Simulium (Gomphostilbia) cauveryense Anbalagan

Anbalagan, Sankarappan, Balachandran, Chellapandian, Prasanna, Vimalanathan Arun, Kannan, Mani, Dinakaran, Sundaram & Krishnan, Muthukalingan, 2015, A new species of Simulium (Gomphostilbia) (Diptera: Simuliidae) from South India, with keys to Indian members of the subgenus Gomphostilbia, Zootaxa 3974 (4), pp. 555-563 : 556-561

Simulium (Gomphostilbia) cauveryense Anbalagan sp.n.

(Figs. 1–3)

Description. Female. Body length 2.4 mm. Head. Narrower than width of thorax. Frons gray, shiny when illuminated at certain angles, thinly yellowish pruinose, with several stout dark hairs along lateral and lower margins; frontal ratio 1.5:1.0:2.0; frons-head ratio 1.0:4.9. Fronto-ocular area well developed, narrow, directed dorso-laterally. Antenna composed of scape, pedicel and 9 flagellomeres, brown except scape, pedicel and basal 1/ 2 of 1st flagellomere yellow. Clypeus grayish-black, slightly shiny when illuminated at certain angles, densely covered with yellow hairs interspersed with several dark longer hairs on each side. Labrum 0.66 times as long as clypeus. Maxillary palp composed of 5 segments; proportional lengths of 3rd, 4th and 5th segments 1.0:1.2:2.1; 3rd segment (Fig. 1A) moderately enlarged; sensory vesicle (Fig. 1A) medium-sized (0.39 times as long as 3rd segment), with medium-sized round opening. Maxillary lacinia with 9 inner and 11 outer teeth. Mandible with 14 or 16 inner teeth and lacking outer teeth though outer margin with several very low round ridges at some distance from apex. Cibarium (Fig. 1B) medially forming sclerotized plate folded forward from posterior margin, with moderately sclerotized mediolongitudinal ridge. Thorax. Scutum dark brown except anterolateral calli dark ochreous, with 3 brownish-black longitudinal vittae (1 narrow median and 2 submedian), median vitta united anteriorly to anterior margin, submedian vittae united posteriorly to brownish-black prescutellar area; scutum shiny when illuminated at certain angles, densely covered with yellow scale-like recumbent short hairs interspersed with dark brown long upright hairs on prescutellar area. Scutellum shiny, covered yellow fine short hairs and dark brown long upright hairs. Postnotum dark brown, shiny when illuminated at certain angles and bare. Pleural membrane bare. Katepisternum medium to dark brown, longer than deep, shiny when illuminated at certain angles, moderately covered with fine short hairs. Legs. Foreleg: coxa yellow; trochanter yellow except apical portion somewhat darkened; femur light brown (though somewhat darkened toward apex, and extreme apex yellowish); tibia white except apical 1/4 brownish-black, with whitish sheen on outer surface of basal 3/4; tarsus black, with moderate dorsal hair crest; basitarsus moderately dilated, 6.4 times as long as its greatest width. Midleg: coxa medium brown except posterior surface brownish-black; trochanter yellow except apical portion dark brown; femur light to medium brown with base and extreme apical tip yellowish; tibia medium to dark brown with basal 1/ 3 or little more whitish-yellow, covered with whitish fine hairs on basal 2/3 and white sheen on posterior surface of basal 2/3 when illuminated at certain angles; tarsus brownish-black except basal 1/2 of basitarsus dark yellow. Hind leg: coxa light to medium brown; trochanter yellow to light brown; femur light brown with base yellow and apical cap dark brown (though extreme apical tip yellowish); tibia (Fig. 1C) light to dark brown with basal 1/2 white to yellowish-white, covered with whitish fine hairs on outer and posterior surfaces of basal 3/4 and white sheen on posterior surface of basal 3/4 when illuminated at certain angle of light; tarsus brownish-black except basal 2/3 of basitarsus (though base light brown) and little less than basal 1/2 of 2nd tarsomere white; basitarsus (Fig. 1D) narrow, nearly parallel-sided, 6.71 times as long as wide, and 0.54 and 0.39 times as wide as greatest width of tibia and femur, respectively; calcipala (Fig. 1D) slightly shorter than width at base, and 0.46 times as wide as greatest width of basitarsus. Pedisulcus (Fig. 1D) well defined. Claw (Fig. 1E) with large basal tooth 0.63 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. White except basal stem darkened. Abdomen. Basal scale ochreous, with fringe of whitish-yellow hairs. Dorsal surface of abdomen medium brown to dark brownish except basal 1/2 of segment 2 yellow, moderately covered with yellow fine short hairs and dark short to long hairs; tergites of segments 2 and 6–9 shiny when illuminated at certain angles. Ventral surface of segments 2 and 3 entirely whitish-yellow, and those of other segments light to dark brown; sternal plate on segment 7 undeveloped. Genitalia. Sternite 8 (Fig. 1F) well sclerotized and bare medially, covered with 11–13 long hairs on each side. Ovipositor valves tongue-like, thin, membranous, moderately covered with microsetae interspersed with 6 or 7 short hairs; inner margins concave, somewhat sclerotized, and slightly separated from each other. Genital fork (Fig. 1G) of usual inverted-Y forms; stem slender and well sclerotized; arms of moderate width, lateral plate of each arm with thin lobe directed posteromedially and small stout projection directed anterodorsally. Paraproct in ventral view (Fig. 1H) concave anterolaterally, with 3 sensilla on anteromedial surface; paraproct in lateral view (Fig. 1I) somewhat produced ventrally, 0.45 times as long as wide, with about 14 medium-long to long hairs on lateral and ventral surfaces. Cercus in lateral view (Fig. 1I) short, rounded posteriorly, 0.41 times as long as its greatest width. Spermatheca (Fig. 1J) ellipsoidal, 1.65 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 in diameter to major one.

Male. Body length 2.7 mm. Head. 0.97 times wider than thorax. Upper eye yellowish brown, consisting of 13 vertical columns and 15 horizontal rows of large facets. Face brownish black, grayish-white pruinose. Clypeus grayish black, whitish pruinose, densely covered with golden-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, 1.67 times as long as 2nd one. Maxillary palp light to medium brown, with 5 segments, proportional lengths of 3rd, 4th, and 5th segments 1.0:1.3:2.5; 3rd segment (Fig. 2A) widened apically; sensory vesicle (Fig. 2A) globular, small (0.23 times as long as 3rd segment), and with small opening. Thorax. Nearly as in females except scutum slightly darker than that of female and short hairs on scutum golden yellow. Legs. Foreleg: coxa yellow; trochanter yellow with some portions light brown; femur light brown except apical cap brown; tibia brown with median 2/3 light brown and covered with dark brown hairs; tarsus brown to dark brown; basitarsus moderately dilated 6.6 times as long as its greatest width. Midleg: coxa yellowish brown; trochanter yellow to brown; femur yellow except apical 1/4 brown; tibia medium brown to dark brown; tarsus dark brown to brownish-black except anterior surface of little less than basal 1/2 of basitarsus dark yellow to light brown. Hind leg: coxa dark yellow to brown; trochanter yellow; femur light brown except apical 1/2 dark brown; tibia (Fig. 2B) brown except base and apical cap 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. 2C) enlarged, spindle-shaped, 4.18 times as long as wide, and 0.69 and 0.79 times as wide as greatest width of tibia and femur, respectively; calcipala (Fig. 2C) nearly as long as wide, and 0.38 times as wide as greatest width of basitarsus. Pedisulcus (Fig. 2C) well defined. Wing. Length 1.55–1.61 mm. Costa with dark brown spinules as well as dark brown hairs except basal portion with patch of yellowish hairs. Subcosta with dark hairs except near apex bare. 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. Yellow except outer surface ochreous, basal stem darkened and apex brown. Abdomen. Basal scale dark brown, with fringe of light to medium brown hairs. Dorsal surface of abdomen dark brown except segment 2 light brown (though posterior 1/4 of dorsal surface 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. 2D) nearly rectangle, 1.26 times as long as its greatest width. Style in ventral view (Fig.2D) bent inward, slightly tapered from base toward middle, then nearly parallel-sided, rounded apically and with apical spine; style in medial view (Fig. 2E) nearly subequal to coxite, gently bent inward, nearly parallel-sided, with apical spine; style in ventro-lateral view (Fig.

2F) very slightly tapered toward apical 3/4, with rounded apex. Ventral plate in ventral view (Fig. 2G) with body transverse, 0.58 times as long as wide, slightly widened posteriorly, with anterior margin 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 lateral view (Fig. 2H) moderately produced ventrally; ventral plate in end view (Fig. 2I) concave ventrally, densely covered with microsetae on posterior surface. Median sclerite (Fig. 2H) thin, plate-like, wide. Paramere (Fig. 2J) 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. Ventral surface of abdominal segment 10 without distinct hairs near posterior margin. Cercus in lateral view (Fig. 2K) small, rounded, with 16 or 17 hairs.

FIGURE 1. Female of Simulium (Gomphostilbia) cauveryense sp. n. A, 3rd segment of right maxillary palp showing sensory vesicle (front view); B, cibarium (front view); C, left hind tibia (outer view); D, basitarsus and 2nd tarsomere of left hind leg showing calcipala and pedisulcus (outer view); E, tarsal claw; F, 8th sternite, ovipositor valves (ventral view); G, genital fork (ventral view); H & I, right paraprocts and cerci (H, ventral view; I, lateral view); J, spermatheca (lateral view).

Pupa. Body length 2.4–2.5 mm. Head. Integument dark yellow, sparsely covered with small round tubercles; antennal sheath with protuberance; face with pair of simple very long trichomes with uncoiled apices, and frons with 3 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 slightly longer than facial one. Thorax. Integument yellow, moderately covered with round tubercles, with 3 simple very long dorsomedial trichomes with uncoiled apices, 2 simple very long anterolateral trichome with coiled apices, 1 simple very long mediolateral trichome with uncoiled apex, and 3 simple ventrolateral trichome with uncoiled apices (1 medium-long and 2 short) on each side. Gill ( Fig. 3 A) composed of 10 short slender filaments, arranged as [(2+3)+(1+2)]+2 or {[2+(2+1)]+(1+2)}+2 filaments from dorsal to ventral, with very short common basal stalk having somewhat swollen transparent basal fenestra ventrally at base; common basal stalk 0.43 times length of interspiracular trunk; both dorsal and ventral stalks short, length of primary stalks of dorsal filaments combined slightly nearly subequal to stalk of ventral pair; stalk of ventral pair short, 1.6–1.7 times length of common basal stalk and 0.69–0.71 times length of interspiracular trunk; stalk of ventral pair 0.48–0.51 times as thick as primary stalk of dorsal pair, 0.39–0.41 times as thick as primary stalk of first dorsal triplet, and 0.39–0.42 times as thick as primary stalk of second dorsal triplet; primary stalk of dorsal pair lying against stalk of ventral pair at angle of 180 degree or little more when viewed laterally; all filaments yellowish brown, decrease their thickness toward apex; entire length of filaments (measured from base of gill to tips of filaments) based on one pupa as follows: 0.45–0.52 mm for dorsal pair, 0.35–0.40 mm for first dorsal triplet, 0.33–0.40 mm for second dorsal triplet and 0.60–0.65 mm for ventral paired filaments; cuticle of all filaments with indefinite annular ridges and furrows from base to apex, densely covered with minute tubercles. Abdomen. Dorsally, segments 1 and 2 brownish yellow pigmented with tubercles; segment 1 with 1 simple slender mediumlong hair-like seta on each side; segment 2 with 1 simple medium-long and 3 short hair like setae on each side; segments 3 and 4 each with 4 hooked spines and 1 short hair like seta on each side; segment 5 lacking spine–combs and 1 short hair like seta on each side; 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 slightly longer than inner margin and not crenulated ( Fig. 3 B). Ventrally, segment 4 with 1 simple hook and few simple slender very short setae on each side; segment 5 with pair of bifid hooks submedially and few very short simple slender setae on each side; segments 4–8 each with comb-like groups of minute spines. Each side of segment 9 with 3 grapnel-shaped hooklets. Cocoon. Shoe-shaped, thinly and moderately woven, 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; 3.6 mm long by 1.6 mm wide.

Mature larva. Body length 4.3–4.5 mm. Body creamy to color markings as follows: ventral surface of thoracic segment 1 encircled with ochreous broad transverse band (though disconnected ventrally), proleg grayish, thoracic segments 2 and 3 grayish dorsally and each with distinct ochreous wide areas ventrally, abdominal segments 1–4 each encircled with yellowish brown broad band, abdominal segments 5–8 almost entirely covered by yellowish brown transverse broad band on dorsal and dorsolateral surfaces; abdominal segments 5 and 6 each with W-shaped broad transverse band on dorsolateral surfaces of posterior 1/2 of each segment; abdominal segment 7 and 8 with transverse yellowish brown band on ventral surface; Cephalic apotome yellowish brown, and sparsely covered with simple minute setae; head spots indistinct. Lateral surface of head capsule yellowish brown except eye-spot region yellow, and very sparsely covered with simple minute setae; 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, 1.25 times longer than stem of labral fan; proportional lengths of 1st, 2nd, and 3rd segments 1.00:0.9:1.4. Labral fan with 25 main rays. Mandible ( Fig. 3 C) with 3 comb-teeth decreasing in length from 1st to 3rd; mandibular serrations composed of 2 teeth (1 medium-sized and 1 small); major tooth at acute angle against mandible on apical side; supernumerary serrations absent. Hypostoma ( Fig. 3 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; 4 hypostomal bristles per side lying parallel to lateral margin. Postgenal cleft ( Fig. 3 E) lanceolate, 2.71 times as long as postgenal bridge. Cervical sclerite composed of 2 very pale small pieces, not fused to occiput, moderately separated medially from each other. Thoracic cuticle finely covered with minute dark spinules. Abdominal cuticle almost bare except few posterior segments sparsely to moderately covered with simple minute setae dorsally and dorsolaterally and last segment densely 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 little shorter (0.92 times as long as posterior arms) than posterior ones, broadly sclerotized at base; accessory sclerite absent. Last abdominal segment expanded ventrolaterally forming double bulges on each side, visible as large conical ventral papilla when viewed from side. Posterior circlet with 62 rows of hooklets with up to 12–14 hooklets per row.

FIGURE 2. Male of Simulium (Gomphostilbia) cauveryense sp. n. 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 & F, left styles (E, medial view; F, ventrolateral view); G, ventral plate (ventral view); H, ventral plate and median sclerite; I, ventral plate (end view); J, left paramere and aedeagal membrane (end view); K, 10th abdominal segment and cercus (right side and lateral view).

Type specimens. Holotype, ♂, INDIA: Kushalanagar, Kodagu district, Karnataka state, 6-II- 2015, 829 m (12º44′.80″ N, 75º96′.97″E), S. Anbalagan & C. Balachandran. Paratypes, same data as holotype: 2 ♀, 4 ♂, 3 pupae, 9 mature larvae (Coll. S. Anbalagan, Bharathidasan University), 8 ♂♂, 10 ♀♀, 15 pupae, 121 larvae (Coll. S. Anbalagan, BDU, catalogue number: BL0018).

Biological notes. The larvae and pupae of this new species were collected from polythene cover, wooden materials and boulders submerged in water. Associated species were S. (G.) palmatum Puri (1932) and S. (S.) latistriatum Senior-White (1922) .

Etymology. The species name cauveryense is the name of Cauvery River, South India.

Remarks. S. (G.) cauveryense , new species, is morphologically similar to S. (G.) peteri recently described from Kerala, south India ( Anbalagan et al. 2014) in sharing the medium-sized sensory vesicle (Fig. 1A), scutum with three brownish-black longitudinal vittae and tarsal claw with large basal tooth (Fig. 1E) in the female, moderate length of basal arms of ventral plate (Fig. 2G) basal arms of moderate length in the male and the short primary stalk of gill ( Fig. 3 A) in the pupa. However, this new species is distinguished from S. (G.) peteri in the female by the arms of the genital fork which are nearly parallel (Fig. 1G), in the male by the upper eye large facets with 13 vertical columns and 15 horizontal rows and spindle-shaped hind basitarsi (Fig. 2C), in the pupa by the 10 respiratory filaments with indefinite annular ridges ( Fig. 3 A) and shoe-shaped cocoon, and in the larva by the labral fan with 25 main rays and 5 hypostomal bristles per side lying parallel to lateral margin ( Fig. 3 D). In addition, S. (G.) cauveryense sp. n. is easily distinguished from S. (G.) decuplum Takaoka & Davies (1995) by the pupal gill with ten filaments arranged as [(2+3)+(1+2)]+2 or {[2+(2+1)]+(1+2)}+2 filaments from dorsal to ventral.

Figures

FIGURE 3. Pupa and larva of Simulium (Gomphostilbia) cauveryense sp. n. A & B, pupa; C – E, larva. A, left gill filaments (outer view); B, terminal hooks (end view); C, right mandible (lateral view); D, hypostoma (ventral view); E, head capsule showing postgenal cleft and hypostoma (ventral view).