Arixyleborus setosus, Smith & Beaver & Cognato, 2020

Smith, Sarah M., Beaver, Roger A. & Cognato, Anthony I., 2020, A monograph of the Xyleborini (Coleoptera, Curculionidae, Scolytinae) of the Indochinese Peninsula (except Malaysia) and China, ZooKeys 983, pp. 1-442 : 1

Arixyleborus setosus sp. nov. Fig. 29A, B, I

Type material.

Holotype, female, Vietnam: Cao Bang, 22°36.3'N, 105°52.6'E, 1435-1601 m, 13-17.iv.2014, VN16, Cognato, Smith, Pham, ex FIT (MSUC.). Paratypes, female, Vietnam: Cao Bang, 22°36.454'N, 105°52.083'E, 1661 m, 15.iv.2014, VN39, Cognato, Smith, Pham, ex 3-6 cm branches (MSUC, 1); Lao Cai, Hoang Lien N.P., 22.35, 103.77, 1500-2000 m, 22.v.2019, VN186, S.M. Smith, A.I. Cognato, ex FIT (MSUC, 1).

Diagnosis.

2.5 mm long (n = 2); 2.5 × as long as wide. This species is distinguished by the protibiae posterior faces flat, unarmed; antennal club as broad as tall; posterolateral carina oblique, granulate; elytral disc flat, without a transverse depression; elytral striae moderately impressed on disc; elytral interstriae with two rows of granules and long semi-recumbent fine hair-like setae on disc, setae 1-1.5 × width of an interstria; and declivital interstriae densely covered by two or three rows of dense confused golden scales.

Similar species.

Arixyleborus rugosipes .

Description

(female). 2.5 mm long (n = 2); 2.5 × as long as wide. Body color uniformly dark brown. Legs and antennae yellow-brown. Densely setose appearance on elytra, especially the declivity. 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, punctate; punctures above epistoma large, coarse, shallow; punctures decreasing in size, coarseness, and depth from epistoma to upper level of eyes. Eyes deeply emarginate above level of antennal insertion, upper portion of eyes smaller than lower part. Submentum deeply impressed, triangular. Scape short and thick, approximately 3/4 length of club. Pedicle as long as funicle. Antennal funicle 4-segmented, segments equal in size. Club wider than long, asymmetrical, club type 1; obliquely truncate, segment 2 not visible on posterior face; segment 1 covering most of posterior face, its margin completely costate; segment 2 narrow, pubescent with corneous part, visible on anterior face only. Pronotum: 1.0 × as long as wide. In dorsal view long and rounded frontally, type 7, sides parallel in basal 3/4, rounded anteriorly; anterior margin without serrations. In lateral view elongate with disc slightly longer than anterior slope, type 7, summit low. Surface shagreened, anterior 1/2 finely asperate, asperities close, arranged in concentric rings from midpoint of pronotum to anterior margin; anterolateral areas unarmed; disc minutely and sparsely punctate; punctures bearing long, erect hair-like setae, as long as width of discal interstriae 2. Lateral margins obliquely costate. Base weakly bisinuate with a row of erect setae. Elytra: 1.5 × as long as wide, 1.53 × as long as pronotum. Scutellum moderately sized, linguiform, flush with elytra, medially impressed. Elytral base weakly bisinuate, edge oblique, humeral angles rounded, sides straight from base to apical 1/2 of declivity then rounded to apex. Disc longer than declivity, distinctly separated and flat; striae impressed; interstriae shiny, densely, coarsely punctate in semicircular area from base to basal 1/4 and laterally to interstriae 6, punctures strongly confused, each bearing an erect golden hair-like seta equal in length to interstrial width, interstriae 2 × width of striae, posterior 3/4 shagreened, dull, interstriae becoming densely, coarsely tuberculate apically; interstriae laterally diverging from base to declivity and narrowed on declivity. Declivity obliquely truncate, flattened, shagreened, dull; striae not impressed, impunctate; interstriae flattened, densely tuberculate and punctate, punctures dense, coarse, each bearing a short stout semi-erect scale. Posterolateral declivital margin costate, granulate. Legs: procoxae contiguous; prosternal posterocoxal piece short, conical. Protibiae slender, broadest at apical 1/3; posterior faces flattened, unarmed; outer margin of apical 1/2 with six small socketed denticles. Meso- and metatibiae flattened, outer margin evenly rounded with nine socketed denticles; posterior face unarmed.

Etymology.

L. setosus = bristly. In reference to the declivity densely covered with setae. An adjective.

Distribution.

Vietnam.

Host plants.

Unknown.

Figures

Figure 29. Dorsal, lateral and declivital view of Arixyleborus setosus holotype, 2.5 mm (A, B, I), A. silvanus holotype, 1.65 - 1.8 mm (C, D, J), A. sittichayai holotype, 2.3 mm (E, F, K), and A. suturalis, 1.5 - 1.7 mm (G, H, L).