This species is likely polyphagous and has been recorded from numerous host families including Pistacia (Anacardiaceae), Ilex (Aquifoliaceae), Quercus sp. (Fagaceae), Cinnamomum (Lauraceae), Broussonetia (Moraceace), and Ligustrum (Oleaceae) (Smith et al. 2020b).
The morphology of A. osumiensis is highly variable in regard to numerous characteristics that are routinely used to diagnose other xyleborine species. Such variation includes: the antennalclub type either 3 or 4; pronotum basic (type 2) or subquadrate (type 3) from dorsal view; elytraldeclivityshining or shagreened; pronotaldiscshining or shagreened; number and size of tubercles on declivitalinterstriae 2; and a large size range with individuals differing by up to 0.9 mm in length. This variation led to A. osumiensis being described several times. Types of each species are distinct and diagnosable. Examination of the specimens listed above in ‘new records’ as well as the holotypes showed that these species formed a continuous spectrum of variation. During our fieldwork we were able to collect and sequence specimens that fell within the concept of X. metanepotulus (Vietnam), X. hunanensis (China), X. nodulosus (China), A. peregrinus (Georgia, USA), and an additional larger morphospecies from multiple localities in Vietnam. COI sequences showed that all populations differed by no more than 7.4% supporting the hypothesis of one morphologically variable species. Typical intraspecific variation in xyleborines is below 10% (Cognato et al. 2020b).
The identification of this A. nodulosus from East Malaysia by Browne (1980b) and Ohno (1990) appears to be incorrect. We have therefore omitted East Malaysia from the distribution, and also omitted the associated host records. The host records reported in Smith et al. (2017) are therefore incorrect.