Thinophilus subapicalis Samoh & Grootaert

Samoh, Abdulloh, Satasook, Chutamas & Grootaert, Patrick, 2019, New marine Thinophilus species (Diptera: Dolichopodidae: Hydrophorinae) from the Thai Andaman Sea coast and new records from peninsular Thailand, European Journal of Taxonomy 505, pp. 1-20 : 11-15

Thinophilus subapicalis Samoh & Grootaert sp. nov.

urn:lsid:zoobank.org:act:BF708B92-B7E5-44EB-B0AD-0CF1773CECC7

Figs 8–10

Diagnosis

A small sized species of the ‘ Thinophilus spinatus -group’ with black fore coxa. Hind tibia in male with a very long pre-apical dorsal bristle as long as hind tibia. Fore tibia with a ventral protuberance just beyond middle bearing two long ventral bristles. Mid tibia with five long ventral interspaced bristles more than three times as wide as tibia. Mid tarsomeres 2 and 3 flattened, the latter orange. Hind tarsomere 2 with two very long ventral bristles near base.

Etymology

The name ‘ subapicalis ’ refers to the subapical position of the very long subapical bristle on the hind tibia.

Type material

Holotype THAILAND – Phang Nga Prov. • 1 ♂; Meuang district, Khlong Nai Ngop, Ban Tha Dan , Andaman Sea ; 8°24′02.5″ N, 98°30′38.6″ E; 22 Mar. 2018; A. Samoh leg.; sweep netting; PSUNHM (PSUZCDIP0015).

Paratypes

THAILAND • 3 ♀♀; same data as for the holotype; PSUNHM (1 ♀ PSUZCDIP0016) .

Description

Male ( Fig. 8 )

MEASUREMENTS. Body 3.2 mm; wing 3.2 mm.

HEAD. Ocellar bristles very long. Verticals minute. Postocular bristles short, uniseriate throughout, black above, white below.Antenna with postpedicel clear yellow, rounded, but with pointed tip. Palpus orange, with small black marginal bristles only.

THORAX. Subshining, bluish black. Five very short dorsocentral bristles. Humeral minute, a long pre-alar and a long supra-alar, a pair of long scutellars.

COLOUR OF LEGS. Dusky yellowish brown. All coxae black. Femora darker near base. Tarsomeres with a colour pattern.

FORE LEG. Coxa with short black bristles. Femur club-shaped at base, ventrally with several minute bristles. Tibia with a ventral swelling just beyond middle, with a row of short ventral bristles over entire length, but at the swelling with two long bristles ( Fig. 8 ). Tarsomere 1 longer than following four tarsomeres combined; ventrally with a row of interspaced bristles, a little longer than the width of the tarsomere. Tarsomeres 4 and 5 darkened.

MID LEG. Coxa without exterior bristle. Femur even more club-shaped than fore femur; base more swollen and apical portion thinner; with a row of long ventral bristles; longest near middle of femur. Mid tibia longer than mid femur with five interspaced long ventrals, being at least three times as long as tibia width. Tarsomere 1 much longer than the four apical tarsomeres combined. Tarsomere 2 ventrally flattened, ventrally pale yellowish. Tarsomere 3 ventrally also flattened, orange; dorsally covered with dense short black bristles ( Fig. 8 , inset). Tarsomeres 4 and 5 darkened.

HIND LEG. Coxa with a fine exterior bristle. Femur in basal half spindle-shaped (not so pronounced clubshaped as in the fore and mid femora), but dorsoventrally curved. Just beyond middle with a comb of three long ventral bristles, with a few tiny bristles anteroventrally ( Fig. 8 , inset). Tibia much shorter than femur, with a long dorsal pre-apical bristle that is at least as long as the tibia. Tarsomere 1 and 2 long, subequal in length. Tarsomere 2 with two very long ventral bristles near base. Tarsomeres 3, 4, and 5 darkened.

WING. Elongate, brownish tinged with brown veins. Squama whitish with pale cilia. Haltere white.

ABDOMEN. Subshining black with a bluish shine. Tergite 1 with longer apical bristles than the following tergites. Sternite 4 with some long apical bristles. Terminalia ( Fig. 10 ). Cerci pale dusky yellowish, dorsally fused over the entire length, only tips of both cerci free ( Fig. 10C ). Surstylus with spoonshaped apex, lacking bristles. A set of three ventral bristles near middle. A short epandrial bristle present ( Fig. 10 A–B).

Female ( Fig. 6 ) Body 2.9 mm; wing 2.9 mm. Similar to male. Palpus silvery white. All legs simple. Femora indistinctly club-shaped. Bristling on legs minute.

Comments

The new species is closely related to T. superbus Grootaert, 2018 . It differs in many of the male secondary sexual characters of the bristling of the legs. Very obvious is the swelling just beyond the middle of the fore tibia that bears a few long ventral bristles. There is no such swelling in T. superbus . The mid femur has long ventral bristles just beyond the basal swelling and the mid tibia has long, interspaced ventral bristles in the new species. No such bristles are present in T. superbus . The long bristle on the hind tibia is in a more apical position in T. superbus , while distinctly pre-apical in the new species. Thinophilus superbus has several very long dorsal bristles on hind tarsomere 2, and also long dorsals on tarsomeres 3, 4, and 5. The new species lacks these bristles.

Figures

Fig. 8. Thinophilus subapicalis Samoh & Grootaert sp. nov. Male habitus (Abdulloh Samoh leg., PSUNHM (PSUZCDIP0015)).

Fig. 9. Thinophilus subapicalis Samoh & Grootaert sp. nov. Female habitus (Abdulloh Samoh leg., PSUNHM (PSUZCDIP0016)).

Fig. 10. Thinophilus subapicalis Samoh & Grootaert sp. nov. Male terminalia (Abdulloh Samoh leg., PSUNHM (PSUZCDIP0015)). A. Ventral view of hypopygium. B. Lateral view. C. Dorsal view of cerci. Scale = 0.1 mm.

Fig. 6. Thinophilus plektron Samoh & Grootaert sp. nov. Female habitus (Abdulloh Samoh leg., PSUNHM (PSUZCDIP0014)).