Simulium (Gomphostilbia) jerantutense Takaoka, Sofian-Azirun

Takaoka, Hiroyuki, Sofian-Azirun, Mohd & Ya’Cob, Zubaidah, 2014, Two new species of the Simulium batoense species-group of Simulium (Gomphostilbia) (Diptera: Simuliidae) from Peninsular Malaysia, Zootaxa 3774 (5), pp. 473-480 : 477-479

Simulium (Gomphostilbia) jerantutense Takaoka, Sofian-Azirun and Ya’cob, sp. nov.

Female. Body length 2.3 mm. Head. Slightly narrower than width of thorax. Frons brownish-black, shiny, moderately covered with yellowish-white scale-like recumbent short hairs (appearing to lack dark longer hairs along each lateral margin); frontal ratio 1.63:1.00:2.21; frons:head ratio 1.00:4.75. Fronto-ocular area well developed, narrow, directed dorsolaterally. Clypeus dark brown, shiny, gray pruinose, densely covered with yellowish-white hairs interspersed with few dark longer hairs near each ventrolateral corner. Labrum 0.66 times length of clypeus. Antenna composed of scape, pedicel and nine flagellomeres, light to medium brown except scape, pedicel and base of first flagellomere yellow. Maxillary palp composed of five segments, light to medium brown except segments 1 and 2 pale, proportional lengths of third, fourth, and fifth segments 1.00:1.13–1.19:2.51– 2.62; third segment ( Fig. 2 A) of moderate size; sensory vesicle ( Fig. 2 A) ellipsoidal, medium-long, 0.38–0.41 times length of third segment and with medium-sized opening. Maxillary lacinia with 8 or10 inner and 11 or 12 outer teeth. Mandible with 18 inner and 9 outer teeth. Cibarium ( Fig. 2 B) medially forming sclerotized plate folded forward from posterior margin, with strongly sclerotized medial longitudinal ridge. Thorax. Scutum dark brown, shiny when illuminated at certain angles, thinly gray pruinose, with three (median and submedian) brownish-black broad longitudinal vittae, densely covered with whitish scale-like recumbent hairs except three longitudinal vittae with dark recumbent hairs (no dark longer hairs on prescutellar area). Scutellum ochreous, covered with dark short hairs and dark brown long upright hairs along posterior margin. Postnotum dark brown, shiny when illuminated at certain angles and bare. Pleural membrane bare. Katepisternum medium brown, longer than deep, shiny when illuminated at certain angles, moderately covered with short hairs. Legs. Foreleg: coxa yellow; trochanter grayishyellow; femur grayish to light brown with apical cap medium brown; tibia ( Fig. 2 C) medium brown with extreme base yellow and median portion largely grayish, moderately covered with yellow (shiny in light) short hairs on outer surface; tarsus dark brown, with moderate dorsal hair crest; basitarsus somewhat dilated, 5.25 times as long as its greatest width. Midleg: coxa dark brown except posterolateral surface brownish-black; trochanter grayish except posterior surface light brown; femur grayish except apical cap medium brown; tibia ( Fig. 2 D) grayish except basal tip yellow, subbasal spot light brown, apical cap and narrow portion along posterior margin of apical half medium brown, and with yellow (shiny in light) short hairs on outer and posterior surfaces of basal two-thirds; tarsus medium brown except basal two-thords of basitarsus grayish. Hind leg: coxa medium brown; trochanter yellow; femur grayish to light brown except extreme base yellow and apical cap medium to dark brown; tibia ( Fig. 2 E) grayish except base yellow and apical one-third medium to dark brown, moderately covered with white (shiny in light) short hairs on outer and posterior surfaces of basal two-thirds; tarsus ( Fig. 2 F) dark brown except little more than basal two-thirds of basitarsus (though base light brown) and basal half of second tarsomere yellowish-white; basitarsus ( Fig. 2 F) narrow, nearly parallel-sided, 6.59 times as long as wide, and 0.57 and 0.53 times as wide as greatest width of tibia and femur, respectively; calcipala ( Fig. 2 F) well developed, as long as wide, and 0.59 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 2 F) well developed; claw ( Fig. 2 G) with large basal tooth 0.46 times length of claw. Wing. Length 1.7 mm. Costa with dark brown spinules and dark brown hairs except basal patch of hairs mixed with pale hairs. Subcosta haired except apical one-third 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 partially darkened. Abdomen. Basal scale light brown, with fringe of yellowish-white hairs. Dorsal surface of abdomen medium brown except basal two-thirds of segment 2 yellowish-white, moderately covered with dark short to long hairs; tergites of segments 2 and 6–9 shiny when illuminated at certain angles. Ventral surface of abdomen light to medium brown except segment 2 yellowish-white; sternal plate on segment 7 undeveloped. Genitalia. Sternite 8 ( Fig. 2 H) bare medially, with 12 or 13 medium-long to long hairs together with few slender short hairs on each side. Ovipositor valves ( Fig. 2 H) triangular (though medioposterior corners rounded), tapered laterally, thin, membranous, moderately covered with microsetae interspersed with two or three short hairs; inner margins sinuous, moderately sclerotized, and close to each other. Genital fork ( Fig. 2 I) of usual inverted-Y form, with slender stem; arms of moderate width, moderately folded medially, with short posteromedial lobe. Paraproct in ventral view ( Fig. 2 J) with anterolateral tip unsclerotized and anteromedian margin darkened, with five sensilla on anteromedial surface; paraproct in lateral view ( Fig. 2 K) somewhat produced ventrally, 0.61 times as long as wide, with 18–21 medium-long to long hairs on ventral and lateral surfaces. Cercus in lateral view ( Fig. 2 K) short (0.58 times as long as wide), trapezoidal. Spermatheca ( Fig. 2 L) oblong, 1.5 times as long as 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.

Pupa. Body length 2.5 mm. Nearly as in pupa of S. (G.) tekamense sp. nov. except for the following characters. Head. Integument ochreous. Thorax. Integument ochreous. Gill ( Fig. 2 M) composed of eight slender thread-like filaments, arranged as [2+1+(1+2)]+2 filaments from dorsal to ventral, with short common basal stalk having somewhat swollen basal fenestra; common basal stalk short, 0.61–0.63 times as long as interspiracular trunk; dorsal pair, middle triplets and individual filament in-between arising at same level, sharing short stalk; stalk of dorsal pair short, and primary and secondary stalks of middle triplet short and medium-long, respectively; stalk of ventral pair medium-long, 1.61–2.12 times length of common basal stalk and 1.02–1.29 times length of interspiracular trunk; stalk of ventral pair 1.17–1.29 times as thick as primary stalk of middle triplet; stalk of dorsal pair lying against stalk of lower pair at angle of 90 degrees or little more when viewed laterally; all filaments light brown, gradually tapered toward apex; dorsal paired filaments and individual filament subequal in length to one another (2.0 mm), three filaments of middle triplet slightly varying in length (2.4–2.7 mm), and ventral paired filaments subequal in length to each other (3.5 mm). Abdomen. Ventrally, segment 4 with one unbranched or bifid hook and few unbranched short setae on each side.

Male and larva. Unknown.

Type Materials. HOLOTYPE: Female (with associated pupal exuviae and cocoon) (preserved in 80% ethanol) reared from pupa, MALAYSIA: Pahang, Jerantut, Lepar, Tekam, 17-VI-2011, by M. Sofian-Azirun and Z. Ya’cob. Paratypes: One female emerged from pupa, preserved in 80% ethanol, same data as those of holotype.

Etymology. The species name jerantutense represents the district name, Jerantut, where this new species was collected.

Biology. The pupae of this new species were collected from the same stream as pupae of S. (G.) tekamense sp. nov. Collection data and associated species are the same as noted in the biology of S. (G.) tekamense sp. nov.

Discussion. Simulium (G.) jerantutense sp. nov. is assigned to the batoense species-group of the subgenus Gomphostilbia as defined by Takaoka (2012), by having the antenna with 11 articles, pleural membrane bare, katepisternum haired, base of the radial vein with dark tuft hairs, mid and hind tibiae darkened except the base yellowish ( Fig. 2 E), claw with a large basal tooth ( Fig. 2 G) and spermatheca without a sclerotized neck ( Fig. 2 L) in the female, and the gill with eight long filaments ( Fig. 2 M) and cone-like terminal hooks ( Fig. 2 N) in the pupa. This new species is tentatively assigned to the binuanense subgroup although the relative length and thickness of the two filaments of the ventral pair are subequal to each other ( Fig. 2 M).

The female of this new species is similar to that of S. (G.) chuzargangense from Bhutan in many characters including the size of the sensory vesicle, shape of the cibarium, and color of the legs ( Takaoka and Somboon, 2008). However, this new species is distinguished from the latter by the smaller tooth of the tarsal claw (0.46 times the length of the claw) ( Fig. 2 G) and presence of hairs on the subcosta (cf., the tooth of the tarsal claw is 0.52 times the length of the claw and subcosta with no hairs or only one hair in S. (G.) chuzargangense – Takaoka and Somboon, 2008). The pupa of this new species is characterized by the pupal gill filaments arranged as [2+1+(2+1)]+2 filaments from dorsal to ventral ( Fig. 2 M), i.e., three dorsal filaments not forming a triplet but arising as two paired filaments on the outer side and one individual filament on the inner side, leaving no shared stalk between them. A similar arrangement of the pupal gill filaments is recorded in S. (G.) butwalense Takaoka and Shrestha from Nepal ( Takaoka and Shrestha, 2010) (and placed in the binuanense subgroup). However, the inner filament of the ventral pair is much thicker than the outer counter filament in S. (G.) butwalense, as for other species of the binuanense subgroup ( Takaoka and Shrestha, 2010).

Figures

FIGURE 2. Female and pupa of S. (G.) jerantutense sp. nov. (A) – (L) Female, and (M) and (N) Pupa. (A) Third segment of right maxillary palp with sensory vesicle (front view). (B) Cibarium. (C) Tibia of left foreleg (outer view). (D) Tibia of left midleg (outer view). (E) Tibia of left hind leg (outer view). (F) Basitarsus and second tarsomere of left hind leg showing calcipala and pedisulcus (outer view). (G) Claw. (H) Sternite 8 and ovipositor valve (only right half shown; ventral view). (I) Genital fork (ventral view). (J) Right paraproct and cercus (ventral view). (K) Right paraproct and cercus (lateral view). (L) Spermatheca. (M) Right gill (outer view). (N) Terminal hooks (caudal view). Scale bars = 0.1 mm (C, D, E, F, M), 0.02 mm (A, B, H – L) and 0.01 mm (G, N).