Thinolestris nigra Grootaert & Evenhuis

Grootaert, Patrick & Evenhuis, Neal L., 2006, On the distribution of the marine genus Thinolestris Grootaert & Meuffels (Diptera, Dolichopodidae) with a description of a new species from Singapore, Malaysia and Brunei, Zootaxa 1134, pp. 59-68 : 62-64

Thinolestris nigra Grootaert & Evenhuis , sp. nov.

Figs. 1–11 , 13

Thinolestris sp. Evenhuis & Grootaert, 2002: 308.

Material examined: Holotype male: SINGAPORE, Labrador Park, 31.VII.2005 (sample 25275, Si930 leg. P. Grootaert, ZRC). Paratypes: BRUNEI: 9 males, 5 females, Tungku rocks (coast near Bandar Seri Begawan), 15.IV.1993 (leg. P. Grootaert, RBINS). MALAYSIA: 5 males, 6 females, Johor, Sedili kecil, sandy and rocky beach, 11.X.2000, (leg. P. Grootaert, ZRC, RBINS); 16 males, 36 females, Pulau Tioman, Salang, 15.VII.2005 (sample 25220, Tio134, leg. P. Grootaert, RBINS); 17 males, 6 females, Pulau Tioman, Monkey Bay, 17.VII.2005 (sample 25226, Tio26, leg. P. Grootaert, RBINS); 30 males, 20 females, 14.VII.2005 (sample 25216, Tio33, leg. P. Grootaert, RBINS); 2 males, 1 female, Pulau Tioman, Paya, 18.VII.2005 (sample 25230, Tio36, leg. P. Grootaert, RBINS); 1 male, 1 female, Pulau Tioman, Paya, 21.VII.2005 (samples 25250, 25253; Tio92, Tio100, leg. P. Grootaert, RBINS); 38 males, 16 females, Pulau Sibu, 24.XII.2005 (sample 25461, Si1357, leg. P. Grootaert, RBINS). SINGAPORE: 16 males, 4 females, Labrador Park, rocky beach with sand patches, 7.X.2000, (leg. P. Grootaert & N. Evenhuis, ZRC, RBINS, BPBM); 1 male, 8 females, Labrador Beach Park, 3.IV.2005 (sample 25044, Si633 leg. P. Grootaert, ZRC); 1 male, 2 females, Labrador beach, intertidal rocks, II.1961 (leg. D.H. Murphy; in coll. C.E. Dyte); 33 males, 45 females, Labrador Park, 31.VII.2005 (sample 25275, Si930 leg. P. Grootaert, ZRC); 1 male, Pulau Ubin, Chek Jawa, 26.III.2005, (sample 25031, leg. P. Grootaert, ZRC). 2 males, 7 females, Pulau Ubin Jetty, 11.XII.2002 (sample 22058, leg. P. Grootaert, RBINS); 2 males, 2 females, Chek Jawa, 13.XII.2002, (sample 22060, leg. P. Grootaert, RBINS), 1 female, Chek Jawa, 2.XII.2003 (sample 23096, leg. P. Grootaert, ZRC).

Diagnosis: Basal antennal segment pale yellowish; second segment brown; third segment almost black. Palp yellow, with white hairs. Mesonotum and scutellum black in ground­colour, covered with a thick grey­brown dusting; bristles black. Abdomen with all tergites black (including first tergite), covered with black hairs and bristles. Tip of hypandrium indented.

Description. Male:

Body length 1.88–2.13 mm, wing length 2.13–2.25 mm.

Head. Frons, face and occiput dark brown in ground­colour, densely covered by a grey­brown dusting. Large bristles black. Palp yellow with yellow bristles. Antenna ( Fig. 1 ) with basal segment yellow, second segment brownish, third segment brownish­black. Arista black.

Thorax brownish black in ground­colour, covered with a thick brown­greyish dusting. Humeri (postpronotal lobes), suture between notopleural depression and mesopleura yellowish brown. All bristles on mesonotum black.

Legs yellow, but posterior four coxae pale brown and tarsomeres 4 and 5 contrastingly brown. Most hairs and bristles black, but fore coxa densely set with pale hairs and ventral bristles on fore femur also pale. Fore femur with anteroventral row of 7 short spine­like bristles in apical half; ventrally densely set with yellowish bristles being about half as long as femur is wide; posteriorly in apical half a row of fine bristles about half as long as femur. Fore tibia with row of small ventral spine­like bristles. Mid tibia with anterodorsal and posterodorsal bristle on basal quarter and distinct ventral preapical. No other distinct bristling on the legs.

Wing with brownish­grey membrane, veins pale brown. Halter white.

Abdomen with all segments black in ground­colour and covered with dense grey dusting. All bristles on tergites black, bristles on sternites pale. Genitalia as in Figs 8–11 . Cerci strap­like, pale yellowish. Hypandrium and extension of sternite 5 shining black. Tip of hypandrium indented, the dorsal tip with a small notch (2 notches in specimens from Pulau Tioman).

Female

Body length 2.13–2.25 mm, wing length 2.13–2.40 mm.

Identical to male. Fore femur without ventral bristles. Tergite 10 with 10–11 spines on each hemitergite (acanthophorite) ( Figs 3, 4 ).

Derivatio nominis: the species is given the name nigra (Latin., niger: black) because all tergites are black.

Distribution: Singapore: Strait of Singapore; Malaysia: South China Sea; Brunei: South China Sea.

Phenology: Adults are present throughout the year in suitable habitat.

Figures

FIGURES 1 – 4. Thinolestris nigra sp. nov. 1. antenna (male, Brunei), aristal pit indicated; 2. palp (male Brunei); 3. ovipositor female laterally (Singapore); 4. ovipositor female dorsally (Singapore).

FIGURES 5 – 7. Thinolestris nigra sp. nov. male (Brunei). 5. mouthparts (palp, maxilla and labium removed); 6. labium and labella with pseudotracheae; 7. hypopharynx. Scale 0.1 mm.

FIGURES 8 – 11. Thinolestris nigra sp. nov. male (Brunei). 8. genital capsule left lateral view; 9. dorsal view of genital capsule; 10. sternite 5. 11. appendage on sternite 5 (left lateral view). ae: aedeagus; ce: cercus; hy: hypandrium.

FIGURES 12 – 15. Thinolestris extension on sternite 5 and hypandrium (left lateral view): 12. T. luteola (PNG); 13. T. nigra (Singapore, Malaysia, Brunei); 14. T. thaica (Thailand); 15. T. obscura (Sulawesi).