Xyleborus sunisae, 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 sunisae sp. nov. Fig. 91C, D, J

Type material.

Holotype, female, Thailand, Chiang Mai, Doi Pui, 18.841N, 98.899E, 1348 m, 2.ii.2010, S. Sanguansub, ex Fagaceae sp., fallen tree (NHMUK). Paratypes, female, as holotype (MSUC, 1; SSC, 1; RABC, 2).

Diagnosis.

2.7-2.75 mm long (mean = 2.73 mm; n = 4); 3.24-3.38 × as long as wide. This species is distinguished by its elongate form, the presence of denticles or granules on all declivital interstriae, including interstriae 2, the widening of declivital interstriae 1 from the base of the declivity to the apex; declivital striae not impressed; declivital posterolateral margin costate and bearing a row of spinose granules to interstriae 7; and discal interstriae with punctures much finer than strial punctures, very widely spaced.

Similar species.

Xyleborus dryographus (Ratzeburg, 1837) (from western Palearctic), X. muticus .

Description

(female). 2.7-2.75 mm long (mean = 2.73 mm; n = 4); 3.24-3.38 × as long as wide. Body 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 absent; surface shagreened, reticulate, punctate; punctures sparse, large, shallow, setose, each bearing a long, erect hair-like seta. Eyes shallowly emarginate just above antennal insertion, upper part smaller than lower part. Submentum 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 approximately circular, obliquely truncate, type 2; segment 1 corneous, transverse on anterior face, occupying basal 1/2, nearly covering posterior face; segment 2 narrow, corneous; segment 1 present on posterior face. Pronotum: 1.36 × as long as wide. In dorsal view elongate, conical frontally, type 6, sides parallel on basal 2/3, conical anteriorly; anterior margin without serrations. In lateral view type 7, elongate, disc longer than anterior slope, summit on anterior 2/5. Anterior slope with densely spaced small asperities, becoming lower and more strongly transverse towards summit. Disc subshiny with sparse, large, coarse punctures bearing short, erect hair-like setae, some longer hair-like setae at margins. Lateral margins obliquely costate. Base transverse, posterior angles broadly rounded. Elytra: 2.04 × as long as wide, 1.5 × 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 4/5, then broadly rounded to apex. Disc shiny, striae not impressed, with small, shallow punctures separated by three diameters of a puncture, glabrous; interstriae flat, very sparsely finely punctate, punctures 1/2 size of strial punctures, each with a short, thick, erect seta. Declivity steep, strongly convex, shiny; striae not impressed, strial punctures larger, coarser than on disc; interstriae 1 widened from base to apex; all interstriae similarly armed, bearing small spines or granules. Posterolateral margin costate, granulate to interstriae 7, granules spinose. Legs: procoxae contiguous; prosternal coxal piece bulging. Protibiae distinctly triangular; posterior face smooth; apical 1/2 of outer margin with six small socketed denticles, their length as long as basal width. Meso- and metatibiae flattened; outer margins obliquely triangular with eight small socketed denticles.

Etymology.

The species is named for Dr. Sunisa Sanguansub, the collector, for her contributions to our knowledge of bark and ambrosia beetles. Noun in genitive.

Distribution.

Thailand.

Host plants.

Recorded only from an unidentified species of Fagaceae .

Figures

Figure 91. Dorsal, lateral and declivital view of Xyleborus singhi paratype, 1.9 - 2.4 mm (A, B, I), X. sunisae holotype, 2.7 - 2.75 mm (C, D, J), X. volvulus, 2.5 mm (E, F, K), and X. yunnanensis paratype, 2.7 - 2.75 mm (G, H, L).