Webbia spinosulcata 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 : 54-56

Webbia spinosulcata Sittichaya, Smith & Beaver sp. nov.

Fig. 4

Type material. Holotype, female, THAILAND, Songkhla Province, Ton Nga Chang Wildlife Sanctuary , 6°59'32.1"N, 100°08'57.8"E, tropical rainforest, 140msl, ethanol baited trap, 01.iii.2015, (W. Sittichaya) ( NHMW).

Diagnosis. 2.60 mm long; 2.89x as long as wide. This species is distinguished by pronotum only 1.1 times as long as wide, upper margins of elytral declivity angularly produced forwards at the suture and armed with three or four small teeth, denticles increasing in size posteriorly; declivital margin carinate, with a fringe of hair-like setae; declivital face densely covered with semi-recumbent feathery setae, lacking spines or processes, its apical margin entire.

The species is most similar to Webbia penicillata , W. divisa , W. dasyura and W. planicauda sp. nov. The first two species also possess a strongly excavate elytral declivity, with the upper margins extended anteriorly at the suture, but can be distinguished by the absence of denticles on the upper margin. W. dasyura and W. planicauda have a similar dense covering of feathery setae on the elytral declivity, but the upper margin of the declivity is not extended anteriorly.

Description (female) 2.60 mm long (n=1); 2.89× as long as wide. Body and appendages yellowish brown, pronotal anterior slope and elytral summit darker, declivital summit ferruginous. Head: Epistoma entire, transverse, with a dense row of hair-like setae, setae moderately long. Frons weakly convex to upper level of eyes; alutaceous, finely rugose, subshining, sparsely covered with long, hair-like setae. Eyes shallowly emarginate just above antennal insertion, upper portion smaller than the lower. Submentum triangular, deeply impressed. Antennal scape regularly thick, as long as club. Pedicel as wide as scape, 4× shorter than funicle. Funicle 2-segmented, segment 1 shorter than pedicel. Club flattened, broader than tall, type 3, corneous, occupying approximately ba¼ 1/4 of club on anterior face, anterior margin feebly convex; segments 1 and 2 visible on posterior face, segment 2 narrow, corneous, anterior margin convex; segment 3 prominent, appearing soft on anterior side. Pronotum: 1.12× as long as wide, less elongate than usual in genus (type 8 in dorsal view); sides parallel in basal 2/3, quadrate anteriorly, anterior margin without serrations. In lateral view long, flattened and bulging frontally, type b, disc flat, summit approximately at anterior 1/3. Anterior slope subshiny, with transverse, fine, narrow asperities, becoming lower and more strongly transverse towards summit, asperities bearing short, fine, semi-recumbent, hair‒like setae, shorter posteriorly. Disc shiny, near the summit shagreened, base alutaceous, densely, finely punctate, punctures with short, semi-recumbent, hair-like setae (mostly abraded in holotype). Lateral margins weakly carinate. Base feebly broadly concave, edge oblique, posterior angles angulate. Scutellum: minute, scarcely visible. Elytra: 1.53× as long as wide, 1.45× as long as pronotum. Elytral base feebly sinuate, edge carinate, with tuft of mycangial setae along the margin; humeral angles rounded, sides subparallel in basal 4/5, then angulate to apex, apical margin round, entire. Disc convex subshining, alutaceous; striae with small, shallow punctures separated by about 2× their diameter, each puncture with a short minute hair-like seta; interstriae flat, 2× as wide as striae, each bearing two or three rows of short, semi-recumbent, hair‒like setae; interstriae impunctate up to apical 4/5 then with minute, dense, confused punctures. Declivity abruptly truncate, concave, upper margins of elytral declivity angularly produced forwards at the suture and armed with three or four small teeth, teeth increasing in size and becoming more flattened posteriorly; striae and interstriae 1 sulcate anteriorly; declivital margins sharply carinate bearing dense erect hair‒like setae. Declivital face impressed with a dense covering of feather-like setae. Legs: procoxae contiguous. Protibiae slender, broadest at middle; posterior face inflated, granulate; outer margin with ten short, closely placed, socketed denticles, their length less than basal width. Meso- and metatibiae with rounded outer edge, broadest at apical 1/3, each with 12 small, closely placed, socketed denticles, posterior faces unarmed; anterior faces finely granulate.

Etymology. L. spina = a thorn; sulcatus = grooved or furrowed. Adjective. The name refers to the sulcate declivity bearing denticles on its upper margin.

Distribution. Thailand (Songkhla).

Host plants. Unknown.

Figures

FIGURE 4. Webbia spinosulcata sp. nov. holotype A) dorsal view; B) lateral view; C) postero-lateral view; D) frons; E) head lateral and antennae; F) declivital face.