Taxonomy

Diuncus Hulcr and Cognato, 2009: 28.

Diagnosis

Small to moderately sized (1.5−3.0 mm long) stout species (1.33−2.78 times as long as wide). Diuncus species can be recognized by the antennal club obliquely truncate, segment 1 corenous and dominant on both sides (type 1); pronotum stout, with 4−6 serrations on anterior margin; pronotum from lateral view rounded, robust (type 5), from dorsal view rounded (type 1); declivity flat, broad, margins broadened and distinctly carinate; declivital base often armed with 1−2 pairs of denticlesprotibia obliquely triangular, with 3−5 large denticles, denticles distinctly longer than wide; scutellum visible and flush with the elytra, mycangial tufts absent; and contiguous procoxae.

May be confused with

Ancipitis, Leptoxyleborus, and Xylosandrus

Distribution

found in tropical Asia and Oceania, rare in Africa

Gallery system

The gallery systems in Diuncus vary depending on the species and the size of the breeding material. There may be an entrance tunnel leading to a terminal brood chamber in the longitudinal plane (D. ciliatoformis); the gallery may branch in three dimensions and either have very irregular brood chambers (D. mucronatus), or lack brood chambers (D. javanus); in small stems, there are longitudinal branches in the centre of the stem (D. haberkorni).

Remarks

The species of Diuncus are usually mycocleptic, making use of the ambrosia fungi of other ambrosia beetles, and lack mycangia (Hulcr and Cognato 2010b). However, some species also occur alone (Hulcr and Cognato 2009).