Amasa Lea, 1894

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

Amasa Lea, 1894

Amasa Lea, 1894: 322.

Pseudoxyleborus Eggers, 1930: 206. Synonymy: Wood 1984: 223.

Anaxyleborus Wood, 1980: 90. Synonymy: Wood 1983: 647.

Type species.

Amasa thoracica Lea, 1894 = Tomicus truncatus Erichson, 1842; monotypy.

Diagnosis.

2.5-5.0 mm, 2.11-3.4 × as long as wide. Amasa is distinguished by the declivity truncate, margined with a circumdeclivital ring; antennal club flattened, types 4 or 5 (typically type 4), club sutures sinuate, two sutures visible on posterior face; protibiae typically slender, inflated and granulate on posterior face (rarely distinctly triangular or unarmed on posterior face); anterior margin of pronotum with a row of serrations; scutellum flat, flush with elytral surface; declivital face with three striae; procoxae contiguous or narrowly separated; and mycangial tufts absent.

Similar genera.

Cyclorhipidion , Pseudowebbia , Truncaudum , Webbia , Xylosandrus .

Distribution.

Distributed throughout Asia and Australasia, also occurring in Madagascar. One species has been introduced to Brazil, Chile and Uruguay ( Flechtmann and Cognato 2011; Gómez et al. 2017; Kirkendall 2018).

Gallery system.

This usually comprises a short radial tunnel leading to a single, large, flat brood chamber, extending in the longitudinal plane.

Remarks.

Amasa is easily confused with other species possessing truncate declivities in the genera listed above. Most species can be readily distinguished by the type 4 antennal club with sinuate sutures and the presence of only three striae on the declivital face.

Previous morphological studies of Amasa have suggested that species are very morphologically variable ( Hulcr and Cognato 2013). As a result, many species were considered conspecific and part of a morphological continuum. Molecular data generated as part of this study has demonstrated that Amasa species are actually morphologically conserved even across broad ranges ( Smith et al. 2020). Amasa species outside our coverage area are thus in need of revision. Potentially much of the diversity is awaiting discovery.