Thinophilus pallitarsis, 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 : 447-449

Thinophilus pallitarsis sp. nov.

(Figs. 34–36)

Material examined. Holotype male, SINGAPORE, Lim Chu Kang , mangrove, 26 November 2003 (sample 23089, leg. PG).

Paratypes: 1 male, Lim Chu Kang, 9 December 2002 (sample 22056, leg. PG) . 1 male, Pasir Ris, 4 December 2003, beach, mangrove (sample 23106, leg. PG) ; 3 males, Sungei Buloh, 22 June 2005, sweeping ( Si 799, leg. PG) , material sequenced by Lim et al. 2010 in GenBank.

Etymology. The name refers to the pale tarsi (pallere: Latin: to be pale; Greek tarsos: foot).

Diagnosis. Medium-sized species with antennae ventrally yellow, dorsally brownish black; third antennal segment as long as high with a blunt tip; fore coxa yellow, but base darkened; posterior coxae black. Legs yellow, but hind trochanters brown and all tarsi pale yellow in contrast to the yellow tibiae. Articulations of the tarsomeres brown so that each tarsomere has a dark spot at its tip. All femora with ventral bristles (nearly as long as femur is wide). Fore tibia with a row of long ventral bristles, longest in the basal half. 5 almost equally long dc, preceded by a short bristle. Cerci black.

Male. (Fig. 34). Body length 2.9–3.1 mm; wing length 2.55–2.7 mm.

Legs yellow with black hairs and bristles. Fore coxa yellow, but base darkened (Fig. 34); hind and mid coxae black. Tip of mid tibia and hind trochanter brown. All tarsi pale yellow in contrast to the yellow tibiae. Joints of tarsomeres brown so that the tarsomeres seem to have a brown tip. Apical two tarsomeres of hind leg brown.

Fore leg. (Fig. 35F) Coxa anteriorly with about 10 long black bristles with curved tip, the bristles are a little shorter near tip of coxa. At tip a row of short, bent bristles. Femur thickened in basal half and gently narrowing towards tip; ventrally in basal half with a row of bristles as long as femur is deep; more posteroventrally a row of long bristles extending over the entire length of the femur. Tibia shorter than femur, bearing a short black pd bristle beyond its middle; ventrally with a row of long bristles, longest in basal half. Tarsomeres ventrally without bristling, but with a pair of apical bristles.

Mid leg. Coxa with a long exterior bristle, and numerous bristles at its tip and anteriorly. Femur (Fig. 35B) thickened in basal half, narrowing more abruptly in apical half; ventrally in basal 2/3 with a row of black bristles that are longer than femur is wide. Posteroventrally with only short bristles, becoming more prominent near tip. Mid tibia longer than femur; with 2 ad, 2 pd and a circlet of apical bristles. Fig. 36. Thinophilus pallitarsis sp. nov., male. A, Details of tip epandrium and epandrial lobe; B, Epandrium and cercus laterally; C, Epandrium ventrally; D, Cerci dorsally.

Head. Frons and face with shining dark metallic green ground colour. Face below middle, narrower than depth of third antennal segment. Clypeus nearly half as long as epistoma, slightly broader than long, protruding. Palpus yellow to brownish at base, bearing few black bristly hairs. Rostrum large, dark brown with pale hairs. Postcranium shining dark metallic green. 2 long, diverging ocellars; 2 shorter, converging verticals, pointing forward; 2 minute postocellars; 2 postverticals, as long as upper postoculars. Upper postoculars uniseriate, black; lower postoculars uniseriate, white, with a few long hairs behind them.

Antenna yellow, dorsally brown. Dorsal margin of second segment black with black dorsal and ventral bristles. Third segment about as long as high, with a blunt apical point. Arista subapical, 2–2.5 times as long as antenna, black, very shortly pubescent; basal aristal segment very short, black.

Thorax and scutellum shining dark metallic green; no dull black spots. No acr; 5 almost equally long dc, preceded by a short bristle. Scutellum with 2 marginals, with a short lateral hairs at outer side. 2 upper (1 long, one short) and 5 lower white propleural bristles.

Hind leg. Coxa with a long, black exterior bristle (shorter than on mid tibia). Hind femur (Fig. 35C) stouter than mid femur, basally thickened and gently becoming more slender towards tip. A row of ventral bristles, short near base but becoming longer towards tip, there longer than femur is wide; anteroventrally near middle also some long bristles. Near middle with a short distinct anterior, on apical quarter a dorsal bristle. Tibia with 2 short ad, 2 d and a circlet of apical bristles.

Wing feebly brownish tinged, without darker shades. Veins brownish, paler near base. Apical part of M 1+2 practically straight; tip of R 4+5 slightly converging with M 1+2. Tp straight, nearly as long as apical part of M 3+4. Anal vein indicated by a short brown streak. Haltere white. Squama white, with white cilia.

Abdomen shining dark metallic green; tergites with short black hairs and hind-marginal bristles on tergites longer. All sternites with black bristles. Terminalia as in Fig. 36. Epandrium dark brown; cerci black, with black hairs, dorsally fused only near middle.

Female. Unknown.

Remarks. Thinophilus pallitarsis has pale yellow tarsi, but do not always have the tip darkened. It has a row of long ventral bristles on the basal half of the fore tibia only. This character is found in the smaller species T. parvulus Samoh et al., 2017 as well, but the latter has very long white bristles on the fore femur. In T. minor sp. nov. and T. variabilis the ventral bristles on the fore tibia are longest in the apical half of the tibia.

Fig. 37. Thinophilus parmatus Grootaert & Meuffels, 2001 , male habitus. (Photo: Maosheng Foo).

Distribution. Singapore.

Thinophilus parmatus Grootaert & Meuffels, 2001 (Fig. 37)

Thinophilus parmatus Grootaert & Meuffels, 2001: 347 (Figs. 21–26). Type locality: Thailand, Phang-Nga province , Takua Pa .

Material examined. SINGAPORE. 1 male, Pulau Ubin , Chek Jawa, mangrove, 26 March 2005, (reg. 25031, Si532, leg. PG) ; 6 males, mangrove, 12 September 2005, (reg. 25343, Si1036, leg. PG) ; 2 females, mangrove, 11 October 2005, (reg. 25380, Si1085, leg. PG) ; 2 males, mangrove, 11 October 2005, (reg. 25380, Si1091, leg. PG) ; 2 males, mangrove, 11 October 2005, (reg. 25382, Si1093, leg. PG) ; 1 male, mangrove, 26 October 2005, (reg. 25399, Si1142, leg. PG) ; 1 female, mangrove, 26 October 2005, (reg. 25339, Si1764, leg. PG) ; 1 female, mangrove, 22 December 2005, (reg. 25456, Si1378, leg. PG) .

Diagnosis. Small species with yellow antenna and all coxae black. Legs variable in colour from yellowish brown to brown. Male mid tarsus with tarsomere 2 with a black dorsal rounded lobe, tarsomere 3 less widened and contrastingly pale. Fore femur with very short ventral bristles, except for 1 longer at base; mid femur with about 4–5 fine bristles at base, hind femur with some long ventral bristles, in apical third several bristles that are longer than femur is wide. Tip of mid tibia without a row of long curved bristles. Cerci yellowish brown, medially fused.

Remarks. Thinophilus parmatoides Samoh, Satasook & Grootaert, 2017 is a closely related species described recently from peninsular Thailand and similar to T. parmatus in having a black shield-like protuberance on tarsomere 2 of the mid leg. There are a few black bristles at the base of the fore femur, a thick tuft of black bristles at the base of the mid femur, long hair-like bristles on the tip of the mid tibia and only short ventral bristles on the hind femur. In T. parmatus , there is a single long bristle at the base of the fore femur, mid femur with only 4 thin bristles at base and the hind femur with longer bristles in apical half. The shield on tarsomere 2 of the mid leg is rounded in T. parmatoides while elongated in T. parmatus . The shape of the male genitalia is very similar in both species.

Distribution. Southern Thailand (Phang-Nga prov., Trang prov.) and Singapore (Pulau Ubin).