Simulium (Nevermannia) lekhaniense Takaoka & Shrestha, 2010

Takaoka, Hiroyuki & Shrestha, Suchitra, 2010, New species of black flies (Diptera: Simuliidae) from Nepal 2731, Zootaxa 2731, pp. 1-62 : 29-32

Simulium (Nevermannia) lekhaniense Takaoka & Shrestha sp. nov.

Description. Pupa. Body length (excluding gill filaments) 4.2 mm. Head. Integument yellow, moderately covered with round tubercles except dorsal 1/2 of frons sparsely covered with tubercles; antennal sheath bare except near base very sparsely covered with small tubercles; frons with 2 simple very long trichomes with coiled apices ( Fig. 15A) very close together (another 1 trichome probably lost because 1 socket present) on each side; face with 1 simple very long trichome with coiled apex ( Fig. 15B) on each side. Thorax. Integument yellow, moderately covered with small tubercles except anterodorsal surface sparsely covered with small tubercles; thorax with 2 simple very long trichomes with coiled apices mediodorsally ( Fig. 15C), 1 simple very long trichome with coiled apex ( Fig. 15D) (another 1 trichome probably lost) anterolaterally, 1 bifid medium-long trichome with coiled apex mediolaterally ( Fig. 15E), and 3 simple trichomes (1 long with coiled apex, 1 medium-long with coiled apex, 1 medium-long with uncoiled apex) ventrolaterally ( Fig. 15F). Gill ( Fig. 15G) with 4 slender thread-like filaments, slightly longer than pupal body, arranged vertically in dorsal and ventral pairs, each with short stalk arising from short common basal stalk; common basal stalk much thicker than interspiracular trunk, and with transparent swollen portion ventrally; stalks of dorsal and ventral pairs subequal in length to each other and somewhat shorter than common basal stalk; stalk of dorsal pair slightly thicker than stalk of ventral pair; dorsal filament of dorsal pair longest (4.9 mm long), 2 filaments of ventral pair shortest (3.5–3.6 mm long) and ventral filament of dorsal pair intermdiate (4.2–4.5 mm long); all filaments medium brown, directed forward, gradually tapered toward apex, with annular furrows at irregular intervals along basal 1/2 and moderately-defined ridges and furrows at regular intervals along apical 1/2, and densely covered with minute tubercles on outer surface. Abdomen. Dorsally, segments 1 and 2 moderately sclerotized, yellowish-brown and weakly tuberculate; 1 hair-like seta on each side of segment 1 lost; segment 2 with 5 dark spinous short setae (1 hair-like seta lost) on each side; segments 3 and 4 weakly tuberculate, each with 4 dark stout hooks and 1 dark short spinous seta on each side; segments 5–9 each with spine-combs and comb-like groups of minute spines in transverse rows on each side; segment 9 with pair of cone-shaped terminal hooks ( Fig. 15H). Ventrally, segment 4 with 1 dark simple and 1 dark bifid hooklets (slightly shorter and smaller than those on segments 5–7) and few simple short setae on each side; segment 5 with 2 dark bifid hooks and few simple short setae on each side; segments 6 and 7 each with 1 dark bifid inner hook and 1 dark simple outer hook, and few simple short setae on each side; segments 4–8 each with comblike groups of minute spines. Cocoon ( Fig. 15I,J). Wall-pocket-shaped, moderately woven, anterior margin thickly woven, and extending ventrolaterally, with 2 long narrow strong anterodorsal projections first divergent, then, convergent and bent downward, then appearing to unite with each other forming broad thin flap extending forward along surface of substrate; cocoon appearing to bear 3 open windows anteriorly when viewed from above; floor woven on posterior 1/2; individual threads visible; 5.5 mm long (excluding anterior flap) by 3.2 mm wide.

Mature larva. Body length 6.9 mm. Body color creamy though posterior abdominal segments very faintly grayish dorsally. Cephalic apotome yellowish-white though somewhat darkened narrowly along posterior margin; all head spots medium brown. Lateral surface of head capsule yellow though eye-spot region yellowish-white and area in front of posterior margin somewhat darkened; eyebrow darkened and welldefined; 2 large and 1 or 2 small dark spots near posterior margin, and 1 small dark spot below eye-spot region present. Ventral surface of head capsule ( Fig. 16A) yellow, with dark brown area on each side of postgenal cleft; elongate spot on each side of postgenal cleft positive. Cervical sclerites composed of 2 brown rod-like small pieces, not fused to occiput, widely separated from each other. Antenna composed of 3 segments and apical sensillum, much longer than stem of labral fan; proportional lengths of 1st, 2nd, and 3rd segments 1.00: 1.28:0.86. Labral fan with 40 rays. Mandible ( Fig. 16B) with 1st comb-tooth longest, followed by 2nd one which is as long as 3rd one; mandibular serrations composed of 2 teeth (1 large and 1 small); large tooth at obtuse angle to mandible on apical side; 2 or 4 supernumerary serrations present. Hypostoma ( Fig. 16C) with row of 9 apical teeth, median tooth most prominent, followed by corner teeth, and intermediate teeth smallest; lateral margin with 1 blunt tooth near apex; hypostomal bristles 5 in row, lying nearly parallel to lateral margin on each side. Postgenal cleft ( Fig. 16A) of medium-size, as long as postgenal bridge, nearly parallel-sided and rounded anteriorly. Histoblast of pharate pupal gill ( Fig. 16D) with 4 slender filaments arranged in 2 pairs with short stalks. Thoracic cuticle bare. Abdominal cuticle almost bare except few posterior segments sparsely or moderately covered with colorless minute setae dorsally and dorsolaterally (even laterally near ventral papillae) and also on both sides of anal sclerite. Rectal scales appearing to be absent. Rectal organ compound, each lobe with 8–11 finger-like secondary lobules. Anal sclerite X-shaped, with basal juncture broadly sclerotized; anterior arms of medium-long, broad, 0.83 times as long as posterior ones; accessory sclerites absent; sensillum absent. Ventral papillae small and conical. Posterior circlet with 78 rows of up to 12 hooks per row.

Female and male. Unknown.

Type specimens. Holotype pupa with its cocoon (preserved in 80% ethanol), collected from a small water canal (water temperature 21.0˚C, exposed to the sun, altitude 1,606 m, 28˚24’06.8” N, 83˚50’32.4” E) moderately flowing through hilly area, Jhakrithan , Lekhani, Baglung, Nepal, 23.IX.2009 . Paratype: 1 mature larva (preserved in 80% ethanol), collected from a very rapidly-flowing stream (width 2m, water temperature 10.0˚C, exposed to the sun, altitude 2,532 m, 28˚64’32.9” N, 83˚66’32.0” E), Lete , Mustang, Nepal, 23.IX.2009 .

Biological notes. The pupa and larva of this new species were collected from grass leaves trailing in water. Associated species were S. (N.) letense sp. nov., S. (M.) dattai and S. (S.) sp.

Etymology. The species name lekhaniense refers to the locality name, Lekhani, where this new species was collected

Remarks. This new species appears to be assigned to the vernum species-group of the subgenus Simulium (Nevermannia) in having the pupal gill with four long slender filaments ( Fig. 15G) and the larval mandible with supernumerary serrations ( Fig. 16B). This new species is remarkable in having the cocoon with three open windows anteriorly ( Fig. 15I).