Thinophilus minor, 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 : 437-441

Thinophilus minor sp. nov.

(Figs. 25, 26)

Material examined. Holotype male, SINGAPORE: Pulau Ubin ( PU08 ), 14 April 2016 (reg. 4132; Ma9275) NGS barcoded and conserved in ethanol as ZRCBDP0083837 . Paratypes: SINGAPORE: 1 male same provenance as holotype ( ZRCBDP0083839 , Ma 9275) ; 1 female, Pulau Ubin ( PU08 ) , 7 April 2016 ( ZRCBDP0082692 ) ; 1 female, Pulau Ubin ( PU08 ) , 23 March 2016 ( ZRCBDP0083658 , Ma 9270) ; 2 females, Pulau Ubin ( PU08 ) , 20 April 2016 ( ZRCBDP0083825 , Ma 9279) ; 1 male, Sungei Buloh , 27.XI.2003 (reg. 23090, leg. P. Grootaert; MS name sp. 6) ; 1 male, Padan mangrove, 5 December 2003, (reg. 23109, Si 229, leg. PG) .

Rostrum large (a quarter of height of eye) dark brown with white hairs. Postcranium slightly concave, shining dark metallic green. 2 long, diverging ocellars; 2 long (only slightly) shorter, converging verticals, pointing forward; 2 small postocellars pointing forward; 2 distinct postverticals, longer than upper postoculars. All postoculars black and uniseriate, a little longer below and there with a few additional black long hairs behind them.

Antenna yellow, but dorsally and with extreme tip of third segment narrowly brown. Inner protuberance of second segment brown, seamed black; outer one yellow with lateral margin black; second segment with dorsal and slightly longer ventral bristles. Third segment higher than long, apically rounded, with a minute pointed tip. Arista subapical, 2.5–3 times as long as antenna, brown, shortly pubescent; basal aristal segment short.

Thorax and scutellum shining dark metallic green; no dull black spots. No acr; 4 almost equally long dc, preceded by a short bristle. Scutellum with 2 marginals, with a minute lateral hair at outer side. 2 upper and 2–3 lower black propleural bristles (lowest bristle is about as long as fore coxa is wide at base).

Legs yellow with black hairs and bristles. Fore coxa entirely yellow to brown on basal two thirds, mid coxa black, hind coxa rather brownish black, extreme tips paler brownish. All femora slightly brownish dorsally. All tibiae and tarsi with a brown stripe above, paler ventrally.

Fore leg. Coxa with long black bristles anteriorly and apically. Trochanter with a long ventral. Femur swollen in basal third, apically slender. 3–4 long anteroventral bristles in basal quarter and a few preapical posteroventral bristles; the most apical pv is stronger and longer than femur is wide. Tibia (Fig. 26A) with a short dorsal on basal quarter; ventrally on Fig. 25. Thinophilus minor sp. nov. habitus holotype male ( ZRCBDP 0083837). (Photo: Kristy Yi Wen Chang). Fig. 26. Thinophilus minor sp. nov. male. A, Fore leg anteriorly; B, Epandrium ventrally; C, Cerci dorsally; D, Epandrium and cercus laterally.

apical two thirds a row of long bristly hairs (about twice as long as tibia is wide). First tarsomere ventrally with spine-like bristles about as long as metatarsus is wide. Following tarsomeres with a pair of apical bristles.

Mid leg. Coxa with a long black exterior bristle. Femur swollen in basal half, anteroventrally with 3–4 long bristles in basal half (nearly as long as femur is wide); a strong preapical anterior on apical quarter. Tibia with an ad on basal quarter and a longer ad near middle; 2 pd and a crown of apicals (pd bristle very long).

Hind leg. Coxa with a black exterior bristle. Femur ventrally straight, dorsally swollen in basal half. A strong anterior near middle, a row of ventral bristles, short near base and about half as long as femur is wide near middle. Hind tibia with an ad near middle, 2 pd and a crown of long apicals that are a little shorter than on mid tibia.

Wing brownish tinged, without darker shades. Veins brownish 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 about one Tp length from Tp. Apical part of M 3+4 2 times as long as tp. Anal vein dark brown at its base, indicated for a little more than half its length. Haltere white. Squama white, with pale cilia with a longer brown hair in the row.

Abdomen with a shining metallic green ground-colour. Tergites covered with short black bristles and somewhat

Fig. 27. Thinophilus murphyi Evenhuis &Grootaert male habitus.

longer marginals (those at side of first tergum longest). Sternum 1 not sclerotised lacking bristles. Sternites 2–4 with long, fine, black hairs (longer than those on tergites). Surstyli and genital capsule pale brownish (Fig. 26B–D); cerci yellowish white, dorsally not fused.

Female. Body length 2 mm. Similar to male in most respects. Bristling on fore coxa is not as dense and long as in male (at most 2–4 anterior bristles that are not as long as coxa is long). Fore, mid and hind femora with only very short ventral bristles. Posterodorsal preapical bristle on fore femur present but shorter than in male. Fore tibia lacking the long ventral bristles.

Remarks. T. minor sp. nov. belongs to a species group where the fore tibia has long ventral bristles on at least the apical 3/4. These bristles are at least 1.5 times as long as tibia is wide. The row of long ventral bristles on the fore tibia is quite unique in Thinophilus , especially because they are nearly twice as long as tibia is wide. This is a character shared with T. variabilis Samoh et al., 2017 . Note that the fore tibia in T. variabilis has an anterodorsal and a posterodorsal bristle on the basal quarter, which is not in the original description.

There is Thinophilus lungosetole Ramos & Grootaert, 2018 (in Ramos et al., 2018), a species of about 3 mm long recorded from Bohol Island ( Philippines) that is very similar in having 4 dc only and the fore tibia with a row of long ventral bristles. In the latter the bristles are 3 times as long as the tibia is wide while at most twice as long in T. minor sp. nov. and T. variabilis .

Thinophilus variabilis is larger than T. minor sp. nov. and it has a row of long posteroventrals on the fore femur. This row may be interrupted near the tip, as if one bristle is missing. In addition, it has an anterodorsal and a posterodorsal bristle on the basal quarter of the fore tibia that is not mentioned in the original description. T. minor has on the fore femur only one stronger posterodorsal preapical bristle and a few weaker bristle near the base, not a row over the entire length. The fore tibia bears only a short dorsal bristle on basal quarter.

Thinophilus minutus Samoh et al., 2017 described from Thailand, is another small species with only 4 dc but it has no long ventral bristles on the fore tibia.

Distribution. Singapore. A very rare species.