Telosticta iban, Dow, Rory A., 2014

Dow, Rory A., 2014, Telosticta iban sp. nov. from Sarawak (Odonata: Zygoptera: Platystictidae), Zootaxa 3784 (1) : -

Telosticta iban sp. nov.

( Figs. 1–12 )

Type material: Holotype: ♂ (SAR13_14_PST87), Malaysia, Sarawak, Kapit Division, Lanjak Entimau Wildlife Sanctuary, Nanga Bloh Field Station, seepage at head of high gradient tributary to Sungai Kelimau, N 1.640º, E 112.262º, 24 viii 2013, leg. R. A. Dow, to be deposited in SMSM. Paratypes: ♀ (SAR13_14_PST88), data as holotype, 23 vi 2013, in coll. R. A. Dow; ♂ (SAR13_14_PST95), same area, tributary to Sungai Bloh, N 1.630º, E 112.282º, 24 vi 2013, leg. R. A. Dow, in coll. R. A. Dow.

Etymology. iban , a noun in apposition. Named for the Iban people, the majority Dayak race in Sarawak, and the inhabitants of the area around the Lanjak Entimau Wildlife Sanctuary where this new species was discovered.

Description of holotype male. Head: Labium pale. Basal 2/3 of labrum pale blue, black along free margin. Anteclypeus blue, postclypeus shining black. Mandible bases blue in corner by clypeus, black below. Vertex and frons bronzy black, occiput shining black. Ratio of width of compound eye to width of vertex measured at level of lateral ocelli slightly less than 9/10. Transverse occipital carina with lateral extremities angulated and prominent. Ocelli yellowish. Antenna with scape and pedicel pale yellowish, dark at top of pedicel, remainder black.

Thorax: Prothorax yellow except to rear of propleuron where there are irregular dark markings; a few brown patches at rear of middle pronotal lobe and whole posterior pronotal lobe, where black centrally, brown laterally and becoming greyish brown on lateral process, which is moderately long ( Fig. 2 ) with the tip not reaching the level of the lower margin of the propleuron. Synthorax: Mesepisternum bronzy black, with a pair of blue antehumeral stripes, each divided into a longer part near the prothorax and a short part near the wing bases ( Fig. 5 ).

Antealar triangles yellow along mid-dorsal carina and in half at wing bases, rest black. Mesepimeron dark brown, paler adjacent to wing bases. Metepisternum largely occupied by pale band, with short brown triangle based at antealar carina below, this extended as brownish band along metapleural suture to level of spiracle ( Fig. 6 ). Metepimeron almost entirely pale. Venter of synthorax pale. Legs: each with coxa and trochanter yellow, femur yellow with faint and incomplete dark stripe on extensor surface, dark above tibia. Tibia dark immediately below femur, then pale, dark just above tarsus, which is pale with some darker areas and brown claws. Wings: 12 Px in Fw, 11 (left) to 12 (right) Px in Hw. Vein ab present. Arculus slightly distal to Ax2. R4 arising distal (Fw) or at (Hw) to subnodus, IR3 joined to it by a short stalk. Pterostigma trapezoidal with costal side slightly shorter than anal side, very dark brown with narrow pale border, covering slightly more than one underlying cell.

Abdomen: Largely brown. S1 mostly yellowish cream with narrow apical darker annulus. S2 with yellowish cream basal annulus, just divided dorsally, laterally this extending to posterior carina as a pale wedge, otherwise brown. S3–7 brown with a narrow pale basal annulus, narrowly interrupted dorsally on S3 but complete on S4–7; on S7 faded so hardly visible. S8 dark brown with pale band along lower margin, extended basally as an incomplete annulus. S9–10 very dark brown with pale blue dorsal marking occupying much of dorsum of S9 ( Fig. 8 ). Anal appendages ( Figs. 10–12 ) largely black and dark brown, with pale areas on inner apical halves of cerci and scoop of paraprocts. Cerci slightly less than 2.5 times length of S10, interior projection poorly developed as small knob directed rearwards at just over two fifths length, only visible in dorsal view ( Fig. 10 ), dorsal projection absent. Expanded abruptly dorsal-ventrally and interiorly in distal ca. two thirds, lower margin irregular, small cleft at tip ( Fig. 11 ). Paraprocts slightly longer than cerci, scoop almost square ( Fig. 12 ), spine of moderate length and directed inwards, to rear and upwards. Genital ligula of typical form for genus, with tongue-like structure of terminal segment short ( Fig. 7 ).

Measurements (mm): abdomen without anal appendages 34, cercus just over 1, Hw 20.5.

Description of paratype female (SAR13_14_PST88). As male except as noted.

Head: Labrum with basal half blue.

Thorax: Posterior pronotal lobe lacking lateral processes, but with hind margin produced as pair of rearward directed horns ( Figs. 3–4 ). Legs with well-defined black stripe on extensor surface of each femur. Wings: R4 arising distal to subnodus in all wings, 11 Px in all wings.

Abdomen: S10 short. A blue mark covering much of the dorsum of S9 ( Fig. 9 ). Cerci shorter than S10, approximately triangular. Ovipositor extending beyond cerci, pale with obscure dark markings.

Measurements (mm): abdomen without appendages or ovipositor 32, Hw 21.

Variation in male paratype. The male paratype is immature and the terminal abdominal segments are somewhat distorted. The blue dorsal mark on S9 is smaller than in the holotype. R4 arises distal to subnodus in all wings.

Measurements (mm): abdomen without anal appendages 34, Hw 20.

Diagnosis. A small Telosticta with antehumeral stripes divided into two well separated parts and with blue dorsal markings on abdominal S9 only. Both sexes are easily distinguished from all other species of Telosticta by the form of the antehumeral markings. The male is further distinguished by the absence of a dorsal projection on the cerci and the almost square scoops of the paraprocts.

Remarks. The holotype male and paratype female were caught separately at the same seepage, both found sitting back from the seepage. The paratype male was taken while sitting back from a small high gradient stream, in contrast to its congener T. longigaster Dow & Orr, 2012 , males of which were perched on vegetation overhanging the stream. Evidently T. iban exhibits more secretive behaviour than some other members of the genus and would be easy to overlook, especially as its markings, although distinctive, were not bright even in life. However, it does not appear to be as elusive as T. belalongensis Dow & Orr, 2012 , or T. tubau (Dow, 2010) , for each of which the only definite example known is the holotype. The locations at which the type series were collected are best described as small moderately high gradient streams and seepages in lightly disturbed to undisturbed lowland mixed dipterocarp forest.

Of the provisional species groups defined in Dow & Orr (2012), T. iban fits best into the feronia -group; using the key in Dow & Orr (2012), T. iban would key out as T. dayak Dow & Orr, 2012 , or break the key, depending on how liberally couplet 7 was interpreted. The key could most easily be modified to accommodate T. iban by introducing a new first couplet distinguishing between species with interrupted antehumeral stripes (e.g. T. iban ) and those with uninterrupted antehumeral stripes (e.g. all of the rest). Another unique feature of T. iban is the lack of a dorsal projection on the cerci; however, this character is so poorly developed in some species that it is easily overlooked, so it may not be a good character for use in identification.

Although the posterior pronotal lobe ( Figs 3–4 ) of the female is distinctive, given the variation known to exist in the same structure in T. longigaster ( Dow & Orr 2012: 393 and Fig. 15), it may not prove to be reliable for identification. However, the distinctive antehumeral markings will serve to separate both sexes from the other known members of the genus.

Figures

FIGURE 1. Telosticta iban holotype male habitus.

FIGURES 2 – 4. Telosticta iban posterior pronotal lobe: (1) holotype male, lateral view; (2) paratype female, dorsal view; (3) paratype female, lateral view.

FIGURES 5 – 6. Telosticta iban holotype male synthorax: (4) dorsal view; (5) lateral view.

FIGURE 7 – 9. Telosticta iban holotype male (6) genital ligula; (7) terminal abdominal segments, dorsal view. (8) terminal abdominal segments paratype female, dorsal view.

FIGURES 10 – 12. Telosticta iban holotype male anal appendages: (9) dorsal view; (10) lateral view; (11) apical part right paraproct in ventral view.