Cymatopus mayakunae, Samoh & Satasook & Grootaert, 2018

Samoh, Abdulloh, Satasook, Chutamas & Grootaert, Patrick, 2018, New data on the marine genera Cymatopus Kertèsz and Thambemyia Oldroyd (Insecta, Diptera, Dolichopodidae) from rocky shores in southern Thailand with the description of a new species, Raffles Bulletin of Zoology 66, pp. 258-267 : 260-262

Cymatopus mayakunae new species

Figs. 3–5

Material examined. Holotype male: THAILAND, Laem Pakarang, Khao Lak, Takuapa , Phang Nga Province (Andaman Sea), 8°44′09.9″N, 98°13′21.5″E, 10 February 2015, sweep netting, coll. A. Samoh ( PSUNHM) Paratypes: 30 males, 10 females, same collection as holotype. 13 males, 6 females, Tarutao Island, Langu , Satun Province (Andaman Sea), 6°44′19.2″N 99°38′45.4″E, 9 January 2015, sweep netting, coll. A. Samoh ( PSUNHM, RBINS) .

NGS barcodes see annex 1.

Etymology. The species is dedicated to Dr. Jaruwan Mayakuna who was so kind to take the first author to sample Cymatopus flies in the Langu mangroves, Satun Province (Andaman Sea).

Diagnosis. A small species (2–2.5 mm) with yellow legs. Fore tibia without black foliaceous bristle and without apical spur and apical bristle. Fore tibia dorsally near base with short bent bristles. Hind tibia with a dorsal row of bristles with dilated tips. Wing with veins R 1 and R 2+3 deformed and thickened. Posterior wing border a little deformed with longer hairs.

Male ( Fig. 3 ). Body length 2.5 mm; wing length 2.5 mm.

Head. Frons and face black in ground-colour, greyish dusted. Clypeus protruding. Face wider than postpedicel is wide. Palpus brown with short black hairs, tips of apical bristles pale. A pair of strong ocellars, a pair of slightly shorter fronto-orbitals and a pair of minute postocellars. Postocular bristles black above, becoming whitish and hair-like below. Antenna black, pedicel darker than scape and postpedicel. Postpedicel conical, 1.5 times as long as wide. Arista nearly twice as long as scape, pedicel and postpedicel together.

Thorax black in ground-colour, greyish dusted. No acrostichals, 5 dc (anterior 4 equally long, prescutellar dc longer); a pair of long scutellars with a minute hair at outside. A minute humeral, a very long posthumeral, a short sutural, a minute notopleural, a longer supra-alar and a long postalar. 3 pale propleurals.

Legs yellow ( Fig. 3 ) with mid and hind coxae black, apical two tarsomeres slightly brownish. Fore leg. Coxa with 2–3 short black bristles at base and some longer black apical bristles. Femur swollen in basal half with long posteroventral bristles, near base as long as femur is wide, in apical half longer than femur is wide. The row is interrupted at the basal third where there are 2 shorter bristles. Tibia as long as femur, without apical spur and without apical spine-like bristle; ventrally set with a double row of spine-like bristles as long as tibia is wide; basal fifth of tibia dorsally set with a double row of short bristles with curved tip. Tarsomeres not flattened. Mid leg: Coxa with 2 short black exterior bristles. Femur much longer and thinner than fore femur. Tibia shorter than femur without particular bristles. Hind leg: Coxa with a short black exterior bristle. Femur a little wider than mid femur and shorter. Tibia dorsally set with a double row of short bristles with enlarged tips ( Fig. 3 ).

Wing brownish tinged with brown veins. Costa near middle darker brown and slightly bowed. Costa and R 2+3 ( Fig. 3 ) thickened and undulating near middle. Apical half of Cu pale, the hind border is a little notched there and the wing membrane is folded to the exterior and bears some longer bristles at that level. Haltere and squama white, bearing long white cilia.

Abdomen black in ground-colour, greyish dusted. Tergites with minute black bristles on apical border. Terminalia ( Fig. 5 ). Cercus yellow with brown bristles longer than cercus is wide.

Female ( Fig. 4 ). Body length: 2.0 mm, wing length: 2.0 mm.

Identical to male but fore legs with shorter bristles and wing with veins not deformed. Fore tibia and hind tibia with normal bristling.

Bionomics. The adult flies are found in the splash zone of rocky shores.

Distribution. Shores of the Andaman Sea.

Remarks. The new species is unique in the genus in having the fore tibia dorsally near base set with short bent bristles. The hind tibia has a dorsal row of bristles with dilated tips. Veins R 1 and R 2+3 are deformed and thickened. In addition, the posterior wing border is a little deformed bearing longer hairs.

Figures

Fig. 3.Cymatopus mayakunae new species male habitus.cb: curved bristles on fore tibia; ht: hind tibia with dorsal row of bristles with swollen tip; arrow indicates fold in hind margin of wing set with long bristles.

Fig. 4. Cymatopus mayakunae new species female habitus.

Fig. 5. Cymatopus mayakunae sp. nov. male terminalia. c: cercus; hy: hypandrium; sur: surstylus.