Arixyleborus mediosectus (Eggers, 1923)

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 mediosectus (Eggers, 1923) Fig. 26G, H, L

Xyleboricus mediosectus Eggers, 1923: 215.

Arixyleborus mediosectus (Eggers): Schedl 1958c: 145.

Arixyleborus angulatus Schedl, 1942a: 183. Synonymy: Wood 1989: 170.

Type material.

Holotype (NMNH).

New records.

Laos: 10 km N Luang-Prabang, Mekhong river, 240 km N Vientiane, hills c. 250 m, poor settlem[ent], prim[ary] veget[ation], lux, iii.1993, Insomsay Somsy (MFNB, 1); Vientiane, Nan Van Eue, 15.xii.1966, native collector, ex light trap (BPBM, 1); as previous except: Gi Sion vill. De Tha Ngone, 28.ii.1965, J.L. Gressitt, ex light trap (BPBM, 1). Vietnam: Dong Nai, Cat Tien N.P., 11.42232, 107.42834, 128 m, 19.ii.2017, VN74, A.I. Cognato, T.A. Hoang, ex bottle trap (MSUC, 1).

Diagnosis.

1.9-2.1 mm long (mean = 1.98 mm; n = 5); 2.86-3.33 × as long as wide. This species is distinguished by the protibiae posterior faces inflated, granulate; antennal club wider than long; pronotum lateral margin oblique; pronotum anterior margin without serrations; posterolateral carina acute, granulate.

It can be further distinguished from the closely related A. silvanus by the more elongate form (2.6-2.7 × as long as wide in A. silvanus ), more elongate pronotum (1.3 × longer than wide vs. 1.1-1.2 × in A. silvanus ), the more finely granulate interstriae, and shallowly impressed striae at the apex of the elytral disc, and the presence of short coarse setae on the declivity rather than fine hair-like setae. It can be further distinguished from the closely related A. crassior by the more elongate form (2.5 × as long as wide in A. crassior ) and short coarse setae on the declivity.

Similar species.

Arixyleborus crassior , A. phiaoacensis , A. silvanus .

Distribution.

‘Borneo’, Cambodia, India (Andaman Is, Assam), Indonesia (Sumatra), Laos*, East & West Malaysia, Philippines, Sri Lanka, Thailand, Vietnam.

Host plants.

Polyphagous ( Maiti and Saha 2004). It has also been collected from the crop of an edible-nest swiftlet ( Collocalia fuciphaga ) ( Beaver and Browne 1979).

Figures

Figure 26. Dorsal, lateral and declivital view of Arixyleborus hirsutulus, 2.0 mm (A, B, I), A. leprosulus, 1.9 - 2.0 mm (C, D, J), A. malayensis, 2.1 mm (E, F, K), and A. mediosectus, 1.9 - 2.0 mm (G, H, L).