Xylosandrus spinifer, 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

Xylosandrus spinifer sp. nov. Fig. 97A, B, G

Type material.

Holotype, female, Thailand: SE Chanthaburi, 45 m, 25-30.iv.1958 (BPBM). Paratypes, female, China: Hong Kong, Tai Po Kau, vi.2017, J. Skelton, P. Carlson, Y. Li, J Hulcr, uffeID: 31231 (UFFE, 1), uffeID: 31217 (UFFE, 2); Vietnam: N, (Na Hang), 160 km NNW Hanoi, NE env. of Na Hang, 150-200 m NN, 03-13.vi.1996, A. Napolov, I. Roma (RABC, 1).

Diagnosis.

3.3 mm long (n = 1); 2.3 × as long as wide. This species is unique among all Xylosandrus because of the unmistakable pair of very large spines on the declivital summit and a flat antennal club, type 4, with three sutures visible on the posterior face.

Xylosandrus spinifer superficially resembles Diuncus spp. but can be differentiated by the following characteristics: base of the pronotum has an elongate patch of dense punctures bearing a tuft of setae; anterior margin of pronotum evenly rounded, asperities just above the margin are of equal size, rather than with a median, larger pair; procoxae separated; and posterolateral margin carinate and granulate.

Similar species.

Diuncus spp.

Description

(female). 3.3 mm long (n = 1); 2.3 × as long as wide. Head, pronotum and elytral disc light red-brown, declivity dark red-brown, antennae and legs 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, impunctate, alutaceous, asperate; asperities longitudinal, larger, denser above epistoma, decreasing in density and height dorsally, becoming more weakly raised and sparse by upper level of eyes. Eyes very shallowly emarginate just above antennal insertion, upper part smaller than lower part. Submentum narrow, triangular, slightly impressed. Antennal scape regularly thick, approximately as long as club. Pedicel as wide as scape, shorter than funicle. Funicle 4-segmented, segment 1 as long as pedicel. Club longer than wide, flattened, type 4; segment 1 corneous, small, convex; segment 2 larger than segment 1, narrow, transverse, corneous; segments 1-3 present on posterior face. Pronotum: 0.97 × as long as wide. In dorsal view rounded, type 1, sides parallel in basal 1/2, rounded anteriorly; anterior margin with a row of serrations. In lateral view basic, type 0, disc flat, summit at midpoint. Anterior slope with densely spaced, moderate asperities, becoming lower and more strongly transverse towards summit, bearing long, fine, erect hair-like setae, some longer hair-like setae at anterior and lateral margins. Disc shiny, alutaceous with very dense, fine punctures, glabrous. Lateral margins obliquely costate. Base transverse, posterior angles broadly rounded. Mycangial tuft present along basal margin and basal median 1/2 of disc along median line, tuft broad, dense, approximately the width of scutellum. Elytra: 1.31 × as long as wide, 1.39 × 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 shiny, striae not impressed, seriate; interstriae impunctate, moderately setose, setae semi-erect, hair-like. Declivity sharply distinct from disc, declivital summit armed by large denticles on interstriae 1, 2, 4, and 5 and a very large spine on interstriae 3, its apex incurved; interstrial punctures replaced by uniseriate denticles, each denticle bearing a long, erect hair-like seta equal in length to width of distance between interstriae 1 and 3; six striae present, striae 1 impressed at declivital summit, strial punctures larger, deeper than those of disc. Posterolateral margin carinate, granulate to interstriae 7. Legs: procoxae moderately separated; prosternal coxal piece tall, pointed. Protibiae distinctly triangular, broadest at apical 1/4; posterior face smooth; outer margin of apical 1/3 with five large socketed denticles, their length much longer than basal width; apical mucro prominent, strongly incurved. Meso- and metatibiae flattened, outer margins evenly rounded with nine and 12 small, similarly sized, socketed denticles, their length no longer than basal width, respectively.

Distribution.

China (Hong Kong), Thailand, Vietnam.

Host plants.

Unknown.

Etymology.

L. spinifer = thorn-bearing. In reference to the spines on the declivity which are atypical for the genus. A noun in apposition.

Figures

Figure 97. Dorsal, lateral and declivital view of Xylosandrus spinifer holotype, 3.3 mm (A, B, G), X. subsimiliformis holotype, 2.45 - 3.0 mm (C, D, H), and X. subsimilis, 2.5 - 2.9 mm (E, F, I).