Simulium (Gomphostilbia) takaokai Anbalagan

Anbalagan, Sankarappan, Prasanna, Vimalanathan Arun, Dinakaran, Sundaram & Krishnan, Muthukalingan, 2014, Two new species of Simulium (Gomphostilbia) (Diptera: Simuliidae) from Peninsular India with keys to Peninsular Indian members of the genus Simulium, Zootaxa 3861 (5), pp. 451-465 : 458-463

Simulium (Gomphostilbia) takaokai Anbalagan sp. nov.

(Figs. 4–6)

Type series. Holotype, ♂, INDIA: Kulathupuzha, Kollam district, Kerala state, 01-I- 2014, 127 m (08º54′.11″ N, 77º03′.29″E), S. Anbalagan (Coll. S. Anbalagan, BDU). Paratypes, same data as holotype: 12 ♂♂, 14 ♀♀, 15 pupae, 85 larvae (Coll. S. Anbalagan, BDU). 2 ♂♂, 4♀♀ (Department of Environmental Biotechnology, BDU, Catalogue number: BL0015).

FIGURE4. Female of Simulium (Gomphostilbia) takaokai sp. nov. A, 3rd segment of right maxillary palp showing sensory vesicle (front view); B, right hind tibia (outer view); C, basitarsus and 2nd tarsomere of left hind leg showing calcipala and pedisulcus (outer view); D, tarsal claw; E, 8th sternite, ovipositor valves (ventral view); F, genital fork; G, right paraprocts and cerci (lateral view). Scale bars. 0.01 mm for A and D–G; 0.05 mm for B and C.

Diagnosis. Female: scutum with 3 brownish-black longitudinal vittae; hind tibia light to dark brown with basal 1/4 white; tarsal claw with large basal tooth; sternite 8 covered with 11 or 12 long hairs and few short fine hairs on each side. Male: upper eye consisting of 12 vertical columns and 10 horizontal rows of large facets; segments 2 and 5–7 each with shiny dorsolateral or lateral patches; ventral plate with anterior margin somewhat produced anteromedially, and posterior margin convex medially. Pupa: gill composed of 8 slender thread-like filaments, arranged as [(1+2)+(1+2)]+2 filaments from dorsal to ventral, with medium-long common basal stalk; cocoon wall pocket-shaped, thinly and moderately woven, widely extended ventrolaterally. Larva: labral fan with 38 main rays; mandible with 4 comb-teeth decreasing in length from 1st to 4th except 3rd tooth somewhat equal to 1st tooth; hypostoma with row of 9 apical teeth and 4 hypostomal bristles per side lying parallel to lateral margin; posterior circlet with 53–55 rows of up to 8–12 hooklets per row.

FIGURE 5. Male of Simulium (Gomphostilbia) takaokai sp. nov. A, 3rd segment of left maxillary palp showing small sensory vesicle (frontal view); B, left hind tibia (outer view); C, basitarsus and 2nd tarsomere of left hind leg showing calcipala and pedisulcus (outer view); D, coxites, styles, ventral plate and median sclerite (ventral view); E, right style with coxite (ventrolateral view); F & G, ventral plate (F, ventral view and G, end view). Scale bars. 0.01 mm for E–G; 0.02 mm for A; 0.05 mm for B–D.

Description. Female. Body length 1.9 mm. Head. Narrower than width of thorax. Frons grey, shiny when illuminated at certain angles, thinly pale yellowish pruinose with several stout dark hairs along lateral and lower margins; frontal ratio 1.50:1.00:1.89; frons-head ratio 1.00:3.16. Fronto-ocular area well developed, narrow, directed dorsolaterally. Antenna composed of scape, pedicel and 9 flagellomeres, brown except scape, pedicel and basal 1/2 of 1st flagellomere yellow. Clypeus grayish white, shiny, thinly whitish pruinose with dark stout hairs. Labrum 0.51 times as long as clypeus. Maxillary palp composed of 5 segments; proportional lengths of 3rd, 4th and 5th segments 1.00:1.51:2.96; 3rd segment (Fig. 4A) moderately enlarged; sensory vesicle (Fig. 4A) mediumsized (0.41 times as long as 3rd segment), with small round opening. Maxillary lacinia with 8 inner and 12 outer teeth. Mandible with 16 inner and 7 outer teeth. Cibarium bare. Thorax. Scutum dark brown except anterolateral calli dark ochreous, with 3 brownish-black longitudinal vittae (1 narrow median and 2 lateral), median vitta united anteriorly to anterior calli, lateral vittae united posteriorly to brownish-black prescutellar area; scutum shiny when illuminated at certain angles, densely covered with yellow scale-like recumbent short hairs. Scutellum shiny, with dark brown long upright hairs. Postnotum shiny and bare. Pleural membrane bare. Katepisternum medium to dark brown, longer than deep, shiny when illuminated at certain angles, densely covered with fine short hairs. Legs. Foreleg: coxa yellow; trochanter yellow except apical portion somewhat darkened; femur yellowish brown except base of posterior part brownish black; tibia brown; tarsus brownish black with moderate dorsal hair crest; basitarsus slightly dilated, 4.16 times as long as its greatest width. Midleg: coxa yellowish brown except posterior surface dark brown; trochanter yellow; femur yellowish brown and tibia brown; tarsus brownish-black except basal 1/2 of basitarsus dark yellow. Hind leg: coxa yellowish brown except posterior surface dark brown; trochanter yellow; femur medium brown with base yellow and apical cap dark brown; tibia (Fig. 4B) light to dark brown with basal 1/4 white, covered with brownish fine hairs on outer and posterior surfaces; tarsus dark brown to brownishblack except basal 2/3 of basitarsus (though base light brown); basitarsus (Fig. 4C) narrow, nearly parallel-sided, 7.1 times as long as wide, and 0.56 and 0.47 times as wide as greatest width of tibia and femur, respectively; calcipala (Fig. 4C) slightly shorter than width at base, and 0.44 times as wide as greatest width of basitarsus. Pedisulcus (Fig. 1C) well defined. Claw (Fig. 4D) with large basal tooth 0.4 times as long as claw. Wing. Length 1.75 mm. Costa with dark spinules and hairs except hairs on basal portion yellow. Subcosta with dark hairs except near apex bare. Hair tuft on stem vein dark brown. Basal section of vein R fully haired; R1 with dark spinules and hairs; R2 with hairs only. Basal cell absent. Haltere. Light to medium brown. Abdomen. Base of each segment dark brown, basal scale dark brown, with fringe of dark brown hairs, dorsal surface of abdomen brown to brownish black except basal 1/2 of segment 2 yellow, moderately covered with brown short to long hairs; tergites of segment 2 and 6–8 shiny when illuminated at certain angles. Ventral surface of segments 2 and 3 whitish-yellow except lateral side brownish yellow, and those of other segments light to dark brown; sternal plate on segment 7 undeveloped. Genitalia. Sternite 8 (Fig. 4E) well sclerotized and bare medially, covered with 11–12 long hairs and few short fine hairs on each side. Ovipositor valves tongue-like, thin, membranous, moderately covered with microsetae interspersed with three short hairs; inner margins slightly concave, somewhat sclerotized, and slightly separated from each other. Genital fork (Fig. 4F) of usual inverted-Y form; stem slender and well sclerotized; arms of moderate width, lateral plate of each arm with thin lobe directed medioposteriorly and small projection directed anterodorsally. Paraproct in ventral view concave, with 2 or 3 sensilla on anteromedial surface; paraproct in lateral view (Fig. 4G) somewhat produced ventrally, 0.75 times as long as wide, with about 17 medium-long to long hairs on lateral and ventral surfaces. Cercus in lateral view (Fig. 4G) short, rounded posteriorly, 0.55 times as long as its greatest width. Spermatheca similar in shape to that of S. (G.) peteri sp. nov. (Fig. 1H), 1.64 times as long as its greatest width, well sclerotized except duct and small area near juncture with duct unsclerotized, and with many fissures on surface; internal setae absent; both accessory ducts slender, subequal diameter to major one.

Male. Body length 1.8 mm. Head. 0.92 times wider than thorax. Upper eye medium brown, consisting of 12 vertical columns and 10 horizontal rows of large facets. Face grayish black, yellowish-white pruinose. Clypeus black, whitish pruinose, densely covered with pale yellow scale-like medium-long hairs (directed upward and lateral) interspersed with several dark brown simple longer hairs. Antenna composed of scape, pedicel and 9 flagellomeres, yellow to brown; 1st flagellomere elongate, 1.66 times as long as 2nd one. Maxillary palp light to medium brown, with 5 segments, proportional lengths of 3rd, 4th, and 5th segments 1.00:1.19:2.42; 3rd segment (Fig. 2A) widened apically; sensory vesicle (Fig. 5A) globular, small (0.26 times length of 3rd segment), and with large opening. Thorax. Scutum slightly darker than female and short hairs on scutum golden yellow. Legs. Foreleg: coxa brown; trochanter yellow with outer surface light brown; femur light brown; tibia brown with median 2/3 pale yellow and covered with dark brown hairs; tarsus brown to dark brown; basitarsus moderately dilated, 5.27– 5.43 times as long as its greatest width. Midleg: coxa yellow except base brown; trochanter yellow to brown; femur yellow except apical 1/4 brown; tibia medium brown to dark brown; tarsus brown to dark brown except anterior surface of little less than basal 1/2 of basitarsus pale yellow to light brown. Hind leg: coxa brown; trochanter yellow; femur light to dark brown except base yellow; tibia (Fig. 5B) light brown except basal and apical dark brown; tarsus medium to dark brown except basal 1/2 (or little less) of basitarsus whitish-yellow and little less than basal 1/3 of 2nd tarsomere white; basitarsus (Fig. 5C) slender, parallel-sided, 6.33–6.42 times as long as wide, and 0.55–0.58 and 0.49–0.51 times as wide as greatest width of tibia and femur, respectively; calcipala (Fig. 5C) nearly as long as wide, and 0.46 times as wide as greatest width of basitarsus. Pedisulcus (Fig. 5C) well defined. Wing. Length 1.5 mm. Costa with dark brown spinules as well as dark brown hairs except basal portion with patch of yellowish hairs. Subcosta with very sparsely dark brown hairs. Hair tuft on stem vein dark brown. Basal portion of radius fully haired; R1 with dark spinules and hairs and R2 with hairs only. Basal cell absent. Haltere. Yellowish brown except outer surface ochreous and basal stem darkened. Abdomen. Basal scale dark brown, with fringe of light to medium brown hairs. Dorsal surface of abdomen dark brown except segment 2 yellow (though posterior 1/ 4 of dorsal surface medium brown), covered with dark brown short to long hairs; segments 2 and 5–7 each with shiny dorsolateral or lateral patches; ventral surface of segment 2 yellow, those of segments 3 and 4 yellow except sternites medium brown, and those of other segments medium to dark brown. Genitalia. Coxite in ventral view (Fig. 5D) nearly rectangular, 1.42 times as long as its greatest width. Style in ventral view (Fig. 5D) bent inward, slightly tapered from base toward middle, then slightly widened, tapered to round apex and with apical spine; style in medial view 0.86 times as long as coxite, gently bent inward, nearly parallel-sided from base to apical 3/4, then tapered to apex, and with apical spine; style in ventrolateral view (Fig. 5E) very slightly tapered toward apical 3/4, with rounded apex. Ventral plate in ventral view (Fig. 5F) with body transverse, 0.91 times as long as wide, nearly parallel-sided, with anterior margin somewhat produced anteromedially, and posterior margin convex medially, densely covered with microsetae on ventral surface; basal arms of moderate length, directed forward, then slightly convergent apically; ventral plate in end view (Fig. 5G) concave ventrally, densely covered with microsetae on posterior surface. Median sclerite thin, plate-like, wide. Paramere of moderate size, with 4 distinct long and stout hooks and several smaller ones. Aedeagal membrane moderately setose, slightly sclerotized at base but dorsal plate not well defined. Cercus in lateral view small, rounded, with 7 or 8 hairs.

Pupa. Body length 1.9–2.1 mm. Head. Integument dark yellow, moderately covered with small round tubercles; antennal sheath with protuberances; face with pair of simple long trichomes with uncoiled apices, and frons with 2 pairs of simple very long trichomes with coiled or uncoiled apices; 3 frontal trichomes on each side arising close together, subequal in length to one another and 1.6 times longer than facial one. Thorax. Integument yellow, moderately covered with round tubercles, with 2 long (1 simple and 1 bifurcate) anterolateral trichome with uncoiled apices, 1 simple small mediolateral trichome with uncoiled apex, and 1 simple ventrolateral trichomes with uncoiled apex. Gill ( Fig. 6 A) composed of 8 slender thread-like filaments, arranged as [(1+2)+(1+2)]+2 filaments from dorsal to ventral, with medium-long common basal stalk having somewhat swollen transparent organ ventrally at base; common basal stalk medium sized (0.89–0.92 times length of interspiracular trunk); dorsal and middle triplet sharing medium-long common stalk; both primary and secondary stalks of dorsal triplet medium-long, primary stalk of middle triplet long, but secondary stalk short; length of primary and secondary stalks of middle triplet combined longer than stalk of ventral pair; stalk of ventral pair medium-long, 1.25–1.32 times length of common basal stalk and 0.92–0.95 times length of interspiracular trunk; stalk of ventral pair 0.88–0.91 times as thick as primary stalk of middle triplet, and 1.15–1.18 times as thick as primary stalk of dorsal triplet; primary stalk of dorsal triplet lying against stalk of ventral pair at angle of 40–60 degrees or little more when viewed laterally; all filaments yellowish brown, gradually tapered toward apex; entire length of filaments (measured from base of gill to tips of filaments) based on one pupa as follows: 1.7–1.8 mm for dorsal triplet, 1.9–2.4 mm for middle triplet and 1.5–1.6 mm for ventral paired filaments; cuticle of all filaments with welldefined annular ridges and furrows though gradually becoming indistinct from middle to apex, densely covered with minute tubercles. Abdomen. Dorsally, segments 1–7 pigmented with small to large tubercles; segment 1 with 1 simple slender medium-long hair-like seta on each side; segment 2 and 3 with 1 simple slender medium-long hair-like seta; segments 3 and 4 with 4 hooked spines and 1 short hair like seta on each side; segment 5 lacking spine-combs; segments 6–9 each with spine-combs in transverse row (though those on segment 9 slightly smaller than those on segment 8) and comb-like groups of minute spines on each side; segment 9 with pair of triangular flat terminal hooks of which outer margin is 3.0–3.1 times as long as inner margin and crenulated ( Fig. 6 B). Ventrally, segments 4 with 1 simple hook and 1 simple very short setae on each side; segment 5 with a pair of bifid inner and simple outer hooks somewhat spaced from each other and 1 simple slender very short setae on each side; segments 6 and 7 with pair of bifid inner and simple outer hooks somewhat spaced from each other on each side; segment 8 with 1 bifid inner and simple outer hook somewhat spaced from each other; segments 4–7 with comb-like groups of minute spines; segment 9 with 3 grapnel-shaped hooklets on each side. Cocoon. Wall pocket-shaped, thinly and moderately woven, widely extended ventrolaterally; anterior margin somewhat thickly woven, with dorsal portion slightly produced anteriorly when viewed dorsally; posterior 1/2 with floor roughly or moderately woven; individual threads visible; 2.5–2.6 mm long by 1.8–1.9 mm wide.

Mature larva. Body length 3.8–4.1 mm. Body creamy to dark ochreous except proleg grayish, ventral surface of thoracic segments 2 and 3 grayish or ochreous, and abdominal segments 1–4 almost entirely light grayish; body with grayish black markings, i.e., thoracic segment 1 encircled with broad transverse band (though disconnected ventrally), abdominal segments 5–8 with dorsolateral spots in transverse row of dorsal surfaces of posterior 1/2 of each segment. Cephalic apotome yellowish brown, and very sparsely covered with simple minute setae; head spots indistinct or very faintly positive. Lateral surface of head capsule yellowish brown except eye-spot region yellowish white, and very sparsely covered with simple minute seta; spots indistinct. Ventral surface of head capsule yellowish brown except somewhat darkened area near posterior margin on each side of postgenal cleft, and very sparsely covered with simple minute setae. Antenna composed of 3 segments and apical sensillum, 1.2 times longer than stem of labral fan; proportional lengths of 1st, 2nd, and 3rd segments 1.00:0.85:0.83. Labral fan with 38 main rays. Mandible ( Fig. 6 C) with 4 comb-teeth decreasing in length from 1st to 4thexcept 3rd tooth somewhat equal to 1st tooth; mandibular serration composed of 2 teeth (1 long and 1 small); major tooth at acute angle against mandible on apical side; supernumerary serrations absent. Hypostoma ( Fig. 6 D) with row of 9 apical teeth; median and each corner tooth prominent (though median tooth slightly longer than corner teeth) and much longer than 3 intermediate teeth on each side; lateral margin smooth though 2 teeth present apcially; 4 hypostomal bristles per side lying parallel to the lateral margin. Postgenal cleft ( Fig. 6 E) lanceolate, 1.77 times as long as postgenal bridge. Cervical sclerite composed of 2 dark small pieces, not fused to occiput, widely separated medially from each other. Thoracic cuticle bare. Abdominal cuticle almost bare except few posterior segments sparsely to moderately covered with simple minute setae dorsally and dorsolaterally and last segment moderately covered with colorless simple setae on each side of anal sclerite. Rectal scales absent. Rectal papilla compound, each of 3 lobes with 5 finger-like secondary lobules. Anal sclerite of usual X-form, with anterior arms 1.43 times as long as posterior ones, broadly sclerotized at base; accessory sclerite present. Last abdominal segment expanded ventrolaterally forming double bulges on each side, visible as large conical ventral papilla when viewed from side. Posterior circlet with 53–55 rows of up to 8–12 hooklets per row.

Etymology. The species name takaokai is in honor of Professor Hiroyuki Takaoka, Institute of Biological sciences, Faculty of Science, University of Malaya, Kuala Lumpur, who greatly contributed to the taxonomy of Oriental black flies.

Habitat. S. (G.) takaokai sp.nov. larvae and pupae are found on stream substrates (boulders, pebbles, leaf litter and woody debris) but they mainly were associated with the aquatic weed of Eichhornia crassipes .

Affinities. S. (G.) takaokai sp. nov. is assigned to the subgenus Gomphostilbia by having a bare pleural membrane and haired katepisternum in the female and male and is placed in the batoense species group by having a dark hair tuft on the stem vein, dark brown male and female tibiae, slender and parallel-sided male hind basitarsus. The characters of the sensory vesicle, longitudinal vittae on the scutum and hind basitarsus of S. (G.) takaokai indicate a close relationship with S. (G.) pattoni , S. (G.) bucolicum and S. (G.) fidum but the new species can be distinguished by the female genitalia, smaller number of male upper-eye large facets, pupal gill with a medium-long common basal stalk and larval hypostoma with 4 bristles on each side.

Figures

FIGURE 6. Pupa and larva of Simulium (Gomphostilbia) takaokai sp. nov. A & B, pupa; C – E, larva. A, left gill filaments (outer view); B, terminal hooks (end view); C, left mandible (lateral view); D, hypostoma (ventral view); E, head capsule showing postgenal cleft and hypostoma (ventral view). Scale bars. 0.01 mm for B – D; 0.1 mm for E; 0.2 mm for A.