Simulium (Simulium) titarense Takaoka & Shrestha, 2010

Takaoka, Hiroyuki & Shrestha, Suchitra, 2010, New species of black flies (Diptera: Simuliidae) from Nepal 2731, Zootaxa 2731, pp. 1-62 : 37-40

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

Description. Male. Body length 3.0 mm. Head. Wider than thorax. Upper eye consisting of large facets in 20 vertical columns and in 20 horizontal rows. Clypeus brownish-black, thickly white pruinose and brightly iridescent when illuminated at certain angle of light, sparsely covered with dark brown hairs along and near lateral margins (most of central portion bare). Antenna composed of scape, pedicel and 9 flagellomeres, medium to dark brown except scape and pedicel dark yellow and base of 1st flagellomere yellow when viewed dorsally (though 1st to 3rd flagellomeres appearing dark yellow to light brown when viewed ventrally); 1st flagellomere elongate, 1.82 times as long as 2nd one. Maxillary palp dark brown, composed of 5 segments with proportional lengths of 3rd, 4th, and 5th segments 1.00:1.29:2.78; 3rd segment ( Fig. 20A) of normal size; sensory vesicle ( Fig. 20A) ellipsoidal, 0.31 times as long as 3rd segment, and with small opening. Thorax. Scutum brownish-black to black, with whitish-gray pruinose pattern, i.e., anterior pair of large spots on shoulders extending posteriorly along lateral margins and connected to large transverse spot entirely covering prescutellar area; either anterior or posterior 1/2 of large pruinose spot on each shoulder disappearing depending on angle of light; pruinose areas brightly iridescent when illuminated at certain angle of light; scutum uniformly and moderately covered with yellow recumbent short hairs interspersed with dark brown long upright hairs on prescutellar area. Scutellum dark brown, with several dark long upright hairs as well as yellow short recumbent hairs. Postnotum dark brown, bare. Pleural membrane bare. Katepisternum brownish-black, bare. Legs. Foreleg: coxa yellow; trochanter yellow except ventral surface light brown; femur yellow except apical cap medium brown; tibia yellowish-white except apical cap and inner margin dark brown, and with white large sheen on outer surface; tarsus dark brown, with moderate dorsal hair crest; basitarsus greatly dilated, 5.33 times as long as its greatest width. Midleg: coxa brownish-black; trochanter dark brown except base whitish-yellow; femur yellow except apical cap dark yellow; tibia yellowish-white to yellow except apical cap medium brown; tibia with white large sheen on posterior surface; tarsus medium brown except basal 1/2 of basitarsus yellow. Hind leg: coxa dark brown to brownish-black; trochanter yellow; femur yellow except apical cap medium brown; tibia medium to dark brown except base yellowish-white; tarsus medium brown except little less than basal 1/2 of both basitarsus and 2nd tarsomere yellowish-white ( Fig. 20B); basitarsus ( Fig. 20B) enlarged, gradually widened from base toward apical 1/4, then narrowed to apex, 3.75 times as long as wide, and 0.96 and 1.14 times as wide as greatest width of hind tibia and femur, respectively; calcipala ( Fig. 20B) developed, small, 0.82 times as long as its basal width, and 0.22 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 20B) well developed at basal 1/3 of 2nd tarsomere. Wing. Length 2.2 mm. Costa with dark brown spinules and hairs. Subcosta with 1 or 2 hairs. Hair tuft on stem vein dark. Basal portion of radius fully haired. R 1 with dark spinules and hairs. R 2 with dark hairs only. Basal cell and basal median cell absent. Abdomen. Basal scale brownish-black, with fringe of dark brown long hairs. Dorsal surface of abdomen medium to dark brown, moderately covered with brassy short hairs intermixed with dark brown short to medium-long hairs; segments 2 and 5–7 each with pair of bright iridescent pruinose spots dorsolaterally, those on segment 2 connected broadly to each other in middle; segment 8 also with pair of shiny spots laterally when illuminated at certain angle of light. Genitalia. Coxite in ventral view ( Fig. 20C) nearly quadrate, 1.16 times as long as wide; coxite in ventrolateral view ( Fig. 20D) 0.86 times as long as wide. Style in ventral view ( Fig. 20C) and in ventrolateral view ( Fig. 20D) elongate, slightly sinuous, nearly parallel-sided, 1.48 times as long as coxite, with subapical spine; style in medial view ( Fig. 20E) with long basal protuberance directed dorsomedially, bearing 3 or 4 spinules on its apex. Ventral plate in ventral view ( Fig. 20C) with nearly quadrate body, though lateral margins slightly widened posteriorly and posterior margin somewhat concave, and moderately covered with minute setae on anterior and anterolateral surfaces; arms diverged basally from each other at obtuse angle; ventral plate in lateral view ( Fig. 20F) triangular, though ventral tip rounded, with no serrated posterior margin; ventral plate in end view ( Fig. 20G) bell-shaped, without seta. Median sclerite ( Fig. 20H) well sclerotized, plate-like, gradually widened, and with round apical tip. Paramere ( Fig. 20I) wide basally, with several short to long hooks. Aedeagal membrane very densely covered with minute setae; dorsal plate ( Fig. 20J) small, moderately sclerotized. Abdominal segment 10 ( Fig. 20K,L) without distinct hair on ventral surface. Cercus ( Fig. 20K,L) small, rounded, with 10 distinct hairs.

Pupa. Body length 3.2 mm. Head. Integument yellow to dark yellow, densely and elaborately covered with small round tubercles except antennal sheaths mostly bare; frons with 2 pairs of simple short trichomes ( Fig. 21A); face with pair of simple medium-long trichomes ( Fig. 21B). Thorax. Integument yellow to dark yellow, densely and elaborately covered with small round tubercles except most tubercles on dorsal surface of posterior area covered with cone-shaped tubercles; thorax on each side with 3 trifid or quadrifid long stout trichomes anterodorsally ( Fig. 21C), 2 trichomes (1 simple, medium-long, 1 bifid, very long and stout) anterolaterally ( Fig. 21D), 1 simple medium-long stout trichome mediolaterally ( Fig. 21E), and 3 simple trichomes (2 long, stout, 1 short, slender) ventrolaterally ( Fig. 21F). Gill ( Fig. 21G) with 6 thread-like filaments arranged as 2+1+1+1+1 from dorsal to ventral; dorsal pair with short stalk, 4 filaments of ventral and middle groups independently arising (i.e., bases of these filaments not touching each other); lowermost filament shortest (0.95 mm long) and uppermost filament probably longest (tip of this filament on each side lost, then exact length unmeasureable, probably 1.3 mm) and other filaments intermediate in length (1.0– 1.2 mm); relative thickness of filaments from dorsal to ventral 1.00:0.82:0.91:0.82:1.00:0.73 (right gill) and 1.00:0.82:0.82:0.82:1.00:0.82 (left gill) when compared basally (inner filament of middle group of left gill and ventralmost filament of right gill very slightly constricted at base); all filaments light ocherous, covered with annular ridges and furrows except basal short portion without such ridges and furrows and densely covered with minute tubercles on entire surface. Abdomen. Dorsally, nearly transparent except segment 1 weakly sclerotized and light ocherous; segment 1 without tubercles, with 1 simple short seta on each side; segment 2 without tubercles, with 1 simple short seta and 5 simple very short setae, of which 3 somewhat stout and spinous, on each side; segments 3 and 4 each with 4 distinct simple hooks and 1 simple very short seta on each side; segments 5–7 and 9 lacking spine-combs; segment 8 with distinct spine-combs in transverse row; segments 6–9 each with comb-like groups of minute spines on each side; segment 9 without pair of terminal hooks. Ventrally, segments 3–8 transparent, each with comb-like groups of minute spines; segment 4 with few simple very short setae on each side; segment 5 with pair of bifid stout hooks submedially and few simple very short setae on each side; segments 6 and 7 each with pair of bifid inner and simple outer stout hooks somewhat separated from each other and few simple very short setae on each side. Grapnel-shaped hooklets absent on each side of segment 9. Cocoon ( Fig. 21H). Light yellow, wall-pocket shaped, with anterolateral windows (1 large open space on right side and 2 medium-sized open spaces on left side), tightly woven and not extending ventrolaterally; individual threads invisible; 3.3 mm long by 1.4 mm wide.

Female and mature larva. Unknown.

Type specimen. Holotype male (with its associated pupal exuviae and cocoon) (preserved in 80% ethanol), collected from a stream (width 2 m, water temperature 18.0˚C, exposed to the sun, altitude 1,700 m, 28˚56’37.3” N, 83˚63’59.1” E), moderately flowing along the road, on the way to Titar , Mustang, Nepal, 23.IX.2009.

Biological notes. The pupa of this new species was collected from a grass leaf trailing in water. No other speices was collected.

Etymology. The species name titarense refers to the locality name, Titar, where this new species was collected.

Remarks. This new species is assigned to the griseifrons species-group of the subgenus Simulium (Simulium) in that it has the style bearing an elongate basal protuberance ( Fig. 20E), the ventral plate without toothed posterolateral margins ( Fig. 20F,G) in the male, combined with the gill with six filaments ( Fig. 21G) in the pupa.

This new species is similar to S. (S.) hongpingense Chen, Luo & Yang, S. (S.) multifurcatum Zhang & Wang , S. (S.) ramulosum Chen, S. (S.) shangchuanense An, Hao & Yan , and S. (S.) shennongjianense Yang, Luo & Chen, all from China ( An et al. 1998; Chen 2000; Chen et al. 2006; Yang et al. 2005; Zhang & Wang 1991) in sharing the following pupal characteristics: head and thoracic integument densely covered with tubercles, thoracic integument with branched trichomes, abdominal segment 9 lacking terminal hooks and cocoon with a large anterolateral window on each side. However, S. (S.) titarense sp. nov. is distinguished in the male from S. (S.) hongpingense , S. (S.) shangchuanense and S. (S.) shennongjianense by the shape of the ventral plate which is flat in all these three known species, and also in the pupa from S. (S.) hongpingense , S. (S.) ramulosum and S. (S.) shennongjianense by the absence of spine-combs on the seventh abdominal segment and from S. (S.) multifurcatum by the middle and ventral paired filaments which are almost sessile in this new species ( Fig. 21G) but short-stalked in S. (S.) multifurcatum .

Simulium (S.) biforaminiferum Datta described from India ( Datta 1974) shows some similarities to this new species in having the six pupal gill filaments and the cocoon with an anterolateral window on each side, but differs by the presence of terminal hooks in the last abdominal segment as well as the presence of spinecombs on the abdominal segments 7–9.