Arixyleborus halabala Sittichaya, Beaver & Smith, 2024

Sittichaya, Wisut, Beaver, Roger A. & Smith, Sarah M., 2024, Four new species of Arixyleborus Hopkins, 1915, ambrosia beetles from Thailand (Coleoptera: Curculionidae: Scolytinae: Xyleborini), Zootaxa 5446 (1), pp. 65-76 : 66-68

Arixyleborus halabala Sittichaya, Beaver & Smith sp. nov.

http://zoobank.org/ urn:lsid:zoobank.org:act:3AB69B89-BCCE-476B-9CC3-1AC062F33205

( Fig. 1 )

Type material. Holotype, female: THAILAND: Narathiwat Province, Hala-Bala Wildlife Sanctuary , 5°48’02.4”N, 101°49’58.2”E, 140m, lowland tropical rainforest, ethanol baited trap, 01.vii.2014., W. Sittichaya ( NHMW) ; Paratypes, female, same as holotype (6) (6, WSTC); same as holotype except; 01.iii.2012 (3) (1, RABC; 1, MSUC; 1, THNHM); same as holotype except; 01.xi.2014 (3) (3, WSTC).

Diagnosis: 2.10–2.28 mm long (mean 2.20, n = 12); 2.33–2.51× as long as wide. This species is distinguished by the pronotum type 7 in dorsal view, evenly rounded anteriorly, anterior margin without serrations; elytral disc almost flat, with a very weak transverse impression in middle; striae not impressed; declivity steep, matt, interstriae 1 raised and strongly convex near apex; declivital interstriae with dense, hair-like setae; apex angularly rounded; posterolateral margin tuberculate; protibiae with posterior surface inflated, granulate. This species resembles A. okadai Browne , but is distinguished by ( A. halabala given first): larger size, 2.10–2.28 mm long vs 1.95‒2.05 mm long; anterior margin of pronotum unarmed vs anterior margin of pronotum with a row of asperities; interstriae 1 raised and convex near apex vs interstriae 1 not raised on declivity; elytral apex angularly rounded vs elytral apex evenly rounded. It is distinguished from A. moestus (Eggers) by the following characters ( A. halabala given first): smaller size, 2.10–2.28 mm long vs 2.50−2.70 mm long; elytral disc feebly transversely depressed vs elytral disc flat; elytral striae flat not impressed vs elytral striae weakly impressed; granules on elytra small vs granules on elytra larger.

Description (female) 2.10–2.28 mm long (mean 2.20, n = 12); 2.33–2.51× as long as wide. Body dark brown to black except appendages brown, body covered with grayish brown hair-like setae. Head. Epistoma complete, anterior margin transverse, with a row of hair-like setae. Frons convex from epistoma to upper level of eyes; moderately shiny, lower half alutaceous, upper half reticulate; surface with rounded, shiny granules of varying size, densely placed near epistoma, more sparsely toward vertex, each with an erect, hairlike seta inserted close to it; upper part of frons with a weakly raised, shiny median line Eyes deeply emarginate above level of antennal insertion, upper part of eyes almost equal in size to lower part. Submentum strongly impressed, broadly triangular. Scape clavate, approximately as long as club. Pedicel as long as funicle. Antennal funicle 4-segmented, segment 1 shorter than pedicel. Club as long as wide, type 2; segment 1 corneous, anterior margin completely costate, feebly concave on anterior face, occupying approximately basal half of club; segment 2 narrow, partly corneous on anterior side, margin costate, visible on posterior face. Pronotum. 1.01–1.20× as long as wide. In dorsal view, type 7, sides parallel in basal 2/3, evenly rounded anteriorly; anterior margin without serrations. In lateral view with disc much longer than anterior slope, type 8; summit low, indistinct. Anterior half with small, low, densely placed asperities, becoming lower posteriorly. Disc convex, alutaceous, sub-shining, finely, moderately densely punctured, each puncture bearing a short, curved, semi-erect, posteriorly-directed, hair-like seta, some longer hairlike setae on margins. Lateral margins obliquely costate. Base weakly bisinuate. Elytra. 1.22–1.33× as long as wide, 1.10– 1.20× longer than pronotum. Elytral bases transverse, edge oblique, weakly costate near scutellum, humeral angles rounded. Scutellum moderately sized, linguiform, flat, flush with elytra, its surface finely punctate, shiny. Elytral sides parallel from base for 3/4 of elytral length, then angularly rounded to apex; disc longer than declivity, very feebly transversely impressed in middle, densely covered with semi-recumbent, moderately long, moderately thick, grayish hair-like setae (some abraded in holotype); disc in basal 1/3 mostly shiny (except dull close to suture in holotype and some paratypes), rugulose, striae and interstriae indistinct, flat, with some minute, confused granules, slightly increasing in size from dorsal surface to lateral margins; posterior part of disc matt, with densely spaced granules increasing in size posteriorly; interstriae with 2‒3 irregular rows of granules, striae with a single row of smaller granules. Declivity steep, shagreened, matt, flat on upper middle part, interstriae 1‒4 extending to apex of declivity, interstriae 1 raised and strongly convex near apex; granules much smaller than those on disc; densely covered with moderately thick, hair-like setae, shorter than setae on declivital summit, but of similar size and form on all interstriae; posterolateral margin tuberculate to interstriae 7. Legs. Protibiae slender, broadest at apical 1/3, posterior face strongly inflated, granulate, outer margin with five comparatively large, shorter than wide, socketed denticles in apical 2/3. Meso- and metatibiae flattened, posterior face unarmed; mesotibiae outer margin rounded with ten socketed denticles; metatibiae outer margin evenly rounded, more slender than mesotibiae, with nine socketed denticles.

Male: Unknown.

Etymology: Halabala (ฮาลา-บาลา), Thai name of the Hala-Bala Wildlife Sanctuary, the collection locality of the type series. Noun in apposition.

Distribution: THAILAND: Narathiwat Province.

Figures

FIGURE 1. Arixyleborus halabala sp. nov. holotype female A) dorsal view B) lateral view C) postero-lateral view D) frons E) antenna.