Thinophilus minutus, Samoh & Satasook & Grootaert, 2017

Samoh, Abdulloh, Satasook, Chutamas & Grootaert, Patrick, 2017, Eight new species of marine dolichopodid flies of Thinophilus Wahlberg, 1844 (Diptera: Dolichopodidae) from peninsular Thailand, European Journal of Taxonomy 329, pp. 1-40 : 12-15

Thinophilus minutus sp. nov.

urn:lsid:zoobank.org:act:150A1E50-9F4E-466B-9765-2BF976ACECE4

Figs 12–15

Diagnosis

A small species with completely yellow antenna, yellow fore coxa, brown mid and hind coxa and legs further completely yellow. Fore tibia without a ventral row of spine-like bristles. Only mid and hind femur with distinct black ventral bristles.

Etymology

The specific epithet refers to the small size of the species.

Type material

Holotype

THAILAND: ♂, Ban Laem Son, Langu , Satun Province, 6°56 ′ 27.9 ″ N, 99°42 ′ 12.4 ″ E, sweep netting, 27 Feb. 2015, A. Samoh leg. ( NHM-PSU ).

Paratypes

THAILAND: 1 ♂, same collection data as for holotype; 1 ♂, Phanang Tak, Muang, Chumphon Province, 10°30 ′ 23.9 ″ N, 99°13 ′ 55.6 ″ E, sweep netting, 17 Feb. 2015, A. Samoh leg.; 1 ♂, Bang Yai, Bang Nai Si, Takuapa, Phang-Nga Province, 9 Feb. 2015, A. Samoh leg.

Description

Male ( Fig. 12 )

LENGTH. Body 2.4 mm; wing 2 mm.

HEAD. Frons and face with shiny dark metallic green ground colour. A pair of long, divergent, black ocellars. Two very short postocellars. A pair of convergent, proclinate, long verticals, a little shorter than ocellars. Postcranium dark metallic green. Two converging postverticals, stronger and longer than, and not in row with upper postoculars. Postoculars uniseriate, black above, white and becoming multiseriate below. Antenna pale brownish. Arista dorsal, 2.5 times as long as antenna, shortly pubescent. Basal article short. Palpus yellow, with short, black bristly hairs, only anteriorly. Proboscis dark brown. THORAX. Thorax and scutellum shiny dark metallic green, with coppery and purple reflections. No dull black spots. Bristles on thorax black. Acr lacking; 4 equally long dc in one row, preceded by a short bristle and prescutellar outside the row and hardly longer than preceding bristles. Scutellum with 2 marginals, without lateral hairs. Three short lower pale brownish propleural bristles.

LEGS. Yellow including all tarsomeres. Fore coxa yellowish white; mid and hind coxae entirely brownish. Fore coxa anteriorly with short brown bristles. Trochanter bare. Fore femur club-shaped, a little thickened in basal half, apical half thin. No ventral bristles; 3 distinct posterior bristles on apical third. Fore tibia shorter than femur, no ventral bristling. First tarsomere densely set with spine-like bristles. Mid coxa with a long black exterior near middle and a long anterior bristle at tip. Mid femur slightly thinner than fore femur; with row of short ventral bristles in basal half. Mid tibia with a short ad and pd in basal quarter and a short ad and pd near middle; a crown of short apical bristles. Hind coxa with a black exterior bristle. Hind femur wider and longer than mid femur; short ventral bristles, short, upright anterior bristles near middle. Hind tibia with 1 ad and 2 dorsal bristles, a crown of long apicals.

WINGS. Yellowish brown, without spots. Tp straight, brownish seamed, apical part of M 3+4 1.5 times as long as Tp. Anal vein not reaching wing margin.

ABDOMEN. Shining dark metallic green. Hairs and hind-marginal bristles on tergites black. Sternites with short brown hairs.

TERMINALIA ( Figs 13–15 ). Phallus long, strap-shaped ( Fig. 13 ). Cercus whitish, with long brown apical bristles ( Figs 14–15 ), epandrium brown.

Female

Unknown

Distribution

Southern Thailand (Andaman Sea and Gulf of Thailand).

Remarks

Thinophilus minutus sp. nov. is quite unique among Thinophilus in southern Thailand by having only a few distinct bristles on the legs. Only mid and hind femora have distinctly longer ventral bristles. It is similar to T. peninsularis Parent, 1935 , a sympatric species that also exhibits only a few distinctive characters on the legs. The latter species, however, has a dorsal bristle on the basal quarter of the fore tibia, lacking in T. minutus sp. nov. Further, it has the fore coxa darkened on the basal two-thirds and the apical tarsomere darkened as well. The fore coxa and even the apical tarsomere of all legs are yellow in T. minutus sp. nov. Finally, in T. peninsularis the first tarsomere of the fore leg is as long as the following tarsomeres together, while in T. minutus sp. nov. the first tarsomere is half as long as the following four tarsomeres together. Both species share a brownish tinged wing. In T. minutus sp. nov. the Tp and M are brownish seamed.

Thinophilus minutus sp. nov. should also be compared with T. dongae Grootaert et al., 2015 , known from southern China. The latter species also has yellow fore coxae, no ventral bristles on the fore femur, no ventral spinules or bristles on the fore tibia. It has, however, the apical tarsomere of all legs black and mid and hind femora without ventral bristles. In T. minutus sp. nov. all tarsomeres are yellow and the mid and hind femora have short but distinct bristles. Both species are likely related in a species-group characterized by the similar shape of the cerci and surstyli.

Figures

Fig. 12. Thinophilus minutus sp. nov., ♂, habitus.

Figs 13–15. Thinophilus minutus sp. nov., ♂, terminalia. 13. Genital capsule, ventral view. 14. Genital capsule, lateral view. 15. Genital capsule, dorsal view.