Simulium (Nevermannia) ledangense

Ya’Cob, Zubaidah, Takaoka, Hiroyuki & Sofian-Azirun, Mohd, 2014, Simulium ledangense, a new species of the Simulium feuerborni species-group of the subgenus Nevermannia (Diptera: Simuliidae) from Mount Ledang, Peninsular Malaysia, Zootaxa 3881 (3), pp. 228-236 : 228-235

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

Female (n = 3). Body length 2.1 to 2.5 mm. Head. Slightly narrower than thorax. Frons dark brown, thinly grey pruinose, densely covered with yellow hairs and several dark longer hairs along each lateral margin. Frontal ratio 1.81–1.90:1.00:2.75–2.96. Frons:head ratio 1.00:4.76–4.79. Clypeus dark brown, whitish-gray pruinose and covered with whitish-yellow hairs and several dark longer hairs on lower half and bare in middle. Labrum 0.84–1.00 times length of clypeus. Antenna composed of scape, pedicel and 9 flagellomeres, dark brown except scape, pedicel and base of first flagelomere yellow; first flagellomere 2.50–2.62 times length of second flagellomere. Maxillary palp consisting of 5 segments, proportional lengths of third, fourth, and fifth segments 1.00:0.78–0.93:1.47–1.61; third segment much enlarged, sensory vesicle elongate ( Fig. 1 A), 0.64 times length of third segment, with medium-sized opening. Maxillary lacinia with 6 or 8 inner teeth and 13 or 14 outer teeth. Mandible with 19–20 inner and lacking outer teeth. Cibarium ( Fig. 1 B) with 40–44 dark minute conical processes with pointed apices as well as numerous minute spinous processes near lower margin. Thorax. Scutum light to medium brown except anterolateral calli yellow, two submedian longitudinal vittae and narrow portion along lateral margin and prescutellar area dark brown, white pruinose except 3 longitudinal vittae (1 narrow median, 2 little wider submedian) and slightly shiny when illuminated at certain angles; scutum covered with yellow short hairs and several dark-brown longer hairs on prescutellar area. Scutellum dark yellow, slightly shiny when illuminated at certain angles, with whitish-yellow hairs and dark longer hairs. Postnotum medium to dark brown, thinly gray pruinose and slightly shiny when illuminated at certain angles. Pleural membrane and ketepisternum medium brown, thinly grey pruinose and slightly shiny when illuminated at certain angles and bare; Halter . White except basal portion light brown. Legs. Foreleg: coxa yellow and trochanter yellow to light brown; femur yellow to light brown except apical cap dark brown; tibia dark brown except median large portion of outer surface light brown and basal tip yellow; tarsus dark brown. Basitarsus slender, slightly dilated, 7.64–7.73 times as long as its greatest width. Midleg: coxa medium brown except posterolateral surface dark brown; trochanter yellow; femur yellow to light brown except apical cap dark brown; tibia dark brown except medium large portion light brown; tarsus dark brown except fourth segment light brown with basal portion lighter. Hind leg: coxa light to median brown; trochanter yellow; femur yellow to light brown except apical cap dark brown; tibia ( Fig. 1 C) dark brown except median large portion of outer surface medium brown and basal tip yellow; tarsus dark brown except basal two-thirds of basitarsus ( Fig. 1 D) whitish-yellow though basal tip dark brown and basal half of second tarsomere whitish-yellow; basitarsus 7.64–7.73 times as long as it greatest width; basitarsus parallel-sided, 6.00–6.33 times as long as width, and 0.77 and 0.58–0.67 times as wide as grestest width of tibia and femur, respectively. Wing. Length 2.2 mm. Costa with two parallel rows of dark-brown spinules as well as dark-brown hairs except sub-basal patch of hairs yellow. Subcosta with dark-brown hairs except near apex bare. Basal portion of radius fully haired; R1 with dark brown spinules and hairs; R2 with dark-brown hairs. Hair tuft on base of radial vein dark brown. Basal medial cell absent. Halter . Entirely dark brown. Abdomen. Basal scale light brown with fringe of whitish-yellow long hairs. Dorsal surface of abdomen medium to dark brown; tergites of segment 2 and 5 to 7 shiny. Abdomen whitish-yellow short hairs and brownish-black short hairs mixed with dark-brown long hairs. Genitalia. Sternite 8 wide ( Fig. 1 E), bare medially and furnished with 14–21 medium to long hairs and few short hairs on each side. Ovipositor valves ( Fig. 1 E) triangular (through posteromedial corner rounded), thin, membranous except inner margin narrowly sclerotized, densely covered with microsetae interspersed with 6 or 7 short hairs; inner margin sinuous, narrowly separated from 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 triangular lobe-like projection directed medioposteriorly and short narrow stout projection directed anterodorsally. Paraproct ( Fig. 1 G) in ventral view subquadrate, slightly longer than its greatest width; anteromedial surface nearly transparent, with 5–10 sensilla; paraproct in lateral view ( Fig. 1 H) somewhat protruded ventrally beyond ventral margin of cercus, and with 21–24 medium to long hairs on ventral and lateral surfaces. Cercus in lateral view ( Fig. 1 H) rounded posteriorly, short, 0.62 times as long as basal width. Spermatheca ( Fig. 1 I) nearly ovoidal, 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 (n = 5). Body length 2.1–2.5 mm. Head. Slightly wider than thorax. Holoptic; upper eye consisting of large facets in 13 or 14 vertical columns and 15 horizontal rows. Clypeus dark brown, gray pruinose when illuminated at certain angles, moderately covered with yellow hairs intermixed with dark-brown longer hairs except medial portion widely bare. Antenna medium brown except scape and pedicel dark yellow to light brown and base of first flagellomere whitish-yellow. Maxillary palp composed of 5 segments, light dark except third segment dark brown. Proportional length of third, fourth and fifth segments 1.00:0.96–1.04:1.79–1.93; third segment ( Fig. 2 A) of moderate size; sensory vesicle ( Fig. 2 A, B) small, ellipsoidal, 0.16–0.18 times length of third segment. Thorax. Scutum light to medium brown except anterolateral calli yellow, submedian longitudinal vittae and narrow portion along lateral margin and prescutellar area dark brown, whitish pruinose except 3 longitudinal vittae (1 narrow median, 2 little wider submedian) non-pruinose and slightly shiny when illuminated at certain angles, densely covered with yellow short hairs and several dark brown longer hairs on prescutellar area. Scutellum dark yellow, slightly shiny when illuminated at certain angles, with whitish-yellow hairs and dark longer hairs. Postnotum medium to dark-brown, thinly gray pruinose and slightly shiny when illuminated at certain angles. Pleural membrane and ketepisternum medium brown, thinly gray pruinose, slightly shiny when illuminated at certain angles and bare. Legs. Foreleg: coxa yellow; trochanter yellow with somewhat dark portion on outer surface; femur dark yellow to light brown except apical cap dark brown; tibia dark brown though median large area on outer surface light to median brown; tarsus entirely brownish-black; basitarsus slender, slightly dilated, 7.8–8.8 times as long as its greatest width. Midleg: coxa medium brown though dark brown on posterolateral surface; trochanter yellow with somewhat dark portion on outer surface; femur dark yellow to light brown with apical cap dark brown; tibia dark brown with median large portion; tarsus dark brown. Hind leg: coxa light to medium brown; trochanter yellow; femur dark yellow to light brown with apical cap dark brown; tibia dark brown with extreme base dark yellow and median large portion light to medium brown; tarsus medium brown except base and apical portion of basitarsus dark brown, and basal half of basitarsus and second tarsomere light brown; basitarsus ( Fig. 2 C) enlarged, spindle-shaped, 4.46–4.64 times as long as its greatest width, and 0.96–1.00 and 0.89–0.93 times as wide as greatest widths of hind tibia and femur, respectively; calcipala well developed, nearly as long as basal width and 0.37 times as wide as greatest width of basitarsus; pedisulcus moderately developed. Wing. As in female except subcosta bare or 1–7 hairs; length 2.4–2.5 mm. Halter . Entirely dark brown. Abdomen. Basal scale brownish-black, with fringe of dark and pale long hairs. Dorsal surface of abdominal segments entirely dark brown to brownish-black, and moderately covered with light brown to black short to long hairs mixed with brassy short hairs. Segments 2–8 each with pair of white pruinose dorsolateral patches which are shiny when illuminated at certain angles. Genitalia. Coxite in ventral view ( Fig. 2 D) rectangular, 1.78 times as long as its greatest width. Style in ventral view ( Fig. 2 D) short, 0.70 times as long as coxite, bent inwardly, with outer margin angled medially and with short stout spine apically; style in medial view gently curved dorsally and nearly parallel-sided; style in ventrolateral view ( Fig. 2 E) broad, nearly parallel-sided from base to little beyond middle, then abruptly tapered apically; style in end view tapered inward, with round apex. Ventral plate in ventral view ( Fig. 2 D) lamellate, subquadrate, 0.52 times as long as its greatest width, well sclerotized except anteromedian portion unsclerotized, with posterior margin slightly concave medially and submedially, and moderately covered with fine short setae on ventral surface except lateral portion widely bare; arms short, slender, directed anteriorly; ventral plate in lateral view ( Fig. 2 F) with ventral margin nearly straight and arm short, tapered anterodorsally; ventral plate in caudal view ( Fig. 2 G) with dorsal margin markedly concave, with fine short setae centrally on posterior surface. Median sclerite ( Fig. 2 H) simple, club-shaped, narrow and strongly sclerotized except weakly sclerotize apical portion. Paramere ( Fig. 2 I) with 5 or 6 hooks decreasing in length toward apex. Aedeagal membrane ( Fig. 2 J) moderately covered with minute setae; dorsal plate triangular in shape, thin, weakly sclerotized. Ventral surface of segment 10 without any distinct hairs near each posterolateral corner. Cercus ( Fig. 2 K, L) small, rounded and encircled by 5–9 simple hairs.

Pupa (n = 8). Body length 3.0 mm. Head. Integument yellow to light brown, moderately covered with round tubercles of various sizes on frons and sparsely covered with similar tubercles of various sizes on lateral surface of face; antennal sheath bare; frons with pair of short minute trichomes on each side; face with 1 medium-long unbranched trichome on each side. Thorax. Integument yellow to light brown, moderately covered with round tubercles of different sizes on dorsal and lateral surfaces of anterior half and sparsely covered with smaller ones on dorsal surface of posterior half; thorax on each side with 3 long trichomes with coiled apices mediodorsally ( Fig. 3 G), 2 trichomes (1 long with coiled apex, 1 medium-long with uncoiled apex) anterolaterally, 1 medium-long trichome with uncoiled apex mediolaterally and 3 short trichomes with uncoiled apices ventrolaterally ( Fig. 3 H), all trichomes unbranched. Gill ( Fig. 3 A, B) with 6 long thread-like slender filaments, arranged as [1 + (2+ 1)] + 2 filaments in vertical plane from dorsal to ventral; common basal stalk of moderate length, subequal in length to interspiracular trunk, and stalk of ventral pair 0.52 times total length of ventral paired filaments including common basal stalk (varying from 1.05 mm to 1.50 mm in individual pupae); stalk of middle pair short; all filaments tapered toward tip, subequal in length (4.4–5.5 mm) and thickness to one another except 2 filaments of ventral pair somewhat shorter (3.5–4.3 mm) and slightly thinner than others; cuticular surface with distinct annular ridges and furrows though becoming less distinct near apex, and densely covered with minute tubercles. Abdomen. Dorsally, all segments weakly yellowish, moderately and neatly covered with minute tubercles; segment 1 with 1 longmedium slender setae on each side; segment 2 with 1 hair-like seta and 5 short setae, of which 4 stout and spinous and 1 slender on each side; segments 3 and 4 each with 4 hooks and 1 very short spinous seta on each side; segment 5 bare; segments 6–8 each with spine-combs directed backwards in transverse row and comb-like group of minute spines on each side; segment 9 with pair of distinct conical terminal hooks as well as comb-like groups of minute spines. Ventrally, segments 3–8 with comb-like groups of minute spines; segment 4 with 1 simple hooklet and few short unbranched slender setae on each side; segment 5 with pair of bifid hooks submedially and few very short slender setae on each side; segments 6 and 7 each with pair of bifid inner and unbranched outer hooks and few slender very short setae on each side. Cocoon. Simple, wall-pocket shaped, compactly woven without open spaces in web, with anterior margin thickly woven, without anterodorsal projection; individual threads invisible; 3.7 mm long by 2.5 mm wide.

Mature larva (n = 3). Body length 5.1 mm. Body ( Fig. 3 C) creamy, with reddish-brown markings on abdominal segments 3–4. Cephalic apotome whitish-yellow to yellow; head spots very faintly positive. Lateral surface of head capsule yellow except eye-spot region white; eyebrow indistinct though 1 dark sport present medially; 2 large spot and 1 small spot near posterior margin and 2 small spots below eye-spot region faintly to moderately positive. Ventral surface of head capsule ( Fig. 3 D) yellow except medial large portion darkened, and basal area on each side of postgenal cleft dark brown; 1 elongate and 1 round spot on each side of postgenal cleft markedly positive. Cervical sclerite compose of 2 faint small elliptical pieces, not fused to occiput, widely separated medially from each other. Antennae consisting of 3 articles and apical sensilium, much longer than stem of labran fan; proportional lengths of first, second, and third articles 1.00:0.97:0.64. Labran fan with 19 main rays. Mandible ( Fig. 3 F) with serrations consisting of 2 teeth (1 large and 1 small); large tooth at obtuse angle with mandible on apical side; comb-teeth composed of 3 teeth shortened from first to third; supernumerary serration absent. Hypostoma ( Fig. 3 E) with 9 apical teeth in row; median and corner teeth well developed; lateral margin nearly smooth except apical portion with 2 or 3 weakly developed teeth; 3 or 4 hypostomal bristles lying slightly divergent posteriorly from lateral margin on each side. Postgenal cleft small, 0.73 times length of postgenal bridge. Thoracic cuticle bare. Histoblast of pharate pupal gill with 6 slender thread-like filaments. Abdominal cuticle bare except both sides of anal sclerite moderately covered with unbranched colorless setae and each lateral surface just above ventral papilla also sparsely covered with unbranched colorless setae. Rectal scales minute, colorless. Secondary lobules of rectal papillae uncountable. Anal sclerite of usual X-form, with anterior arms nearly as long as 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 ventrolaterally forming large ventral papilla on each side. Posterior circlet with 82 rows of up to 18 hooklets per row.

Type specimens. HOLOTYPE: male (with associated pupal exuviae and coccon) (preserved in 80% ethanol), reared from pupa, manually collected from a slow running small stream (width 0.5–0.6 m, depth 12 cm, water temperature 18.9°C, completely shaded, altitude 1000 m, 02°22′45.6″N, 102°36´36.9”E), Mount Ledang, or originally known as Mount Ophir National Park, located in Ledang District, Johor Province, Peninsular Malaysia, 11. III. 2013, by Z. Ya’cob and M. Sofian-Azirun. Paratypes: 5 males, 3 females (with associated pupal exuviae and coccons), 1 male without associated pupal exuviae and coccon, and 3 mature larvae, preserved in 80% ethanol, same data and date as those of holotype.

Biological notes. The pupae and larvae of this new species were collected together with S. (Gomphostilbia) roslihashimi Takaoka & Sofian-Azirun. The habit of biting of the female remains unknown.

Etymology. The species name ledangense refers to the name of the mountain, Mount Ledang, where this new species was collected.

Remarks. Simulium (N.) ledangense sp. nov. is readily assigned to the S. feuerborni species-group redefined by Takaoka (2003) by the combination of the following characteristics: male genitalia with a simple lamellate ventral plate, a short inwardly-twisted style, a simple narrow median sclerite and several parameral hooks ( Fig. 2 D–H); pupal gill with six long thread-like filaments per side ( Fig. 3 A, B); and larval head with a small short postgenal cleft ( Fig. 3 D).

The pupa of this new species is easily distinguished from those of known species within this species-group by having a very long stalk of the ventral paired gill filaments which is almost five times longer than the interspiracular trunk ( Fig. 3 A, B) and by the unique arrangement of gill filaments (i.e., arranged as [1+ (1+2)] +2 filaments from dorsal to ventral, of which two individual filaments arise close together with the stalk of the middle pair). The pupa of this new species is similar to that of S. (N.) qiongzhouense Chen, Zhang & Yang from China in having a very long stalk of ventral paired gill filaments. However S. (N.) qiongzhouense is distinguished from S. (N.) ledangense sp. nov. by the different arrangement of the gill filaments: i.e., 6 filaments in 3 pairs (2 + 2 + 2), male upper-eye enlarged facets in 15 vertical columns and 16 horizontal rows, and paramere with three hooks.

Simulium (N.) feuerborni , the only known species of the S. feuerborni species-group in Peninsular Malaysia, is distinguished from S. (N.) ledangense by having the cocoon with an anterodorsal projection and the ventral paired gill filaments with a short stalk. In Sabah, S. (N.) fuscinervis Edwards, 1933 , which was described from a male ( Edwards 1933), differs from the new species by having the reduced number of large eye facets, i.e., ca 12 vertical columns and 12–14 horizontal rows, and paramere with 10 hooks; another Sabah species, S. (N.) borneoense Takaoka, 2001 , differs by having four pupal gill filaments in place of six gill filaments.

The simple coccon and the long stalk of the ventral pair of filaments separate S. (N.) ledangense sp. nov. from all other known species of the feuerborni species-group, of which the pupa is known.

Figures

FIGURE 1. Female of S. ledangense sp. nov. (A) Third segment of left maxillary palp with sensory vesicle (front view). (B) Cibarium. (C) Tibia of left hind leg (outer view). (D) Basitarsus and second tarsomere of left hind leg (outer view). (E) Sternite 8 and ovipositor valves. (F) Genital fork (ventral view). (G) Right paraproct and cercus (ventral view). (H) Right paraproct and cercus (lateral view). (I) Spermatheca. Scale bars = 0.1 mm (C, D) and 0.02 mm (A, B, E – I)

FIGURE 2. Male of S. ledangense sp. nov. (A) Third segment of right maxillary palp with sensory vesicle having moderatesized opening (front view). (B) Third segment of left maxillary palp with sensory vesicle of small-sized opening (front view). (C) Basitarsus and second tarsomere of left hind leg showing calcipala and pedisulcus (outer view). (D) Coxites, styles and ventral plate (ventral view). (E) Left style (ventrolateral view). (F) Ventral plate and median sclerite (lateral view). (G) Ventral plate (caudal view). (H) Median sclerite ventral view). (I) Parameres each with 5 or 6 hooks (end view). (J) Aedeagal membrane and dorsal plate (end view). (K) 10 th abdominal segment and cercus (right side; lateral view). (L) Right cercus (end view). Scale bars = 0.1 mm (C) and 0.02 mm (A, B, D – L).

FIGURE 3. Pupa and larva of S. ledangense sp. nov. (A) Gill filaments (left side, outer view) (arrow showing the beginning of the branching). (B) Basal portion of gill filaments (left side, dorsal view). (C) Larva body (dorsal view). (D) Larva head capsule (ventral view). (E) Hypostoma. (F) Mandible. (G, H) Thoracic trichomes (G, mediodorsal; H, ventrolateral). Scale bars = 0.2 mm (A, B), 0.1 mm (C, D), 0.01 mm (H, G) and 0.02 mm (E, F).