Brachycoraebus aeneus, Cheong, 2016

Cheong, Loong-Fah, 2016, Two new species of the genus Brachycoraebus Kerremans and Metasambus Kerremans (Coleoptera: Buprestidae: Coraebini) from Southeast Asia, Raffles Bulletin of Zoology 64, pp. 284-289 : 285-286

Brachycoraebus aeneus , sp. nov.

( Figs. 1 , 2 )

Description. Small, slender species; dorsal side nitid dark, with aeneus reflection depending on angle of light, covered with short, stout, adpressed golden setae, almost evenly distributed except for some small bare patches (but not forming distinct spots or fasciae) and slightly more dense in the hind elytral third; ventral side black with very slight bronze tinge. Size: male, 3.6 mm length × 1.5 mm width; female, 4.2 mm length × 1.9 mm width.

Head: Median impression deep. Epistome with arcuately emarginate apical margin, 1.2 times as long as wide, about 1.2 times narrower than diameter of one antennal socket, without transverse carina, supra-antennal carinae strongly elevated, unconnected. Inner eye margins straight, almost parallel-sided. Head sculptured like pronotum. Antenna not reaching base of pronotum, obtusely and shortly serrate from 4 th joint, joints 1 and 2 elongately oval, 3 somewhat shorter and much slenderer, conical.

Pronotum 1.9 times wider than long, broadest at middle, disc convex, with shallow pre-basal depression, sides broadly explanate; lateral pronotal margin regularly rounded, entire lateral margins finely but deeply crenulate ( Fig. 1b ); posterior pronotal margin bisinuous; sculpture almost entirely homogenous, becoming wrinkled on the sides and near the hind angle but not forming long, transverse furrows like that of B. viridis . Laterodiscal carinae inconspicuous.

Scutellum subcordate, almost twice as wide as long, flat. Elytra 1.7–1.8 times longer than wide, each with two shallow depressions: transverse along base and longitudinal behind humeri, extending to the level of metacoxae; lateral margin finely crenulate, with crenulations more or less vanishing before midlength, apices subtruncate and finely serrate. Texture composed of tightly-packed, tiled formation; each tile slightly more elongate than that of pronotum, laterally and posteriorly elevated, defining a pit in the centre ( Fig. 1b ).

Underside with similar textures as above, setae adpressed and yellowish; anterior margin of prosternum arcuately emarginate, gular lobe separated by furrows and broadly rounded, prosternal process wide and broadly truncated.

The male holotype genitalia is damaged and therefore not illustrated.

Female ( Fig. 2 ) larger, slightly more robust (elytral lengthto-width ratio is 1.7 in female, 1.8 in male), without slight cupreous red on the head, stronger aeneus reflection on the dorsal surface, and slightly different pattern formed by the bare patches, otherwise there is no significant difference from the male.

Diagnosis. Brachycoraebus aeneus differs from B. viridis ( Kerremans, 1900) ( Fig. 3 ) from Sumatra in colouration, sculpture, slender body, and deeply crenulate lateral pronotal margins. Other species similar in size and coloration (especially the females) include B. herychi Obenberger, 1940 from Borneo and B. helferi Obenberger, 1922 from Thailand and Burma, but the elytra in the males of these two species are marked with patches with bluish-violet reflection and pilose fasciae.

Etymology. The specific name is the Latin adjective aeneus referring to the bright brassy reflection of this species.

Type specimens. Holotype male ( ZRC.COL.100), “ Singapore, jungle”, coll. C.J. Saunders, 29 April 1922 ; Paratype female ( ZRC.COL.101), “ Singapore, Nee Soon swamp forest”, coll. L.F. Cheong & YW Cheong, 29 September 2013 .

Remarks. The holotype’s genitalia is damaged, and its left hind leg is broken off.

Figures

Fig. 1. Brachycoraebus aeneus, sp. nov., holotype male (a) habitus dorsal, (b) sculpture on sides of pronotum and its lateral margin, and reticulation on elytra.

Fig. 2. Brachycoraebus aeneus, sp. nov., paratype female, taken when still alive (Photograph by: L.F.Cheong).

Fig. 3. Dorsal habitusof Brachycoraebus viridis (Kerremans, 1900), non-type, Sumatra, RBH.