Terocelion melanoleucum, Ševčík, 2012

Ševčík, Jan, 2012, Terocelion gen. nov., a new Oriental genus of Keroplatidae (Diptera) with pectinate antennae, Acta Entomologica Musei Nationalis Pragae 52 (2), pp. 495-503 : 499-500

Terocelion melanoleucum sp. nov.

( Figs. 1 , 3, 5 , 7 )

Type material. HOLOTYPE: J, THAILAND: PETCHABURI: ‘ Kaeng Krachan NP, Panernthung /km27/water pump, 12°49.151‘N 99°22.483‘E, 950 m, 4.-11.vii.2008, Malaise trap, Chusak & Sirichai & Arkom leg., T4337 ’ ( QSBG) . PARATYPE: J, THAILAND: PETCHABURI: ‘Kaeng Krachan NP, Panernthung/km27/water pump, 12°49.151‘N 99°22.483‘E, 970 m, 12.-19.ix.2008, Malaise trap, Sirichai & Chusak leg., T 4371’ ( JSOC).

Description. Male. Body length (without antennae) 6.5 mm. Wing length 4.2 mm (holotype). Ratio of wing length to width 2.86.

Head. Compound eyes relatively narrow, 1.6 times as high as broad in lateral view, distinctly emarginated above the bases of antennae. Three ocelli, the median one smaller, the lateral one almost touching the eye margin (distance between the eye margin and lateral ocellus is about half the diameter of the latter). Ocelli placed on a dark tubercle, medially divided by a distinct frontal furrow. Face narrow (three times as high as broad), light brown, bare, weakly sclerotised and in its upper half medially divided by a dark sagittal furrow. Clypeus small and indistinct. Mouthparts reduced. Maxillary palpus consists of a small palpifer and a larger oval yellowish palpomere.

Antenna long, about 1.7 times as long as the head and thorax together, pectinate, with 14 flagellomeres ( Fig. 1 ). Flagellum laterally flattened, flagellomeres 2 to 13 anteriorly slightly prolonged and narrowing. F1 to F11 plus F14 dark brown, F12 and F13 white. Scape and pedicel dark brown, slightly shorter than wide.

Thorax. Scutum weakly arched, evenly covered with short setae, yellowish brown with lateral margins and two submedian longitudinal stripes (V-shaped, connecting posteriorly) dark. Scutellum dark brown, with subapical transverse row of short black setae. Mediotergite brown, proximally lighter, bare, posteriorly distinctly protruding. Subscutellar membranous area subtriangular, proximally wide but tapering posteriorly into a narrow sagital groove ( Fig. 5 ). Lateral sclerites dark brown. Laterotergite bare. Antepronotum and proepisternum setose. Anterior spiracle and membranous area around it without setae. Anepisternum and the other lateral sclerites bare. Prosternum without setae. Haltere dark brown, basally lighter, slightly longer than the first abdominal tergite.

Wing ( Fig. 3 ) hyaline, distinctly marked ( Figs. 1 , 3 ), its membrane covered only with microtrichia, without macrotrichia. Sc short, reaching to the base of R-M fusion. Vein C produced beyond R 5 to about half the distance between the tips of R 5 and M 1. R 4 ending in C. M 2 shortened, not reaching wing margin. CuA 2 downcurved towards the tip. A 1 strong, ending just before the wing margin. Costa, R 1 and R 5 covered with setae.

Legs mostly dark brown, tibiae and tarsi lighter. Coxae and femora all dark brown. Tibiae light brown, darkened at proximal and apical ends. All tibiae with trichia arranged in dense longitudinal rows, without strong bristles. The apex of fore tibia without any tibial organ. Fore tibia with one apical spur, slightly longer than maximum tibial diameter. Two spurs present on both mid and hind tibia, the posteroventral spurs twice as long as the anteroventral ones. Hind tibia ventrally (except proximal and distal ends) with a longitudinal area of dense trichia not arranged in rows. A distinct transverse comb of closely set posterior setulae apically on mid and hind tibia.

Abdomen relatively long, mostly dark brown, tergites 2–5 with light dorsal triangular markings ( Fig. 1 ). Sternites 2–5 yellowish with dark apical margins. Terminalia ( Fig. 7 ) dark brown. Tergite 9 subtriangular, about as broad as long. Gonocoxites ventrobasally fused, posteriorly forming a V-shaped excavation reaching to about the proximal third of the gonocoxites. Gonostylus 1.2 times as long as gonocoxite, 2.6 times as long as wide, dorsoventrally flattened, apically rounded, without teeth, in basal half with a longitudinal submedial furrow.

Female. Unknown.

Differential diagnosis. The dark male antenna with white flagellomeres 12 and 13 is a diagnostic feature of this species. Similar pattern of coloration is found within the Keroplatidae only in several species of Heteropterna Skuse, 1888 , which differ in many other characters, mainly in the shape of eyes, shorter wings and irregularly arranged tibial trichia.

Etymology. The specific epithet is an ajective derived from the Greek μέλαίνω, meaning “blackened” and λευκός, meaning “white” and refers to the almost black and white coloration of the new species.

Distribution. Thailand (Petchaburi).

Figures

Figs. 1–2. Habitus. 1 – Terocelion melanoleucum gen. & sp. nov.; 2 – T. terezae gen. & sp. nov.

Figs. 3–6. Diagnositic characters of Terocelion species. 3–4. wing (3 – Terocelion melanoleucum gen. & sp. nov.; 4 – T. terezae gen. & sp. nov.). 5–6 – mediotergite with subscutellar membranous area in posterior view (5 – Terocelion melanoleucum gen. & sp. nov.; 6 – T. terezae gen. & sp. nov).

Figs. 7–8. Male terminalia in dorsal view. 7 – Terocelion melanoleucum gen. & sp. nov.; 8 – T. terezae gen. & sp. nov.