Taxonomic history

Xyleborus dimidiatus Eggers, 1927a: 404.

Stictodex dimidiatus (Eggers): Hulcr and Cognato, 2013: 125.

Synonyms

Xyleborus dorsosulcatus Beeson, 1930: 219. Smith et al. 2020b: 310.

Xyleborus tunggali Schedl, 1936d: 32. Hulcr and Cognato, 2013: 125.

Xyleborus decumans Schedl, 1953b: 301. Hulcr and Cognato, 2013: 125.

Xyleborus cruciatus Schedl, 1973: 90. Hulcr and Cognato, 2013: 125.

Diagnosis

2.4−3.3 mm long (mean = 2.96 mm; n = 5); 2.54−2.89 times as long as wide. Stictodex dimidiatus can be readily distinguished by the antennal club very broad, type 2 (obliquely truncate), with segment 1 straight; elytral declivity with first and second interstriae divergent, broadest at elytral summit; declivity flat and gradually sloped; scutellum flat, flush with elytra; pronotum tight around head; protibiae inflated on posterior face.

Specimens of this species demonstrate an extreme morphological continuum of variation in the elytral striae (both on disc and declivity) with it ranging from slightly to deeply impressed.

May be confused with

Arixyleborus species which share a broad antennal club but possesses distinctive elytral ridges and furrows.

Distribution

Indonesia (Maluku), Laos, East and West Malaysia, Myanmar, New Guinea, Sri Lanka, Thailand, Vietnam

Host plants

Most host records are from the Dipterocarpaceae, but other tree families are also occasionally attacked (Browne 1961b as Xyleborus decumans and X. tunggali).

Remarks

This species is remarkably morphologically variable. Further study using molecular data will be required to assess species limits.

DNA data

Sequences available for COI and CAD:

COI: HM064122MN620003

CAD: HM064300HM064301