Simulium (Nevermannia) karavalliense, Anbalagan & Rekha & Vijayan & Balachandran & Dinakaran & Krishnan, 2020

Anbalagan, Sankarappan, Rekha, Kalimuthu, Vijayan, Suruliyandi, Balachandran, Chellapandian, Dinakaran, Sundaram & Krishnan, Muthukalingan, 2020, A new black fly species of Simulium (Nevermannia) (Simuliidae: Diptera) from the Southern Eastern Ghats, India, Zootaxa 4768 (3), pp. 374-382 : 375-380

Simulium (Nevermannia) karavalliense sp. nov.

(Fig. 1–3)

Description. Female (n = 1). Body length 3.1 mm. Head. Nearly as wide as thorax. Frons grey, shiny, moderately covered with yellowish-white scale-like recumbent short hairs; frontal ratio 1.3:1.0:3.1; head ratio 1.0:5.7. Fronto-ocular area well developed, narrow, directed dorsolaterally. Clypeus yellowish-brown, densely covered with yellowish-white recumbent hairs interspersed with few to several dark longer hairs on each side. Labrum 0.75 times as long as clypeus. Antenna composed of scape, pedicel and nine flagellomeres, grey to white except scape, pedicle and base of first flagellomere dark yellow, proportional length of first and second flagellomeres 1.0:0.6. Maxillary palp composed of five palpomeres, dark brown, proportional length of third, fourth, and fifth palpomeres 1.0:1.2:2.5; third palpomere of moderate size (Fig. 1A); sensory vesicle ellipsoidal, long, 0.65 times length of third palpomere and with small opening. Maxillary lacinia with 11 inner and 15 outer teeth. Mandible with 30 inner and 10 outer teeth. Cibarium (Fig. 1B) medially forming sclerotized plate folded forward from posterior margin, with strongly sclerotized medial longitudinal ridge with well-sclerotized cup-like apex. Thorax. Scutum brownish-black except anterolateral calli ochreous, slightly shiny when illuminated at certain angle, densely covered with yellow scale-like recumbent hairs interspersed with several yellow medium-long to long hairs as well as dark brown long upright hairs on prescutellar area. Scutellum shiny, with dark brown short hairs. Postnotum brownish-yellow and bare. Pleural membrane bare. Katepisternum dark brown to yellowish-brown, longer than deep, slightly shiny when illuminated at certain angle, and bare. Legs. Foreleg: coxa dark yellow; trochanter light brown except basal 1/2 of outer surface yellow; femur dark yellow except apical cap medium brown; tibia medium brown, with median large portion on outer surface grayish light brown; tarsus dark brown, with moderate dorsal hair crest; basitarsus slightly dilated, 5.8 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. Hind leg: coxa yellowish-brown; trochanter dark yellow except anterior surface light brown; femur dark yellow with apical cap medium brown and basal tip light brown on anterior surface; tibia medium to dark brown except extreme base yellow, and medial large portion on outer surface grayish light brown; tarsus dark brown except basitarsus light to medium brown (though base dark brown) and basal 1/2 of second tarsomere grayish; basitarsus (Fig. 1C) narrow, nearly parallel-sided, 4.5 times as long as wide, and 0.63 and 0.83 times as wide as greatest width of tibia and femur, respectively; calcipala (Fig. 1C) slightly shorter than width at base, and 0.51 times as wide as greatest width of basitarsus. Pedisulcus (Fig. 1C) well defined. Claw (Fig. 1D) with large basal tooth 0.46 times as long as claw. Wing. Length 2.3 mm. Costa with dark brown spinules and hairs except basal portion covered with patch of yellow hairs. Subcosta fully haired. Hair tuft on stem vein light to dark brown. Basal portion of radius fully haired; R1 with dark spinules and hairs; R2 with hairs only. Basal cell absent. Halter. Clear white except margin and basal stem darkened. Abdomen. Basal scale ochreous to light brown, with fringe of whitish-yellow hairs. Dorsal surface of abdomen dark brown to brownish-black except segments 2 and 7–9 light brown (though base of segment 2 ochreous), moderately covered with dark short to long hairs and yellow short hairs; tergites of segments 3–6 relatively narrow, those of segments 2 and 7–9 wide and all dull. Ventral surface of abdomen mostly pale ochreous; sternal plate on segment 7 developed medially. Terminalia. Sternite 8 (Fig. 1E) bare medially, covered numerous short hairs and with 10–12 long hairs on each side. Ovipositor valves triangular, thin, membranous and moderately covered with microsetae; inner margins convex, somewhat sclerotized, and slightly separated from each other. Genital fork (Fig. 1F) of usual inverted-Y form, with slender stem; arms of moderate width medially; lateral plate of each arm strongly sclerotized along dorsolateral margin, and with thin lobe directed medioposteriorly. Paraproct in ventral view (Fig. 1G) nearly pentagonal, with 4 or 5 sensilla on unpigmented anteromedial surface; paraproct in lateral view (Fig. 1H) somewhat produced ventrally, 0.66 times as long as wide, with 5–7 medium-long to long hairs on ventral and lateral surfaces. Cercus in lateral view (Fig. 1H) short, rounded posteriorly, 0.45 times as long as wide. Spermatheca (Fig. 1I) ovoidal, 1.6 times as long as its greatest width, well sclerotized except small are at juncture with duct with hexagonal surface pattern and not well pigmented; internal setae absent; both accessory ducts slender, subequal in diameter to major one.

FIG. 1. Female of Simulium (Nevermannia) karavalliense sp. n. A, 3 rd segment of right maxillary palp showing sensory vesicle (front view); B, cibarium (front view); C, basitarsus and 2 nd tarsomere of left hind leg showing calcipala and pedisulcus (outer view); D, tarsal claw; E, 8 th 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. 0.01 mm for D and I; 0.05 mm B, E, F, G and H; 0.1 mm for A and C.

FIG. 2. Male of Simulium (Nevermannia) karavalliense 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, ventral plate and median sclerite; E, ventral plate (end view); F, median sclerite (end view); G, left paramere and aedeagal membrane (end view); H, 10 th abdominal segment and cercus (right side and lateral view). Scale bars. 0.01 mm for (D–G); 0.05 mm for A, C and H; 0.1 mm for B.

Male. Body length 3.4 mm. Head. wider than thorax. Upper eye yellowish brown, consisting of 14 vertical columns and 16 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, dark brown except base of first flagellomere yellow; first flagellomere elongate, 1.75 times length of second one. Maxillary palp light to medium brown, proportional lengths of 3rd, 4th, and 5th segments 1.0:1.1:2.1; 3 rd segment (Fig. 2A) widened apically; sensory vesicle (Fig. 2A) ellipsoidal, small (0.25 times as long as 3 rd segment), and with medium-sized opening. Thorax. Scutum slightly darker than female and short hairs on scutum golden yellow. Legs. Color nearly as in female except following characteristics: fore coxa dark yellow to light brown, mid trochanter yellowish-brown except anterior surface pale, and basal 1/4 of hind second tarsomere grayish. Fore basitarsus slightly dilated, 7.2 times as long as its greatest width. Hind basitarsus (Fig. 2B) slender, spindle–shaped, 4.7 times as long as wide, and 0.6 and 0.7 times as wide as greatest width of tibia and femur, respectively; calcipala (Fig. 2B) nearly as long as wide, and 0.39 times as wide as greatest width of basitarsus. Pedisulcus (Fig. 2B) well defined. Wing. Length 2.6 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 yellowish-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, 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. Terminalia. Coxite in ventral view (Fig. 2C) nearly rectangular, 1.35 times as long as its greatest width. Style in ventral view (Fig. 2C) bent inward, nearly parallel-sided, rounded apically and with apical spine; style in medial view shorter than coxite (0.72 times as long as coxite), boot-shaped, with triangular apical lobe directed dorsomedially; Ventral plate in ventral view (Fig. 2C) with body transverse, 0.5 times as long as wide, without anterior margin produced medioanteriorly, posterior margin with setose median keel; basal arms of short, curved inward; ventral plate in lateral view (Fig. 2D) with ventral margin of body concave; ventral plate in caudal view (Fig. 2E) with body appearing as shallow inverted-V shape, having similar width, posteroventral margin roughly undulate, and densely covered with microsetae medially on posterior surface. Median sclerite (Fig. 2F) slender, with forked apex, and with base located in front of anterior margin of ventral plate. Parameres (Fig. 2G) large, each with small apical appendix directed forwardly, and with 1 distinct long and stout hook. Aedeagal membrane moderately setose, dorsal plate well defined, broadly produced ventrally with round apex, though constricted subbasally. Ventral surface of abdominal segment 10 (Fig. 2H) with 3–5 distinct hairs near each posterolateral margin. Cercus (Fig. 2H) small, rounded, encircled with 8–10 hairs.

Pupa (n = 5). Body length 3.1–3.2 mm. Head. Integument light to dark yellow, densely covered with round tubercles, though frons with few to several tubercles; antennal sheath without any protuberances; face with pair of simple long trichomes with coiled apices, and frons with 2 simple long trichomes with uncoiled apices on each side (Fig. 3A), face with 1 simple very long trichome with coiled apex (Fig. 3B) on each side. Thorax. Integument light yellowish-brown, densely covered with small tubercles except anterodorsal surface sparsely covered with small tubercles; thorax with 2 simple very long trichomes with coiled apices mediodorsally (Fig. 3C), 1 simple very long trichome with coiled apex (Fig. 3D), 1 bifid medium-long trichome with coiled apex mediolaterally (Fig. 3E), and 3 simple trichomes (1 long with coiled apex, 1 medium-long with coiled apex, 1 medium-long with uncoiled apex) ventrolaterally (Fig. 3F). Gill (Fig. 3G) composed of 8 slender thread-like filaments, arranged as [(1 + 2) + (1 + 2)] + 2 filaments from dorsal to ventral, with short common basal stalk having somewhat swollen transparent organ ventrally at base; common basal stalk 0.57 times length of interspiracular trunk; both primary and secondary stalks of dorsal triplet medium-long, primary and secondary stalks of middle triplet short; length of primary and secondary stalks of middle triplet combined slightly shorter than stalk of ventral pair; stalk of ventral pair long, 0.8–0.9 times length of common basal stalk and 0.55–0.60 times length of interspiracular trunk; stalk of ventral pair 1.5–1.6 times as thick as primary stalk of middle triplet, and 1.2–1.3 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: 1.9–2.1 mm for dorsal triplet, 2.3–2.4 mm for middle triplet and 3.5–3.7 mm for ventral paired filaments; cuticle of all filaments with well-defined annular ridges and furrows, and densely covered with minute tubercles. Abdomen. Dorsally, segments 1–4 brownish and without distinct tubercles; segment 1 with 1 medium-long simple slender hair-like seta on each side; segment 2 with 1 short simple slender hair-like seta and 5 short somewhat spinous setae submedially on each side; segments 3 and 4 each with 4 hooked spines and 1 short somewhat spinous seta on each side; segments 5–8 each with spine-combs in transverse row on each side, and segments 6–9 each with comb-like groups of minute spines on each side; segment 9 with pair of cone-like terminal hooks (Fig. 3H). Ventrally, segment 4 with 1 simple hook and few simple slender short setae on each side; segment 5 with pair of bifid hooks submedially and few short simple slender 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 short simple slender setae on each side; segments 4–8 with comb-like groups of minute spines. Segment 9 without grapnel-shaped hooklets. Cocoon. Slipper-shaped, moderately woven, slightly extended ventrolaterally, anterior margin thickly woven; posterior 2/3 with floor roughly or moderately woven; individual threads visible; 3.4–3.6 mm long by 1.7– 1.9 mm wide.

FIG. 3. Pupa and larva of Simulium (Nevermannia) karavalliense sp. n. (A–H) pupa and (I–L) larva; A, frontal trichome; B, facial trichome, C–F, thoracic trichomes (C, mediodorsal; D, anterolateral; E, mediolateral; F, ventrolateral), G, left gill filaments (outer view); H, terminal hooks (end view); I, head (dorsal view); J, right mandible (lateral view); K, hypostoma (ventral view); L, head capsule showing postgenal cleft and hypostoma (ventral view). Scale bars. 0.01 mm for J; 0.02 mm for A–G and I; 0.05 mm for K; 0.1 mm for L; 0.2 mm for H.

Mature larva (n = 7). Body length 6.3–6.8 mm. Body creamy. Cephalic apotome whitish-yellow, though narrow area along posterior margin somewhat darkened; head spots moderately positive except anterior spot of posterolateral spots usually obscure. Lateral surface of head capsule whitish-yellow except eye-spot region whitish; eyebrow moderately positive; among spots in front of posterior margin, 2 relatively large spots moderately positive, and 2 small spots faintly positive; 1 or 2 small round spots below eye-spot region indistinct or faintly positive (Fig. I). Ventral surface of head capsule whitish-yellow to yellow except darkened area near posterior margin on each side of postgenal cleft; horizontal long spot and round spot on each side of postgenal cleft faintly or moderately positive. Antenna composed of 3 segments and apical sensillum, somewhat longer than stem of labral fan; proportional lengths of 1 st, 2 nd, and 3 rd segments 1.00:1.07:0.96. Labral fan with 35–37 main rays. Mandible (Fig. 3J) with 3 comb-teeth, of which 1 st tooth longest and 2 nd tooth as long as or slightly longer than 3 rd one; mandibular serration composed of 2 teeth (1 medium-sized and 1 small); major tooth at obtuse angle against mandible on apical side; supernumerary serration absent. Hypostoma (Fig. 3K) with row of 9 apical teeth; median tooth longer than others; lateral margin serrated; 6 hypostomal bristles per side lying parallel to lateral margin. Postgenal cleft (Fig. 3L) medium-size, somewhat flattened apically, 0.71–0.76 times as long as postgenal bridge. Cervical sclerites composed of 2 light to medium brown small oblong pieces, not fused to occiput, widely separated medially from each other. Thoracic cuticle bare. Abdominal cuticle almost bare except few posterior segments sparsely covered with colorless simple setae, and last segment densely covered with colorless simple setae on each side of anal sclerite. Rectal scales present. Rectal papillae compound, each of 3 lobes with 6–8 finger-like secondary lobules. Anal sclerite of usual X-form, with anterior arms 0.78–0.82 times as long as posterior ones, broadly sclerotized at base; accessory sclerites absent. Last abdominal segment with pair of large conical ventral papillae. Posterior circlet with 72–78 rows of up to 14–17 hooklets per row.

Type specimens. Holotype (in alcohol): Female , reared from pupa, collected from a small stream (water temperature 24.3°C, exposed to the sun, altitude 229 m, 11°19’63.8” N, 78°18’79.6” E) moderately flowing through foot hills area, Karavalli village , Kolli hills, Namakkal district, Tamil Nadu state, India, 23. XI.2018 . Paratypes (in alcohol): 3 females, 5 males, 8 pupae, 15 mature larvae, same data as the holotype ; 1 male, 3 pupae, 5 larvae collect- ed from a stream at Nachiamman odai, Semmedu village, Kolli hills, altitude 1131 m, 11°19’06.7” N, 78°20’89.5” E, 23. XI.2018 .

Biological notes. The pupa and larva of this new species were collected from grass leaves trailing in water. Associated species were Hydropsyche (Caddisfly) and Baetis (Mayfly) .

Etymology. The species name karavalliense refers to the locality name, Karavalli, where this new species was collected

Remarks. This new species is readily assigned to the ruficorne species-group of the subgenus Nevermannia , by having the male genitalia with ventral plate with a distinct median keel ( Crosskey, 1969). This new species is characterized by the pupal gill with eight thread-like filaments, of which stalk of ventral pair long and 0.8–0.9 times length of common basal stalk. The arrangement and relative length of the pupal gill filaments of this new species are almost identical to those of S. (N.) glatthaari Takaoka and Davies , described from Sumatra, Indonesia ( Takaoka and Davies, 1995). However, this new species is distinguished from S. (N.) glatthaari (those of S. (N.) glatthaari in parenthesis) in the female by the long sensory vesicle and 0.65 times length of 3 rd palpomere (0.47 times length of 3 rd palpomere) and tarsal claw with large basal tooth and 0.46 times as long as claw (0.35 times as long as claw), in the male by the coxite in ventral view, 1.35 times as long as its greatest width (1.46 times as its greatest width), in the pupa by the common basal stalk 0.57 times length of interspiracular trunk (0.38 times length of interspiracular trunk) and slipper-shaped cocoon (wall-pocket shaped cocoon), and in the larva by 6 hypostomal bristles lying parallel to lateral margin (7–9 hypostomal bristles lying parallel to lateral margin).

This new species is morphologically similar to S. (N.) aureohirtum Puri (1932) described from India, by a combination of the triangular ovipositor valves of the females, plate-like ventral plate with median keel of the males, cuticle of all respiratory filaments with well-defined annular ridges and densely covered with minute tubercles of pupae and 6 hypostomal bristles lying parallel to lateral margin. However, this new species is distinguished from S. (N.) aureohirtum by the following characters (S. (N.) aureohirtum in parenthesis): scutum without any longitudinal vitta (scutum with a pair of sub-median longitudinal vittae) in the female, the hind basitarsus spindle–shaped, 0.6 times as wide as greatest width of tibia (parallel-sided, 0.75 times as wide as greatest width of tibia) in the male, 8 slender thread-like filaments (6 gill filaments) in the pupa, and posterior circlet with 72–78 rows of up to 14–17 hooklets per row (60 rows of up to 10–13 hooklets per row) in the larva.