Drepanosticta attala Lieftinck

Orr, Albert G. & Dow, Rory A., 2015, Description of two final stadium platystictid larvae from Borneo, including that of Drepanosticta? attala Lieftinck, identified using DNA barcoding (Odonata: Zygoptera: Platystictidae), Zootaxa 3985 (4), pp. 565-574 : 567-571

Drepanosticta attala Lieftinck

Figs 1 , 2, 3 a, c, d, e, g, i.

Material. One F larva, ♂, Brunei, Kuala Belalong Field Studies Centre, 4°32’49.1”N 115°09’22.9”E. 19.xi. 2004, 105 m a.s.l., leg. V.J. Kalkman, K.-D.B. Dijkstra, N.J. Dingermanse & K. Goudsmits.

Description. In general appearance a small, slender zygopteran, with a relatively massive head, very large eyes, moderately long legs and tapered abdomen terminating in inflated, but distinctly laterally compressed, caudal lamellae bearing terminal filaments ( Fig. 2). Coloration overall neutral brown, with distinct darker markings on dorsum of head, thorax and legs, and a distinctive delicate tracery on wing pads. Most parts of body bearing moderately dense, fine, long setae.

Head in dorsal view broad, elongate and strongly prognathous, posterior margin concave, producing a roughly cardioid outline overall. Compound eyes relatively huge, with a sinuous line of setae running across the eye surface for about two-thirds its length, starting near the posterior boarder. Anteclypeus rather broad and labrum about same width, sub-quadrate, bearing a dense fringe of strong, moderately long setae along its anterior margin. Mandibles and outer edge of labial palps very apparent in dorsal view. In ventral view ( Fig. 3 g) mandibles with four welldefined teeth on incisor lobe; molar lobe of right mandible with minute thorn-like process medially and another near inner margin; molar lobe of left mandible with single strong broad tooth with a substantial sub-basal shoulder. Seen in ventral view ( Fig. 3 e) galeolacinea of maxilla with three short outer (ventral) spines, one longer terminal spine and three inner spines; maxillary palp narrow, curved and bearing long, dense, fine setae. Articulation of mask reaching posterior margin of procoxae when retracted. Prementum ( Fig. 3 a) flat ventrally, only slightly concave dorsally with slight rugosity in posterior half; broad (length: maximum breadth ratio 1.31); laterally strongly convex with margins bearing sparse fringe of long fine setae; anterior margin (ligula) moderately produced to form a convex flap, with margins fairly straight, thus forming a shallow inverted ‘V’; terminal cleft sealed; margins bearing 24–26 short, thick peg-like setae terminating in a crown of spines ( Fig. 3 c); tuft of long fine setae on either side of ligula. Labial palp short and stout (length palp: length prementum 0.26), terminating in a smooth, simple broad shallow hook, with very slight serrations on its inner margin; outer margin basally bearing sparse tuft of long setae; movable hook stout, short and only slightly curved. Antennae ( Fig. 3 i) seven segmented, S2–7 bearing long fine setae, those on S2–5 arranged in sub-terminal tufts. Thorax with well defined pronotal shield. Legs moderately long; femora stout and somewhat angular, with distinct dark marking and bearing sparse moderately long fine setae; tibiae thin, bearing dense, very long, fine setae. Wing pads separate and divergent, surpassing hind margin of S4; with intricate pattern of dark markings. Abdomen unpatterned, gradually tapered posteriorly, generally bearing short fine setae. Caudal lamellae partially inflated but clearly dorso-ventrally flattened with distinct dorsal and ventral crease; median lamella almost half as long as abdomen including a well developed terminal filament bearing long, fine setae; right lamella about half length of median lamella, with terminal filament short, bearing sparse fine setae; left lamella missing; cerci short, slightly incurved, clavate; in ventral view ( Fig 3 d) margin of S10 strongly produced medially. Male gonapophyses absent.

Measurements (mm): Total length (without caudal lamellae) 13.4; maximum width of head 2.9; hind femur 3.4; cercus 0.2; right lamella 2.1; median lamella with filament 4.1.

Remarks. The exact collecting locality and microhabitat are not known for certain, but it is likely the specimen came from the seepage area within the forest characterized in Orr (2001, 2006). This is a marshy site in deep forest with deep leaf litter, barely a trickle of water and constant high humidity (RH normally> 90%). It was at this site that a male specimen of adult D. attala was taken during a routine canopy fog by R.L. Kitching on 26.vi.1997. The collector, V.J. Kalkman writes: “During our visit to KBFSC we took samples in the main river, the small brook ( Mata Ikan) and the seepage area. I think (but cannot be sure) that it is from the seepage area. I did collect some bags with leaves and went through these in the evening in order to pick out small larvae”. The coordinates given above are for this site.

Figures

FIGURE 1. Neighbour joining COI gene tree using uncorrected p – distance for Drepanosticta attala and D. barbatula adults and larva plus related platystictid taxa with Sinosticta hainanense as outgroup. All voucher specimens except that of D. barbatula have a six digit collection number with an RMNH. INS. prefix; this prefix is omitted in the figure for clarity.

FIGURE 3. Details of Drepanosticta? attala: (a) mask, dorsal view; (c) dorsal detail of crown-like setae on margin of ligula; (d) ventral detail of caudal appendages; (e) Ight maxilla, ventral view; (g) mandibles ventral view; (i) right antenna, and Platystictidae sp.: (b) mask, dorsal view; (f) right maxilla, ventral view; (h) mandibles ventral view.