Simulium (Gomphostilbia) kumbakkaraiense, 2019

Anbalagan, Sankarappan, Vijayan, Suruliyandi, Dinakaran, Sundaram & Krishnan, Muthukalingan, 2019, A new species of Simulium (Gomphostilbia) (Diptera: Simuliidae) from South India, Zootaxa 4551 (4), pp. 479-486 : 480-486

Simulium (Gomphostilbia) kumbakkaraiense sp. n.

( Fig. 2–4 )

Female. Body length 2.5–2.6 mm. Head. Slightly narrower than thorax. Frons brownish black, densely covered with yellowish-white recumbent hairs interspersed; frontal ratio 2.0:1.0:1.2; frons:head ratio 1.0:3.3. Fronto-ocular area well developed, narrow, directed dorsolaterally. Clypeus brownish black, densely covered with yellowishwhite recumbent hairs interspersed with few to several dark longer hairs on each side. Labrum 0.7 times as long as clypeus. Antenna composed of scape, pedicel and nine flagellomeres, dark brown except scape and pedicel yellow and basal extreme of first flagellomere light brown. Maxillary palp composed of five segments, light brown except first and second segment ochreous and third segment medium brown, proportional lengths of third, fourth, and fifth segments 1.0:1.2:2.0; third segment ( Fig. 2A ) of moderate size; sensory vesicle ( Fig. 2A ) elongate, 0.4 times as long as third segment and with medium-sized opening. Maxillary lacinia with 13 inner and 26 outer teeth. Mandible with 16 inner teeth and 13 outer teeth at some distance from apex. Cibarium ( Fig. 2B ) 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 lateral), median vitta united anteriorly to anterior calli, lateral vittae united posteriorly to prescutellar area; scutum shiny when illuminated at certain angles, densely covered with yellow scale-like recumbent shorthairs interspersed with dark brown long upright hairs on prescutellar area. Scutellum shiny, with dark brown short 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 light brown; tibia brown; tarsus brownish black, with moderate dorsal hair crest; basitarsus slightly dilated, 5.0 times as long as its greatest width. Midleg: coxa yellowish brown except posterior surface dark brown; trochanter yellow to light brown; femur and tibia brown; tarsus brownish-black except basal 1/2 of basitarsus dark yellow. Hindleg: coxa yellowish brown; trochanter yellow; femur medium brown with base yellow and apical cap dark brown; tibia ( Fig. 2C ) light to dark brown with basal 1/4 white, covered with brownish fine hairs on outer and posterior surfaces; tarsus brownishblack except basal 2/3 of basitarsus (though base light brown); basitarsus ( Fig. 2D ) narrow, nearly parallel-sided, 5.3 times as long as wide, and 0.8 and 0.6 times as wide as greatest width of tibia and femur, respectively; calcipala ( Fig. 2D ) slightly shorter than width at base, and 0.4 times as wide as greatest width of basitarsus. Pedisulcus ( Fig. 2D ) well defined. Claw ( Fig. 2E ) with large basal tooth 0.4 times as long as claw. Wing. Length 2.4–2.5 mm. Costa with dark-brown spinules and light-brown hairs except basal patch of yellow hairs. Subcosta haired except near apex bare. Hair tuft on base of radial vein dark brown. Basal portion of radius fully haired. Basal cell absent. Halter . Clear white except basal stem darkened. Abdomen. Basal scale dark yellow, with fringe of yellowish-white hairs. Dorsal surface of abdomen medium to dark brown except segment 2 light brown with middle portion of tergite ochreous, moderately covered with dark short to long hairs; tergites of segments 2 and 6–9 shiny when illuminated at certain angles. Ventral surface of segments 2–4 creamy, those of other segments light to dark brown; sternite 7 undeveloped. Terminalia . Sternite 8 ( Fig. 2F ) well sclerotized and bare medially, covered with 10–13 long hairs on each side. Ovipositor valves tongue-like, thin, membranous, moderately covered with microsetae; inner margins convex, somewhat sclerotized, and slightly separated from each other. Genital fork ( Fig. 2G ) of usual inverted-Y form; 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. 2H ) concave anterolaterally, with 3 sensilla on anteromedial surface; paraproct in lateral view ( Fig. 2I ) much produced ventrally, 0.6 times as long as wide, with 19–21 medium-long to long hairs on ventral and lateral surfaces. Cercus in lateral view ( Fig. 2I ) short, rounded posteriorly, 0.4 times as long as wide. Spermatheca ( Fig. 2J ) ellipsoidal, 2.3 times as long as its greatest width, well sclerotized except duct and small area near juncture with duct unsclerotized, and with hexagonal pattern on surface; internal setae absent; both accessory ducts slender, subequal in diameter to major one.

Male. Body length 2.7–2.8 mm. Head, somewhat wider than thorax. Upper eye yellowish brown, consisting of 13 vertical columns and 13 or 14 horizontal rows of large facets. Face brownish black, grayish-white pruinose. Clypeus brownish 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; 1 st flagellomere elongate, 1.3 times as long as 2 nd one. Maxillary palp light to medium brown, with 5 segments, proportional lengths of 3rd, 4th, and 5th segments 1.0:0.9:1.5; 3 rd segment ( Fig. 3A ) widened apically; sensory vesicle ( Fig. 3A ) ellipsoidal, small (0.25 times as long as 3 rd segment), and with small opening. Thorax. Scutum slightly darker than 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 6.0 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. Hindleg: coxa dark yellow to brown; trochanter yellow; femur light brown except apical 1/2 dark brown; tibia ( Fig. 3B ) brown except basal and apical portion 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. 3C ) slender, spindle-shaped, 4.9 times as long as wide, and 0.6 and 0.7 times as wide as greatest width of tibia and femur, respectively; calcipala ( Fig. 3C ) nearly as long as wide, and 0.5 times as wide as greatest width of basitarsus. Pedisulcus ( Fig. 3C ) well defined. Wing. Length 2.1–2.3 mm. Costa with dark brown spinules as well as dark brown hairs except basal portion with patch of yellowish hairs. Subcosta bare. Hair tuft on stem vein dark brown. Basal portion of radius fully haired; R 1 with dark spinules and hairs and R 2 with hairs only. Basal cell absent. Halter . Yellowish brown except outer surface ochreous, basal stem darkened and apex white. 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, 5–7 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. 3D ) nearly rectangle, 1.1 times as long as its greatest width. Style in ventral view ( Fig. 3D ) slightly bent inward, slightly tapered from base to apex, sharped apically and with apical spine; style in medial view ( Fig. 3E ) longer than coxite (0.8 times as long as coxite), gently bent inward, nearly parallel-sided, with apical spine; style in ventro-lateral view ( Fig. 3F ) very slightly tapered toward apical 3/4, with rounded apex. Ventral plate in ventral view ( Fig. 3G ) with body broad, 0.6 times as long as wide, slightly widened posteriorly, with anterior margin concave, and posterior margin rounded, densely covered with microsetae on ventral surface; basal arms of long, directed forward, then convergent apically; ventral plate in lateral view ( Fig. 3H ) moderately produced ventrally; ventral plate in end view ( Fig. 3I ) body and ventrally-produced median process nearly equilateral triangular. Median sclerite ( Fig. 3H ) thin, plate-like, wide. Paramere ( Fig. 3J ) of moderate size, with 3 distinct long, stout hooks plus 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. 3K ) small, rounded, with 9 or 10 hairs.

Pupa. Body length 3.0– 3.1 mm. Head. Integument dark yellow, moderately 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; 2 frontal trichomes on each side arising close together, subequal in length to one another and slightly longer than facial one. Thorax. Integument yellow, covered with round tubercles, with 3 simple very long dorsomedial trichomes with coiled apices, 1 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. 4A ) composed of 8 slender thread-like filaments, arranged as [(1 + 2) + (1 + 2)] + 2 filaments from dorsal to ventral, with short basal stalk having somewhat swollen transparent organ ventrally at base; common basal stalk 1.0 times length of interspiracular trunk; dorsal and middle triplet sharing medium-long common stalk; primary stalks of dorsal and middle triplets short, but secondary stalks of both triplet medium-long; length of primary and secondary stalks of middle triplet combined longer than stalk of ventral pair; stalk of ventral pair short, 0.25–0.3 times length of common basal stalk and 0.2 times length of interspiracular trunk; stalk of ventral pair 0.8 times as thick as primary stalk of middle triplet, and 0.7 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: 1.4 or 1.5 mm for dorsal triplet, 1.3–1.5 mm for middle triplet and 1.6 or 1.7 mm for ventral paired filaments; cuticle of all filaments with well-defined annular ridges and furrows though gradually becoming indistinct from middle to apex, densely covered with minute tubercles. Abdomen. Dorsally, segments 1 and 2 brownish yellow and with tubercles; segment 1 with 1 simple slender medium-long 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. 4B ). Cocoon. Wall-pocket-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; 3.5 mm long by 2.2 mm wide.

Mature larva. Body length 4.9–5.2 mm. Body creamy to colored with markings as follows: thoracic segment 1 encircled with ochreous broad transverse band (not continuous 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 grayish-brown 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 articles and apical sensillum, 1.1 times longer than stem of labral fan; proportional lengths of 1 st, 2 nd, and 3 rd segments 1.0:1.2:1.2. Labral fan with 29 main rays. Mandible ( Fig. 4C ) 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. 4D ) 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 arrayed parallel to lateral margin. Postgenal cleft ( Fig. 4E ) arrow-head-shaped, 1.5 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 (0.8 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 66 rows of hooklets with up to 11–13 hooklets per row.

Type series. Holotype (in alcohol): Female, reared from pupa, 10°18'30.3'' N, 77°52'95.8'' E, altitude 402 m, Kumbakkarai Falls , Periyakulam taluk, Theni district, Tamil Nadu State, India, 11-II-2017, Colls. S. Anbalagan & S. Vijayan ; Paratypes (in alcohol): two females, one male, 21 pupae, seven mature larvae; same data as for holotype. (All deposited in Department of Zoology , Government Arts College, Melur, Catalogue number: WP003)

Etymology. The species name kumbakkaraiense refers to the stream name, Kumbakkarai Falls, where this new species was collected.

Biological notes. The pupae and larvae of this new species were collected from leaf litter and woody debris catchments area in stream. It is a fast-flowing stream, characterized by width 5–8 m, depth 5–20 cm, water velocity 0.2m /sec, diversified substrates, water temperature 23.2°C, exposed to the sun, pH 6.4 and conductivity 121.2 µS/ cm. Associated insects were mayflies ( Dudgeodes and Baetis ) and caddisfly ( Hydropsyche sp.).

Remarks. Since the above diagnostic characters are possessed by S. (G.) kumbakkaraiense sp. n., we assign it to the subgenus Gomphostilbia . Further, the new species is placed in the Simulium batoense species-group of this subgenus by possession of antenna with nine flagellomeres, bare pleural membrane, dark hair tuft on the base of the radius, dark tibiae of the female and male, and slender male hind basitarsus, eight gill filaments and in the pupa grapnel-like hooklets ( Takaoka, 2012).

S. (G.) kumbakkaraiense sp. n. is morphologically similar to S. (G.) kottoorense recently described from Tamil Nadu, south India ( Anbalagan et al. 2015a) in sharing the following characters: scutum with three brownish-black longitudinal vittae and tarsal claw with large basal tooth in the female, coxite 1.1 times as long as its greatest width in the male, the respiratory gill with 8 slender thread-like filaments in the pupa and wall-pocket-shaped cocoon and 4 hypostomal bristles per side lying parallel to lateral margin in the larva. However, the new species is distinguished from S. (G.) kottoorense in the female by the hind basitarsus 5.3 times as long as wide and sternite 8 covered with 10–13 long hairs on each side, in the male by the upper eye large facets with 13 vertical columns and 13 or 14 horizontal rows and spindle-shaped hind basitarsi, in the pupa by the gill with short common basal stalk, and in the larva by the postgenal cleft arrow-head-shaped, 1.5 times as long as postgenal bridge.

Figures

FIGURE 2. Female of Simulium (Simulium) kumbakkaraiense sp.n. A, 3 rd segment of right maxillary palp showing sensory vesicle (frontal view); B, cibarium (frontal view); C, basitarsus and 2 nd tarsomere of left hind leg showing calcipala and pedisulcus (frontal view); D, tarsal claw; E, 8th sternite, ovipositor valves (ventral view); F, genital fork (ventral view); G & H, right paraprocts and cerci (G, ventral view; H, lateral view); I, spermatheca (lateral view). Scale bars. 0.02 mm for D–I; 0.05 mm for A and B; 0.1 mm for C.

FIGURE 3. Male of Simulium (Simulium) kumbakkaraiense sp.n. A, 3 rd segment of left maxillary palp showing small sensory vesicle (frontal view); B, basitarsus and 2 nd tarsomere of left hind leg showing calcipala and pedisulcus (outer view); C, coxites, styles, ventral plate and median sclerite (ventral view); D left styles (ventrolateral view); E, ventral plate and median sclerite; F, ventral plate (end view); G, left paramere and aedeagal membrane (end view); H, 10 th abdominal segment and cercus (right side and lateral view). Scale bars. 0.02 mm for A and E–H; 0.05 mm for C and D; 0.1 mm for B.

FIGURE 4. Pupa and larva of Simulium (Simulium) kumbakkaraiense 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). Scale bars. 0.02 mm for B–D; 0.05 mm for E; 0.1 mm for A.