Thinophilus yeoi, Grootaert, 2018

Grootaert, Patrick, 2018, Revision of the genus Thinophilus Wahlberg (Diptera: Dolichopodidae) from Singapore and adjacent regions: A long term study with a prudent reconciliation of a genetic to a classic morphological approach, Raffles Bulletin of Zoology 66, pp. 413-473 : 467-468

Thinophilus yeoi sp. nov.

(Figs. 55–57)

Material examined. Holotype Male. SINGAPORE: Pulau Ubin , Chek Jawa, mangrove, 12 September 2005, (reg. 25243, Si1049, leg. PG) . Paratypes: 5 males, 4 females, mangrove, 11 October 2005, (reg. 25380, Si1084, leg. PG) ; 14 females, 26 October 2005, (reg. 25399, Si1137, leg. PG) ; 6 males, 3 females, mangrove, 22 December 2005, (reg. 25456, Si1373, leg. PG) .

Numerous additional records can be found in Annex 1.

Additional material. Male , Sungei Mandai, Mandai creek, 24 July 1976, (dry on pin, leg. D.H. Murphy, ZRC LKCNHM; third antennal segment missing) .

Diagnosis. A large species with basal half of fore coxae black. Fore femur with a row of pv over the entire length, short near base, the preapical ones as long as femur is wide. Cerci long, half as long as abdomen, brown with short brown hairs. Fore tarsus with only the posterior claw present, anterior pulvillus enlarged.

Male. (Fig. 55). Body length: 4.5–5.2 mm, wing length: 4–5 mm.

Head. Frons and face with shining dark metallic green ground colour. Frons slightly concave. Face wide, at its narrowest point near upper third as wide as third antennal segment is long. Clypeus, sharply delineated from epistoma, protruding. Palpus yellow with black hairs. Postcranium slightly concave, shining dark metallic green. 2 long, diverging ocellars, twice as long as the three antennal segments; 2 shorter, verticals, converging and pointing forward; no postocellars; 2 distinct postverticals. Postoculars black and uniseriate above (5–6), longer and white below.

Antenna (Fig. 56) completely yellow. Second segment with dorsal and slightly longer ventral bristles. Third segment shorter than wide, tip a little produced and apically rounded. Arista subapical, 2.5 times as long as antenna, black; basal aristal segment short; apical segment shortly pubescent, tip naked.

Thorax and scutellum dark metallic green in ground colour, covered with a brownish dusting, two dull black stripes between the rows of dc, separated by a central brown strip; no dull black spots present. No acr; 6 rather short dc, short in front gradually growing longer to the rear and ending in a long prescutellar. Scutellum with 2 long marginals, with a minute lateral hair at outer side. 3–4 upper and 2 lower, white propleural bristles.

Legs yellow with hairs and bristles black. Fore coxa black on basal half, mid and hind coxae black, all trochanters yellow. Hind tibia brown on basal third, rest yellowish brown. All legs with tarsomere 1–3 of fore leg pale, following tarsomeres apically brown, tarsomere 5 completely brown.

Fore leg. Coxa anteriorly with 4 long bristles, apically with 5 long bristles. Femur slightly swollen in basal third, apically slender, with a row of short ventral bristles at base; in basal quarter some short pv, in apical third a row of about 5-6 bristles as long as femur is wide. Tibia ventrally with a double row of diverging bristles, the longest near base, as long as tibia is wide, 2 d, and a crown of weak apicals. Tarsomere 1 ventrally with short bristles, not spinulose, anteriorly a bit longer, but no soft hairs. Apico-ventral bristles on all tarsomeres present, not very long, the longest on tarsomere 4 and there as long as tarsomere 4. Anterior pulvillus long and about as wide as tarsomere 5; posterior pulvillus shorter and not so wide; only posterior claw present. Length femur, tibia and tarsomeres: 1.50: 1.42: 0.62: 0.22: 0.17: 0.12: 0.2.

Mid leg. Coxa with a strong, black bristle and some long anterior bristles. Femur slightly swollen in basal half, in basal half with a row of short ventral bristles being half as long as femur is wide; a strong preapical anterior, 2-3 weaker preapical pv. Tibia with 2 ad, 2 pd, and a crown of strong apical bristles. Each tarsomere with a pair of apico-ventral spinules and a long hair anterior hair. Length femur, tibia and tarsomeres: 1.67: 2: 1.12: 0.35: 0.25: 0.12: 0.12.

Hind leg. Coxa with a strong black exterior bristle. Hind femur as wide as mid femur. A long anterior near middle, two strong ad in apical third (also in female), a weak preapical anterior, a stronger preapical pv. Tibia with 2 ad, 2 pd, and a crown of strong apicals.

Length femur, tibia and tarsomeres: 2.45: 2.5: 0.62: 0.62: 0.32: 0.25: 0.27.

Wing anteriorly above vein M 1+2 brown, posteriorly more greyish. Veins black, hardly paler near base. Apical part of M 1+2 practically straight; tip of R 4+5 slightly converging with M 1+2. Wing boss present at one Tp length from Tp. Apical part of M 3+4, 1.5 times as long as tp. Anal vein dark brown at its base, apical half not indicated. Haltere white. Squama white, with short white cilia.

Abdomen with a shining metallic green ground-colour. Tergites covered with short black bristles and somewhat longer marginals (those at side of first tergite longest). Sternite 1 sclerotised. All sternites with short, black hairs. Sternite 4 with long marginal bristles covering the tip of the male genitalia. Aedeagus, surstyli, genital capsule (Fig. 56) and cerci brown. Surstyli symmetrical. Hypandrium asymmetrical (Fig. 56B). Cerci not fused, with broadly rounded tips; bristling brownish.

Female. Body length: 4.8–5.2; wing length: 4.3–5.

In most respect similar to male. The posteroventral bristle on the fore femur are present but much shorter and there is no double row of ventral bristles on the fore tibia. Bristling on mid femur short. All tibiae can be completely brownish.

Distribution. Singapore, southern Thailand (Samoh et al., in litteris), Brunei.

Although the NGS barcode of specimens from Surat Thani (southern Thailand) differs 2.6% from those of Brunei and Singapore, I did not see any morphological differences.

Phenology. Thinophilus yeoi sp. nov. is present throughout the year in low numbers. However, there was a distinct peak of activity from September to November in 2014. It is not clear if there is a relation to the amount of rain fall.