Thinophilus langkawensis, 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 : 7-12

Thinophilus langkawensis sp. nov.

urn:lsid:zoobank.org:act:EE41F65A-641F-4D96-87FE-9228A57D4155

Figs 6–11

Diagnosis

A large species. Antenna completely yellow. Tibiae and tarsomeres completely yellowish white. Hypopygium elongate, more than half length of abdomen. Cerci in male reaching almost to thorax. Surstyli are movable and out-folding with a veil-like membrane.

Etymology

The specific epithet refers to the island of Langkawi ( Malaysia), where the species was found for the first time.

Type material

Holotype

THAILAND: ♂, Ko Tarutao, Molae Bay , Satun Province, 6°40 ′ 21.0 ″ N, 99°38 ′ 20.9 ″ E, sweep netting, 9 Jan. 2015, A. Samoh leg. ( NHM-PSU ).

Paratypes

THAILAND: 5 ♂♂, 7 ♀♀, same collection data as for holotype (1 ♂ and 1 ♀ in RBINS).

MALAYSIA: 6 ♂♂ (destroyed for DNA extraction, Lim et al. 2009), 8 ♀♀, Langkawi, Mutiara Burau Bay, from crab burrows on sandy beach, 1 Sep. 2005, I. Van de Velde & P. Grootaert leg. ( RBINS).

Description

Male ( Fig. 6 )

LENGTH. Body 6.4 mm; wing 5 mm.

HEAD. Frons and face with shiny dark metallic green ground colour. Face twice as wide as length of postpedicel. Clypeus a third of length of face. Ocellar tubercle pronounced but sunken between the eyes, not surpassing eye borders ( Fig. 6 ). A pair of long divergent black ocellars. No postocellars. A pair of convergent proclinate verticals, a little shorter than ocellars. Vertex excavated; postcranium metallic green. Two converging postverticals, stronger and longer than, and not in row with, upper postoculars. Postoculars uniseriate, black above, white and becoming multi-seriate below. Antenna yellow; pedicel and postpedicel hardly darkened dorsally. Arista dorsal, 2.5 times as long as antenna, not pubescent. Basal article short, yellowish brown; arista white, base a little browned. Palpus yellow, with short white bristly hairs. Proboscis brown.

THORAX. Thorax and scutellum shiny dark metallic green, with coppery and purple reflections. No dull black spots. Bristles on thorax black. Acr lacking; 5 equally long dc, prescuttelar a litle longer and dc row preceded by a short bristle. Scutellum with 2 marginals and a short lateral bristle. Four short white propleurals above and 7 longer white propleural brisles below.

LEGS. Yellowish white including all tarsomeres. Fore coxa black on basal two-thirds, yellowish on apical third; mid and hind coxae brownish, apices pale. Fore coxa anteriorly with short white bristles. Trochanter bare. Fore femur narrower than mid femur. Ventrally almost bare, except for some minute white hairs; 2 short posterior preapical bristles. Fore tibia shorter than femur, with only minute ventral bristles. Mid coxa with a long, black exterior bristle near middle, with short, white anterior bristles at tip. Mid femur wider than fore femur; ventrally with an anterior row of 3 short brown bristles and a posterior row of 5 bristles. Mid tibia as long as femur, with 3 short ad, 2 longer ad and 2 pd. Hind coxa with black exterior bristle and minute white anterior bristles. Hind femur only a little wider than mid femur; ventrally on apical ⅔ with a row of long white bristles, twice as long as femur is wide; in addition a few minute ventral bristles on basal third; 2 long black ad bristles on apical third. Hind tibia with 3 ad, 2 very long pd; a row of short black pd on basal third as long as tibia is wide; 2 somewhat recurved ventral bristles at basal third.

WINGS. Clear, without spots. Tp straight, 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 pale hairs.

TERMINALIA ( Figs 8–11 ). Elongate, more than half length of abdomen, with surstyli reaching tip of sternite 3 but cerci almost reaching to base of thorax. Cerci pale yellowish ( Fig. 6 ), ventrally not fused. Apex cercus with remarkable pattern of bristling ( Fig. 11 ). Surstylus movable, connected by a veil-like membrane to epandrium, suspended by black, rod-like structures. Phallus long, strap-shaped, but not coiled ( Fig 10 ). Epandrium elongate, brown.

Female ( Fig. 7 )

LENGTH. Body 6.4 mm long; wing 5.6 mm long.

BODY. Stouter than male, otherwise similar except following characters: hind femur lacking long white ventral bristles; sternites with minute pale bristling.

Distribution

Southern Thailand and northern Malaysia (Andaman Sea coast).

Remarks

The male of this robust species with yellow legs has very long terminalia, which in rest position are partly hidden in a cavity formed by the sternites 4 to 6. When the terminalia are extended, the surstyli move and open a veil-like lined cavity ( Figs 8 , 10 ). This phenomenon was not previously observed in Thinophilus . This large species was found on the adjacent islands of KoTarutau in Thailand and Langkawi Island in Malaysia.

Figures

Fig. 6. Thinophilus langkawensis sp. nov., ♂, habitus.

Fig. 7. Thinophilus langkawensis sp. nov., ♀, habitus.

Figs 8–9. Thinophilus langkawensis sp. nov., ♂, terminalia. 8. Genital capsule, lateral view. 9. Genital capsule, dorsal view.

Figs 10–11. Thinophilus langkawensis sp. nov., ♂, terminalia. 10. Genital capsule and surstyli, ventral view. 11. Detail of apex of cerci, dorsal view.