Webbia granulosa Sittichaya, Smith & Beaver, 2023

Sittichaya, Wisut, Smith, Sarah M. & Beaver, Roger A., 2023, New species, taxonomic changes and newly recorded species of Webbia Hopkins, ambrosia beetles from Thailand and neighbouring countries (Coleoptera: Curculionidae: Scolytinae: Xyleborini), Zootaxa 5264 (1), pp. 47-63 : 51-53

Webbia granulosa Sittichaya, Smith & Beaver sp. nov.

Fig. 2

Type material. Holotype, female, THAILAND, Sakon Nakhon, Phu Pan National Park , 17°03′55.5"N 103°58'10.1"E, dry deciduous dipterocarp forest, 340msl, ethanol baited trap, 01.iii.2020, W. Sittichaya ( NHMW) . Paratypes, female, as holotype (4) (1, WSTC) (1, MSUC) (1, RABC) (1, THNHM) .

Diagnosis. 1.75–2.15 mm long (mean = 1.92 mm, n=5); 2.92–3.09× as long as wide (mean = 2.97×, n=5). This species is distinguished by the elytral declivity subshining, declivital face flat not impressed, circumdeclivital margin with small, acute denticles; declivital striae and interstriae granulate, granules small, stronger on interstriae, bearing short, brownish, hair‒like setae; posterolateral declivital margin with a short acute process; elytral apex with small, triangular processes.

The species is similar to Webbia aculeata sp. nov., W. cornuta and W. hatanakai . W. aculeata can be distinguished by the much larger size and greater length of the processes on the posterolateral margin of the elytral declivity ( Fig. 1 ); W. hatanakai by the very coarse, closely placed strial punctures on the elytral declivity; W. cornuta by the smooth, shining elytral declivity lacking granules.

Description (female) 1.75–2.15 mm long (mean = 1.92 mm; n = 5); 2.92–3.09× as long as wide (mean = 2.97, n = 5). Frons, pronotum and elytral bases dark brown (brown in two paratypes), elytral disc, abdomen and appendages pale yellowish, declivital summit and declivity ferruginous. Head: epistoma entire, transverse, with a row of short, hair-like setae. Frons feebly convex to upper level of eyes, shining, shagreened, with feebly elevated, vertical median line extending nearly to vertex, sparsely, shallowly punctured below upper level of eyes, each puncture with an erect hair-like seta, setae much finer than those on epistoma. Eyes moderately deeply emarginate just above antennal insertion, upper and lower portions subequal in size. Submentum triangular, deeply impressed. Antennal scape thickened, slightly longer than club. Pedicel narrower than scape, 2× longer than the 2-segmented funicle. Club flattened, circular, as broad as tall (slightly deformed, appearing taller in holotype), type 2, segment 1 corneous, corneous portion small, occupying approximately ¼ of club, its margin concave on anterior face; segments 1 and 2 visible on posterior face, segment 2 narrow, corneous part an anterior side slender. Pronotum: 1.25‒1.31× as long as wide (mean = 1.28, n = 5). In dorsal view elongate, quadrate frontally, type a, sides parallel in basal 4/5; anterior margin without serrations. In lateral view elongate, flattened, bulging frontally, type b, disc flat, summit approximately at anterior 1/5. Anterior slope subshining, with transverse, fine, narrow asperities, becoming lower and more strongly transverse towards summit, apical half bearing short, fine, semi-recumbent hair-like setae; setae longest at anterior margin becoming shorter posteriorly. Disc subshining, alutaceous, moderately densely, finely punctate, punctures with a very short, pale yellowish hair-like seta. Lateral margins weakly carinate. Base feebly bisinuate, margin oblique, posterior angles angulate. Scutellum: not visible from above. Elytra: 1.53‒1.73× as long as wide (mean = 1.60, n = 5), 1.18‒1.37× as long as pronotum (mean = 1.27×, n = 5). Elytral base V‒shaped, concave, with tuft of mycangial setae along the margin, edge costate, humeral angles rounded; sides subparallel in basal 2/3, then angulate to apex. Elytra smooth, alutaceous, except near scutellum and declivital summit. Disc convex, shining, subtransparent, striae punctate, punctures minute, inconspicuous, separated by 1–1.5× diameters of a puncture, each puncture with a very short, fine hair‒like seta, setae longer toward lateral margin; interstriae flat, 2× as wide as striae. Declivital summit dull, weakly, irregularly rugulose; declivity abruptly truncate, declivital margins armed with short, pointed denticles, each denticle with several moderately long brownish hair‒like setae. Declivital face flat not impressed, granulate, subshining; striae weakly granulate-punctate, interstriae granulate, granules larger than on striae, all granules with a short, strong, semi-recumbent seta; strial and interstrial setae subequal in size, but many interstrial setae slightly flattened. Posterolateral margin of declivity armed with a short, acutely pointed process on each side, processes weakly curved towards midline. Apical margin with a short, triangular process on each side next to suture. Legs: procoxae contiguous. Protibiae slender, broadest at middle; posterior face inflated, granulate; outer margin with ten short and small socketed denticles, their length shorter than basal width. Meso- and metatibiae with outer margin rounded, broadest at middle, each with nine small, socketed denticles, posterior faces flat, unarmed; anterior faces very finely granulate.

Etymology. L. granulosus = with small granules. Adjective. The name refers to the granules on the declivital striae and interstriae.

Distribution. Thailand (Sakon Nakhon).

Host plants. Unknown.

Figures

FIGURE 1. Webbia aculeata sp. nov. holotype A) dorsal view; B) lateral view; C) postero-lateral view; D) frons; E) venter and antennae; F) declivital face.

FIGURE 2. Webbia granulosa sp. nov. holotype A) dorsal view; B) lateral view; C) postero-lateral view; D) frons; E) head lateral and antenna; F) declivital face.