Arixyleborus vellus 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 : 72

Arixyleborus vellus Sittichaya, Beaver & Smith sp. nov.

http://zoobank.org/ urn:lsid:zoobank.org:act:2C7E7B78-0903-4117-9E38-5E4B49BE0C60

( Fig. 4 )

Type material. Holotype, female: THAILAND: Nan Province, Pua District, Doi Phu Kha National Park , 19°12’18.5”N 101°04’39.5”E; 1320m, montane forest, ethanol baited traps, 01.vi.12, W. Sittichaya ( NHMW) ; Paratypes, as holotype (2) (1, RABC; 1, WSTC).

Diagnosis. 2.50–2.60 mm long (mean 2.55, n = 3); 2.43–2.60× 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 with striae impressed and interstriae raised from basal fifth; declivity angularly separated from disc, apex angulate; declivital face truncate, flattened, dull; striae not impressed, punctures forming slightly raised discs, interstriae flattened, biseriate granulate on upper portion, becoming uniseriate on apical half, except for interstriae 1, each granule with a long semi-erect hair-like seta; posterolateral margin denticulate; protibiae with posterior face inflated, granulate. This species is similar to A. puberulus but is distinguished by ( A. vellus given first): pronotal disc approximately as long as anterior slope, summit in middle of pronotum vs disc shorter, 0.8× as long as anterior slope, summit behind middle of pronotum; declivity abruptly truncate, apex angulate vs declivity broadly rounded, apex broadly rounded.

Description (female): 2.50–2.60 mm long (mean 2.53, n = 3); 2.43–2.60× as long as wide. Body dark brown to black, appendages paler. Head. Epistoma entire, transverse, with a row of hair-like setae. Frons strongly convex from epistoma to upper level of eyes, subshiny, reticulate with moderately sized, densely placed, rounded granules near epistoma, sparser, weaker rugosities in mid-part, upper part of frons punctate to just above upper level of eyes, each puncture with a moderately long, very fine, hair-like seta; frons with a raised, smooth, median line from lower level of eyes to just above upper level; vertex strongly reticulate, impunctate. Eyes deeply emarginate above level of antennal insertion, upper part of eyes slightly smaller than lower part. Submentum deeply impressed, small, triangular. Scape short, moderately thick, approximately equal in length to the club. Pedicel as long as funicle. Antennal funicle 4-segmented, first segment the longest. Club as long as wide, type 1; segment 1 corneous, encircling anterior face, concave on anterior side, with sharp marginal costa; segment 2 narrow, concave, corneous on anterior face; sutures absent on posterior face. Pronotum. 1.07‒1.10× as long as wide. In dorsal view, type 7, elongate, sides parallel in basal 2/3; anterior margin rounded without serrations. In lateral view, type 8, disc much longer than anterior slope, summit low. Anterior slope finely asperate, asperities low, closely placed, decreasing in size towards summit, each asperity with a fine, tapering hair-like seta. Disc with surface reticulate, subshiny, moderately densely, minutely punctured, each puncture with a short, fine hair-like seta directed anteriorly, some longer setae present along margin. Lateral margins obliquely costate. Base weakly bisinuate. Elytra. 1.26‒1.32× as long as wide, 1.18‒ 1.23× as long as pronotum. Scutellum moderately sized, linguiform, raised above surrounding impressed elytra, finely punctured. Elytral bases transverse, edge oblique, humeral angles rounded, sides subparallel for 2/3 of length, feebly widened posteriorly, rounded to apex. Disc 2× as long as declivity, shiny in basal half, matt posteriorly, basal 1/5 flat, then striae impressed, furrowed, increasing deeply posteriorly, punctate; punctures large, circular, shallow, separated by about half the diameter of a puncture; interstriae 2× width of striae, increasingly elevated posteriorly, biseriate punctate in basal half of disc; punctures minute, each with a semi-appressed, moderately long hair-like seta; posterior half of disc with interstriae densely, coarsely tuberculate, tubercles uniseriate on interstriae 1, biseriate on other interstriae. Declivity abruptly truncate, angularly separated from disc, flattened, shagreened, dull; striae not impressed, narrower than on the disc, punctures forming flat, circular discs with a slightly raised circumference, each with a very short fine hair-like seta; interstriae flattened, biseriate granulate on upper portion, becoming uniseriate on apical half, except for interstriae 1, granules mostly coarse, densely spaced, each bearing a moderately long, semi-erect, hair-like seta. Posterolateral declivital margin denticulate. Legs. Protibiae slender, broadest at apical 1/3; posterior face inflated, granulate; outer margin with five or six small socketed denticles. Meso- and metatibiae flattened, posterior face unarmed, outer margin evenly rounded with ten and eleven socketed denticles respectively.

Male: Unknown.

Etymology: Latin noun, vellus = wool, referring to the wool-like setae on the declivital face.

Distribution: Thailand: Nan Province.

Figures

FIGURE 4 Arixyleborus vellus sp. nov. holotype female A) dorsal view B) lateral view C) postero-lateral view D) frons E) antenna.