Arixyleborus titanus, Smith & Beaver & Cognato, 2020

Smith, Sarah M., Beaver, Roger A. & Cognato, Anthony I., 2020, A monograph of the Xyleborini (Coleoptera, Curculionidae, Scolytinae) of the Indochinese Peninsula (except Malaysia) and China, ZooKeys 983, pp. 1-442 : 1

Arixyleborus titanus sp. nov. Fig. 30A, B, G

Type material.

Holotype, female, 云南西双版纳 1200-1600 公尺 1958.VII.26 采集者:王書永 [China: Yunnan, Xishuangbanna, Menghai, 1200-1600 m, 26.vii.1958, Shuyong Wang] (NMNH).

Diagnosis.

5.2 mm long (n = 1); 2.6 × as long as wide. This species is distinguished by the protibiae posterior faces flat, unarmed; antennal club wider than long; posterolateral carina oblique, granulate; elytral disc with deep transverse saddle-like depression; and large size.

Similar species.

Arixyleborus granifer .

Description

(female). 5.2 mm (n = 1); 2.6 × as long as wide. Body dark brown with red-brown declivity. 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; weakly medially impressed between upper level of eyes; surface shagreened, dull, punctate; punctures above epistoma small, fine, shallow; punctures increasing in size, coarseness, and depth from epistoma to upper level of eyes; lower 1/2 of frons granulate. Eyes deeply emarginate above level of antennal insertion, upper portion of eyes smaller than lower part. Scape regularly thick, approximately 3/4 length of club. Pedicle shorter than 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, corneous, visible on anterior face only. Pronotum: 1.02 × 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 elongate with disc as long as declivity, type 7, summit moderate. Surface shiny, anterior 1/2 finely asperate, asperities close, arranged in concentric rings from midpoint of pronotum to anterior margin; anterolateral areas unarmed; disc finely, densely punctate; very long, erect hair-like setae, equal in length to 1.5 × discal interstriae 1. Lateral margins obliquely costate. Base weakly bisinuate; setal tuft absent. Elytra: 1.43 × as long as wide, 1.27 × longer than pronotum. Scutellum moderately sized, linguiform, clearly depressed below level of elytra. Elytral base weakly bisinuate, edge oblique, humeral angles rounded, sides straight from base to apical 1/2 of declivity then rounded to apex. Disc longer than declivity, indistinctly separated, shiny, median area concave, densely, finely punctate on basal 1/4; striae deeply impressed; interstrial punctures strongly confused, each bearing an erect golden hair-like seta equal in length to 3 interstrial widths, posterior 3/4 shagreened, dull, interstriae 3 × width of striae, interstriae becoming sparsely tuberculate and granulate apically, interstriae laterally diverging from base to declivity and narrowed on declivity; declivity obliquely truncate, shagreened, dull; striae weakly impressed, distinctly punctate; interstriae impunctate, densely tuberculate, each tubercle bearing a long, erect golden hair-like seta equal in length to 3 interstrial widths; interstriae 1-3 inflated on apical 1/2. Posterolateral margin feebly costate, granulate to interstriae 7. Legs: procoxae contiguous. Protibiae slender, broadest at apical 1/3; posterior face flat, unarmed. Meso- and metatibiae flattened, outer margin evenly rounded; posterior face unarmed.

Etymology.

L. titanus = of giants, large. In reference to its relatively large size. Noun in apposition.

Distribution.

China (Yunnan).

Host plants.

Unknown.

Remarks.

The holotype is card mounted with a large amount of glue. Characters on the ventral surface including the submentum, prosternal posterocoxal piece, and denticles on the outer margins of the tibia were unable to be viewed. Socketed denticles are present on all tibiae. Locality labels on the holotype are in Chinese and were translated by You Li. An English locality label has been placed on the specimen below the original locality labels.

Figures

Figure 30. Dorsal, lateral and declivital view of Arixyleborus titanus holotype, 5.2 mm (A, B, G), A. tuberculatus paratype, 1.35 - 1.5 mm (C, D, H), and A. yakushimanus, 2.0 - 2.2 mm (E, F, I).