Simulium (Simulium) tamorense Takaoka & Shrestha, 2010

Takaoka, Hiroyuki & Shrestha, Suchitra, 2010, New species of black flies (Diptera: Simuliidae) from Nepal 2731, Zootaxa 2731, pp. 1-62 : 41-48

Simulium (Simulium) tamorense Takaoka & Shrestha sp. nov.

Description. Female. Body length 2.3–2.5 mm. Head. Slightly narrower than thorax. Frons dark brown, shiny, with several dark stout hairs along lateral margins; frontal ratio 1.15–1.36:1.00:1.18–1.26; frons-head ratio 1.00:3.77–4.59. Fronto-ocular area ( Fig. 22A) well developed, short, directed laterally, and round or pointed apically. Clypeus dark brown, thinly white pruinose, shiny, moderately covered with dark stout hairs as well as yellow hairs (though upper 1/2 widely bare medially). Labrum 0.72–0.77 times as long as clypeus. Antenna composed of scape, pedicel and 9 flagellomeres, yellow on scape, pedicel, and 1st to 3rd flagellomeres, and light to dark brown on rest of flagellomeres in front view; antenna light to dark brown except scape, pedicel, and 1st flagellomere yellow in posterior view. Maxillary palp with 5 segments, light brown except 3rd segment medium brown, proportional lengths of 3rd, 4th, and 5th segments 1.00:0.94– 0.95:2.00–2.09; 3rd segment ( Fig. 22B) of normal size, with large oblong sensory vesicle (0.37–0.43 times as long as 3rd segment) having large opening (very large opening in right sensory vesicle in 1 female — Fig. 22C). Maxillary lacinia with 11 or 12 inner and 15 or 16 outer teeth. Mandible with 29–33 inner and 10 or 11 outer teeth. Cibarium ( Fig. 22D) with 10–22 minute processes near posterodorsal margin. Thorax. Scutum dark brown to brownish-black except anterolateral calli light to medium brown, shiny, densely covered with yellow recumbent short hairs interspersed with several dark brown long upright hairs on prescutellar area; when illuminated in front and viewed dorsally, scutum thickly white pruinose, with 5 longitudinal nonpruinose vittae, of which 1 median vitta is very narrow, 2 submedian and 2 sublateral vittae rather wide (though sublateral vittae somewhat wider than submedian ones), all vittae united with broad transverse band on prescutellar area; when illuminated from behind, scutum having reversed color pattern. Scutellum medium brown, covered with dark brown upright long hairs as well as yellow short hairs. Postnotum dark brown to brownish-black, shiny, whitish-gray pruinose, bare. Pleural membrane bare. Katepisternum dark brown, longer than deep, bare. Legs. Foreleg: coxa, trochanter and femur whitish-yellow; tibia whitish-yellow except apical cap light brown, and with whitish sheen widely on outer surface; tarsus dark brown, with moderate dorsal hair crest; basitarsus greatly dilated, 5.62–5.74 times as long as its greatest width. Midleg: coxa dark brown; trochanter and femur whitish-yellow; tibia whitish-yellow except apical cap dark yellow to light brown, and with whitish sheen on posterior surface; tarsus medium brown except basal 4/5 of basitarsus and base of 2nd tarsomere whitish-yellow. Hind leg: coxa dark brown; trochanter and femur whitish-yellow; tibia whitish-yellow except apical cap medium brown, with whitish sheen on posterior surface; tarsus mediumbrown except basal 4/5 of basitarsus, and basal 1/2 of 2nd tarsomere yellowish-white; basitarsus ( Fig. 22E) nearly parallel-sided, 6.04–6.13 times as long as wide, and 0.67–0.68 and 0.52 times as wide as greatest widths of hind tibia and femur, respectively; calcipala ( Fig. 22E) moderately developed, nearly as long as wide, and 0.44 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 22E) well developed at basal 1/3 of 2nd tarsomere. All tarsal claws simple, without any tooth. Wing. Length 1.9–2.0 mm. Costa with dark spinules and hairs except most hairs of basal patch yellow; subcosta haired except apical 2/5 bare; basal section of radial vein bare; R 1 with dark brown spinules and hairs; R 2 with dark brown hairs; hair tuft on stem vein dark brown; basal cell absent. Abdomen. Basal scale light yellow to light brown, with fringe of pale hairs. Dorsal surface of abdomen medium brown except basal 1/4–1/2 of 2nd segment yellowish, with dark brown short hairs and yellow short ones; tergite 2 shiny, white iridescent when illuminated, and tergites 6–8 shiny. Ventral surface of 7th segment with large weakly sclerotized sternal plate medially. Genitalia. Sternite 8 ( Fig. 22F) with 21–30 dark medium-long to long stout hairs and pale 4 or 5 short to medium-long haires on each lateral surface. Ovipositor valves ( Fig. 22F) triangular, rounded posteromedially, widely separated from each other, membranous except inner margins moderately sclerotized, moderately covered with microsetae and 6–8 pale and dark short to medium-long hairs except narrow portion along posterior margin bare; inner margin widely concave. Genital fork ( Fig. 22G) of inverted-Y form, with narrow well sclerotized stem; arms of moderate width, each with distinct projection directed anterodorsally. Paraproct in ventral view ( Fig. 22H) nearly triangular, moderately sclerotized on outer surface, weakly sclerotized on narrow part of anteromedial surface, with 29–35 pale and dark short to long hairs on lateral and ventral surfaces, and with 2 or 3 short sensilla on anteromedial surface; paraproct in lateral view ( Fig. 22I) much shorter than wide, and much protruding ventrally beyond ventral margin of cercus. Cercus in lateral view ( Fig. 22I) short, 0.6 times as long as wide, with numerous medium-long to long hairs, and rounded posteriorly. Spermatheca ( Fig. 22J) nearly ovoid, 1.3 times as long as greatest width, well sclerotized except small portion of junction with duct unsclerotized, appearing to bear very faintly defined reticulate patterns on its surface; internal setae present; accessory ducts subequal in thickness to each other, and slightly thicker than major duct.

Male. Body length 2.0 mm. Head. Width subequal to that of thorax. Upper eye consisting of large facets in 14 vertical columns and in 15 horizontal rows. Clypeus brownish-black, whitish-gray pruinose, not shiny, covered with dark brown hairs along and near lateral margins (most of central portion bare). Antenna composed of scape, pedicel and 9 flagellomeres, yellow on scape, pedicel and 1st flagellomere, and light to dark brown on rest flagellomeres in anterior view, and yellow on scape and pedicel and light to dark brown on all flagellomeres though base of 1st flagellomere yellow in posterior view; 1st flagellomere elongate, 1.69 times as long as 2nd one. Maxillary palp light brown, composed of 5 segments with proportional lengths of 3rd, 4th, and 5th segments 1.00:1.09:2.34; 3rd segment ( Fig. 23A) of normal size; sensory vesicle ( Fig. 23A) small (0.21–0.23 times as long as 3rd segment), nearly globular, and with small opening. Thorax. Scutum dark brown except anterolateral calli light brown, thicky whitish-gray pruinose (widely at least along each lateral margin and on prescutellar area, though border between pruinose and non-pruinose areas not well discernible due to thick covering of yellow short hairs) and shiny when illuminated at certain angle of light; scutum uniformly and densely covered with yellow recumbent short hairs interspersed with dark brown long upright hairs on prescutellar area. Scutellum dark brown, shiny, with several dark brown long upright hairs as well as yellow short hairs. Postnotum, pleural membrane and katepisternum as in female. Legs. Color similar to that of female except mid basitarsus yellow with apical 1/4 light brown, hind femur yellow with apical cap light brown, hind tarsus light to medium brown with basal 3/5 of basitarsus and basal 1/2 of 2nd tarsomere yellow; fore basitarsus moderately dilated, 5.40 times as long as its greatest width; hind basitarsus ( Fig. 23B) much enlarged, gradually widened toward apical 1/3, then slightly narrowed toward apex, 4.13 times as long as its greatest width, and 0.79 and 0.73 times as wide as greatest widths of hind tibia and femur, respectively; calcipala well developed, nearly as long as wide and 0.33 times as wide as greatest width of basitarsus; pedisulcus well developed. Wing. Length 2.0 mm; other characters as in female except subcosta bare. Abdomen. Basal scale dark brown, with fringe of dark long hairs. Dorsal surface of abdomen medium to dark brown except basal 2/3 of 2nd segment yellow to light brown, with dark brown short to medium-long hairs and yellow short hairs; segments 2 and 6–9 each with pair of shiny white-pruinose (even silvery iridescent when illuminated at certain angle of light) spots dorsolaterally, those on segment 2 connected broadly to each other in middle. Genitalia. Coxite in ventral view ( Fig. 23C) nearly quadrate though protruding posterolaterally. Style in ventral view ( Fig. 23C) elongate, 1.37 times as long as coxite, somewhat widened from base to basal 1/3, then nearly parallel-sided toward apex, and with rounded apex, without apical or subapical spine (though short slender seta present); style in ventrolateral view ( Fig. 23D) elongate, 2.82 times as long as its greatest width near basal 1/3, nearly parallel-sided from basal 1/3 to apex, with lateral margins sinuous; style in medial view ( Fig. 23E) flattened dorsoventrally, with medium-long triangular protuberance near base on dorsal surface, bearing several small spinules on its anterior surface and at apex; style in end view ( Fig. 23F) with broad subbasal protuberance bearing apex truncated and several spinules lying along apical margin. Ventral plate in ventral view ( Fig. 23C) with base nearly rectangular (though somewhat narrowed basally, and rounded on each posterolateral corner), bearing anteromedial projection directed ventally which is moderately covered with minute setae anterolaterally and very sparsely posterolaterally, and almost bare posteromedially; arms short, stout, with widened apex, divergent from each other at angle of ca. 120 degrees; ventral plate in anteroventral view ( Fig. 23G): base flat, elliptical, bearing medial projection directed ventrally; ventral plate in lateral view ( Fig. 23H): base tapered posteriorly bearing its ventral margin irregularly ragged and few setae on each side near base of anteromedian projection, which is tapered ventrally and moderately covered with minute setae on each anterolateral surface; ventral plate in end view ( Fig. 23I): base rounded ventrally and concave dorsally, bearing median projection with rounded apex and constricted base and with few setae on and near each lateral margin. Median sclerite ( Fig. 23J) plate-like, narrow at base, then widened toward apex, with wide round apex; median sclerite dark brown basally, light to medium brown medially and apically except medial small portion at apex unpigmented. Paramere ( Fig. 23K) wide basally, with 6 distinct hooks. Aedeagal membrane ( Fig. 23L) moderately covered with minute setae; dorsal plate ( Fig. 23M) weakly pigmented only laterally and medially. Abdominal segment 10 ( Fig. 23N,O) without any distinct hair on ventral and lateral surfaces. Cercus ( Fig. 23N,O) small, rounded, with 10 or 11 distinct hairs.

Pupa. Body length 2.2–2.6 mm. Head. Integument yellow to yellowish-brown; frons somewhat raised along ventral and lateral margins, moderately covered with round tubercles in male pupal exuviae ( Fig. 24A) or almost bare except moderately or sparsely covered with round tubercles near margins in female pupal exuviae ( Fig. 24B); antennal sheaths almost bare in female pupal exuviae or sparsely covered with tubercles in male pupal exuviae; frons with 2 pairs of medium-long trichomes each with 2–4 branches ( Fig. 24A,B); face almost bare except small area near dorsal margin moderately covered with small tubercles, and with pair of medium-long trichomes with 2 or 3 branches ( Fig. 24C). Thorax. Integument yellow to yellowish-brown, moderately covered with round tubercles of various sizes except dorsal surface of posterior 1/4 covered with small cone-like tubercles with pointed apices; thorax on each side with 3 medium-long trichomes each with 4–9 branches ( Fig. 24D) mediodorsally, 2 medium-long trichomes each with 3 or 4 branches anterolaterally, 1 medium-long bifid or trifid trichome mediolaterally, and 3 medium-long trichomes each with 2–6 branches ventrolaterally. Gill ( Fig. 24E,F) with 8 short filaments in 4 pairs (1 dorsal, 2 middle and 1 ventral) arising from short common basal stalk; dorsal pair short-stalked, ventral pair almost sessile, and 2 middle pairs with short to medium-long stalks (variable in length among pupal exuviae), which are always nearly as long as or somewhat longer than stalk of dorsal pair ( Fig. 24E,F); stalk of dorsal pair and lower filament of ventral pair diverged from each other at angle of 90 degrees or slightly more when viewed laterally; lower filament of outer middle pair of male pupal exuviae with very short round nipple-like branch near base ( Fig. 24G); all filaments subequal in length (about 0.5 mm long) and thickness to one another (though thickness of filaments slightly variable from one another in some pupal exuviae depending on length of stalks of 2 middle pairs when basal portions were compared); all filaments always thinner than interspiracular trunk; all filaments light yellow to light grayish except apical 2/5 or little more unpigmented, very slightly tapered from base to apical 2/5 or little more, then moderately tapered toward apex, with distinct annular ridges and furrows (which are though indistinct on basal short portion and apical unpigmented portions), and densely covered with minute tubercles. Abdomen. Dorsally, all segments almost transparent and without tubercles; segment 1 with 1 medium-long simple or bifid slender seta on each side; segment 2 with 1 medium-long simple slender seta, 5 very short stout spinous setae on each side; segments 3 and 4 each with 4 distinct simple hooks and 1 short simple seta on each side; segments 5–9 lacking spine-combs (though comb-like groups of minute spines present on segments 6–8); segment 9 without terminal hooks. Ventrally, segments 3–8 each with comb-like groups of minute spines; segment 4 with few slender minute setae on each side; segment 5 with pair of bifid stout hooks submedially and few simple short setae on each side; segments 6 and 7 each with pair of simple inner and outer stout hooks and few simple short setae on each side. Grapnel-shaped hooklets absent on each side of segment 9. Cocoon ( Fig. 24H,I). Shoe-shaped with anterior collar, thinly to moderately woven except anterior margin thickly woven, without anterolateral window(s) on each side, not extending ventrolaterally; individual threads invisible; light yellow; 2.1–2.5 mm long (excluding length of collar) by 1.0– 1.2 mm wide; collar 0.5 mm long by 0.4–0.6 mm high.

Mature larva. Body length 3.8–4.1 mm. Body grayish. Abdomen ( Fig. 25A) gradually widened from segment 1 to segment 7, then narrowed to segment 9. Cephalic apotome yellowish-brown except narrow area along posterior margin medium to dark brown with median dark portion slightly extended forward; head spots indistinct or very faintly negative; lateral surface of head capsule dark yellow to yellowish-brown except eyespot region yellowish and area above eye-spot region light to medium brown, and with 2 or 3 faintly positive or negative isolated spots below eye-spot region and 2 faintly negative large spots before posterior margin; ventral surface of head capsule ( Fig. 25B) light yellowish-brown to medium brown except each side of basal portion of postgenal cleft dark brown (though narrow area along posterior margin of hypostoma yellowish in 1 larva). Antenna composed of 3 segments and apical sensillum, slightly longer than stem of labral fan; length ratio of 3 segments (from base to tip) 1.00:1.09–1.16:0.63–0.68. Labral fan with 38–42 main rays. Mandible ( Fig. 25C) with mandibular serrations composed of 2 teeth (1 medium-sized and 1 small); main tooth at obtuse angle against mandible on apical side; supernumerary serrations absent; comb-teeth composed of 8 or 9 teeth, increasing in length from 1st to 3rd. Hypostoma ( Fig. 25D) with 9 anterior teeth, of which corner teeth most prominent, longer than median tooth; 3 intermediate teeth on each side small, subequal in length to one another; lateral margins weakly serrate apically; 5 hypostomal bristles divergent posteriorly from lateral border on each side. Postgenal cleft ( Fig. 25B) large, rounded, 3.75–4.57 times as long as postgenal bridge; subesophageal ganglion not pigmented. Histoblast of pharate pupal gill ( Fig. 25E) with 8 short filaments. Thoracic and abdominal cuticle bare except last segment of abdomen moderately covered with short colorless spinous setae on each side of anal sclerite; abdominal segments 1–7 each with pair of round dorsolateral protuberances though those on segments 1 and 7 much smaller than those on segments 2–6 and those on segment 7 appearing to be absent in 2 larvae. Rectal scales appearing to be absent. Rectal organ compound, each lobe with 10–14 finger-like secondary lobules. Anal sclerite X-shaped, with short broad anterior arms about half as long as posterior ones and with forked apices. Last abdominal segment somewhat bulged laterally and lacking ventral papillae. Posterior circlet with 115–125 rows of hooklets with up to 19 hooklets per row.

Type specimens. Holotype female (with its associated pupal exuviae and cocoon) (preserved in 80% ethanol), reared from pupa collected from a rapid-flowing river (width over 10 m, water temperature 17.0˚C, exposed to the sun, altitude 651 m, 28˚78’67.3” N, 83˚73’38.7” E), Tamor , Taplejung, Nepal, 22.III.2010 . Paratypes: 2 females and 1 male, with their associated pupal exuviae and cocoons, and 3 mature larvae (all preserved in 80% ethanol), same data and date as those of the holotype .

Biological notes. The pupae of S. (S.) tamorense sp. nov. were collected from fallen tree leaves in the water. Associated species were S. (S.) indicum Becher and S. (S.) multistriatum species-group.

Etymology. The specific name tamorense refers to the name of the locality, Tamor, where this new species was collected.

Remarks. According to the keys ( Takaoka 2003), S. (S.) tamorense sp. nov. is assigned to the multistriatum species-group of the subgenus Simulium s. str. in having the scutum with five longitudinal vittae, simple claws in the female, the style with long basal protuberance ( Fig. 23E) in the male, the gill with eight filaments ( Fig. 24E) in the pupa, and the postgenal cleft very large and rounded in the larva ( Fig. 25B).

This new species is striking in having several characteristics which have been never or rarely found in this species-group: i.e., inner margins of the female ovipositor valves are sclerotized and well defined ( Fig. 22F) (c.f., transparent and not well defined); the median process of the male ventral plate located anteriorly ( Fig. 23C) (c.f., located medially or posteriorly); the pupal gill filaments very short, about 0.5 mm long ( Fig. 24E) (c.f., length of filaments over 0.9 mm); spine-combs on the pupal abdominal segment 8 absent (c.f., present); the larval mandibular comb-teeth increasing in length from the first to third tooth ( Fig. 25C) (c.f., decreasing) and paired protuberances on the larval abdomen present (c.f., absent except one known species, S. (S.) hirtinervis Edwards from Peninsular Malaysia — Takaoka & Davies 1995). These characteristics easily separate this new species from all known species in this species-group.

In having a shoe-shaped cocoon without any window or open space, this new species appears to be similar to S. (S.) chaliowae Takaoka & Boonkemtong, S. (S.) chainarongi Kuvangkadilok & Takaoka and S. (S.) takense Takaoka & Choochote , all from Thailand ( Takaoka & Kuvangkadilok 1999; Takaoka & Choochote 2005c).