Simulium (Gomphostilbia) lamdongense Takaoka & Sofian-Azirun

Takaoka, Hiroyuki, Sofian-Azirun, Mohd, Ya’Cob, Zubaidah, Chen, Chee Dhang, Lau, Koon Weng & Pham, Xuan Da, 2015, The black flies (Diptera: Simuliidae) from Thua Thien Hue and Lam Dong Provinces, Vietnam, Zootaxa 3961 (1), pp. 1-96 : 35-41

Simulium (Gomphostilbia) lamdongense Takaoka & Sofian-Azirun sp. nov.

( Figs. 14 A–16G)

Female. Body length 1.9–2.1 mm. Head. Slightly narrower than thorax. Frons brownish-black, white pruinose and shiny when illuminated at certain angles, densely covered with yellowish-white scale-like recumbent short hairs interspersed with few dark longer hairs along each lateral margin; frontal ratio 1.50–1.68:1.00:1.70–1.94; frons:head ratio 1.0:4.3–4.4. Fronto-ocular area well developed, narrow, directed dorsolaterally. Clypeus brownishblack, white pruinose and shiny when illuminated at certain angles, and densely covered with yellowish-white recumbent hairs interspersed with dark longer hairs on each side. Labrum 0.6 times as long as clypeus. Antenna composed of scape, pedicel and nine flagellomeres, dark brown except scape, pedicel and basal extreme of first flagellomere yellow. Maxillary palp composed of five segments, light brown except segments 1 and 2 ochreous and segment 3 dark brown, proportional lengths of third, fourth, and fifth segments 1.0:1.1:2.2; third segment ( Fig. 14 A) of moderate size; sensory vesicle ( Fig. 14 A) elongate, 0.43–0.45 times as long as third segment and with medium-sized opening. Maxillary lacinia with 12 or 13 inner and 19–21 outer teeth. Mandible with 32 inner teeth and three to five minute outer teeth at some distance from apex (tiny and rudimentary outer teeth can be overlooked). Cibarium ( Fig. 14 B) with strongly sclerotized dorsal margin having short tongue-like plate produced forward and downward, and with well sclerotized mediolongitudinal ridge having bifid apex. Thorax. Scutum brownish-black except anterolateral calli ochreous, thinly pruinose and shiny when illuminated at certain angles, densely covered with yellow scale-like recumbent hairs. Scutellum medium-brown, covered with yellow short hairs and dark-brown long upright hairs. Postnotum brownish-black, white pruinose when illuminated at certain angles, and bare. Pleural membrane bare. Katepisternum longer than deep, dark brown, shiny when illuminated at certain angles, moderately covered with pale and dark short hairs. Legs. Foreleg: coxa yellow except anterior surface dark yellow to light brown; trochanter light brown except base yellow; femur light brown with apical cap medium brown (though extreme tip yellow); tibia yellow to dark yellow except subbasal broad band light to medium brown and apical one-fourth dark brown, with whitish-yellow short hairs (brightly shiny when illuminated) on outer surface of basal three-fourths; tarsus brownish-black, with moderate dorsal hair crest; basitarsus moderately dilated, 6.0 times as long as its greatest width. Midleg: coxa medium brown except posterolateral surface dark brown; trochanter yellow except outer surface light brown; femur light brown except base yellow and apical cap medium brown (though extreme tip yellow); tibia light brown except base yellow and apical cap dark brown, and with whitish-yellow short hairs (brightly shiny when illuminated) on outer and posterior surfaces of basal three-fourths; tarsus dark brown except base of basitarsus dark yellow. Hind leg: coxa light brown; trochanter yellow; femur light brown except base yellow and apical cap dark brown (though extreme tip yellow); tibia ( Fig. 14 C) light brown (gradually darkened toward apex) except base yellow, triangular subbasal spot medium brown and apical one-fourth dark brown; tibia moderately covered with whitish-yellow short hairs (brightly shiny when illuminated) on outer and posterior surfaces of basal three-fourths; tarsus ( Fig. 14 D) brownish-black except little more than basal two-thirds of basitarsus (though base light brown) and basal half of second tarsomere yellow; basitarsus ( Fig. 14 D) narrow, nearly parallel-sided, 6.14 times as long as wide, and 0.66 and 0.54 times as wide as greatest widths of tibia and femur, respectively; calcipala ( Fig. 14 D) well developed, slightly longer than wide, and 0.57 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 14 D) well developed; claw ( Fig. 14 E) with large basal tooth 0.53 times length of claw. Wing. Length 1.8 mm. Costa with dark brown spinules and light brown hairs except basal patch of yellow hairs. Subcosta haired except apical one-third bare. Hair tuft on base of radial vein dark brown though apices of hairs yellow. Basal portion of radius fully haired. Basal cell absent. Halter . Clear white except basal portion darkened. Abdomen. Basal scale creamy, with fringe of yellowish-white hairs. Dorsal surface of abdomen light to medium brown except segment 2 creamy to ochreous though both lateral portions of tergal plate light borwn, moderately covered with dark short to long hairs; tergites of segments 2 and 6–9 shiny when illuminated at certain angles. Ventral surface of segment 2 creamy, those of other segments ochreous except sternite 8 dark brown; sternal plate on segment 7 undeveloped. Genitalia. Sternite 8 ( Fig. 14 F) bare medially, with 16–19 medium-long to long hairs together with few slender short hairs on each side. Ovipositor valves ( Fig. 14 F) triangular (though posteromedial corners rounded), tapered laterally, thin, membranous, moderately covered with microsetae interspersed with one to five short hairs; inner margins nearly straight, moderately sclerotized, and somewhat separated from each other. Genital fork ( Fig. 14 G) of usual inverted-Y form, with slender stem; arms of moderate width, moderately folded medially, with short projection directed anterodorsally. Paraproct in ventral view ( Fig. 14 H) nearly triangular, with anteromedial margin somewhat darkened, with four or five sensilla on anteromedial surface; paraproct in lateral view ( Fig. 14 I) much produced ventrally, 0.57 times as long as wide, with 14 or 15 medium-long to long hairs on ventral and lateral surfaces. Cercus in lateral view ( Fig. 14 I) short, rounded posteriorly, 0.42 times as long as wide. Spermatheca ( Fig. 14 J) ellipsoidal, 1.56–1.68 times as long as greatest width, well sclerotized except duct and small area near juncture with duct unsclerotized, and with many fissures on outer surface; internal setae absent; both accessory ducts slender, subequal in diameter to major one.

Male. Body length 2.1–2.4 mm. Head. Slightly wider than thorax. Upper eye medium brown, consisting of 16 or 17 vertical columns and 17 or 18 horizontal rows of large facets. Face black, whitish-gray pruinose, shiny when illuminated at certain angles. Clypeus black, whitish-gray pruinose, shiny when illuminated at certain angles, and moderately covered with yellow short hairs interspersed with several dark-brown longer hairs on lower half on each side. Antenna composed of scape, pedicel and nine flagellomeres, dark brown to brownish-black; first flagellomere elongate, 1.33 times as long as second one. Maxillary palp with five segments, light brown except segment 3 dark brown, proportional lengths of third, fourth, and fifth segments 1.0:1.1:2.2; third segment ( Fig. 15 A) somewhat widened apically; sensory vesicle ( Fig. 15 A) globular or ellipsoidal, small, 0.2 times length of third segment, and with small opening. Thorax. Scutum black, thinly gray pruinose and shiny when illuminated at certain angles on shoulders, along lateral margins and on prescutellar area leaving large central area non-pruinose, densely covered with golden-yellow short hairs. Scutellum brownish-black, with golden-yellow short hairs and dark-brown long upright hairs. Postnotum black, white pruinose and shiny when illuminated at certain angles, and bare. Pleural membrane bare. Katepisternum longer than deep, brownish-black to black, thinly pruinose and shiny when illuminated at certain angles, moderately covered with pale and dark hairs. Legs. Foreleg: coxa and trochanter medium brown; femur medium brown with apical cap dark brown; tibia brownish-black except base and middle portion medium brown, and with yellow short hairs (brightly shiny when illuminated at certain angles) on outer surface of basal five-sixths: tarsus black; basitarsus slightly flattened, 8.75 times as long as greatest width. Midleg: coxa dark brown except posterolateral surface brownish-black; trochanter medium brown; femur medium brown with apical cap dark brown (though extreme tip somewhat paler); tibia medium to dark brown except basal extreme yellow or dark yellow, and with golden-yellow short hairs on posterior surface of basal one-third; tarsus brownish-black. Hind leg: coxa medium brown; trochanter light brown; femur medium brown with apical cap dark brown; tibia medium to brownish-black except base yellow to dark yellow, and covered with golden-yellow short hairs on posterior surface of basal two-thirds; tarsus brownish-black except basal two-thirds of basitarsus and basal half of second tarsomere grayish light-brown; basitarsus ( Fig. 15 B) narrow, nearly parallel-sided, 5.71 times as long as wide, and 0.59 and 0.58 times as wide as greatest widths of tibia and femur, respectively; calcipala ( Fig. 15 B) well developed, slightly longer than width at base, and 0.43 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 15 B) well developed. Wing. Length 1.5 mm. Other features as in female except subcosta without hairs, and hair tuft of base of radial vein dark brown. Halter . Grayish with basal portion darkened. Abdomen. Basal scale brownish-black, with fringe of dark-brown long hairs. Dorsal surface of abdomen medium to dark brown, covered with light-brown short to long hairs; segments 2, 6 and 7 each with pair of shiny dorsolateral patches, when illuminated at certain angles. Genitalia. Coxite in ventral view ( Fig. 15 C) nearly rectangular, 1.83 times as long as its greatest width. Style in ventral view ( Fig. 15 C) 0.9 times length of coxite, slender, curved inward, tapered toward middle, with apical spine; style in medial view ( Fig. 15 D) angulated medially, nearly parallel-sided; style in ventrolateral view ( Fig. 15 E) gradually tapered from base to apical one-third, abruptly narrowed, then nearly parallel-sided, with truncated apex. Ventral plate in ventral view ( Fig. 15 C) transverse, 0.63 times as long as greatest width at base, with body tapered from base to middle, abruptly narrowed, then tapered posteriorly, with anterior margin produced anteromedially, posterior margin shallowly concave, and densely covered with microsetae on ventral surface except anterolateral areas bare; basal arms of moderate length, slightly divergent, then slightly convergent apically; ventral plate in lateral view ( Fig. 15 F) with posterior portion of body somewhat produced posteroventrally; ventral plate in caudal view ( Fig. 15 G) rounded ventrally (width:height ratio 1.00:0.36), moderately covered with microsetae on most of posterior surface. Median sclerite ( Fig. 15 F, H) plate-like, tapered toward apex, arising from near anterior tip of ventral plate, and directed dorsally. Paramere ( Fig. 15 I) with three relatively longer hooks and several shorter ones. Aedeagal membrane ( Fig. 15 I) moderately covered with microsetae, and with no sclerotized dorsal plate. Ventral surface of abdominal segment 10 ( Fig. 15 J, K) without distinct hairs near posterior margin on each side. Cercus ( Fig. 15 J, K) rounded, somewhat produced ventrally, with 12–17 hairs.

Pupa. Body length 2.3–2.4 mm. Head. Integument yellow, moderately covered with small round tubercles except ventral surface of face bare; antennal sheath without protuberances; frons with three pairs of unbranched long trichomes with coiled or uncoiled apices; face with pair of unbranched long trichomes with coiled apices; three frontal trichomes on each side arising close together, subequal in length to one another and somewhat longer than facial one. Thorax ( Fig. 16 A). Integument yellow, sparsely covered with small round tubercles, with three long anterodorsal trichomes with coiled apices, two long anterolateral trichomes (one with coiled apex, one with uncoiled apex), one medium-long mediolateral trichome with uncoiled apex, and three ventrolateral trichomes with uncoiled apices (one long, two medium-long) on each side; all trichomes unbranched. Gill ( Fig. 16 A) composed of 10 slender thread-like filaments, arranged as {3+1+ [1+(1+2)]}+2 or{(1+2)+1+[1+(1+2)]}+2 filaments from dorsal to ventral, with short common basal stalk having somewhat swollen basal fenestra at base; dorsal triplet arising upward, with three filaments arising at same level from short primary stalk, or with one individual and two paired filaments with short primary and secondary stalks; middle outer group consisting of one filament arising near base of dorsal triplet; middle inner group consisting of two individual filaments and two paired filaments with short stalk; two individual filaments arising separately (though close together), or at almost same level; ventral paired filaments with short stalk; all filaments dark yellow to light brown, slightly tapered toward apices; three filaments of dorsal triplet, one filament of middle outer group and one or two filaments of middle inner group subequal in length to one another (0.6–0.8 mm long), and slightly shorter than other filaments which are subequal in length to one another (0.9–1.2 mm long); when compared basally, inner filament of ventral pair slightly thicker than outer filament, which is also slightly thicker than eight other filaments, which are subequal in thickness to one another; cuticle of all filaments smooth, lacking well-defined annular ridges and furrows though some furrows present irregularly near basal portions of filaments, and densely covered with minute tubercles. Abdomen. Dorsally, all segments nearly unpigmented except segment 9 yellowish; segment 1 without tubercles and with one unbranched slender medium-long hair-like seta on each side; segment 2 with one unbranched slender medium-long hair-like seta and five short somewhat spinous setae submedially near posterior margin on each side; segments 3 and 4 each with four hooked spines and one short somewhat spinous seta near posterior margin on each side; segments 5–8 each with two or three unbranched short setae near posterior margin on each side; segments 6–9 each with spinecombs in transverse row and comb-like groups of minute spines near anterior margin on each side; segment 9 with pair of cone-like terminal hooks ( Fig. 16 B). Ventrally, segment 4 with one unbranched hook and few unbranched short setae on each side; segment 5 with pair of bifid hooks submedially and few unbranched short slender 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 unbranched short slender 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. 16 C). Wall-pocket-shaped, moderately woven, extended ventrolaterally; anterior margin somewhat thickly woven, without anterodorsal bulge or projection; posterior half with floor roughly or moderately woven; individual threads visible; 3.0 mm long by 2.4 mm wide.

Mature larva. Body length 3.9–4.2 mm. Body light ochreous though intersegmental areas between thoracic segment 3 and abdominal segment 5 unpigmented; thoracic segment 1 encircled by reddish-brown band along anterior margin though disconnected ventromedially. Cephalic apotome yellowish, though somewhat darkened along posterior margin, and moderately covered with unpigmented minute setae; head spots indistinct or faintly negative. Lateral surface of head capsule yellowish except eye-spot region whitish; eyebrow faintly defined; two relatively large spots and one small spot near posterior margin faintly positive or indistinct; one or two small spots below eye-spot region indistinct. Ventral surface of head capsule yellowish except darkened area near posterior margin on each side of postgenal cleft; one elongate spot and one round spot on each side of postgenal cleft indistinct. Antenna composed of three segments and apical sensillum, somewhat longer than stem of labral fan; length ratio of three segments (from base to tip) 1.00:0.88–0.99:0.82–0.99. Labral fan with 36–39 main rays. Mandible ( Fig. 16 D) with three comb-teeth decreasing in length from first to third; serrations composed of two teeth (one medium-sized, one small); major tooth at acute angle against mandible on apical side; supernumerary serrations absent. Hypostoma ( Fig. 16 E) with row of nine apical teeth, of which median tooth slightly longer than each corner tooth; lateral margin smooth; four or five hypostomal bristles per side lying parallel to lateral margin. Postgenal cleft ( Fig. 16 F) deep, approaching posterior margin of hypostoma. Cervical sclerites indistinct. Thoracic cuticle sparsely or moderately covered with dark branched setae (divided into 6–11 branches) (similar to Fig. 16 G); abdominal cuticle of segments 1–4 moderately covered with similar branched setae, and that of segments 5–9 moderately or densely covered with dark branched setae (divided into 6–16 branches) ( Fig. 16 G) dorsally and dorsolaterally; last abdominal segment moderately covered also with unbranched colorless setae on each side of anal sclerite. Rectal scales present. Rectal organ compound, each of three lobes with six to eight thumb-like or finger-like secondary lobules. Anal sclerite of usual X-form, with anterior arms as long as or slightly shorter than 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 82 or 83 rows of hooklets with up to 14 hooklets per row.

Type material. HOLOTYPE. Female, reared from a pupa collected from a small stream (width 1–2 m, depth 10–20 cm, water temperature 15.0˚C, partially shaded, altitude 1,539 m, 12˚01’24.991” N/108˚25’30.704” E), moderately flowing in Resort Park, Langbiang, Lac Duong District, Lam Dong Province, southern Vietnam, 25-IV- 2014, by H. Takaoka, M. Sofian-Azirun, Z. Ya’cob, C.D. Chen & K.W. Lau. PARATYPES: Three females, six males, four pupae and four mature larvae, same data as those of the holotype; one female and one male, collected from a small moderately flowing stream (width 0.5–1.0 m, depth 3–5 cm, water temperature 15.0˚C, exposed to the sun, altitude 1,746 m, 12˚05’48.964” N/ 108˚22’36.097” E), 50 km from Dalat, Dinh Kno, Lac Duong District, Lam Dong Province, southern Vietnam, 25-IV-2014, by H. Takaoka, M. Sofian-Azirun, Z. Ya’cob, C.D. Chen & K.W. Lau.

Biological notes. The pupae and larvae of this new species were collected from slender pine tree leaves and round grass leaves in the water. Associated species were S. (G.) hongthaii , S. (N.) langbiangense Takaoka , Sofian- Azirun & Ya’cob, S. (N.) phami , and morphoform ‘b’ of S. (S.) tani Takaoka & Davies (complex).

Etymology. The species name lamdongense refers to the province name, Lam Dong, where this new species was collected.

Remarks. This new species is assigned to the S. batoense species-group of the subgenus Gomphostilbia , redefined by Takaoka (2012), based on the antenna with nine flagellomeres, pleural membrane bare, hind tibiae mostly darkened ( Fig. 14 C), spermatheca without sclerotized neck ( Fig. 14 J), male hind basitarsus slender and parallel-sided ( Fig. 15 B), and ventral plate slightly produced ventrally ( Fig. 15 G) (its ratio of the height against the greatest width is 0.36).

Among six subgroups of the S. batoense species-group (Takaoka 2012), S. (G.) lamdongense sp. nov. is placed in the S. decuplum subgroup by having the pupal gill with 10 short slender filaments ( Fig. 16 A). All the four known species of this subgroup differ from this new species as follows: S. (G.) bannaense Chen & Zhang from China differs by having the female claw with a small subbasal tooth and male upper-eye facets in 12 vertical columns and 13 horizontal rows (Chen and Zhang 2003); S. (G.) chongqingense Zhu & Wang from China differs by having the female genital fork with an inflated apex ( Zhu and Wang 1995); S. (G.) jiulianshanense Chen, Kang & Zhang described from pupae and larvae from China is also distinguished by lacking grapnel-shaped hooklets on the pupal abdomen ( Kang et al. 2007); and S. (G.) decuplum Takaoka & Davies from Peninsular Malaysia differs by the elongate female sensory vesicle (0.54 times the length of the third maxillary palpal segment), longer claw tooth (0.61 times the length of the claw), male upper-eye facets in 14 vertical columns and 14 horizontal rows, and pupal thorax moderately covered with tubercles ( Takaoka and Davies 1995; H. Takaoka, unpublished data).

Figures

FIGURE 14. Female of Simulium (Gomphostilbia) lamdongense sp. nov. A, third segment of maxillary palp (right side; front view); B, cibarium (front view); C, tibia of hind leg (left side; outer view); D, basitarsus and second tarsomere of hind leg (left side; outer view); E, claw; F, sternite 8 and ovipositor valve (right half; ventral view); G genital fork (ventral view); H & I, paraprocts and cerci (right side; H, ventral view; I, lateral view); J, spermatheca. Scale bars. 0.1 mm for C and D; 0.02 mm for A, B and F – J; 0.01 mm for E.

FIGURE 15. Male of Simulium (Gomphostilbia) lamdongense sp. nov. A, third segment of maxillary palp (right side; front view); B, basitarsus and second tarsomere of hind leg (left side; outer view); C, coxites, styles and ventral plate (ventral view); D & E, styles (right side; D, medial view; E, ventrolateral view); F, ventral plate and median sclerite (lateral view); G, ventral plate (caudal view); H, median sclerite (ventral view); I, paramere and aedeagal membrane (left side; caudal view); J & K, tenth abdominal segments and cerci (right side; J, lateral view; K, caudal view). Scale bars. 0.1 mm for B; 0.02 mm for A, and C – K.

FIGURE 16. Pupa and mature larva of Simulium (Gomphostilbia) lamdongense sp. nov. A – C, pupa; D – G, larva. A, anterior half of thorax and gill filaments (left side; outer view); B, terminal hooks (caudal view); C, cocoon (dorsal view); D, mandible; E, hypostoma (ventral view); F, head capsule with postgenal cleft (ventral view); G, dark branched spinous setae on dorsal surface of abdominal segment 6 (dorsal view). Scale bars. 1.0 mm for C; 0.1 mm for A; 0.05 mm for F; 0.02 mm for B, D, E and G.