A NEW SPECIES OF TRISSOPELOPIA KIEFFER , 1923 ( DIPTERA , CHIRONOMIDAE , TANYPODINAE , PENTANEURINI ) FROM INDIA

N. Hazra & P. K. Chaudhuri. 2010. A new species of Trissopelopia Kieffer, 1923 (Diptera, Chironomidae, Tanypodinae, Pentaneurini) from India. Graellsia, 66(1): 39-45. The pupae and adults of Trissopelopia bifurcata sp. n. are recorded and described from the Darjeeling Himalayas of India. The genus is recorded for the first time in India. A new key to the world species of Trissopelopia is also included. Key-words: Trissopelopia bifurcata; new species; pupa; imago; Chironomidae; India.


Introduction
In course of our investigation of the dipteran fauna in the Darjeeling Himalayas, three pupae came to our attention in a stream near Mirik lake, which on rearing resulted in one male and two females of the tanypod genus Trissopelopia Kieffer, 1923 of the family Chironomidae.The genus is related to Pentaneura Philippi, 1865 and Pentaneurella Fittkau & Murray, 1983.The males of Trissopelopia lack distinct lyrate tibial spurs and setae on the pos-terior border of tergite IX while that of Pentaneura the terminal spur of gonostylus is very much larger.The absence of distinct scutal tubercle further distinguishes adults of Trissopelopia from those of Pentaneuralla.
The adult of the genus is characterized by medium to large size, distal flagellomere 3.0 x as long as broad, two rows of 9-10 lateral antepronotals, acrostichals merged with dorsocentrals extending up to prescutellar area; wing with dense macrotrichia, C slightly produced and ending little before M 1+2 , MCu just beyond FCu, anal lobe well developed; tibial spurs with 10-14 lateral teeth, outer hind spur much smaller than the inner one with 4 lateral teeth, hind tibial comb indistinct; anal point conical, gonocoxite robust 1.5-2.00x as long as broad with short anterior and long posterior setae, gonostylus slender, curved with a small terminal seta.
The pupa is known by medium to large size, pale to dark brown exuviae, thorax 3-4 x as long as broad and interconnected at the base, outer spinules forming scales, horn sac tubular with swollen base occupying about 1⁄2 lumen width, plastron plate more or less oval, corona 2 x as long as plastron plate and 0.5 x horn length, thoracic comb anteriorly rugose, thoracic membrane smooth, thoracic setae filamentous or simple, Dc 1. and Sa filamentous and of equal length, Dc 2 simple more or less 0.5 x as long as Dc 1 .Tergite I with little pigmented scar, shagreen in short and transverse groups or in arched rows, I-VII more or less granulate at posterior margin, pedes spurii A at the posterior corners of II-VI, D and V setae short and filamentous, L seta filamentous more like the longest D seta, VII with 4 LS setae at the distal half and VIII with 5 LS setae.Anal lobe little convex 3.0 x as long as broad, toothed and genital sac 0.5.
Before the present study, only 7 species represented the genus around the world (01Afrotropical, 01 Nearctic, 02 Oriental and 03 Palaearctic) without any record from India (Cheng & Wang, 2005).

Material and methods
The pupae procured from a slow moving stream near Mirik Lake were subjected to rearing in the laboratory.The fresh imagines and pupal exuviae were processed and mounted on micro-slides after Hazra et al. (2002).In describing the imagine and pupa, terminologies and usages of Saether (1980) were followed.
Measurements are in micrometers (µm) except the total length of the body and the wing which are in millimeters (mm).The average values are before and the ranges are suffixed by "n" and the number of specimens examined is within parentheses Types are presently kept at the Entomology Laboratory of the Department of Zoology, The University of Burdwan, Burdwan and will be deposited in the National Zoological Collections (NZC), Kolkata and The Museum of Natural History (BMNH), London in due time.DIAGNOSTIC CHARACTERS.The male imago may be separated from others by: i) unique marking on TII-VII along the lateral margins, ii) 11 flagellomeres with AR1.75, iii) smaller spur on hind tibia with 4 teeth, iv) 37-40 squamal setae and v) gonocoxite 1.48 times as long as broad.The pupa is recognized by: i) oval plastron plate occupying 0.35 length of the horn, ii) apex of thoracic horn bifurcated with a deflexed swelling below the plastron plate, iii) Thr 2.9, iv) LS 1 seta on segment VII at 0.33 segment length and v) ALR 2.53.DESCRIPTION Male.Total length 5.1 (5.1-5.2, n= 3) mm, wing length 3.6 mm, total length/wing length 1.42; wing length/length of profemur 2.54.Thorax (Fig. 1B).Thorax brown with anepisternum II and two darkly pigmented lateral vittae; antepronotum weakly developed with 5-6 antepronotals, large weakly sclerotized humeral pit, arcrostichals 34 biserial, dorsocentrals 17 uniserial, prealars 18, supra-alars 3 and scutellars 21.
Abdomen (Fig. 1F).Pale yellow in color.TII-VII each with dark brown narrow stripes along the lateral margin; VIII with a dark more or less rounded mark at the middle.
ETYMOLOGY.The name "bifurcata" derives from the bifurcated thoracic horn of the pupa.
DISCUSSION.The new species appears identical with the European species Trissopelopia longimana (Staeger, 1839) and T. ogemawi Roback, 1971 in pupal characters like, thoracic horn, plastron plate, corona, Thr and ALR, and characters of adult male like, anal point, LR of male imagine, but the location of anterior LS seta of segment VII of the pupa AR, smaller spur and number of lateral teeth of hind tibia are quite different from those of the above species.It bears affinities with T. montivaga Harrison, 1978