters; vestiture of short, recumbent setae to base. Discal interstriae flat, 3X the width of striae, with mostly uniseriate punctures to base, smaller than those on striae, each associated with an erect seta with length subequal to strial width. Declivity abrupt, strongly concave, occupying 40% of elytral length, distinctly narrowed posteriorly in dorsal view. Posterolateral margin carinate, elevated from sutural apex to interstria 7, rounded to declivital base at suture. Declivital face shining, with numerous strial and interstrial punctures clearly visible; all setae short and recumbent, similar in length to discal strial setae. Interstria 1 slightly widened at base of declivity and bearing a large, digitate projection, with length about 2X its basal diameter; a large digitate projection at the middle of the declivity on interstria 3, displaced inwards from the declivital margin, about twice the size of the projection on interstria 1, a third, shorter, acute tooth below and more or less in line with it on interstria 3; several small projections on posterolateral carina as high as the base of the second projection. Sutural emargination of declivity clearly visible; in lateral view appearing as a blunt, posterioriad projection of the posterolateral carina.

Male: Not present in material at hand.

Type Material: All specimens were collected in an unidentified branch (not coffee) found on the ground (2¯ 5 cm diameter) in a coffee plantation following brush control in a region of tropical subdeciduous forest at intermediate elevations of coastal facing slopes of the Sierra Madre del Sur in central Oaxaca with the following data: Mexico : Oaxaca, Rancho Dioon (above Santa María Xadani), 15.99262 N, 96.10545 W; 892 m; 24-VI-2009, coll. T.H. Atkinson, THA-878. The holotype is in the Colección Nacional de Insectos, Universidad Nacional Autónoma de México ( CNIN) . Paratypes from the same collection are deposited in UTIC (2), CEAM (2), MSUC (2) and NMNH (2).

Etymology: This species is named in honor of Dr. Silvia Salas Morales, of the Sociedad por el Estudio de los Recursos Bióticos de Oaxaca (SERBO) who has facilitated fieldwork in Oaxaca on several occasions including the collection of this species.

Comments: Hopkins (1915) described the genera Dryocoetoides , Theoborus , and Coptoborus for Neotropical species of Xyleborini . Since then numerous Neotropical species have been assigned to these genera. In these closely related genera the antennal club is type 4, has 2 clearly marked horizontal to recurved or bisinuate sutures on the anterior face and 2 sutures displaced apically and visible on the posterior face. In the most recent published comprehensive classification and key ( Wood 1986) Dryocoetoides , Theoborus , and Coptoborus are grouped together. Dryocoetoides is separated from the other two genera by the protibia inflated and rugose on the posterior face of the protibia. In Coptoborus the posterior third of the elytra is narrowed and the suture is “often” emarginate, while in Theoborus the elytral apex is rounded and the body is "comparatively stout". In general the species treated by Wood (1982) in Coptoborus are slender in form and those treated in Theoborus more robust but this distinction is blurred when species from a wider region are considered ( Wood 2007). Cognato et al. (2011) showed that Theoborus , Coptoborus and Sampsonius (another exclusively Neotropical genus) were closely related and that Coptoborus might be included within Theoborus (i.e., Theoborus are paraphyletic with respect to Coptoborus ). This new species further blurs the distinction between Coptoborus and Theoborus and could arguably be placed in either genus. The generic placement was chosen because the posterior portion of the elytra in dorsal view is clearly narrowed and there is a prominent sutural emargination.

Figures

FIGURE 1. Coptoborus silviasalasi, female holotype. A. dorsal view; B. lateral view; C. frons; D, declivity. Photographs by the author.