A monograph of the Xyleborini (Coleoptera, Curculionidae, Scolytinae) of the Indochinese Peninsula (except Malaysia) and China Author Smith, Sarah M. Department of Entomology, Michigan State University, 288 Farm Lane, East Lansing, Michigan 48824, USA https://orcid.org/0000-0002-5173-3736 camptocerus@gmail.com Author Beaver, Roger A. 161 / 2 Mu 5, Soi Wat Pranon, T. Donkaew, A. Maerim, Chiangmai 50180, Thailand Author Cognato, Anthony I. Department of Entomology, Michigan State University, 288 Farm Lane, East Lansing, Michigan 48824, USA text ZooKeys 2020 983 1 442 http://dx.doi.org/10.3897/zookeys.983.52630 journal article http://dx.doi.org/10.3897/zookeys.983.52630 1313-2970-983-1 7DED4CE2934C4539945F758930C927F9 C890C7FD4B2D57A8B1A062305ED42D53 Arixyleborus sittichayai sp. nov. Fig. 29E, F, K Type material. Holotype , female, Thailand: Nakhon Sri [Thammarat], Khao Luong [sic; = Khao Luang] N.P., 1.vi.2011, Wisut [Sittichaya], ex ET [ethanol trap] (MSUC). Diagnosis. 2.3 mm long (n = 1); 2.3 x as long as wide. This species is distinguished by the protibiae posterior faces flat, unarmed; antennal club as broad as tall; posterolateral carina oblique, granulate; elytral disc flat, without a transverse depression; striae not impressed on disc, feebly impressed on declivity; declivital interstriae bearing two rows of long thick semi-erect hair-like setae, setae as long as 1.5 interstrial widths. Similar species. Arixyleborus granulifer , A. hirsutulus . Description (female). 2.3 mm (n = 1); 2.3 x as long as wide. Body uniformly dark red-brown. Legs and antennae yellow-brown. Head : epistoma entire, transverse, lined with a row of hair-like setae. Frons slightly convex from epistoma to upper level of eyes; surface alutaceous, shiny, sparsely punctate; punctures above epistoma large, coarse, shallow, punctures decreasing in size, coarseness, and depth from epistoma to upper level of eyes. Eyes deeply emarginate above level of antennal insertion, upper portion of eyes smaller than lower part. Scape regularly thick, approximately as long as club. Pedicle as long as funicle. Antennal funicle 4-segmented, segment 1 shorter than pedicel. Club wider than long and asymmetrical, club type 1; obliquely truncate, segment 2 not visible on posterior face; segment 1 covering posterior face, its margin completely costate; segment 2 narrow, pubescent with corneous part, visible on anterior face only. Pronotum : 1.06 x as long as wide. In dorsal view long and rounded frontally, type 7, sides parallel in basal 2/3, rounded anteriorly; anterior margin without serrations. In lateral view with disc much longer than anterior slope, type 8, summit low. Surface shagreened, anterior 1/2 finely asperate, asperities close, arranged in concentric rings from midpoint of pronotum to anterior margin; anterolateral areas unarmed; disc minutely and sparsely punctate; glabrous. Lateral margins obliquely costate. Base weakly bisinuate; setal tuft absent. Elytra : 1.39 x as long as wide, 1.36 x longer than pronotum. Elytral base weakly bisinuate, edge oblique, humeral angles rounded. Scutellum moderately sized, linguiform, flat, flush with elytra, medially impressed, sides straight from base to apical 1/2 of declivity then rounded to apex. Disc longer than declivity, distinctly separated, flat; striae impressed; interstriae shiny, densely, coarsely punctate in basal 1/4, punctures strongly confused, each bearing an erect golden-hair-like seta equal in length to interstrial width, interstriae 4 x width of striae, posterior 3/4 shagreened, dull, becoming densely, coarsely tuberculate apically, interstriae straight from base to declivity and narrowed on declivity. Declivity rounded, convex, strongly shagreened, dull, sculpturing consisting of much weaker interstrial carinae and strial impression; striae feebly impressed, punctate, punctures large, shallow, glabrous; interstriae tuberculate, bearing two rows of long thick semi-erect hair-like setae, setae as long as 1.5 interstrial widths; interstriae 1-3 carinae not extending to apex of declivity. Posterolateral margin costate, granulate to interstriae 7. Legs : protibiae slender, broadest at apical 1/3; posterior face flat, unarmed; outer margin of apical 1/2 with five small socketed denticles. Meso- and metatibiae flattened, outer margin evenly rounded with ten socketed denticles; posterior face unarmed. Etymology. Named for Dr. Wisut Sittichaya in recognition of his contributions to the study of bark and ambrosia beetles. Noun in genitive. Distribution. Thailand. Host plants. Unknown.