Cryptoxyleborus percuneolus (Schedl) Beaver & Hulcr, 2008

Beaver, Roger A. & Hulcr, Jiri, 2008, A Review of the Ambrosia Beetle Genus Cryptoxyleborus Schedl (Coleoptera: Curculionidae: Scolytinae), The Coleopterists Bulletin 62 (1), pp. 133-153 : 133-153

Cryptoxyleborus percuneolus (Schedl) , new combination

Xyleborus percuneolus Schedl, 1951:85 .

Xyleborinus percuneolus (Schedl) : Wood & Bright, 1992:809.

Taxonomy: The species was described from Java. The type is deposited in NHMW and has been examined. Schedl (1951) described the species from ‘Typen in coll. Schedl’. However, he later ( Schedl 1979) cited a ‘holotype’ in his collection. Wood and Bright (1992) note that this citation is invalid. In order to stabilise the assignment of the name, we designate the single specimen currently housed in the Schedl collection in the Naturhistorisches Museum, Wien, as lectotype. It bears the following labels: [female sign]/dgi [partly illegible handwritten label]/Sc 88 1.4 m /Type Xyleborus percuneolus Schedl [red label]/ Holotypus Xyleborus percuneolus Schedl [red-bordered label]. The species was placed in Xyleborinus by Wood & Bright (1992) without comment. However, the absence of conical scutellum, the strongly cuneiform elytra, and antennal club of type 3 place the species in Cryptoxyleborus . The species shares many characters and appearance with C. vestigator and especially C. acutus , but it is much smaller, and the curvature of the anterior edge of the pronotum falls inbetween C. vestigator (rounded) and C. acutus (concave). The male has not previously been described, and this is done below.

Male ( Fig. 3 ): 1.25–1.45 mm long, neither of two males examined was completely sclerotized, although both had strongly sclerotized mandibles. Enlarged mandibles and protruding lobe-like frons are the most conspicuous features of the males. Mandibles are prognathous, as long as antennae, slender, curved and sharply pointed, with a small denticle on dorso-proximal side near the base of each mandible. Frons conspicuously prolonged into a lobe above clypeal area forming a cavity between the lobe and the prolonged mandibles; ventral side of lobe densely covered with setae, lobe narrower than head. Eyes reduced to a long scar with two to four ocelli in the middle. Upper frons chagrined. Antennal 146 club of type 3; flat, slightly prolonged, first segment corneous, covering about 1/2 of the anterior face, sutures of segment 1, 2 and 3 straight, visible on the anterior face; sutures of the segments 1 and 2 visible on the posterior side. Funicle threesegmented (including pedicel). Pronotum nearly rectangular, as long as wide, type 8 from dorsal view, and prolonged and flat, type 9 or b from lateral view; surface shining except the frontal edge bearing a few minuscule asperities and setae; smoothly rounded laterally. Scutellum reduced, not visible. Elytra 1.5 times as long as wide; elytral bases arcuate, costate, frontal slope around the scutellar wedge covered with mycangial setae. Mycangium reduced, probably dysfunctional. Procoxae slightly enlarged, contiguous; prosternum flat both anteriad and posteriad of coxae. Protibiae flat, narrower than in female, with 7–9 socketed teeth, no granules on the posterior face. Meso- and metatibiae, broader, both with 7–8 socketed teeth. Two males from a single brood were collected. No conspicuous variation in shape was observed.

Allotype: MALAYSIA, Sabah, Danum Valley Field Station , 117 ° 48 9 E, 4 ° 58 9 N; dead tree trunk on ground, 19.vii.2006, J. Hulcr . Allotype deposited in NHMW.

Distribution: Indonesia (Java). The species is newly recorded here from East Malaysia (Sabah).

New record: MALAYSIA, Sabah, Danum Valley Field Station , 117 ° 48 9 E, 4 ° 58 9 N; dead tree trunk on ground, 19.vii.2006, J. Hulcr ( MSU) .

Biology: A single family of this species collected at Danum Valley, Sabah, Malaysia, was found in a gallery composed of a flat chamber perpendicular to the xylem fibers, and multiple tunnels leading deeper into the wood. The large and sharp mandibles in males are not suited for wood or mycelium intake, and are perhaps used for fighting with other males or predators ( Hamilton 1979; Jordal et al. 2002)

Figures

Fig. 3. Allotype of Cryptoxyleborus percuneolus (Schedl) 1951, male, dorsal and lateral aspect, 1.4 mm.