Taxonomy

Dryoxylon Bright and Rabaglia, 1999: 333.

Diagnosis

 2.20−2.40 mm long and elongate (3.14−3.43 times 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 weakly emarginated at middle; elytral declivity distinctly moderately sulcatedeclivital face and lateral margins unarmed. Unlike nearly all other Xyleborini, submentum is flat, and there are comparatively fewer socketed denticles on the outer margin of the pro-(5), meso- (6) and metatibiae (5). In addition, the scutellum is flat, flush with elytra, the procoxae are narrowly separated, mycangial tufts are absent, and the elytra is unarmed.

May be confused with

Dryoxylon is superficially similar to Cyclorhipidion which also has elongate species with a setose declivity but can be 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 metatibia (5).

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 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

This genus 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).