Simulium (Gomphostilbia) phulocense Takaoka & Chen

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 : 18-24

Simulium (Gomphostilbia) phulocense Takaoka & Chen sp. nov.

( Figs. 6 A– 8I)

Female. Body length 2.3 mm. Head. Slightly narrower than width of thorax. Frons dark brown, densely covered with whitish-yellow scale-like recumbent short hairs interspersed with few dark longer hairs along each lateral margin; frontal ratio 1.75:1.00:2.59; frons:head ratio 1.0:4.8. Fronto-ocular area well developed, narrow, directed dorsolaterally. Clypeus dark brown, densely covered with whitish-yellow hairs interspersed with several dark longer hairs on each side. Labrum 0.63 times length of clypeus. Antenna composed of scape, pedicel and nine flagellomeres, dark brown except scape, pedicel, and base of first flagellomere yellow. Maxillary palp composed of five segments, light to medium brown, proportional lengths of third, fourth, and fifth segments 1.00:1.06:2.44; third segment ( Fig. 6 A) somewhat widened; sensory vesicle ( Fig. 6 A) small, ellipsoidal (0.26–0.27 times length of third segment), with medium-sized opening. Maxillary lacinia with 12 or 13 inner and 16 outer teeth. Mandible ( Fig. 6 C) with 26 inner teeth and six minute rudimentary outer teeth at some distance from apex. Cibarium ( Fig. 6 B) medially forming sclerotized plate folded forward from posterior margin, with moderately sclerotized mediolongitudinal ridge. Thorax. Scutum dark brown to brownish-black except anterolateral calli ochreous, thinly pruinose and shiny when illuminated at certain angles except three longitudinal vittae (one median and two submedian) unpruinose and not shiny, densely covered with whitish-yellow scale-like recumbent hairs except three longitudinal vittae covered with dark short hairs. Scutellum medium brown, shiny when illuminated at certain angles, covered with whitish-yellow 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 longer than deep, medium to dark brown, shiny when illuminated at certain angles, moderately covered with fine short hairs. Legs. Foreleg: coxa whitish-yellow; trochanter yellow; femur dark yellow to light brown with apical cap medium brown (though extreme tip yellowish); tibia white except apical one-fourth dark brown; tarsus brownish-black, with moderate dorsal hair crest; basitarsus moderately dilated, 6.9 times as long as its greatest width. Midleg: coxa medium brown except posterolateral surface dark brown; trochanter yellow; femur dark yellow to light brown with base yellowish and apical cap medium brown (though extreme tip yellowish); tibia light to dark brown except basal one-third white (though inner surface more extensively white on basal half or little more), covered with whitish and yellowish fine hairs on posterior and inner surfaces of basal three-fourths; tarsus brownish-black except little less than basal half of basitarsus yellow. Hind leg: coxa light brown; trochanter yellow; femur light brown with base yellowish and apical cap medium brown (though extreme tip yellowish); tibia ( Fig. 6 D) yellow on basal half and medium to dark brown on apical half, covered with whitish fine hairs on outer and posterior surfaces of basal three-fourths; tarsus brownish-black except basal two-thirds of basitarsus (though base light brown) and basal half of second tarsomere white; basitarsus ( Fig. 6 E) narrow, nearly parallel-sided though slightly narrowed on apical one-half, 6.67 times as long as wide, and 0.69 and 0.55 times as wide as greatest widths of tibia and femur, respectively; calcipala ( Fig. 6 E) slightly longer than width at base, and 0.48 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 6 E) well developed; claw ( Fig. 6 F) with large basal tooth 0.53 times length of claw. Wing. Length 2.3 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 portion darkened. Abdomen. Basal scale light ochreous, with fringe of whitish-yellow hairs. Dorsal surface of abdomen medium to dark brown except basal half of segment 2 yellow, moderately covered with dark short to long hairs (except segment 2 with yellow fine hairs); tergites of segments 2 and 6–9 shiny when illuminated at certain angles. Ventral surface of segments 2–5 whitish-yellow, those of segments 6 and 7 light brown and that of segment 8 medium to dark brown; sternal plate on segment 7 undeveloped. Genitalia. Sternite 8 ( Fig. 6 G) bare medially, with 17–20 medium-long to long hairs together with few slender short hairs on each side. Ovipositor valves ( Fig. 6 G) triangular (though posteromedial corners rounded), thin, membranous, moderately covered with microsetae interspersed with two or three short hairs; inner margins slightly sinuous, somewhat sclerotized, and moderately separated from each other. Genital fork ( Fig. 6 H) of usual inverted-Y form, with slender stem; arms of moderate width, moderately folded medially; lobe directed posteromedially from each arm weakly sclerotized and short (apical portion unsclerotized). Paraproct in ventral view ( Fig. 6 I) somewhat concave anterolaterally, with four sensilla on anteromedial surface; paraproct in lateral view ( Fig. 6 J) slightly produced ventrally beyond ventral tip of cercus, 0.6 times as long as wide, with 20–23 medium-long to long hairs on ventral and lateral surfaces. Cercus in lateral view ( Fig. 6 J) short, rounded posteriorly, 0.37 times as long as wide. Spermatheca ( Fig. 6 K) ellipsoidal, 1.4 times as long as its 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 2.3 mm. Head. Somewhat wider than thorax. Upper eye medium brown, consisting of 12 or 13 vertical columns and 14 horizontal rows of large facets. Face black, white pruinose. Clypeus black, whitish 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 nine flagellomeres, medium brown except scape and pedicel yellow to dark yellow and base of first flagellomere whitish-yellow; first flagellomere elongate, 1.8 times length of second one. Maxillary palp light to medium brown, with five segments, proportional lengths of third, fourth, and fifth segments 1.0:1.2:2.7; third segment ( Fig. 7 A) widened apically; sensory vesicle ( Fig. 7 A) globular, small (0.18 times length of third segment), and with small opening. Thorax. Scutum brownishblack to black, shiny on narrow areas along lateral margins and prescutellar area when illuminated at certain angles, and densely covered with golden-yellow short recumbent hairs. Scutellum dark brown with yellow short hairs and dark-brown upright longer hairs. Postnostum dark brown and bare. Pleural membrane bare. Katerpisternum longer than deep, dark brown with dark short hairs. Legs. Foreleg: coxa whitish yellow; trochanter dark yellow except base yellow; femur light brown with apical cap medium brown (though extreme tip yellowish); tibia light to dark brown except basal three-fourths of outer surface whitish, and with white sheen on outer surface when illuminated at certain angles; tarsus brownish-black, with moderate dorsal hair crest; basitarsus somewhat dilated, 8.6 times as long as its greatest width. Midleg: coxa medium brown except posterior surface dark brown; trochanter light brown except base yellow; femur light brown with base yellowish and apical cap medium brown (though extreme tip yellowish); tibia light to dark brown except basal one-third white; tarsus brownish-black except little less than basal half of basitarsus light brown. Hind leg: coxa light brown; trochanter yellow; femur light brown with base yellowish and apical cap medium brown (though extreme tip yellowish); tibia yellow on little less than basal half and medium to dark brown on apical half; tarsus brownish-black except little more than basal half of basitarsus (though base light brown) and basal half of second tarsomere white; basitarsus ( Fig. 7 B) much enlarged, spindle-shaped, 4.0 times as long as wide, and 0.93 and 0.90 times as wide as greatest widths of tibia and femur, respectively; calcipala ( Fig. 7 B) slightly shorter than wide, and 0.37 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 7 B) well developed. Wing. Length 2.1–2.3 mm. Other features as in female except subcosta with three or four hairs. Halter .White except basal portion darkened. Abdomen. Basal scale medium to dark brown, with fringe of light to dark brown hairs. Dorsal surface of abdomen medium brown to brownish-black except basal one-third of segment 2 yellow, covered with light to dark brown short to long hairs; segments 2 and 5–8 each with pair of shiny dorsolateral or lateral patches; ventral surface of segment 2 white, those of segments 3–5 dull yellow to light brown except sternites medium brown, and those of other segments medium to dark brown. Genitalia. Coxite in ventral view ( Fig. 7 C) nearly rectangular, 2.5 times as long as its greatest width.

Style in ventral view ( Fig. 7 C) bent inward, nearly parallel-sided toward apex, and with apical spine; style in ventrolateral view ( Fig. 7 D) gradually narrowed from base toward apex, with truncated apex. Ventral plate in ventral view ( Fig. 7 C) with body transverse, 0.6 times as long as wide, widest medially, then slightly narrowed posteriorly, with anterior margin produced anteromedially, and posteroventral margin slightly concave, densely covered with microsetae on ventral surface; basal arms of moderate length, directed forward, then slightly convergent apically; ventral plate in lateral view ( Fig. 7 E) moderately produced ventrally; ventral plate in caudal view ( Fig. 7 F) rounded ventrally, with ventral margin rounded, densely covered with microsetae on posterior surface. Median sclerite ( Fig. 7 C, E) thin, plate-like, wide. Paramere ( Fig. 7 G) of moderate size, with three long hooks and several shorter hooks. Aedeagal membrane moderately setose; dorsal plate not defined. Ventral surface of abdominal segment 10 ( Fig. 7 H, I) without distinct hairs near posterior margin. Cercus ( Fig. 7 H, I) small, rounded, with 11 or 12 hairs.

Pupa. Body length 2.5 mm. Head. Integument yellow, moderately covered with small round tubercles; antennal sheath without protuberances; frons with three pairs of unbranched long trichomes with coiled or uncoiled apices ( Fig. 8 A); face with pair of unbranched long trichomes with coiled apices ( Fig. 8 B); three frontal trichomes on each side arising close together, subequal in length to one another and slightly longer than facial one. Thorax. Integument yellow, moderately covered with round tubercles, with three long anterodorsal trichomes with coiled apices ( Fig. 8 C), two long anterolateral trichomes with coiled apices ( Fig. 8 D), one medium-long mediolateral trichome with uncoiled apex ( Fig. 8 E), and three ventrolateral trichomes with uncoiled apices (one medium-long, two short) ( Fig. 8 F) on each side; all trichomes unbranched. Gill ( Fig. 8 G) composed of eight slender thread-like filaments, arranged as [(1+2) +(1+2)]+2 filaments from dorsal to ventral, with medium-long common basal stalk having somewhat swollen basal fenestra ventrally (often partially broken) at base; common basal stalk 0.6–0.7 times length of interspiracular trunk; dorsal and middle triplets sharing short stalk; dorsal and middle triplets each composed of one individual filament and two paired filaments with short primary and secondary stalks though dorsal triplet composed of three filaments arising at same level from primary stalk in left gill of one pupa; ventral paired filaments with medium-long stalk 0.9–1.6 times length of common basal stalk; primary stalk of dorsal triplet lying against that of lower pair at angle of 60 degrees when viewed laterally; all filaments light brown, gradually tapered toward apex; six filaments of dorsal and middle triplets subequal in length (2.2–2.4 mm long including their own stalks and common basal stalk) and thickness to one another; inner filament of ventral pair longest (2.8– 3.2 mm), slightly longer than outer filament (2.6–2.9 mm); 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 unpigmented and without tubercles; segment 1 with one unbranched slender medium-long hair-like seta on each side; segment 2 with one unbranched slender medium-long hair-like seta and four or five short setae submedially on each side; segments 3 and 4 each with four hooked spines and one short somewhat spinous seta on each side; segment 5 lacking spine-combs; segments 6–9 each with spine-combs in transverse row and comb-like groups of minute spines on each side; segment 9 with pair of flat triangular terminal hooks, of which outer margin about twice length of inner margin and crenulated ( Fig. 8 H). Ventrally, segment 4 with one unbranched hooklet and few simple slender short setae on each side; segment 5 with pair of bifid hooks submedially and few short unbranched slender setae on each side; segments 6 and 7 each with pair of bifid inner and unbranched or bifid outer hooks somewhat spaced from each other and few short simple 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. 8 I). Wall-pocket-shaped, moderately woven, widely extended ventrolaterally; anterior margin thickly woven, with dorsomedial portion markedly produced anteriorly, resembling letter W when viewed dorsally; posterior three-fifths with floor roughly woven; individual threads visible; 2.9–3.0 mm long by 1.6–2.4 mm wide.

Mature larva. Unknown.

Type material. HOLOTYPE: Female, reared from pupa collected from a small stream (width 0.5–1.0 m, depth 5–30 cm, water temperature 15.0˚C, shaded, altitude 1,186 m, 16˚11’45.123” N/107˚50’55.600” E), moderately flowing from a natural forest, near the top of Bach Ma National Park, Phu Loc, Thua Thien Hue Province, central Vietnam, 23-II-2014, by H. Takaoka, M. Sofian-Azirun, Z. Ya’cob, C.D. Chen & K.W. Lau. PARATYPE: One male reared from pupa, same data as those of the holotype.

Biological notes. The pupae of this new species were collected from dead tree leaves in the water. Associated species were S. (G.) thuathienense sp. nov., S. (N.) bachmaense Takaoka, Sofian-Azirun & Ya’cob, S. (S.) atipornae Takaoka, Srisuka & Choochote and S. (S.) cavum sp. nov.

Etymology. The species name phulocense refers to the district name, Phu Loc, where this new species was collected.

Remarks. Simulium (G.) phulocense sp. nov. is placed in the S. asakoae species-group based on the enlarged male hind basitarsus ( Fig. 7 B), ventral plate slightly emarginated basally ( Fig. 7 C), yellow hair tuft of the base of the radial vein, and whitish-yellow fore coxae of both female and male adults.

This new species is characterized by the shape of the cocoon having an anterodorsal margin produced medially and resembling the letter W when viewed dorsally ( Fig. 8 I). Among the 21 species of the S. asakoae species-group (Takaoka 2012; Takaoka et al. 2014a), S. (G.) gyorkosae Takaoka & Davies from Java, Indonesia ( Takaoka and Davies 1996) and S. (G.) jianfengense Long et al. from Hainan Island, China ( Long et al. 1994) and S. (G.)

yunnanense Chen & Zhang from Yunnan, China ( Chen and Zhang 2004) have a similar cocoon. However, S. (G.) phulocense sp. nov. is distinguished from these three known species by the following characters (those of each related species in parentheses): from (G.) gyorkosae by the female hind tibia that is yellow on the basal half and medium to dark brown on the apical half (whitish on the basal two-thirds and brownish black on the apical onethird), and the number of male upper-eye facets in 12 or 13 vertical columns (in 10 or 11 vertical columns); from S. (G.) jianfengense by the length ratio of the sensory vesicle against the third maxillary palpal segment, 0.26 or 0.27 (0.3), ventral plate produced anteromedially when viewed ventrally ( Fig. 7 C) (not produced), ventral plate gently rounded ventrally with its greatest height 0.3 times the width of the ventral plate when viewed posteriorly ( Fig. 7 F) (pointed ventrally, its greatest height about half the width of the ventral plate), male hind basitarsus spindle-shaped and four times as wide as its greatest width ( Fig. 7 B) (wedge-shaped and three times as wide as its greatest width); from S. (G.) yunnanense by the yellow hair tuft of the base of the radial vein (black hair tuft), and the number of male upper-eye facets in 12 or 13 vertical columns (in 10 vertical columns).

Figures

FIGURE 6. Female of Simulium (Gomphostilbia) phulocense sp. nov. A, third segment of maxillary palp with sensory vesicle (right side, front view); B, cibarium (front view); C, mandible (right side); D, tibia of hind leg (left side; outer view); E, basitarsus and second tarsomere of hind leg (left side; outer view); F, claw; G, sternite 8 and ovipositor valve (right half; 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 for D and E; 0.02 mm for A, B and G – K; 0.01 mm for C and F.

FIGURE 7. Male of Simulium (Gomphostilbia) phulocense sp. nov. A, third segment of maxillary palp with sensory vesicle (right side; front view); B, basitarsus and second tarsomere of hind leg (left side; outer view); C, coxites, styles, ventral plate and median sclerite (ventral view); D, style (right side; ventrolateral view); E, ventral plate and median sclerite (lateral view); F, ventral plate (caudal view); G, paramere (right side; dorsal view); H & I, tenth abdominal segments and cerci (right side; H, lateral view; I, caudal view). Scale bars. 0.1 mm for B; 0.02 mm for A and C – I.

FIGURE 8. Pupa of Simulium (Gomphostilbia) phulocense sp. nov. A, frontal trichome; B, facial trichome; C – F, thoracic trichomes (C, anterodorsal; D, anterolateral; E, mediolateral; F, ventolateral); G, anterior part of thorax and gill filaments (right side; outer view); H, terminal hooks (caudal view); I, cocoon (dorsal view). Scale bars. 1.0 mm for I; 0.1 mm for G; 0.05 mm for A – D; 0.04 mm for E and F; 0.02 mm for H.