Euwallacea semirudis (Blandford, 1896) stat. res.

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

Euwallacea semirudis (Blandford, 1896) stat. res. Fig. 58A, B, I

Xyleborus semirudis Blandford, 1896b: 210.

Euwallacea semirudis (Blandford): Wood 1989: 173.

Xyleborus sereinuus Eggers, 1923: 187. Synonymy: Kalshoven 1959b: 139.

Xyleborus dubius Eggers, 1923: 199. Synonymy: Kalshoven 1959b: 139.

Xyleborus hybridus Eggers, 1927b: 90. Synonymy: Kalshoven 1959b: 139.

Xyleborus interruptus Eggers, 1940: 139. Synonymy: Schedl 1958c: 151.

Xyleborus neohybridus Schedl, 1942a: 188. syn. nov.

Xyleborus longehirtus Nunberg, 1956: 209. Unnecessary new name for X. dubius Eggers, 1923: 199.

Type material.

Holotype Xyleborus semirudis (NHMUK). Holotype Xyleborus hybridus (NHMW). Paratypes Xyleborus interruptus (NHMW, 3).

Diagnosis.

3.1-3.3 mm long (mean = 3.18 mm; n = 5); 2.21-2.29 × as long as wide. This species is distinguished by the pronotum basic (type 2) when viewed dorsally, anterior margin appearing rounded; declivity gradual; declivital face flat, opalescent and shagreened; declivital striae impressed, strial punctures large; and declivital posterolateral margin carinate.

Similar species.

Euwallacea fornicatus species complex ( E. fornicatior , E. fornicatus , E. kuroshio , E. perbrevis ), E. andamanensis , E. geminus , E. malloti , E. neptis , E. testudinatus , E. velatus .

Distribution.

‘Borneo’, Brunei, Indonesia (Java, Mentawai Is, Sumatra), East & West Malaysia, Philippines, Sri Lanka, Thailand.

Host plants.

Polyphagous ( Browne 1961b).

Remarks.

Euwallacea semirudis had previously been considered a synonym of the African species E. xanthopus Eichhoff by Wood (1989). Wood and Bright (1992: 696) noted that there were morphological differences between the two species in that the African specimens ( E. xanthopus ) were shiny and Asian specimens ( E. semirudis ) were partly or entirely dull, which strongly suggests that African and Asian populations represent different species. To test this we obtained COI sequences from South Africa sequenced by Stouthamer et al. (2017) (KU727034) and compared these to two individuals sequenced from Sabah (MN619944) and Papua New Guinea (HM064086). The African species differed from each Asian species by 14.6% and 13.7%, respectively while the Asian specimens differed by 16.3%. Typical intraspecific variation in xyleborines is under 10% ( Cognato et al. 2020b). Given the combination of differences in appearance and distribution combined with large COI pairwise differences, we here recognize E. semirudis as a separate species from E. xanthopus . However, the data clearly show that E. semirudis is likely a species complex and additional investigation will be required to further delimit species.

Figures

Figure 58. Dorsal, lateral and declivital view of Euwallacea semirudis, 3.1 - 3.3 mm (A, B, I), E. sibsagaricus, 3.4 - 3.9 mm (C, D, J), E. similis, 2.3 - 2.5 mm (E, F, K), and E. subalpinus holotype, 2.4 mm (G, H, L).