Thinophilus apicatus, 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 : 416-419

Thinophilus apicatus sp. nov.

( Figs. 2–5 )

Material examined. Holotype Male. SINGAPORE: Pulau Ubin , Chek Jawa, mangrove, 12 September 2005 (reg. 25343, Si1042, leg. PG).

Paratypes: SINGAPORE: 1 female, Sungei Buloh, mangrove, 9 December 2002 (reg. 22057, leg. PG) . 1 male, 1 female, mangrove, 27 November 2003 (reg. 23091, leg. PG) ; 2 females, 27 November 2003 (23090, leg. PG) ; 1 female, mangrove, 27 November 2003, (reg. 23092, Si96, leg. PG) ; 1 female, mangrove, 27 November 2003, (reg. 23090, Si182, leg. PG) ; 1 male, mangrove, 28 March 2005, (reg. 25035, Si545, leg. PG) ; 1 male, mangrove, 26 August 2005, (reg. 25321, Si1026, leg. PG) ; 1 female, Lim Chu Kang, 26 November 2003 (sample 23089, leg. PG) ; 2 females, 26 November 2003, (reg. 23089, Si251, leg. PG) ; 6 males, 2 females, Pulau Ubin, Chek Jawa, mangrove, 12 September 2005, (reg. 25343, Si1042, leg. PG) ; 9 males, 2 females, 11 October 2005, (reg. 25380, Si1082, leg. PG) ; 3 males, females, 26 October 2005, (reg. 25399, Si1141, leg. PG) ; 2 males, 2 females, 26 October 2005, (reg. 25339, Si1762, leg. PG) ; 3 males, 4 females, 22 December 2005, (reg. 25456, Si1374, leg. PG) ; 2 males, females, 30 December 2005, (reg. 25475, Si1446, leg. PG) ; 1 male, Pandan, mangrove, 5 December 2003, (reg. 23109, Si226, leg. PG) ; 2 males, 1 female, Semakau, mangrove, 10 March 2005, (reg. 25009, Si404, leg. PG) .

THAILAND: 1 male, Satun province: Pak Bara , mangrove, 28 October 1997 (reg. 97134, leg. P. Grootaert) ; 1 female, Pak Bara Park , beach, rocks, 28 October 1997, (reg. 97136, leg. P.

Grootaert); 1 male, Samut Prakan province: Sakla , mangrove forest, 20 May 1998, (reg. 98060, leg. P. Grootaert) .

The data from the SMIP & MIP material are available in Annex 1.

Etymology. The name refers to the black tips of all tibiae [Lat. apicatus: ‘with (striking) apices’].

Diagnosis. Medium-sized species with yellow palpus; antenna ventrally yellow, dorsally brownish black; fore coxa yellow, posterior four coxae black. Legs yellow, but all tibiae narrowly and contrastingly darkened at tips (less so on hind tibia); apical three segments of all tarsi darkened. Bristling of legs identical in male and female i.e., fore coxa with a vertical row of 2–3 long bristles, fore femur with two long basal, ventral bristles and two to three shorter anteroventral bristles; fore tibia with a long dorsal bristle beyond middle. 5 equally long dc, preceded by a small bristle. Cercus pale yellow, much shorter than aedeagus and surstyli, which are brownish.

Male. ( Fig. 2 ) Body length 2.6 mm; wing length 2.2 mm.

Head. Frons and face with shining dark metallic green ground colour. Face a little narrower than depth of third antennal segment. Clypeus nearly half as long as epistoma, slightly broader than long, hardly protruding. Palpus yellow, bearing a few black bristly hairs. Rostrum dark brown. Postcranium shining dark metallic green. 2 diverging Fore leg. Coxa ( Fig. 3C, D ) anteriorly on apical half anteriorly with a row of 3 (sometimes 2 or 4) rather long black bristles, also a single bristle at base; at apex a few short, bent bristles. Femur ventrally near base with two thin, long black bristles, about as long as greatest depth of femur; more anteroventrally near base 2–3 very thin hairs not as strong as the ventrals. Tibia nearly as long as femur, bearing a rather strong black dorsal bristle beyond its middle. First tarsal segment ventrally shortly spinulose. Length of tibia and tarsal segments (in mm): 0.7: 0.3: 0.12: 0.09: 0.07: 0.11.

Mid leg. Coxa with a very small exterior bristle, and some very short, hair-like bristles at its tip. Femur ( Fig. 3A ) ventrally on basal half with a row of short, hair-like bristles, the longest of which are nearly as long as femur is wide; 1–3 preapical pv. Tibia about as long as femur; 1 short dorsal bristle beyond middle; 3 short apicals. Length of tibia and tarsal segments (in mm): 0.95: 0.5: 0.15: 0.1: 0.08: 0.11.

Hind leg. Coxa with a weak and short, black exterior bristle. Femur ( Fig. 3B ) ventrally with only some short hairs on basal half; a thin preapical av and a slightly stronger preapical pv, both very short. Tibia slightly shorter than femur; a very small ad beyond middle; a long dorsal preapical and a ventral apical. Length of tibia and tarsal segments (in mm): 1.1: 0.25: 0.23: 0.15: 0.1: 0.11.

ocellars; 2 converging verticals, pointing forward; 2 very small postocellars; 2 postverticals, much stronger and longer than, and not in row with upper postoculars. Upper postoculars uniseriate, black; lower postoculars multiseriate white hair-like.

Antenna. First segment yellow, dorsally brown. Second segment brown, encompassing the third segment dorsally. Third segment yellow, dorsally and apically browned, rounded, bearing a rather long pubescence. Arista dorsal, 2.5 times as long as antenna, black, very shortly pubescent; basal aristal segment very short, black.

Thorax and scutellum shining dark metallic green, with coppery and purple reflections; two ill-limited purplish stripes running down the row of dc, with in between them a brightly shining green area. Humerus silvery dusted as well as pleura and all coxae. Notopleural depression dull black. No acr; 5 almost equally long dc, preceded by a short bristle. Scutellum with 2 marginals, no lateral hairs. 1 upper and 2 lower, black propleural bristles.

Legs. Fore coxa yellow; hind and mid coxae dark brown, yellow at their tips. Legs yellow, but apices of all tibiae narrowly, but conspicuously dark brown (less so on hind tibia); bases of fore and mid tibiae, and basal half of hind tibia feebly browned; tarsi progressively darkened from base of third segment.

Wing feebly brownish tinged, without darker shades. Veins brownish, more yellowish at 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 present, short. Haltere pale yellow. Squama yellow, with whitish cilia.

Abdomen shining dark metallic green; but all tergites basolaterally (at sides and base) broadly silvery dusted; dorsally shining metallic green. Hairs and hind-marginal bristles on tergites short, black. Sternites with short white bristles. Epandrium brown; cercus white with white hairs, much shorter than aedeagus and surstyli, which are brownish. Cerci dorsally separated ( Fig. 4B ). Surstylus bifurcate ( Fig. 4A ) with spine-like bristles at tip. Phallus long ( Fig. 4D ).

Female. Body length 2.4 mm; wing length 2.2 mm. As male. Face about as wide as depth of third antennal segment. Clypeus slightly more than half as long as epistoma; a little bulging (flat in male). Legs bristled as in male but mid and hind femora ventrally bare. Sternites with moderate long hairs (in male hairs on sternites minute).

Remarks. This is one of the few Thinophilus of which the female and male have the same remarkable bristling and colouration of the legs i.e., the long erect bristles on the fore coxa, the long ventral bristles at the base of the fore femur, a long dorsal bristle just beyond the middle of the fore tibia. In addition, the female also has the tips of all tibiae brown.

Note that in alcohol preserved specimens, the antennae look much paler than in dry specimens in which the antennae are almost black with a small yellow ventral area.

RAFFLES BULLETIN OF ZOOLOGY 2018

Distribution. Singapore, Thailand and Brunei.

I also examined material collected in southern Thailand by Abdulloh Samoh and in Brunei by Claas Damken that both contained specimens comparable to T. apicatus sp. nov..but they differ genetically respectively by 10% and 5.2% and thus need further examination.

Phenology. Thinophilus apicatus sp. nov. is present throughout the year but generally less active in dryer periods ( Fig. 5 ).

Figures

Fig. 2. Thinophilus apicatus sp. nov., male habitus.

Fig. 3. Thinophilus apicatus sp. nov., male. A, Mid femur; B, Hind femur; C, Posterior view of fore leg; D, Anterior view of fore coxa.

Fig. 4. Thinophilus apicatus sp. nov., male. A, Detail of surstyli ventrally; B, Tips cerci dorsally; C, Ventral view of epandrium; D, Lateral view of epandrium.

Fig. 5. Thinophilus apicatus sp. nov. Phenology during a 2-year survey (MIP).