Diuncus quadrispinosulus Eggers 1923, comb. n.

Diuncus quadrispinosulus (Eggers 1923) comb. n.

Previous genus: Xyleborus

Diagnosis: One of the smallest Diuncus, often very pale, appearing fragile compared to other Diuncus spp. Minute, almost invisible tubercles or hooks in interstriae 2 and 3. Vestiture inconspicuous, appressed. Feebly elevated strial ridges on declivity, almost invisible, only apparent when dry. The impression across striae 2 and 3 and the resulting inflation of the anterolateral surface of declivity present, such as in D. justus, but feeble.

Length: 1.4–2.0 mm.

Discussion. Holotype of X. quadrispinosus was not available. Instead, we examined non-types from Schedl's collection in NHMW and from Browne's collection in BMNH identified as X. quadrispinosulus Eggers, and a holotype of X. parvispinosus Schedl from NHMW (junior synonym of D. quadrispinosulus (Eggers)).

Previously synonymized species: Xyleborus parvispinosus Schedl, Xyleborus parvispinosus palembangensis Schedl

Biology: Kalshoven (1960) reported the tendency of this species to create tunnels next to entrance holes of other ambrosia beetles species. In New Guinea, it is has been found associated with Eccoptopterus spinosus, Cnestus bimaculatus, and Diuncus duodecimspinatus (which itself is parasitizes other beetle’s galleries).

Examined material: Indonesia, Java, (type of X. parvispinosus, NHMW); Indonesia, Java, (NHMW, 2 indiv.); Malaysia, Selangor, (BMNH); Malaysia, Sabah, Danum Valley, Ficus sp. branches (2), J. Hulcr coll. vii.2006; PNG: Madang Prov. (14), Oro Prov. (13), J. Hulcr 2002–2006.