Simulium (Gomphostilbia) huangi Takaoka, 2017

Huang, Yao-Te, 2017, A new black fly species of Simulium (Gomphostilbia) (Diptera: Simuliidae) from Taiwan, with keys to all 13 species of the Simulium varicorne species-group, Zootaxa 4312 (3), pp. 438-448 : 439-446

Simulium (Gomphostilbia) huangi Takaoka sp. nov.

Female. Body length 1.9 mm. Head. Slightly narrower than width of thorax. Frons black, thinly gray pruinose, not shiny, densely covered with white or yellowish-white scale-like recumbent short hairs; frontal ratio 1.55:1.00:1.98; frons:head ratio 1.00:4.22. Fronto-ocular area well developed, narrow, directed dorsolaterally. Clypeus black, densely covered with whitish-yellow hairs interspersed with about 10 dark longer hairs on each side. Labrum 0.54 times as long as clypeus. Antenna ( Fig. 1 A) composed of scape, pedicel and eight flagellomeres, medium to dark brown except scape, pedicel, and basal one-third of first flagellomere yellow. Maxillary palp composed of five segments, light to medium brown, proportional lengths of third, fourth, and fifth segments 1.00:1.30:2.74; third segment ( Fig. 1 B) somewhat swollen; sensory vesicle ( Fig. 1 B) elongate (0.49 times as long as third segment), with medium-sized opening. Maxillary lacinia with 12 or 13 inner and 17 or 18 outer teeth. Mandible with 30 inner teeth and six or seven outer teeth at some distance from tip. Cibarium ( Fig. 1 C) with pair of well-sclerotized triangular projections at posterodorsal margin, which are in front covered by unpigmented transverse thin structures arising from both sides. Thorax. Scutum black except anterolateral calli dark brown, thinly gray pruinose, shiny when illuminated at certain angles, and densely covered with white or yellowish-white scale-like recumbent hairs. Scutellum brownish black, shiny when illuminated at certain angles, covered with yellowishwhite short hairs and brown long upright hairs along posterior margin. Postnotum brownish black, shiny when illuminated at certain angles, and bare. Pleural membrane bare. Katepisternum dark brown to brownish black, longer than deep, shiny when illuminated at certain angles, moderately covered with fine short hairs. Legs. Foreleg: coxa whitish yellow; trochanter whitish yellow except posterior portion somewhat darkened; femur medium brown with apical cap dark brown (though extreme tip yellowish); tibia white or yellowish white except apical one-fourth medium to dark brown, and with light to medium brown subbasal band; tarsus brownish black, with moderate dorsal hair crest; basitarsus moderately dilated, 6.5 times as long as its greatest width. Midleg: coxa dark brown; trochanter dark yellow or light brown; femur medium brown, with base somewhat light brown and apical cap dark brown (though extreme tip yellowish); tibia yellowish white on basal one-fourth or little more, with light brown subbasal spot, light to medium brown on rest, with apical cap dark brown; tarsus medium to dark brown except basal three-fifths of basitarsus yellowish white. Hind leg: coxa medium brown; trochanter yellowish white; femur medium brown, with base yellowish white and apical cap dark brown (though extreme tip yellowish white); tibia ( Fig. 1 D) white on basal three-fifths or little more, with light-brown subbasal spot, and brownish black on rest; tibia covered with whitish fine hairs on outer and posterior surfaces of basal two-thirds, masking subbasal dark spot; tarsus dark brown to brownish black except basal two-thirds of basitarsus and basal one-half of tarsomere 2 white; basitarsus ( Fig. 1 E) narrow, slightly tapered toward apex, 6.41 times as long as wide, and 0.64 and 0.53 times as wide as greatest widths of tibia and femur, respectively; calcipala ( Fig. 1 E) slightly longer than width at base, and one-half as wide as greatest width of basitarsus. Pedisulcus ( Fig. 1 E) well developed. Claw ( Fig. 1 F) with large basal tooth 0.53 times as long as claw. Wing. Length 2.0 mm. Costa with dark spinules and hairs except basal patch of hairs yellow. Subcosta with dark hairs except near apex bare. Hair tuft on base of radial vein yellow. Basal portion of radius fully haired; R1 with dark spinules and hairs; R2 with hairs only. Basal cell absent. Halter . White except basal stem darkened. Abdomen. Basal scale medium brown, with fringe of whitish-yellow hairs. Dorsal surface of abdomen dark brown to brownish black, moderately covered with dark short to long hairs; tergites of segments 2 and 5–9 shiny when illuminated at certain angles. Ventral surface of abdomen darkened except segment 2 mostly whitish yellow; sternal plate on segment 7 undeveloped. Terminalia . Sternite 8 ( Fig. 1 G) bare medially, with 13–17 medium-long to long hairs together with four to six slender short hairs on each side. Ovipositor valve ( Fig. 1 G) triangular (though posteromedial corner rounded), thin, membranous, moderately covered with microsetae interspersed with three or four short hairs; inner margins sinuous, somewhat sclerotized, and moderately separated from each other. Genital fork ( Fig. 1 H) of usual inverted-Y form, with slender stem; arms gradually widened apically, moderately folded medially, and with triangular lobe directed posteromedially. Paraproct in ventral view ( Fig. 1 I) slightly concave anterolaterally, with three or four sensilla on anteromedial surface; paraproct in lateral view ( Fig. 1 J) somewhat produced ventrally, 0.67 times as long as wide, with 15–19 medium-long to long hairs on ventral and lateral surfaces. Cercus in lateral view ( Fig. 1 J) short, rounded posteriorly, 0.47 times as long as wide. Spermatheca ( Fig. 1 K) ellipsoidal, 1.77 times as long as its greatest width, well sclerotized even near juncture with duct, and with many longitudinal fissures on outer surface; internal setae absent; both accessory ducts slender, subequal in diameter to major one.

Male. Body length 2.4 mm. Head. Somewhat wider than thorax. Upper eye dark brown, consisting of large facets in 12 or 13 vertical columns and in 13 or 14 horizontal rows. Face black, grayish white pruinose. Clypeus black, grayish white pruinose, densely covered with golden-yellow scale-like medium-long hairs (mostly directed upward) interspersed with several dark-brown longer hairs. Antenna composed of scape, pedicel and eight flagellomeres, medium to dark brown except scape and pedicel yellow or dark yellow and base of first flagellomere whitish yellow; first flagellomere elongate, 1.60 times as long as second one. Maxillary palp light to medium brown, with five segments, proportional lengths of third, fourth, and fifth segments 1.00:1.17:2.56; third segment ( Fig. 2 A) widened apically; sensory vesicle ( Fig. 2 A) ellipsoidal, small (0.24 times as long as third segment), and with small opening. Thorax. Nearly as in female except fine hairs on scutum and scutellum yellowish, intermixed with dark short hairs near anterior margin of scutum. Legs. Color and shape nearly as in female except following characters: fore basitarsus moderately dilated, 7.27 times as long as its greatest width; mid basitarsus dark brown except basal half white, hind tibia ( Fig. 2 B) white on little less than basal half, with light-brown subbasal spot, light brown on middle one-fifth and brownish black on apical one-third; hind basitarsus ( Fig. 2 C) 6.31 times as long as wide, and 0.65 and 0.59 times as wide as greatest width of tibia and femur, respectively; calcipala ( Fig. 2 C) slightly longer than wide, and 0.46 times as wide as greatest width of basitarsus. Pedisulcus ( Fig. 2 C) well developed. Wing. Length 1.8–1.9 mm; other features as in females except subcosta without hairs. Abdomen. Basal scale dark brown, with fringe of light-brown hairs. Dorsal surface of abdomen medium brown to brownish black, covered with dark-brown short to long hairs; segments 2 and 5–8 each with pair of shiny dorsolateral or lateral patches.

Genitalia. Coxite in ventral view ( Fig. 2 D) nearly rectangular, 1.77 times as long as its greatest width, and 1.31 times length of style. Style in ventral view ( Fig. 2 D) bent inward, slightly tapered from base toward middle, then nearly parallel-sided toward near apex, and with apical spine; style in ventrolateral view ( Fig. 2 E) gradually narrowed from base toward near middle, nearly parallel-sided to apical one-fifth, and then tapered toward apex; style in end view ( Fig. 2 F) with apex slightly protruded close to apical spine to half length of apical spine. Ventral plate in ventral view ( Fig. 2 D) with body transverse, 0.62 times as long as wide, widest in middle, then narrowed posteriorly, with anterior margin produced anteromedially, and posterior margin nearly straight, densely covered with microsetae on ventral surface except anterior half widely bare on each side; basal arms of moderate length, directed forward; ventral plate in lateral view ( Fig. 2 G) moderately produced ventrally; ventral plate in caudal view ( Fig. 2 H) triangular, tapered ventrally, with lateral margins slightly sinuous and dorsal margin deeply concave, and densely covered with microsetae medially on posterior surface. Median sclerite ( Fig. 2 G, I) thin, plate-like, slightly narrowed toward apex. Paramere ( Fig. 2 J) of moderate size, each with three medium-long and several short hooks. Aedeagal membrane ( Fig. 2 K) moderately setose. Ventral surface of abdominal segment 10 without distinct hairs near posterior margin. Cercus ( Fig. 2 L, M) small, rounded, with 11 hairs.

Pupa. Body length 2.0– 2.5 mm. Head. Integument light yellow, moderately covered with small round tubercles; antennal sheath without any protuberances; frons with three pairs of unbranched long trichomes with coiled or uncoiled apices ( Fig. 3 A); face with pair of unbranched long trichomes with uncoiled apices ( Fig. 3 B), and three frontal trichomes on each side arising close together, subequal in length to one another and much longer than facial one. Thorax. Integument yellow, moderately covered with round tubercles, with three long anterodorsal trichomes with coiled or uncoiled apices (anterior and middle trichomes subequal in length to each other, and slightly longer than posterior one) ( Fig. 3 C), two long anterolateral trichomes (one with coiled apex, one with uncoiled apex) ( Fig. 3 D), one medium-long mediolateral trichome with uncoiled apex ( Fig. 3 E), and three ventrolateral trichomes with uncoiled apices (one medium-long, two short) ( Fig. 3 F) on each side; all trichomes unbranched. Gill ( Fig. 3 G, H) composed of 8 slender thread-like filaments, arranged as [(1+2) +(1+2)]+2 from dorsal to ventral, with short common basal stalk having somewhat swollen transparent basal fenestra ventrally (often partially broken) at base; common basal stalk 0.67–0.68 times as long as interspiracular trunk; dorsal and middle triplets sharing short stalk; three filaments of dorsal and middle triplets each composed of one filament and two paired filaments with medium-long primary stalk and short to long secondary stalk; ventral paired filaments with medium-long stalk 1.02–1.57 times as long as common basal stalk; stalk of ventral pair 1.07–1.10 times as thick as primary stalk of middle triplet, 1.07–1.18 times as thick as primary stalk of dorsal triplet, and 0.83–0.94 times as thick as common stalk of middle and dorsal triplets; primary stalk of dorsal triplet lying against that of lower pair at angle of 90 degrees when viewed laterally; all filaments light brown, gradually tapered toward apex, subequal in length to one another (2.4–2.5 mm including their own stalks and common basal stalk); two filaments of ventral pair subequal in thickness to each other, and somewhat thicker than six other filaments when compared basally; cuticle of all filaments with well-defined annular ridges and furrows though becoming less marked apically, densely covered with minute tubercles. Abdomen. Dorsally, all segments light yellow, segments 1–5 each sparsely covered with minute spines; segment 1 with one unbranched slender medium-long hair-like seta ( Fig. 3 I) on each side; segment 2 with one unbranched slender medium-long hair-like seta and five short setae ( Fig. 3 J) submedially on each side; segments 3 and 4 each with four hooked spines and one short seta on each side; segment 5 with five short setae 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; segments 6–8 each with one short seta on each side; segment 9 with pair of wide flat terminal hooks of which outer margin is 5.0–5.2 times as long as inner margin and crenulated ( Fig. 3 K). Ventrally, segment 4 with one unbranched hook and few slender short setae on each side; segment 5 with pair of bifid hooks submedially and few slender short setae on each side; segments 6 and 7 each with pair of bifid inner and unbranched outer hooks somewhat spaced from each other and few slender short setae on each side; segments 4–8 each with comb-like groups of minute spines. Each side of segment 9 with three grapnel-shaped hooklets. Cocoon ( Fig. 3 L). Wall-pocket-shaped, thinly and moderately woven, widely extended ventrolaterally; anterodorsal margin not thickly woven, often somewhat produced anteriorly forming short bulge when viewed dorsally; posterior one-half with floor roughly or moderately woven; individual threads visible; 3.0– 3.1 mm long by 2.0– 3.1 mm wide.

Mature larva. Body length 3.9 mm. Body color creamy, with reddish-brown markings: thoracic segment 1 encircled with distinct broad band, though tapered from dorsal to ventral, and disconnected dorsomedially and ventromedially; thoracic segment 1 ventrally with distinct broad band posterior to base of thoracic proleg; abdominal segment 1 encircled with distinct broad band though disconnected dorsomedially and ventromedially; abdominal segments 2 and 3 each dorsally with thin transverse band though disconnected dorsomedially, abdominal segment 4 with thin transverse band dorsally, though disconnected dorsomedially, and lateral spot on each side; abdominal segment 5 with distinct broad band dorsally, though disconnected dorsomedially, and distinct lateral spot on each side; abdominal segments 6–8 each with color markings on dorsal and dorsolateral surfaces, though dorsomedial portion of each of segments 6 and 7 widely unpigmented; abdominal segments 6 and 7 each with thin transverse band ventrally, though two bands are connected to each other by thin narrow longitudinal band. Cephalic apotome pale yellow with somewhat darkened transverse band along posterior margin; head spots faintly positive; densely covered with unbranched colorless minute setae. Lateral surface of head capsule pale yellow except eye-spot region whitish and moderately covered with unbranched colorless minute setae; spots indistinct. Ventral surface of head capsule pale yellow except somewhat darkened area near posterior margin on each side of postgenal cleft, and sparsely covered with unbranched colorless setae. Antenna composed of three articles and apical sensillum, somewhat longer than stem of labral fan; proportional lengths of first, second, and third articles 1.00:0.84:0.84. Labral fan with 32 main rays. Mandible ( Fig. 4 A) with three comb-teeth decreasing in length from first to third; mandibular serration composed of two teeth (one medium-sized and one small); major tooth at acute angle against mandible on apical side; supernumerary serrations absent. Hypostoma ( Fig. 4 B) with row of nine apical teeth; median tooth subequal in length to corner teeth, which are slightly longer than three intermediate teeth on each side; lateral margin smooth; four or five hypostomal bristles per side lying nearly parallel to lateral margin. Postgenal cleft ( Fig. 4 C) medium-long, 1.29 times as long as postgenal bridge. Cervical sclerite composed of two pale small pieces, not fused to occiput, widely separated medially from each other. Thoracic segments 1–3 and abdominal segments 1–5 each covered with few to several unbranched colorless setae ( Fig. 4 D) on each dorsolateral surface, and abdominal segments 6–9 moderately or densely covered with bifid to quadrifid branched minute dark setae ( Fig. 4 E) on dorsal and dorsolateral surfaces interspersed with few unbranched colorless setae on each dorsolateral surface, and last segment moderately or densely covered with unbranched colorless setae on each side of anal sclerite. Rectal scales absent. Rectal papilla compound, each of three lobes with finger-like secondary lobules, though their number uncountable. Anal sclerite of usual X-form, with anterior arms 0.8 times length of 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 65 rows of up to 13 hooklets per row.

Type material. HOLOTYPE: Female (with associated pupal exuviae and cocoon) (in 80% ethanol) reared from pupa, collected from Keelung River , Section 2, Jing’an Road, Pingxi District, New Taipei City, TAIWAN, 25- X-2012, by Y.T. Huang. PARATYPES: One male, reared from pupa, one pupa, one pupal exuviae, and one larva (all in 80% ethanol), data same as those of the holotype .

Distribution. Taiwan.

Etymology. The species name, huangi , is in honor of Dr. Yao-Te Huang, who collected this new species and greatly contributed to studies of black flies in Taiwan.

Biological notes. The pupae and larva of this new species were collected from grass leaves trailing in the current of a river (width 2–3m, water temperature 14˚C, elevation 300–310 m, 25°01’15.1” N, 121°42’49.9” E). Associated species were Simulium (Simulium) chungi Takaoka & Huang , S. (S.) quinquestriatum (Shiraki) , S. (S.) tani Takaoka & Davies (complex) and S. (S.) sp. nr. bidentatum (Shiraki).

Discussion. Simulium (G.) huangi sp. nov. is assigned to the S. varicorne species-group because it has eight flagellomeres on its adult antenna ( Fig. 1 A), and is further placed in the S. burtoni subgroup by having the female subcosta haired, spermatheca ellipsoidal ( Fig. 1 K), and male ventral plate moderately produced ventrally ( Fig. 2 H), as defined by Takaoka (2012). Among the four known species of this subgroup, S. (G.) burtoni Takaoka & Davies , originally described from Peninsular Malaysia ( Takaoka & Davies 1995) and also recorded from Thailand ( Takaoka and Choochote 2004), appears to be most similar to this new species by having a shiny tergite 5 of the female abdomen, broad terminal hooks ( Fig. 3 K) on the pupal abdomen, and reddish-brown markings on the larval body. However, S. (G.) huangi sp. nov. is distinguished from S. burtoni by the following morphological characters (those of S. burtoni in parentheses): in both female and male by flagellomeres of antennae almost uniformly darkened except the basal one-third of the first flagellomere yellow ( Fig. 1 A) (third and fifth to eighth flagellomeres darkened and other flagellomeres entirely or partially yellow or dark yellow); in the female by the mandible with 30 inner and six or seven outer teeth (24 inner and three outer teeth), relative length of the fore basitarsus against its greatest width 6.5 (4.7), relative length of the hind basitarsus against its greatest width 6.41 (7.2), relative length of the claw tooth against the claw 0.53 (0.50), and stem of the genital fork with a widened apex (with a narrow apex); in the male by the relative length of the sensory vesicle against the third segment of the maxillary palp 0.24 (0.3) and relative length of the fore basitarsus against its greatest width 7.3 (6.1); in the pupa by the relative length of the common basal stalk against the interspiracular trunk 0.67–0.68 (0.82) and terminal hooks ( Fig. 3 K) with the outer margin crenulated (undulated), and relative length of the outer margin against the inner margin 5.5–5.7 (2.3–3.0); in the larva by the postgenal cleft ( Fig. 4 C) with its relative length against the postgenal bridge 1.3 (7.5).

This new species is also similar to S. (G.) breviflagellum Takaoka & Sofian-Azirun from Vietnam, which was described from a male and its pupal exuviae ( Takaoka et al. 2015), in sharing the wide terminal hooks, but differs from the latter species by the smaller male sensory vesicle and cocoon without an anterodorsal projection (sensory vesicle is long, 0.44 times as long as the third maxillary palpal segment and cocoon with an anterodorsal projection in S. (G.) breviflagellum ).

The two other related species, S. (G.) shogakii Rubtsov from Japan, Korea and China ( Bentinck 1955) and S. (G.) synanceium Chen & Cao from China ( Chen and An 2003), are distinguished from this new species by having a dull female abdominal tergite 5 and cone-like pupal terminal hooks.

This new species represents the first record of the S. varicorne species-group from Taiwan.

Simulium (G.) huangi sp. nov. is distinguished from 12 known species of the S. varicorne species-group as shown in following keys, which were modified from keys provided by Takaoka et al. (2014).

Figures

FIGURE 1. Female of Simulium (Gomphostilbia) huangi sp. nov. (A) Antenna (right side; dorsal view). (B) Third segment of maxillary palp with sensory vesicle (right side; front view). (C) Cibarium. (D) Hind tibia (left side; outer view). (E) Basitarsus and tarsomere 2 of hind leg showing calcipala and pedisulcus (left side; outer view). (F) Claw. (G) Sternite 8 and ovipositor valve (only right half shown; ventral view). (H) Genital fork (ventral view). (I) & (J) Paraprocts and cerci (right side; I, ventral view; J, lateral view). (K) Spermatheca. Scale bars = 0.1 mm (D, E), 0.05 mm (A); 0.02 mm (B, C, G – K) and 0.01 mm (F).

FIGURE 2. Male of Simulium (Gomphostilbia) huangi sp. nov. (A) Third segment of maxillary palp with sensory vesicle (right side; front view). (B) Hind tibia (left side; outer view). (C) Basitarsus and tarsomere 2 of hind leg showing calcipala and pedisulcus (left side; outer view). (D) Coxites, styles and ventral plate (ventral view). (E) & (F) Styles (E, right side, ventrolateral view; F, left side, caudal view). (G) Ventral plate and median sclerite (lateral view). (H) Ventral plate (caudal view). (I) Median sclerite (caudal view). (J) Paramere (right side; caudal view). (K) Aedeagal membrane (caudal view). (L) & (M) Abdominal segment 10 and cerci (L, lateral view; M, caudal view). Scale bars = 0.1 mm (B, C), and 0.02 mm (A, D – M).

FIGURE 3. Pupa of Simulium (Gomphostilbia) huangi sp. nov. (A) Frontal trichome. (B.) Facial trichome. (C) – (F) Thoracic trichomes (C, dorsomedial; D, anterolateral; E, mediolateral; F, ventrolateral). (G) Gill showing long secondary stalks of middle and dorsal triplets (right side; outer view). (H) Basal portion of gill showing short secondary stalks of middle and dorsal triplets (left side; outer view). (I) Hair-like seta on dorsal surface of abdominal segment 1. (J) Hair-like seta and minute seta on dorsal surface of abdominal segment 2. (K) Terminal hooks (caudal view). (L) Cocoon (dorsal view). Scale bars = 1.0 mm (L), 0.1 mm (G, H) and 0.02 mm (A – F, I – K).

FIGURE 4. Larva of Simulium (Gomphostilbia) huangi sp. nov. (A) Mandible (lateral view). (B) Hypostoma (ventral view). (C) Head capsule showing postgenal cleft (ventral view). (D) Unbranched colorless setae on dorsolateral surface of abdominal segment 5. (E) Dark branched setae on dorsal surface of abdominal segment 8. Scale bars = 0.05 mm (C), 0.02 mm (A, B, D, E).