Simulium (Gomphostilbia) hongthaii Takaoka, Sofian-Azirun

Takaoka, Hiroyuki, Sofian-Azirun, Mohd, Ya’Cob, Zubaidah, Chen, Chee Dhang, Lau, Koon Weng & Pham, Hong Thai, 2014, New species and records of black flies (Diptera: Simuliidae) from Vinh Phuc Province, Vietnam, Zootaxa 3838 (3), pp. 347-366 : 348-350

1. Simulium (Gomphostilbia) hongthaii Takaoka, Sofian-Azirun & Ya’cob sp. nov.

Male. Body length 2.5 mm. Head. Somewhat wider than thorax. Upper eye medium brown, consisting of 16 vertical columns and 16 horizontal rows of large facets. Face brownish-black, white pruinose. Clypeus brownishblack, 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 9 flagellomeres, medium brown except scape and pedicel yellow and base of first flagellomere whitish-yellow; first flagellomere elongate, 1.9 times length of second one. Maxillary palp light to medium brown, with 5 segments, proportional lengths of third, fourth, and fifth segments 1.0:1.2:2.4; third segment ( Fig. 1A ) slender; sensory vesicle ( Fig. 1A ) globular, small (0.2 times length of third segment), and with opening of medium-size. Thorax. Scutum dark-brown to brownish-black, without longitudinal vittae, shiny and thinly gray pruinose on shoulders, on wide area along each lateral margin and on prescutellar area when illuminated at certain angles, densely covered with golden-yellow scale-like recumbent hairs. Scutellum medium brown, covered with yellow short hairs and dark-brown long upright hairs along posterior margin. Postnotum brownish-black, shiny and white pruinose when illuminated at certain angles, and bare. Pleural membrane bare. Katepisternum dark brown, longer than deep, shiny when illuminated at certain angles, moderately covered with fine short hairs. Legs. Foreleg: coxa whitish-yellow; trochanter light brown except base yellow; femur light brown with apical cap medium brown (though apical tip yellowish); tibia white to grayish except base light brown and little less than apical 1/3 brownish-black, and covered with white and yellow hairs on basal 2/3 of outer surface and white sheen on basal 2/3 of outer surface when illuminated at certain angles; tarsus brownish-black; basitarsus moderately dilated, 7.5–8.4 times as long as its greatest width. Midleg: coxa dark brown except posterior surface brownish-black; trochanter light brown except base whitish-yellow; femur light brown with posterior surface of base somewhat whitish-yellow and apical cap medium brown (though apical tip yellow); tibia medium brown except basal 1/4 or little more whitish-yellow; tarsus dark brown except extreme base of basitarsus yellow. Hind leg: coxa light brown though apical portion whitish-yellow; trochanter whitish-yellow; femur light brown with base narrowly whitish-yellow and apical cap dark brown (though apical tip whitish-yellow); tibia ( Fig. 1B ) dark brown to brownish-black except little less than basal 1/2 whitish-yellow, covered with yellow hairs on basal 2/3 of outer surface; tarsus ( Fig. 1C ) medium to dark brown except little less than basal 1/2 of basitarsus (border not well defined) and basal 1/3 of second tarsomere yellowish; basitarsus ( Fig. 1C ) enlarged, 3.9–4.0 times as long as wide, and 0.9–1.0 and 1.0 times as wide as greatest width of tibia and femur, respectively; calcipala ( Fig. 1C ) slightly shorter than basal width, and 0.3 times as wide as greatest width of basitarsus. Pedisulcus ( Fig. 1C ) well defined. Wing. Length 2.1 mm. Costa with dark spinules and hairs except hairs on basal portion yellow. Subcosta bare. Hair tuft on base of radial vein yellow. Basal portion of radius fully haired; R 1 with dark spinules and hairs; R 2 with hairs only. Basal cell absent. Halter . Grayish except basal stem darkened. Abdomen. Basal scale dark brown, with fringe of light-brown hairs. Dorsal surface of abdomen medium to dark brown except anterior 1/2 of segment 2 yellowish, 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. 1D ) nearly rectangular, 2.2 times as long as its greatest width. Style in ventral view ( Fig. 1D ) bent inward, bluntly rounded apically and with apical spine; style in medial view ( Fig. 1E ) shorter than coxite (0.8 times length of coxite), gently bent inward, nearly parallel-sided to apex; style in ventrolateral view ( Fig. 1F ) nearly parallelsided from base to basal 1/3, then slightly tapered toward apex, with truncated apex. Ventral plate in ventral view ( Fig. 1D ) with body transverse, 0.5 times as long as wide, with anterior margin produced anteromedially, and posterior margin somewhat concave medially (though posterior margin slightly convex medially when ventral plate is slightly inclined), lateral margins slightly emarginated sub-basally, and densely covered with microsetae on ventral surface; basal arms of moderate length, directed forward, then convergent apically; ventral plate in lateral view ( Fig. 1G ) moderately produced ventrally; ventral plate in end view ( Fig. 1H ) trapezoidal, with ventral margin shallowly concave medially, densely covered with microsetae on posterior surface except portion near each lateral tip narrowly bare. Median sclerite thin, plate-like, wide. Parameres ( Fig. 1I ) of moderate size, each with 4 distinct long and medium-long stout hooks and several smaller ones including smallest one on middle part of basal arm. Aedeagal membrane moderately setose, not sclerotized at base; dorsal plate not defined. Ventral surface of abdominal segment 10 ( Fig. 1J, K ) without distinct hairs near posterior margin. Cercus in lateral view ( Fig. 1J ) small, rounded, with 14 hairs.

Pupa. Body length 2.4 mm. Head. Integument yellow, moderately covered with small round tubercles except antennal sheaths and ventral surface almost bare; antennal sheath without any protuberances; face with pair of unbranched long trichomes with coiled apices, and frons with 3 pairs of unbranched long trichomes with coiled or uncoiled apices; 3 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, and with 3 unbranched long dorsomedial trichomes with coiled or uncoiled apices, 2 unbranched long anterolateral trichomes (1 with coiled apex, 1 with uncoiled apex), 1 unbranched medium-long mediolateral trichome with uncoiled apex, and 3 unbranched ventrolateral trichomes with uncoiled apices (1 medium-long, 2 short) on each side. Gill ( Fig. 1L ) composed of 8 slender thread-like filaments, arranged as [3+ (1+2)]+2 or [(2+1)+3]+2 filaments from dorsal to ventral, with medium-long common basal stalk having somewhat swollen transparent basal fenestra at base; common basal stalk 0.5–0.8 times length of interspiracular trunk; dorsal and middle triplets share short stalk and each composed of 3 individual filaments arising at same level, with short stalk, or composed of 1 individual and 2 paired filaments and bearing short primary and secondary stalks; stalk of ventral pair of filaments medium-long, 1.2–1.3 times length of common basal stalk, and 0.9–1.0 times length of interspiracular trunk, and 1.1–1.3 and 1.2–1.4 times as thick as primary stalks of middle and dorsal triplets, respectively, and 0.9 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 about 50 degrees when viewed laterally; 6 filaments of dorsal and middle triplets subequal in length (1.8–2.0 mm) and thickness to one another; 2 filaments of ventral pair subequal in length (2.6 mm) and thickness to each other, and 1.3–1.5 times as thick as 6 other filaments when compared basally; all filaments light brown, gradually tapered toward apex; cuticle of all filaments with well-defined annular ridges and furrows though becoming less marked apically, densely covered with minute tubercles. Abdomen. Dorsally, segments 1 and 2 not pigmented and without tubercles; segment 1 with 1 unbranched slender medium-long hair-like seta on each side; segment 2 with 1 unbranched slender medium-long hair-like seta and 5 short somewhat spinous setae submedially on each side; segments 3 and 4 each with 4 hooked spines and 1 short somewhat spinous seta on each side; segment 5 lacking spine-combs and comb-like groups of minute spines on each side; segments 6–9 each with spine-combs in transverse row (those on segment 9 slightly to much smaller than those on segments 6–8) and comb-like groups of minute spines on each side; segments 5–8 each with 2 or 3 short setae near posterior margin on each side; segment 9 with pair of wide flat terminal hooks, of which outer margin is 2.8–3.0 times length of inner margin and crenulated ( Fig. 1M ) when viewed caudally. Ventrally, segment 4 with 1 unbranched hook (subequal in size to those on segments 5–7) and few slender short setae on each side; segment 5 with pair of bifid hooks submedially and few 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 short slender setae on each side; segments 4–8 with comb-like groups of minute spines. Each side of segment 9 with 3 grapnel-shaped hooklets. Cocoon. Wallpocket-shaped, thinly and moderately woven, widely extended ventrolaterally; dorsomedial portion of anterior margin somewhat produced anteriorly, with short anterodorsal bulge; 3.0– 3.2 mm long by 1.9–2.4 mm wide.

Female and larva. Unknown.

Type specimens. Holotype. Male (reared from pupa and preserved with its associated pupal exuviae and cocoon in a vial with 80% ethanol), collected from a small stream (width 0.5 m, bed rocky, water temperature 17˚C, shaded, altitude 975 m, N21˚27’501’’/E105˚38’941’’), flowing slowly in a bush along the road in the Tam Dao National Park, Vinh Phuc Province, Vietnam, 8-XI-2013, by M. Sofian-Azirun . Paratype. One male (reared from a pupa and preserved with its associated pupal exuviae and cocoon in a vial with 80% ethanol), collected from a small stream (width 0.5 m, shaded, water temperature 17 ˚C, shaded, altitude 997 m, N21˚27’819’’/E105˚38’946’’) flowing slowly in a forest, about 500 m inside the gate, Tam Dao National Park, Vinh Phuc Province, Vietnam, 9-XI-2013, by Z. Ya’cob .

Biology. The pupae of this new species were collected from trailing grasses. The associated species were S. (G.) brinchangense Takaoka, Sofian-Azirun & Hashim , S. (Nevermannia) sp. ( Simulium feuerborni species-group) and S. (S.) brevipar Takaoka & Davies.

Etymology. The species name hongthaii is in honor of Dr. Hong Thai Pham, head of Insect systematics Department, Institute of Biodiversity and Biological Resources, Vietnam Academy of Science and Technology, Hanoi, Vietnam, for his contribution in insect systematics and ecology.

Remarks. This new species is assigned to the Simulium asakoae species-group of the subgenus Gomphostilbia defined by Takaoka (2012) by having the yellow hair tuft on the base of the radial vein, enlarged male hind basitarsi and ventral plate with lateral margins emarginated medially ( Fig. 1D ). The male of this new species is characterized by the greater number of upper-eye large facets in 16 vertical columns and 16 horizontal rows. Such a greater number of upper-eye facets was recorded in five of the 21 species of the asakoae species-group, i.e., S. (G.) jianfengense Long, An & Hao from China, S. (G.) sofiani Takaoka & Hashim and S. (G.) lurauense Takaoka, Sofian-Azirun & Hashim , both from Peninsular Malaysia, and S. (G.) taitungnese Huang & Takaoka , and S. (G.) tuenense Takaoka , both from Taiwan ( Long et al. 1994; Takaoka et al. 2011a, b; Huang et al. 2011). However, the male of S. (G.) hongthaii sp. nov. is easily distinguished from S. (G.) jianfengense by the ventral plate which is trapezoidal in caudal view (cf., triangular in S. (G.) jianfengense ), and all the other four species by the relative width of the hind basitarsus against the hind tibia (0.9–1.0 in S. (G.) hongthaii sp. nov. versus 0.8 in the other four species).

Figures

FIGURE 1. Male and pupa of S (G.) hongthaii sp. nov. A–K, male; L & M, pupa. A, third segment of right maxillary palp with sensory vesicle (front view); B, tibia of left hind leg (outer view); C, basitarsus with calcipala and second tarsomere with pedisulcus of left hind leg (outer view); D, coxites, styles and ventral plate (ventral view); E & F, right styles (E, medial view; F, ventrolateral view); G, ventral plate and median sclerite (lateral view); H, ventral plate (caudal view); I, left paramere (caudal view); J & K, right cerci (J, lateral view; K, caudal view); L, anterior portion of thorax and gill filaments (right side, outer view); M, terminal hooks (caudal view). Scale bars = 0.1 mm for B, C & L, and 0.02 mm for A, D–K & M.