Simulium (Gomphostilbia) baglungense Takaoka & Shrestha, 2010

Takaoka, Hiroyuki & Shrestha, Suchitra, 2010, New species of black flies (Diptera: Simuliidae) from Nepal 2731, Zootaxa 2731, pp. 1-62 : 15-18

Simulium (Gomphostilbia) baglungense Takaoka & Shrestha sp. nov.

Description. Female. Body length 1.7 mm. Head. Nearly as wide as thorax. Frons brownish-black, dull, densely covered with yellowish-white scale-like recumbent hairs interspersed with few dark simple long hairs along each lateral margin; frontal ratio 1.46:1.00:1.46; frons-head ratio 1.00:3.85. Fronto-ocular area ( Fig. 7A) well developed, deep, directed laterally and upward. Clypeus brownish-black, thinly white pruinose, shiny when illuminated at certain angle of light, densely covered with yellowish-white scale-like long hairs interspersed with several dark simple long hairs mainly along lateral margin on each side (except area along dorsal margin narrowly bare). Labrum 0.67 times as long as clypeus. Antenna composed of scape, pedicel and 9 flagellomeres, dark brown except scape, pedicel and base of 1st flagellomere yellow. Maxillary palp composed of 5 segments, light to medium brown, proportional lengths of 3rd, 4th and 5th segments 1.00: 1.03:2.21; 3rd segment ( Fig. 7B) somewhat swollen; sensory vesicle ( Fig. 7B) enlarged, ellipsoidal, 0.51 times as long as 3rd segment, with medium-sized opening medially. Maxillary lacinia with 11 or 13 inner and 16 or 17 outer teeth. Mandible with 25 inner and 8 outer teeth though short distance of outer margin from apex without teeth. Cibarium ( Fig. 7C) with posterodorsal margin medially folded anteriorly forming short wide plate, and with darkened mediolongitudinal band bearing forked apex. Thorax. Scutum dark brown, shiny, densely covered with yellowish-white scale-like recumbent short hairs. Scutellum dark brown, covered with yellowish-white short hairs as well as dark brown upright long hairs. Postnotum dark brown, bare, slightly shiny and white pruinose when illuminated at certain angle of light. Pleural membrane bare. Katepisternum dark brown, longer than deep, moderately covered with yellowish fine hairs interspersed with dark brown hairs. Legs. Foreleg: coxa whitish-yellow; trochanter whitish-yellow except apical 1/2 dark yellow; femur light brown, with apical cap medium brown (though extreme tip light brown); tibia medium brown except base and median large portion on outer surface yellow to light brown; tarsus dark brown, with moderate dorsal hair crest; basitarsus somewhat dilated, 6.79 times as long as its greatest width. Midleg: coxa medium brown with posterior surface dark brown; trochanter whitish-yellow; femur light brown, with apical cap medium brown (though base much lighter and extreme apical tip light brown); tibia whitish-yellow at base, gradually darkened from light brown to medium brown; tarsus light to medium brown except basal 1/2 or little less of basitarsus dark yellow. Hind leg: coxa medium brown; trochanter whitish-yellow; femur light brown except base whitish-yellow and apical cap medium brown (though extreme tip light brown); tibia ( Fig. 7D) light brown except base whitish-yellow and apical cap medium to dark brown (though subbasal area somewhat darkened appearing as subbasal band; tibia moderately covered with yellow fine hairs on outer and posterior surface of basal 3/4; tarsus ( Fig. 7E) medium brown except little more than basal 2/3 of basitarsus (though base light brown) and basal 1/2 of 2nd tarsomere whitish-yellow; basitarsus ( Fig. 7E) narrow, nearly parallelsided, 6.19 times as long as wide, and 0.70 and 0.58 times as wide as greatest width of tibia and femur, respectively; calcipala ( Fig. 7E) well developed, 1.12 times as long as wide, and 0.48 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 7E) well developed. Claw ( Fig. 7F) with large basal tooth 0.50 times as long as claw. Wing. Length 1.6 mm. Costa with dark brown spinules as well as dark brown hairs except basal portion with patch of yellowish hairs. Subcosta with dark brown hairs except near apex bare. Hair tuft on stem vein yellowish. Basal portion of radius fully haired. Basal cell absent. Abdomen. Basal scale light ocherous, with fringe of yellowish-white fine hairs. Dorsal surface of abdomen light to medium brown, moderately covered with dark brown hairs; tergites of segments 2 and 6–8 shiny; sternal plate on segment 7 undeveloped.

Genitalia. Sternite 8 ( Fig. 7G) bare medially, with 13–16 short to very long stout hairs and few short setae on each side. Ovipositor valves ( Fig. 7G) nearly triangular, thin, membranous, moderately covered with microsetae interspersed with 3 or 4 short setae; inner margins slightly sinuous, moderately sclerotized. Genital fork ( Fig. 7H) of usual inverted-Y form, with arms of moderate width; arm folded medially, with large projection directed medioposteriorly. Paraproct in ventral view ( Fig. 7I) subquadrate, with 15 or 16 long hairs on ventral and lateral surface, and with 5 sensilla on anteromedial surface; paraproct in lateral view ( Fig. 7J) about half as long as wide, much produced ventrally beyond ventral margin of cercus. Cercus in lateral view ( Fig. 7J) rounded posteriorly, half as long as wide. Spermatheca ( Fig. 7K) ellipsoidal, 1.50 times as long as wide, well sclerotized except duct and small area of juncture with duct unsclerotized, and with reticulate pattern on surface near juncture and many fissures on rest of surface; internal setae absent; both accessory ducts slender, very slightly larger in diameter than major one.

Pupa. Body length 2.0 mm. Head. Integument light yellow, without any tubercles; frons with 3 pairs of simple very long stout trichomes with or without uncoiled apices, all arising close together ( Fig. 8A), and face with pair of simple very long stout trichomes with coiled apices ( Fig. 8B). Thorax. Integument dark yellow, without any tubercle on dorsal and dorsolateral surface of anterior 3/4, sparsely covered with small coneshaped or round tubercles on dorsal surface of posterior 1/4; thorax with 3 simple very long mediodorsal trichomes with coiled apices ( Fig. 8C), 2 simple anterolateral trichomes (1 very long, stout, with coiled apex, 1 medium-long, slender, with uncoiled apex) ( Fig. 8D), 1 simple short somewhat stout mediolateral trichome with uncoiled apex ( Fig. 8E) and 3 simple short slender ventrolateral trichomes with uncoiled apices ( Fig. 8F) on each side. Gill ( Fig. 8G) composed of 8 slender thread-like filaments arranged as (2+1)+(2+1)+2 filaments from dorsal to ventral; common basal stalk very short, with round transparent swollen organ ventrally; filaments of dorsal triplet subequal in length (0.6–0.8 mm according to 3 intact filaments (1 left side, 2 right side) of dorsal triplet groups) and thickness, filaments of middle triplet subequal in length (1.1 mm according to 1 intact filament of middle triplet on right side) and thickness, inner filament of ventral paired filaments very slightly thicker than outer filament and their exact length unmeasurable because apical portion of filaments is lost (length of remaining portion of filaments about 1.4 mm); proportional thickness of 8 filaments from dorsal to ventral 0.8:0.8:0.8:0.8:0.8:0.9:1.3:1.4; all filaments light yellow, with well-defined annular ridges and furrows on outer surface, and densely covered with minute tubercles. Abdomen. Dorsally, whole of segment 1, most of segments 2 and 9 light yellow, without tubercles; other segments almost transparent; segment 1 with 1 simple medium-long slender seta on each side; segment 2 with 1 simple medium-long slender seta and 5 or 6 very short setae submedially on each side; segments 3 and 4 each with 4 hooked spines and 1 very short seta on each side; segment 5 lacking spine-combs; segments 6–8 each with spine-combs in transverse row and comb-like groups of minute spines on each side; segment 9 with pair of distinct flat terminal hooks ( Fig. 8H) and comb-like groups of minute spines on each side. Ventrally, segment 4 with 1 simple hook and few short setae on each side; segment 5 with pair of bifid hooks submedially and few simple slender short setae on each side; segments 6 and 7 each with pair of bifid inner and simple outer hooks somewhat spaced from each other and few simple slender short setae on each side; segments 4–8 each with comb-like groups of minute spines. Each side of segment 9 with 2 or 3 grapnel-shaped hooklets. Cocoon. Wall-pocket shaped, moderately and neatly woven, thin, not extending ventrolaterally; anterior margin somewhat thickly woven; floor roughly woven; individual threads invisible; 2.0 mm long by 0.8 mm wide.

Male and mature larva. Unknown.

Type specimen. Holotype female (together with its associated pupal exuviae and cocoon) (preserved in 80% ethanol), reared from pupa collected from a small, slow-flowing stream (water temperature 19.5˚C, exposed to the sun, altitude 1,469 m, 28˚24’45.5” N, 83˚51’02.0” E), Padhera , Lekhani, Baglung, Nepal, 25.IX.2009.

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

Etymology. The species name baglungense refers to the locality name, Baglung, where this new species was collected.

Remarks. This new species is assigned to either the batoense species-group or the ceylonicum speciesgroup of the subgenus Gomphostilbia in having the antenna with nine flagellomeres, the bare pleural membrane, haired katepisternum and the claw with a large basal tooth ( Fig. 7F) in the female and the eight thread-like gill filaments ( Fig. 8G) in the pupa.

This new species is characterized by the pupal frons and thorax (except posterior 1/3) with no tubercle and the pupal gill with a relatively large transparent bulb-like organ at its base ( Fig. 8G). There is no record of other known Gomphostilbia species which lack tubercles on the frons and most of the thoracic integument.

The female of this new species is similar in the leg color to those of S. (G.) bhutanense Takaoka & Somboon and S. (G.) chuzargangense Takaoka & Somboon, both of which were described from female specimens collected from Bhutan ( Takaoka & Somboon 2008). However it is easily distinguished from these known species by the following characteristics: claw with a large basal tooth (claw with a medium-sized basal tooth in S. (G.) bhutanense ) and by the subcosta which is almost entirely haired (subcosta almost bare in S. (G.) chuzargangense).