Oligoaeschna platyura, M.A. Lieftinck, 1940

M. A. Lieftinck, 1940, Descriptions and records of South-East Asiatic Odonata (II), Treubia 17 (4), pp. 337-392 : 378-380

Oligoaeschna platyura , sp. n. ( fig. 16 - 17 ).

Material studied: — 2 ♂, 3 ♀ (ad.) 1 ♀ (juv.), E. Borneo, N. Koetai, Sang- koelirang distr., Kariorang , Pelawan Besar and Batau Besi , May-June, 1937 ; 1 ♂, 1 ♀ (ad.), E. Borneo, Samarinda, Dec. 1938 & March, 1939; all M. E. WALSH leg., in the Buitenzorg Museum, Holotype ♂ and allotype ♀: Pelawan Besar&Batau Besi, May1937. Male (ad.). - Labium orange-cinnamon, labrum tawny or ochraceous-orange, mandibles bister-coloured. Clypeus tawny-olive, sides and lower third of anterior surface of frons similarly coloured but soon becoming black from below upwards, forming a crescent-shaped black streak on top; ridge sub-acute, horizontal part of frons flattened, dark olive-brown in colour. Vertex and occipital triangle blackish-brown. Rear of the head tawny.

Synthorax velvet blackish-brown, almost black above. Dorsum with a pair of oblique, elongate-oval, green antehumeral bands, incomplete above, and with a pair of transverse, rather crescent-shaped streaks of the same colour on each side of the dorsal crest, just in front of the ante-alar triangles. On the sides are two broad, rather diffuse, green bands, one under each wing; the anterior band occupies most of the mesepimeron and ceases at level of spiracle; the posterior band is still broader, rather rounded on both ends and covers most of the metepimeron. Between these bands, on the middle of the upper half gf each metepisternite, lies il third much narrower, S-shaped or rather angular, green spot that runs parallel to the others. Infraepisternites and under surfaces brown.

M. A. LIEFTINCKZ Descriptions and records of S.E. Asiatic Odonata . 379

Legs dark reddish-brown, apices of femora and tarsi obscured. Wings enfumed throughout with golden brown, this forming an areola around the network of venation. Pterostigma braced, 2.2-2.5 mm in length, Very Slightly Shorter in the hind wing, raw sienna (RIDGWAY), covering two underlying cells. Venation very similar to modiglianii , but- decidedly denser; two rows of cells between Ml-Mspl from level of nodus to near the wing-margin in both pairs of wings. Triangles 3 - celled, those of fore wings occasionally 4-celled; supratriangles with 0 - 3 crossnerves. Anal angle decidedly more pronounced than in modiglianii and amata ( fig.16 ). Antenodals 18-20/12-14, postnodals 9-10/12.

Abdomen constricted on segment 3 (1.0 - 1.3 mm), rather strongly spindleshaped beyond, acquiring its maximum width (2.7 - 3.2 mm) towards the end of segm. 5, from where the abdomen diminishes very gradually in width till the end of 8; 9 and 10 again very slightly broadened. Terminal segments depressed. Dark brown, basal segments paler; markings obscured (discoloured), except on basal segments of type: Segm. 1 with a green mid-dorsal mark on its distal half and a roundish lateral spot; dorsum of 2 with a basal and a terminal pair of green semi-lunar spots, interrupted in the middle line, a green point just inside the auricles and a longitudinal streak of the same colour on the posterior half of the sides. Basal two-thirds of segm. 10 dull reddish-brown, apical third blackish; basal half of segment with its dorsal surface smooth on each side of a median, longitudinal area, which is covered with numerous microscopical, transverse striae; apical half entirely, and very finely, transversely striate; the median area of this part of the segment carries in addition numerous closely set, rasp-like warts, which arc crowded together on each side of a distinct longitudinal impression.

Auricles truncated apically, armed with 5 - 6 fine teeth.

Accessory genitalia not differing from those of amata and modiglianii .

380 TRnUmA Deel 17, 1940, AFL. 4.

Anal appendages shaped as shown in fig. 17 ; superior pair black, inferior appendage reddish-brown, its borders black.

Female (ad.). — Very similar to the male.

Frons olive-brown above, dirty orange-brown in front; superior margin finely obscured. Vertex and occipital triangle brown. Thoracic pattern similar to the male but all dorsal green marks a little narrower.

Legs coloured similarly to the male.

Wings stained with golden yellow all over the membrane (juv.); or light golden yellow with the posterior margin of the fore wings narrowly, the anal area and the apical portion of the hind wings, from the inner end of pt to the end of Cu2, broadly hyaline; bases to level of Ax1-Ax., deep golden yellow (ad.); or throughout brownish yellow with only the anal area of the hind wings sub-hyaline (aged individuals). Pterostigma as in the male.

Abdomen in one specimen shaped much as in the type of O. elacatura (Needham) (— modiglianii ) 1); in the other females the abdomen is only slightly spindle-shaped (much less so than in the male) and the segments are sub-cylindrical. All markings obscured and discoloured. Anal appendages broken off in all specimens. Dentigerous plate shaped similarly to modiglianii , amata and mutata .

Length: ♂ abd. + app. 47 - 50, hw. 376 - 40; ♀ 39.5 - 43.5, 37 - 39 mm. Holotype ♂: 49.5, 39; allotype ♀: 40.5, 39 mm.

Figures

Fig. 16. Basal portion of right hind wing of Oligoaeschna platyura, sp. n. ♂ (left), and of O. amata (FORST.) ♂ right.

Fig.17. Oligoaeschnaplatyura, sp.n. ♂. Analappendages, dorsal view and right side.