Dryoxylon Bright & Rabaglia, 1999

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

Dryoxylon Bright & Rabaglia, 1999

Dryoxylon Bright & Rabaglia, 1999: 333.

Type species.

Xyleborus onoharaensis Murayama, 1934; original designation.

Diagnosis.

2.2-2.4 mm and elongate (3.14-3.43 × as long as wide). Dryoxylon is most easily distinguished by the anterior margin of pronotum in lateral view evenly arched, summit not elevated or evident; anterior margin of pronotum weakly emarginated at middle; declivity distinctly moderately sulcate; declivital face and lateral margins unarmed; submentum not impressed; comparatively few socketed denticles on the outer margin of the pro- (five), meso- (six) and metatibiae (five); scutellum flat, flush with elytra; procoxae narrowly separated; mycangial tufts absent; and elytra unarmed.

Similar genera.

Dryoxylon is superficially similar to Cyclorhipidion which also has elongate species with a setose declivity but is distinguished by the unique pronotum described above. Dryoxylon may also be confused with Dryocoetini because of the reduced number of socketed denticles on the pro- and metatibiae (five).

Distribution.

Known only from China, Japan and South Korea. Introduced and established in USA.

Gallery system.

Unknown. The biology of the only species in the genus, D. onoharaense has been investigated in the USA. Bright and Rabaglia (1999) reported D. onoharaense in the xylem associated with other xyleborines, but galleries solely containing this species were not found. Bateman et al. (2015) examined the fungal associates of D. onoharaense in Florida. The authors were unable to locate a mycangium or isolate fungi from the species. This suggests that the species is not engaged in typical fungus farming but may be entering established galleries of other ambrosia beetles rather than establishing their own, similar to the Neotropical genus Sampsonius . The species could also be mycocleptic similar to Diuncus which steal fungi from nearby galleries ( Bateman et al. 2015; Hulcr and Cognato 2010b).

Remarks.

Dryoxylon was originally placed in the Dryocoetini . Molecular data clearly indicates that this genus belongs in the Xyleborini ( Jordal et al. 2000; Jordal 2002; Gohli et al. 2017) into which it was transferred by Alonso-Zarazaga and Lyal (2009).