Drepanosticta barbatula, M.A. Lieftinck, 1940

M. A. Lieftinck, 1940, Descriptions and records of South-East Asiatic Odonata (II), Treubia 17 (4), pp. 337-392 : 351-352

Drepanosticta barbatula , sp. n. ( fig. 6 ).

Material studied: — E. Borneo, N. Koetai, Sangkoelirang distr., Batoe Besi , June 1937, M. E. Walsh leg. Holotype in the Buitenzorg Museum .

Male (ad.). — Labium pale yellow, tips of lateral lobes brown. Labrum and anteclypeus creamy greenish-white; labrum with the anterior border sharply defined black. Mandibles shining black, upper angle (between labrum and anteclypeus) filled up with a triangular creamy-white spot. Postclypeus shining bronzy-black, finely and transversely striate. Frons and vertex bronzy-black with slight lustre; epicranial lobes dull bronzy-black, rear of the head shining black with purplish reflections. Antennae with the first joint blackish-brown, second joint light brown, the remaining joints missing. Parorbital and transverse postoccipital carinae well developed, the former narrow but rounded, the latter acute, without angulate lateral extremities.

Prothorax chrome-yellow intermingled with green; a deep black spot over the middle, widest posteriorly and almost pointed anteriorly, ceasing at base of anterior lobe and covering the median third of posterior lobe (this dorsal mark almost identical in shape to that of D. attala Lieft., cf. Treubia, 14, 1934, p. 472 fig. 2 , ♂). Propleurae bronzy-black. Posterior lobe short and broad (still shorter than in attala ), of simple structure, depressed, hind margin perfectly straight in dorsal view, side-portions evenly rounded.

Synthorax, as far down as the first lateral suture, including the mesinfraepisternum, shining greenish bronzy-black with slight coppery reflections on mesepimeron. Sides light ochreous, intermingled with green, with a strongly contrasting black stripe joining the second suture, tapering ventrally, at extreme dorsal end; this stripe is about twice as wide as the metepisternal pale band, but soon diminishes in width, attaining only half its width at level of the spiracle, which it does not include; posterior limit of this black stripe rather diffuse ventrally. Metepimeron for the greater part and under surfaces pale yellow or whitish. Ante-alar triangles pale-coloured (blue in life?).

Legs pale; coxae and trochanters pale yellow; femora somewhat darker with an irregularly broken stripe along exterior surfaces, and with traces of two pale brownish bands; knees blackish. Tibiae and tarsi dirty ochreous, tibiae obscured basally and distal fourth of last tarsal joint black. Claws reddish; spines all brown.

Wings hyaline. Accessory basal postcostal nervure situated midway between base of wing and Ax1. Ac oblique, placed midway between Ax1 and Ax2, it meets the wing-margin well before the production of the proximal side of q, joining Ab at margin under an obtuse angle an all wings. Ab almost 1 1/2 times longer than Ac. Cu1 reaching the hind margin at 4 cells distal to level of subnodus. Postnodals 12 in all wings. Ma arises slightly distal to subnodus in all four wings, Rs between nodus and Px1. M 2 originates at the 6th or 7th postnodal in fore, at the 6th in hinder wing. M a 2 - 3 cells distal to M 2 in fore as well as in hinder wings. Two postquadrangular antenodal cells. Pterostigma jet-black surrounded by a very fine pale line, about 1% to 2 times longer than high, slightly widened distally; costal side only very little shorter than anal side; proximal angle rather acute, distal side slightly convex.

352 Treubia Deel 17, 1940, Afl. 4.

Abdomen enormously drawn out and very slender, apical segments strongly dilated. Segm. 1 -2 brownish above, greenish-yellow aside; dorsum of 2 blackish basally and with a yellow longitudinal mid-dorsal stripe, widest basally and fading away posteriorly; 3 - 7 with narrow yellow basal rings, thence brown, becoming black apically. Segm. 8 -1 0 deep black, lateral tergal margins of 8 broadly yellow; 9 with two widely distant squarish blue spots, one on each side of the middle, reaching half the length of segment; 10 black. Membrane between segm. 9 and 10 also blue.

Anal appendages, superiors about twice as long as segm. 10, moderately stout; basal part black, hollowed out interiorly and strongly inwardly curved; distal part yellowish, rather abruptly downbent. A small but very acute spine projects from the inner (mesial) margin of the dorsal surface. Proximal portion of distal part of superior appendage expanded and slightly hollowed out, shining yellow framed in black; from the exterior surface originates a dense brush-like bunch of stiff ochreous hairs, placed in a row and directed backwards like a whale’s beard; distal portion of same cylindrical, dull ochreous in colour. Inferior appendages pale ochreous, slightly obscured apically, bent at first upwards, then outwards and finally twisted and bent upwards again. At about half-way its length each appendage carries a strong acute spine, arising from its inner surface and directed obliquely upwards, inwards and a little backwards ( fig. 6 ).

Length: abd. + app. 48, hw. 24.5 mm. Female unknown.

This new species is probably most closely related to the rufostigma-group of Drepanosticta , but it is abundantly distinguished from all Bornean species of this group by the dense brush-like row of hairs on the innerside of the superior appendages of the male. In this respect barbatida approaches a small group of Malayan species, described by Dr. Laidlaw, which are remarkable for the presence on the superior anal appendages of a curious process, which itself carries a pencil-like brush of long hairs. The lower appendages in these species are of very complex structure, differing widely in shape from those of barbatula . Our new species is also peculiar for the extreme length of the abdomen. D. barbatula is the tenth species known to occur in Borneo.

Figures

Fig. 6. Drepanosticta barbatula, sp. n. ♂. Anal appendages, dorsal view and right side.

Fig. 2. Ventral aspect of seminal vesicle (top) and left side-view of anal appendages of Euphaea subnodalis Laid., from Mt. Marapok (bottom).