Webbia planicauda Beaver, Sittichaya & Smith, 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 : 53-54

Webbia planicauda Beaver, Sittichaya & Smith sp. nov.

Fig. 3

Type material. Holotype. Female, THAILAND: Lamphun Province, Maeping National Park, 17 o 33'25.4′'N, 98 o 52'57.4''E, Dry dipterocarp forest, 630m, 01.x.2019, W. Sittichaya ( NHMW) . Paratypes. Female, BRUNEI: Andalau Forest Reserve, E 114.30 o, N4.40 o, Dipterocarp forest, Dryobalanops beccarii, Fog 11: Site 7, 50m alt., 27.viii.[19]91, N. Mawdsley, NM369 (1, NHML) ; MALAYSIA: Sabah, Sipitang, Long Meng, 4.269N, 115.442E, 1500‒2000m, Plantation forest , PL-2, ex EtOH trap, 6.x.2018, M.L. Lardizabal et al. (1, RABC) .

Diagnosis: The species is one of a small group of Webbia species with a circular, truncate elytral declivity without ridges, spines or processes on the declivital face. W. penicillata (Hagedorn) , W. divisa (Browne) , W. spinosulcata sp. nov. and W. dasyura Browne have similar feathery setae on the face of the elytral declivity. The first three species are distinguished from W. planicauda by the deeply excavate declivity with its upper margins extended anteriorly at the suture. W. dasyura is distinguished by the concave, not flat elytral declivity, the upper margin close to the suture rounded not acute, the granules on the central part of the declivital face larger, more closely spaced and equally sized, separated by less than their own diameter. W. subuculae (Browne) and W. talautica (Eggers) have a similar, almost flat elytral declivity, with a continuous, acute margin, but the declivital vestiture is sparser, and lacks the feathery setae of W. planicauda . W. sarawakensis Schedl and W. philippinensis (Schedl) have a convex declivity, and also lack the feathery setae of W. planicauda .

Description (female). 2.3‒2.8 mm long (mean = 2.55 mm; n = 3); 2.8‒3.1× as long as wide. Body subnitid, yellowish brown, elytra becoming darker brown apically, declivity dark brown, declivital margin black. Head: frons subnitid, alutaceous, weakly convex, densely granulate-punctate above epistoma, with a dense fringe of hair-like setae covering epistoma, gradually becoming more sparsely punctate above, punctures with fine, erect, hairlike setae, a weak median ridge extending to upper level of eyes, vertex shining, impunctate. Eyes large, coarsely facetted, slightly extending onto frons, emargination triangular, deep, extending nearly half width of eye, upper part smaller than lower part. Submentum deeply impressed, broadly triangular. Antennae with scape a little shorter than club, pedicel about as wide as scape, funicle 3-segmented, segments transverse, gradually increasing in width towards club; club approximately circular, flat, type 3, segment 1 corneous, extending less than one-quarter of club length, its anterior margin concave, segment 2 narrow, corneous, visible on both sides of club. Pronotum: 1.25‒1.4× as long as wide. In dorsal view, elongate, sides subparallel, anterior margin subtransverse, a very weak emargination in middle, type a; anterior margin without serrations. In lateral view, long, flat, convex anteriorly, type b. Anterior slope with small, dense, transverse asperities, becoming smaller, less transverse and more granular towards summit situated at about one-third from anterior margin, bearing short, suberect, hairlike setae, longer near anterior margin. Disc subshining, finely alutaceous, moderately densely, finely, regularly punctate, punctures more closely spaced towards base, bearing short, fine, erect, hairlike setae. Lateral margins costate, more strongly at posterior angles. Base transverse, posterior angles almost rectangular in dorsal view. Scutellum: not visible. Elytra: 1.5‒1.75× as long as wide, 1.2‒1.4× as long as pronotum. Elytral bases weakly concave, humeral angles anterior to scutellar angles, anterior margin sharply angled close to scutellar angles, becoming rounded at humeral angles. Elytra parallelsided in basal 5/6 then broadly rounded to apex. Disc flat, shining, finely, rather indistinctly punctured, striae not impressed, their punctures separated by 1.5‒2× their diameter, interstriae flat, smooth, minutely, irregularly punctured, punctures becoming stronger and denser close to declivital margin. Declivity abruptly truncate, acutely margined, margin unarmed, face circular, matt, almost flat, a very weak convexity in the middle on each side, granulate, granules of very varied sizes, separated by more than their own diameter, and partly concealed by a dense vestiture of greyish-white, subrecumbent setae, hair-like towards sides, feather-like towards middle, especially in a V-shaped central area extending from the apices to the upper margin, this area very distinct when viewed at an appropriate angle. Legs: procoxae contiguous; prosternal coxal piece inconspicuous. Protibiae slender, outer margin weakly rounded, posterior side inflated, granulate, 11-12 small protibial denticles extending along 5/6 of external margin from apex. Meso- and metatibiae broader, flattened, with numerous small denticles in apical 2/3.

Distribution. Brunei Darussalam, East Malaysia, Thailand (Lamphun).

Host plants. Unknown.

Etymology. L. planus = flat; cauda = tail, referring to the flat elytral declivity.

Figures

FIGURE 3. Webbia planicauda sp. nov. holotype A) dorsal view; B) lateral view; C) postero-lateral view; D) frons; E) head lateral and antenna; F) declivital face.