Xyleborus opacus, 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

Xyleborus opacus sp. nov. Fig. 90C, D, J

Type material.

Holotype, female, Vietnam: Cao Bang, 22°36.454'N, 105°52.083'E, 1661 m, 17.iv.2014, VN40, Cognato, Smith, Pham, ex 3 pieces “firewood” (MSUC). Paratypes, female, as holotype (MSUC, 1); as previous except: 22°36.3'N, 105°52.6'E, 1435-1601 m, 13-17.iv.2014, VN16, Cognato, Smith, Pham, ex FIT (MSUC, 1).

Diagnosis.

2.7 mm long (mean = 2.9 mm; n = 3); 3.0 × as long as wide. This species is distinguished by the antennal club distinctly wider than long; protibiae with evenly rounded outer edge; elytral posterolateral costa absent, replaced by a short row of tubercles; declivity strongly shagreened, strial punctures large, very shallow, difficult to distinguish; and discal interstrial setae biseriate.

Similar species.

Xyleborus muticus .

Description

(female). 2.7 mm long (mean = 2.9 mm; n = 3); 3.0 × as long as wide. Body red-brown to dark brown. Legs and antennae light brown. Head: epistoma entire, transverse, with a row of hair-like setae. Frons weakly convex to upper level of eyes; median carina present; surface shagreened, alutaceous, punctate; punctures sparse, shallow, setose, each bearing a long, erect hair-like seta. Eyes moderately emarginate just above antennal insertion, upper part smaller than lower part. Submentum narrow, triangular, deeply impressed. Antennal scape regularly thick, slightly longer than club. Pedicel as wide as scape, as long as funicle. Funicle 4-segmented, segment 1 shorter than pedicel. Club wider than long, obliquely truncate, type 2; segment 1 corneous, transverse on anterior face, occupying basal 2/5 of club, nearly covering posterior face; segment 2 narrow, corneous; segments 1 and 2 present on posterior face. Pronotum: 1.03 × 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, disc longer than anterior slope, type 7, summit on anterior 1/3. Anterior slope with densely spaced small asperities, becoming lower and more strongly transverse towards summit. Disc shagreened, alutaceous, with dense, fine punctures bearing long, fine, erect hair-like setae, some longer hair-like setae at margins. Lateral margins obliquely costate. Base transverse, posterior angles broadly rounded. Elytra: 1.5 × as long as wide, 1.57 × as long as pronotum. Scutellum moderately sized, linguiform, flush with elytra, flat, shiny. Elytral base transverse, edge oblique, humeral angles rounded, parallel-sided in basal 3/4, then broadly rounded to apex. Disc subshiny, striae not impressed, with moderately coarse, shallow punctures separated by 2-3 diameters of a puncture, each puncture bearing a short, recumbent seta slightly longer than puncture diameter; interstriae flat, finely punctate, punctures smaller than those of striae and strongly confused, punctures more widely separated than those of striae bearing two rows of semi-erect long, fine, erect hair-like setae, setae approximately as long as width of interstriae 2. Declivity steeply rounded, strongly shagreened; three striae present, striae parallel, strial punctures much larger than on disc, glabrous; interstriae impunctate, setose, setae uniseriate and similar in size to those of discal interstriae. Posterolateral margin rounded, denticulate from interstriae 4-8. Legs: procoxae contiguous; prosternal coxal piece tall, pointed. Protibiae obliquely triangular, broadest at apical 1/3; posterior face smooth; apical 1/2 of outer margin with eight large socketed denticles, their length longer than basal width. Meso- and metatibiae flattened; outer margins evenly rounded with ten and 12 small socketed denticles, respectively.

Etymology.

L. opacus = dark. In reference to the species’ habitus. An adjective.

Distribution.

Vietnam.

Host plants.

Unknown.

Figures

Figure 90. Dorsal, lateral and declivital view of Xyleborus mysticulus holotype, 2.2 - 2.5 mm (A, B, I), X. opacus paratype, 2.7 mm, 2.2 - 2.5 mm (C, D, J), X. perforans, 2.3 - 2.6 mm (E, F, K), and X. pfeilii, 2.9 - 3.2 mm (G, H, L).