Simulium (Nevermannia) langbiangense Takaoka, Sofian-Azirun

Takaoka, Hiroyuki, Sofian-Azirun, Mohd, Ya’Cob, Zubaidah, Chen, Chee Dhang, Lau, Koon Weng & Pham, Xuan Da, 2014, Three new species of Simulium (Nevermannia) (Diptera: Simuliidae) from Vietnam, Zootaxa 3866 (4), pp. 555-571 : 556-563

Simulium (Nevermannia) langbiangense Takaoka, Sofian-Azirun & Ya’cob sp. nov.

( Figs. 1–4 )

Female. Body length 3.0 mm. Head. Slightly narrower than thorax. Frons brownish-black, thinly whitish-gray pruinose, densely covered with whitish-yellow recumbent hairs interspersed with several dark-brown longer and stouter hairs along each lateral margin. Frontal ratio 1.6:1.0:2.6. Frons:head ratio 1.0:5.3. Fronto-ocular area well developed, triangular, directed laterally and slightly upward. Clypeus brownish-black, whitish-gray pruinose, densely covered with whitish-yellow recumbent hairs intermixed with several dark-brown longer and stouter hairs on each side. Labrum 0.9 times length of clypeus. Antenna composed of scape, pedicel and nine flagellomeres, dark brown except scape and pedicel yellow or dark yellow, and base of first flagellomere whitish-yellow. Maxillary palp consisting of five segments, grayish except third segment brownish-black; proportional lengths of third, fourth, and fifth segments 1.0:0.8:1.4; third segment ( Fig. 1 A) much enlarged; sensory vesicle ( Fig. 1 A) elongate, 0.6 times length of third segment, with large elliptical opening; numerous minute papillae on each inner side of opening. Maxillary lacinia with 8 inner and 15 outer teeth. Mandible with 18–20 inner teeth and lacking outer teeth. Cibarium with 32 minute conical processes with pointed apices ( Fig. 1 B) as well as numerous minute spinous processes near lower margin. Thorax. Scutum yellowish-brown except anterolateral calli ochreous, each shoulder, wide portion along each lateral margin and prescutellar area medium brown, with three medium brown narrow longitudinal vittae (one medial, two submedial), thinly whitish-gray pruinose with three dark narrow nonpruinose longitudinal vittae (one medial, two submedial) when illuminated at certain angles, and densely covered with whitish-yellow recumbent hairs intermixed with several dark-brown upright hairs on prescutellar area. Scutellum ochreous, with several dark brown upright hairs and whitish-yellow shorter hairs. Postnotum dark brown, whitish-gray pruinose and shiny when illuminated at certain angles and bare. Pleural membrane bare. Katepisternum longer than deep, dark brown, and bare. Legs. Foreleg: coxa and trochanter yellow; femur light brown with apical cap dark brown, though inner surface dark yellow; tibia dark brown except median large portion of outer surface medium brown, and basal tip yellow; tarsus brownish-black to black; basitarsus slender, slightly dilated, 7.7 times as long as its greatest width. Midleg: coxa medium brown except posterolateral surface brownishblack; trochanter yellow; femur yellow to light brown with apical cap dark brown; tibia dark brown except median large portion light to medium brown and basal tip yellow; tarsus dark brown to black. Hind leg: coxa dark yellow except posterolateral surface light brown; trochanter yellow; femur dark yellow to light brown (though inner surface widely yellowish) except basal one-fourth yellow and apical cap dark brown; tibia dark brown except base yellow, and median large portion medium brown; tarsus dark brown to brownish-black except basal two-thirds of basitarsus grayish-white (though base dark brown), and basal half of second tarsomere yellowish-white; basitarsus ( Fig. 1 C) nearly parallel-sided, 6.4 times as long as its greatest width, and 0.7 and 0.6 times as wide as hind tibia and femur, respectively; calcipala well developed, 1.4 times as long as width at middle, and 0.6 times as wide as greatest width of basitarsus; pedisulcus well developed. Claw ( Fig. 1 D) with large basal tooth 0.48 times length of claw. Wing. Length 2.6 mm. Costa with two parallel rows of black spinules and light-brown hairs except on subbasal portion near humeral cross vein with patch of whitish hairs. Subcosta with light-brown hairs except apical one-third bare. Basal portion of radius fully haired; R1 with black spinules and light-brown hairs; R2 with lightbrown hairs. Hair tuft on stem vein and base of radial vein black. Basal cell absent. Halter . Whitish except base grayish. Abdomen. Basal scale light brown, with fringe of whitish-yellow long hairs. Dorsal surface of abdomen dark brown to brownish-black except segment 2 light brown though basal one-third pale, moderately covered with whitish-yellow short hairs mixed with dark-brown short hairs, and dark-brown longer hairs on posterior segments; tergites 2 and 6–8 somewhat shiny (in addition, tergite 5 partially and slightly shiny) when illuminated at certain angles; ventral surface of segment 7 with large sternal plate medially. Genitalia. Sternite 8 ( Fig. 1 E) wide, bare medially but furnished with 19–21 long hairs and few short hairs on each side. Ovipositor valves ( Fig. 1 E) tonguelike, rounded posteromedially, thin, membranous except inner margin narrowly sclerotized, densely covered with microsetae interspersed with 5–9 short hairs; inner margins moderately concave medially, and narrowly separated from each other except apices touching each other. Genital fork ( Fig. 1 F) of inverted Y-form, with well sclerotized stem and relatively wide arms; each arm with lateral plate bearing unpigmented lobe-like projection directed posteromedially and distinct black narrow projection directed anterodorsally. Paraproct in ventral view ( Fig. 1 G) rounded, somewhat longer than its greatest width; anteromedial surface nearly transparent, with four or five sensilla; paraproct in lateral view ( Fig. 1 H) slightly protruding ventrally beyond ventral margin of cercus, and with 32 short to long hairs on ventral and lateral surfaces. Cercus in lateral view ( Fig. 1 H) rounded posteriorly, 0.7 times as long as basal width. Spermatheca ( Fig. 1 I) nearly ovoidal, 1.1 times as long as its greatest width, strongly sclerotized except small area around juncture with duct and duct itself unsclerotized, with distinct reticulate surface pattern and without internal setae; main spermathecal duct narrow, somewhat narrower than both accessory ducts.

Male. Body length 2.6–3.0 mm. Head. Slightly wider than thorax. Holoptic; upper eye bright vermilion, consisting of large facets in 17 or 18 vertical columns and 18 or 19 horizontal rows. Clypeus brownish-black, not shiny, whitish pruinose, moderately covered with yellow hairs intermixed with dark-brown longer hairs. Antenna composed of scape, pedicel and nine flagellomeres, light brown except scape and pedicel medium brown, and base of first flagellomere yellowish-white; first flagellomere elongate, 2.3 times length of second one. Maxillary palp composed of five segments, and grayish except third segment brownish-black; proportional lengths of third, fourth, and fifth segments 1.0:1.0:1.7; third segment ( Fig. 2 A) of moderate size; sensory vesicle ( Fig. 2 A) small, ellipsoidal, 0.2–0.3 times length of third segment, with small opening. Thorax. Scutum medium brown except anterolateral calli ochreous, each shoulder, wide portion along each lateral margin and prescutellar area dark brown, with three medium to dark-brown narrow longitudinal vittae (one medial, two submedial), thinly whitishgray pruinose except three dark narrow longitudinal vittae (one medial, two submedial) non-pruinose when illuminated at certain angles, and densely covered with golden-yellow recumbent hairs intermixed with several dark-brown upright hairs on prescutellar area. Other characters of thorax as in female. Legs. Color and shape almost as in female except following characters: fore trochanter light brown except base yellow; hind coxa light brown; hind basitarsus mostly grayish though more blackish near base and apex; basal half of hind second tarsomere grayish; fore basitarsus slender, 9.1–9.2 as long as greatest width; hind basitarsus ( Fig. 2 B) enlarged, spindle-shaped, 4.4–4.8 times as long as its greatest width, and 0.9 and 0.8 times as wide as greatest widths of hind tibia and femur, respectively; calcipala well developed, 1.3–1.4 times as long as width in middle, and 0.4 times as wide as greatest width of basitarsus; pedisulcus moderately developed. Wing. As in female except subcosta bare in one male, one or two hairs in one male, and seven hairs on each wing of one male; length 2.6 mm. Halter . Grayish ochreous. Abdomen. Basal scale brownish-black, with fringe of light to dark-brown long hairs. Dorsal surface of abdominal segments entirely dark brown to brownish-black except base of segment 2 whitish, not shiny, and moderately covered with brassy short hairs interspersed with light brown to black short to long hairs. Genitalia. Coxite in ventral view ( Fig. 2 C) rectangular, 1.9 times as long as its greatest width. Style in ventral view ( Fig. 2 C) short, 0.7 times length of coxite, bent inwardly, with outer margin angled medially and with short stout spine apically; style in medial view ( Fig. 2 D) gently curved dorsally and nearly parallel-sided; style in ventrolateral view ( Fig. 2 E) broad, nearly parallel-sided from base to slightly beyond middle, then abruptly tapered apically; style in caudal view ( Fig. 2 F) tapered inward, with round apex. Ventral plate in ventral view ( Fig. 2 C) lamellate, subquadrate, 0.4 times as long as its greatest width, well sclerotized except anteromedian portion weakly sclerotized, with posterior margin slightly concave submedially, and moderately covered with fine short setae on ventral surface except most of lateral portions widely bare; arm ( Fig. 2 C) short, slender, directed anteriorly; ventral plate in lateral view ( Fig. 2 G) with ventral margin nearly straight and arm short; ventral plate in caudal view ( Fig. 2 H) with dorsal margin moderately concave, with fine short setae centrally on posterior surface. Median sclerite ( Fig. 2 G, I) simple, club-shaped, narrow and strongly sclerotized except apical portion weakly sclerotized or transparent. Paramere ( Fig. 2 J) with six or seven hooks decreasing in length toward apex, of which four hooks are long or medium-long and darkened and rests are small and short (only three or four distinct hooks are recognizable when paramere is viewed caudally). Aedeagal membrane ( Fig. 2 K) moderately covered with microsetae; dorsal plate ( Fig. 2 K) of broad horizontal band form with medial portion somewhat expanded anteriorly, thin, weakly sclerotized. Ventral surface of tenth segment ( Fig. 2 L, M) without any distinct hairs near each posterolateral corner. Cercus ( Fig. 2 L, M) small, rounded and encircled by 8–13 unbranched hairs.

Pupa. Body length 3.5 mm. Head. Integument yellowish brown, densely covered with round tubercles except most of middle portion of face bare; antennal sheaths bare; frons with one minute seta in female pupa ( Fig. 3 A) or one minute seta and one short seta ( Fig. 3 B) or two short setae ( Fig. 3 C) in male pupae near lateral margin on each side; face with one long unbranched somewhat stout trichome with coiled apex ( Fig. 3 D) on each side. Thorax. Integument dark yellow to yellowish brown, densely covered with round tubercles, with three long somewhat stout trichomes with coiled apices ( Fig. 3 E) mediodorsally, two trichomes (one long, somewhat stout, with coiled apex, and one medium-long, slender, with uncoiled apex) ( Fig. 3 F) anterolaterally, one medium-long somewhat stout trichome with uncoiled apex ( Fig. 3 G) mediolaterally, and three short slender trichomes with uncoiled apices ( Fig.

3H) ventrolaterally on each side; all trichomes unbranched. Gill ( Fig. 3 I–L) with six long thread-like slender filaments, arranged as 2+2+2 filaments in three pairs (inner dorsal, outer dorsal, and ventral), inner dorsal pair almost sessile, outer dorsal pair with short stalk, and ventral pair with short to medium-long stalk 0.4–1.0 times length of interspiracular trunk; common basal stalk short, 0.5–0.6 times length of interspiracular trunk; all filaments tapered toward tip, two filaments of inner dorsal pair longest (3.9–5.2 mm), nearly as long as or slightly longer than dorsal filament of outer dorsal pair (3.6–5.0 mm), followed by ventral filament of outer dorsal pair which is variable in length (2.0–4.0 mm) (in one pupa, it measures 2.0 mm, much shorter than outer filament of ventral pair, which is usually shortest, as in Fig. 3 I) and two filaments of ventral pair (3.0– 3.7 mm), though inner filament slightly longer than outer filament; relative thickness of two filaments of inner dorsal pair, dorsal and ventral filaments of outer dorsal pair and inner and outer filaments of ventral pair 1.0:1.0:0.7–0.8:0.7–0.8:0.7–0.8:0.7; all filaments grayish to blackish-brown and their cuticular surface with welldefined annular ridges and furrows though becoming less distinct near apex, and densely covered with minute tubercles. Abdomen. Dorsally, all segments pigmented (segments 1 and 2 grayish brown, and others yellowish except segment 3 partially grayish brown), and densely and elaborately covered with weakly-defined tiny tubercles; segment 1 with one medium-long slender seta ( Fig. 3 L) and two minute setae medially ( Fig. 3 M) on each side; segment 2 with one medium-long slender seta (similar to Fig. 3 L), five short spinous setae ( Fig. 3 N) near posterior margin and one minute seta (similar to Fig. 3 M) submedially near anterior margin, on each side; segments 3 and 4 each with four hooks and one short spinous seta (similar to Fig. 3 N) near posterior margin, and one minute seta (similar to Fig. 3 M) submedially near anterior margin, on each side; segment 5 with spine-combs directed backward ( Fig. 3 O) on each side or only on one side, and with four short setae near posterior margin on each side; segments 6–8 each with spine-combs directed backward in transverse row, comb-like groups of minute spines, and two short setae, on each side; segment 9 with pair of distinct horn-shaped terminal hooks, comb-like groups of minute spines near anterior margin and minute tubercles scattered medially ( Fig. 3 P); all setae unbranched. Ventrally, segments 3–8 each with comb-like groups of minute spines; segment 4 with four short unbranched slender setae, of which one somewhat spinous, on each side; segment 5 with pair of bifid hooks submedially and few short slender setae on each side; segment 6 with pair of bifid inner and unbranched outer hooks and few slender short setae on each side; segment 7 with bifid inner hook (lacking outer hook) and few slender short setae on each side. Cocoon ( Fig. 3 Q). Wall-pocket-shaped, compactly woven without open spaces in web, thin, with anterior margin somewhat thickly woven, without any bulge or projection on anterodorsal margin, and extending ventrolaterally; individual threads invisible; 4.2–4.3 mm long by 2.9–3.8 mm wide.

Mature larva. Body length 6.0–7.0 mm. Body whitish yellow, though parts of thoracic segments and abdominal segments 1 and 2 (and also 3 and 4 in a few larvae) light grayish, with color markings as follows: thoracic segment 1 encircled with vermilion transverse band though disconnected dorsomedially and ventromedially,which is distinctive in one larva and faint in eight other larvae; thoracic segment 3 faintly with vermilion spot on ventral surface; and abdominal segments 2–8 with purplish-brown markings, i.e., segment 2 with small spot on each lateral surface in two larvae, segments 3 and 4 each with one large dorsolateral spot extending and tapering laterally on each side, of which spot on segment 4 is divided into two spots in one larva or three spots in one larva, segments 5–8 each pigmented dorsally and dorsolaterally, though unpigmented dorsomedially to varying extent and leaving pair of small dorsal spots near anterior margin each on segments 5 and 6, and segments 5 and 6 each with one faint narrow mediolongitudinal band and one faint narrow transverse band on ventral surface. Cephalic apotome ( Fig. 4 A) yellow though narrow area along posterior margin darkened, with distinct head spots, of which posterolateral spots fused with darkened area along posterior margin. Lateral surface of head capsule yellow except posterodorsal area along posterior margin darkened, and eye-spot region white; eyebrow distinct, with one dark round spot medially; two large spots and one small spot near posterior margin and two small spots below eye-spot region markedly positive; dorsal large spot fused with darkened posterodorsal area of lateral surface. Ventral surface of head capsule ( Fig. 4 B) yellow with wide light to dark-brown medial area (except narrow area near posterior margin of hypostoma) and dark brown basal area on each side of postgenal cleft; one horizontal and two round spots on each side of postgenal cleft markedly positive. Cervical sclerite ( Fig. 4 A) composed of two small dark elliptical pieces, not fused to occiput, widely separated medially from each other. Antenna consisting of three segments and apical sensillum, much longer than stem of labral fan; proportional lengths of first, second, and third segments 1.0:1.1:0.7. Labral fan with 40–44 main rays. Mandible ( Fig. 4 C) with mandibular serrations consisting of two teeth (one large and one small); large tooth making nearly right angle with mandible on apical side; comb-teeth composed of three teeth shortened from first to third; supernumerary serrations absent. Hypostoma ( Fig. 4 D) with nine apical teeth in row; median and corner teeth well developed; middle tooth of three intermediate teeth on each side shortest; lateral margin nearly smooth or with one or two weakly developed teeth apically; four to six hypostomal bristles lying slightly divergent posteriorly from lateral margin on each side. Postgenal cleft ( Fig. 4 B, E) small, variable in shape, quadrate or rounded or somewhat pointed apically, 0.6–0.7 times length of postgenal bridge. Thoracic cuticle bare; histoblast of pupal gill with six filaments arising from short common basal stalk. Abdominal cuticle bare except both sides of anal sclerite moderately covered with simple colorless setae. Rectal scales present. Rectal organ compound, each of three lobes with several finger-like secondary lobules (The exact number of secondary lobules was uncountable because the rectal organs were withdrawn in all larvae). Anal sclerite of usual X-form, with anterior arms 1.1–1.3 times length of posterior ones, broadly sclerotized at basal juncture; sensilla absent on and just posterior to basal juncture area; accessory sclerite absent. Last abdominal segment much expanded ventrally forming large ventral papillae. Posterior circlet with 72–74 rows of up to 14 hooklets per row.

Type specimens. HOLOTYPE: Female (with associated pupal exuviae and cocoon) (preserved in 80% ethanol), reared from pupa, collected from a small stream (width 0.5–1.5 m, depth 10–20 cm, water temperature 15.0˚C, partially shaded, altitude 1,540 m) moderately flowing in hilly coffee plantations about 100 m (left side) from the stream of the type locality of S. (N.) phami sp. nov., Langbiang, Lac Duong District, Lam Dong Province, Vietnam, 25-IV-2014, by H. Takaoka, M. Sofian-Azirun and Z. Ya’cob. PARATYPES: One female, three males (with associated pupal exuviae and cocoon) (preserved in 80% ethanol), all reared from pupae, and nine mature larvae (all preserved in acetic alcohol), same data as those of holotype.

Biological notes. The pupae and larvae of this new species were collected from wide leaves and narrow stalks of grasses. Associated species were S. ( Gomphostilbia ) sp. ( Simulium asakoae species-group), S. (N.) phami sp. nov. and S. (Simulium) tani Takaoka and Davies. The habit of biting of the females remains unknown.

Etymology. The species name langbiangense refers to the name of the area, Lang Biang, where this new species was collected.

Remarks. Simulium (N.) langbiangense sp. nov. is readily assigned to the S. feuerborni species-group, by the combination of the following characteristics: male genitalia with a simple lamellate ventral plate ( Fig. 2 C), a short inwardly-twisted style ( Fig. 2 E), a simple narrow median sclerite ( Fig. 2 I) and several parameral hooks ( Fig. 2 J); the pupal gill with six long thread-like filaments per side ( Fig. 3 I); and the larval head with a small short postgenal cleft ( Fig. 4 B).

The female of S. (N.) langbiangense sp. nov. is distinctive among the members of the S. feuerborni speciesgroup in having the sensory vesicle with a large elliptical opening ( Fig. 1 A).

The pupa of this new species is also remarkable in this species-group in having the short common basal stalk, 0.5–0.6 times the length of the interspiracular trunk ( Fig. 3 K). Simulium (N.) lepnevae (Rubtsov) from Tadzhikistan ( Rubtsov 1956), S. (N.) chiangklangense Takaoka & Choochote from Thailand ( Takaoka & Choochote 2005), and S. (N.) izuense Takaoka & Saito from Japan ( Takaoka & Saito 2005), also have the short common basal stalk of the pupal gill filaments. However, all three species differ from S. (N.) langbiangense sp. nov. in the pupa by the ventral paired filaments with an extremely short stalk.

The mature larva of this new species has reddish-brown markings on the abdomen as in most known species of the S. feuerborni species-group, but appears to be distinguished from other species by the relatively larger postgenal cleft ( Fig. 4 B), which is 0.6–0.7 times as long as the postgenal bridge. The length ratio of the postgenal cleft against the postgenal bridge of most species of this group is 0.3–0.5 except S. (N.) subratai Takaoka, Thapa & Henry , described from India, which has a relatively larger postgenal cleft (the ratio is 0.7) ( Takaoka et al. 2011). However, S. (N.) subratai is distinguished from this new species by lacking purplish-brown markings on the larval abdomen.

Figures

FIGURE 1. Female of Simulium (Nevermannia) langbiangense sp. nov. A, third segment of right maxillary palp with sensory vesicle bearing enlarged opening (front view); B, middle portion of cibarium with numerous minute processes; C, basitarsus and second tarsomere of left hind leg (outer view); D, claw; E, eighth sternite and ovipositor valve (ventral view; left half); F, genital fork (ventral view); G & H, right paraprocts and cerci (G, ventral view; H, lateral view); I, spermatheca. Scale bars 0.1 mm for C; 0.02 mm for A, B & E – I; 0.01 mm for D.

FIGURE 2. Male of Simulium (Nevermannia) langbiangense sp. nov. A, third segment of left maxillary palp with sensory vesicle (front view); B, basitarsus and second tarsomere of left hind leg (outer view); C, coxites, styles and ventral plate (ventral view); D & E, right styles (D, medial view; E, ventrolateral view); F, right coxite and style (caudal view); G, ventral plate and median sclerite (lateral view); H, ventral plate (caudal view): I, median sclerite (ventral view); J, left paramere with four distinct hooks and three small hooks (mediocaudal view); K, aedeagal membrane and dorsal plate (caudal view); L & M, right half of tenth abdominal segments with cerci (L, lateral view; M, caudal view). Scale bars. 0.1 mm for B; 0.02 mm for A & C – M.

FIGURE 3. Pupa of Simulium (Nevermannia) langbiangense sp. nov. A, minute seta on frons in female pupa (front view; left side); B, minute seta and short seta on frons in one male pupa (front view; left side); C, two short setae on frons in another male pupa (front view; left side); D, facial trichome; E – H, thoracic trichomes (E, dorsomedial; F, anterolateral; G, mediolateral, H, ventrolateral); I, right gill filaments (dorsal view); J, basal portion of right gill (dorsal view); K, basal portion of left gill and anterior portion of thorax with interspiracular trunk shown in broken like (outer view); L, medium-long seta on dorsal surface of abdominal segment 1; M, minute seta on dorsal surface of abdominal segment 1; N, short spinous seta on dorsal surface of abdominal segment 2; O, spine-comb on left side of abdominal segment 5; P, dorsal surface of abdominal segment 9 with terminal hook, comb-like groups of minute spines directed posteriorly near anterior margin and minute tubercles scattered medially (left half); Q, cocoon (dorsal view). Scale bars. 1.0 mm for Q; 0.2 mm for I; 0.1 mm for J & K; 0.02 mm for D – G, O & P; 0.01 mm for A – C, L – N & H.

FIGURE 4. Mature larva of Simulium (Nevermannia) langbiangense sp. nov. A, head capsule (dorsal view); B, head capsule with small postgenal cleft (ventral view); C, apical portion of mandible; D, hypostoma (ventral view); E, postgenal cleft (ventral view). Scale bars. 0.1 mm for A, B & E; 0.02 mm for C & D.