Simulium (Simulium) taythienense 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 : 353-361

3. Simulium (Simulium) taythienense Takaoka, Sofian-Azirun & Ya’cob sp. nov.

Female. Body length 2.6–3.5 mm. Head. Slightly narrower than thorax. Frons black, shiny with bluish reflection when illuminated at certain angles, with several dark stout hairs along lateral margins; frontal ratio 1.3–1.4:1.0:1.4; frons:head ratio 1.0:4.4. Fronto-ocular area well developed, short, directed laterally, and pointed apically. Clypeus brownish-black, shiny with bluish reflection when illuminated at certain angles, moderately covered with darkbrown medium-long hairs (though mediolongitudinal portion of upper 2/3 widely bare) interspersed with several dark-brown longer curved hairs on each side of lower portion. Labrum 0.6 times length of clypeus. Antenna composed of scape, pedicel and 9 flagellomeres; first flagellomere 1.5 times length of second one; antenna yellow to dark yellow, except 5 or 6 apical flagellomeres dark brown (though in 1 female antenna almost entirely yellow to dark yellow except flagellomere 5 and apical half or little less of flagellomere 8 dark brown). Maxillary palp with 5 segments, medium brown except first and second segments ochreous or light brown, and third segment dark brown; proportional lengths of third, fourth, and fifth segments 1.0:1.1:2.6–2. 7; third segment ( Fig. 3A ) of normal size, with medium-sized ellipsoidal sensory vesicle (0.3–0.4 times length of third segment) having large opening. Maxillary lacinia with 14 or 15 inner and 12–14 outer teeth. Mandible with 24 or 25 inner and 13–15 outer teeth. Cibarium ( Fig. 3B ) with 30–32 minute processes near posterodorsal margin. Thorax. Scutum black, shiny, densely covered with whitish-yellow recumbent short hairs interspersed with dark-brown short hairs on anterior portion near anterior margin and lateral portions near lateral margins, and several dark-brown long upright hairs on prescutellar area; scutum gray pruinose with 5 non-pruinose longitudinal vittae (1 medial, 2 submedial, and 2 sublateral), medial and submedial vittae well defined from anterior margin to posterior portion but sublateral vittae not well defined and their anterior halves indistinct), all vittae united with transverse non-pruinose band on prescutellar area, when illuminated in front and viewed dorsally; scutum gray pruinose except 4 non-pruinose longitudinal vittae, when illuminated posteriorly and viewed dorsally. Scutellum medium brown, covered with dark-brown upright long hairs and whitish-yellow short hairs. Postnotum brownish-black, shiny, white pruinose when illuminated at certain angles, and bare. Pleural membrane bare. Katepisternum brownish-black, longer than deep, shiny, white pruinose when illuminated at certain angles, and bare. Legs. Foreleg: coxa whitish; trochanter whitish, with outer surface somewhat darkened; femur whitish-yellow basally, then yellow except apical tip brownish-black on inner surface, dark yellow, gradually darkened toward apex, with apical tip brownish-black on outer surface; tibia brownish-black to black except basal tip light to medium black; tarsus black, with moderate dorsal hair crest; basitarsus greatly dilated, 5.4–5.6 times as long as its greatest width. Midleg: coxa brownishblack; trochanter brownish-black except anterior surface of base whitish; femur brownish-black except basal tip light to medium brown; tibia dark brown to brownish-black except base yellow, and with whitish sheen widely on posterior surface when illuminated at certain angles; tarsus light to medium brown except basal 4/5 to 2/3 of basitarsus and basal1/6 to 1/2 of second tarsomere yellowish-white. Hind leg: coxa brownish-black; trochanter yellowish-white; femur brownish-black except base whitish-yellow; tibia ( Fig. 3C ) brownish-black except base whitish-yellow and with whitish sheen on basal 1/2 or more of posterior surface when illuminated at certain angles; tarsus dark brown except basal 2/3 of basitarsus yellowish-white and basal 1/2 of second tarsomere yellowish; basitarsus ( Fig. 3D ) nearly parallel-sided, 6.2–6.3 times as long as wide, and 0.6–0.7 and 0.6 times as wide as greatest widths of hind tibia and femur, respectively; calcipala ( Fig. 3D ) moderately developed, nearly as long as wide, and 0.4 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 3D ) well developed at basal 1/3 of second tarsomere. Tarsal claw simple, without tooth. Wing. Length 2.4 mm. Costa with dark spinules and hairs; subcosta haired except near apex bare; basal section of radial vein haired except basal 1/6 to 2/5 bare; R 1 with dark brown spinules and hairs; R 2 with dark-brown hairs; hair tuft on base of radial vein dark brown; basal cell absent. Halter . White except base darkened. Abdomen. Basal scale brownish-black, with fringe of dark hairs. Dorsal surface of abdomen medium-brown to brownish-black, with light to dark-brown short hairs; tergite 2 shiny and silvery iridescent when illuminated at certain angles and tergites 6–9 shiny. Ventral surface of seventh segment with pair of weakly sclerotized submedian sternal plates. Genitalia. Sternite 8 ( Fig. 3E ) with posterior margin concave medially in form of reversed-U shape, bare medially, with 28–39 dark brown medium-long to long stout hairs and 16–21 yellow short hairs on each lateral surface. Ovipositor valves ( Fig. 3E ) rounded posteromedially, with ventrally produced lobe near inner margin, membranous except narrow area along inner margin slightly sclerotized, covered with 28–37 short yellow hairs and numerous microsetae; inner margins slightly sinuous, somewhat separated from each other. Genital fork ( Fig. 3F ) of inverted-Y form, with narrow well sclerotized stem; arms of moderate width, each with moderately sclerotized lateral portion. Paraproct in ventral view ( Fig. 3G ) rounded, subequal in length to greatest width, strongly pigmented on anterior surface, with 30–39 dark short to medium-long hairs (except several hairs yellow) on lateral and ventral surfaces, and with 7–10 short sensilla on anteromedial surface; paraproct in lateral view ( Fig. 3H ) nearly half as long as wide, and much protruding ventrally beyond ventral margin of cercus. Cercus in lateral view ( Fig. 3H ) short, 0.6 times as long as wide, with numerous medium-long hairs, and rounded posteriorly. Spermatheca ( Fig. 3I ) nearly ovoid, 1.2–1.3 times as long as greatest width, well sclerotized except portion of junction with duct somewhat widely unsclerotized, without definite reticulate patterns on its surface; internal setae present; accessory ducts subequal in thickness to each other, and slightly thicker than major duct.

Male. Body length 3.0– 3.2 mm. Head. Slightly wider than thorax. Upper eye consisting of large facets in 17 or 18 vertical columns and in 17 or 18 horizontal rows. Clypeus black, thickly white pruinose and brilliantly iridescent when illuminated at certain angles, sparsely covered with dark brown hairs along and near lateral margins (most of central portion bare). Antenna similar in number of articles and color to that of female; first flagellomere elongate, 1.5 times length of second one. Maxillary palp similar in number of segments and color to that of female; proportional lengths of third, fourth, and fifth segments 1.0:1.3:2.8; third segment ( Fig. 4A ) of normal size; sensory vesicle ( Fig. 4A ) ellipsoidal, 0.2 times length of third segment, and with small opening.

Thorax. Scutum black, with whitish-gray pruinose pattern, i.e., anterior pair of large spots on shoulders extending posteriorly along lateral margins and connected to large transverse spot entirely covering prescutellar area, anterior pair of large spots divided into anterior half and posterior half, either of which disappears depending on direction of lights; all these spots brilliantly iridescent when illuminated at certain angles; scutum uniformly and moderately covered with brassy recumbent short hairs interspersed with dark-brown short hairs near anterior margin and darkbrown long upright hairs on prescutellar area. Scutellum medium brown, with dark-brown long upright hairs and dark short hairs. Postnotum brownish-black, shiny and whitish-gray pruinose when illuminated at certain angles and bare. Pleural membrane bare. Katepisternum longer than deep, brownish-black, and bare. Legs. Color similar to that of female except hind basitarsus yellowish-white on basal3/5 or little less and dark brown on rest; fore basitarsus moderately dilated, 5.6–7.3 times as long as its greatest width; hind basitarsus ( Fig. 4B ) enlarged, gradually widened toward apical 1/3, then nearly parallel-sided or slightly narrowed, 4.4–4.6 times as long as wide, and 0.8 and 0.8–0.9 times as wide as greatest width of hind tibia and femur, respectively; calcipala ( Fig. 4B ) developed, small, little shorter than its basal width, and 0.3 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 4B ) well developed. Wing. Length 2.3–2.4 mm. Other characters as in female except basal portion of radial vein and subcosta bare. Abdomen. Basal scale brownish-black, with fringe of dark-brown long hairs. Dorsal surface of abdomen medium-brown to brownish-black except basal half or less of segment 2 whitish-yellow, moderately covered with dark-brown short to medium-long hairs; segments 2, 5, 6 and 7 each with pair of whitish pruinose spots (brilliantly iridescent when illuminated at certain angles) dorsolaterally, those on segment 2 connected broadly to each other in middle. Genitalia. Coxite in ventral view ( Fig. 4C ) nearly quadrate, nearly as long as wide; coxite in ventrolateral view ( Fig. 4D ) rectangular, 0.8 times as long as wide. Style in ventral view ( Fig. 4C ) elongate, slightly narrowed toward middle, then nearly parallel-sided to apex, inner margin gently concave, with subapical spine (2 subapical spines in 1 male); style in ventrolateral view ( Fig. 4D ) 1.7 times length of coxite, 2.9 times as long as greatest width near apex; style in medial view ( Fig. 4E ) somewhat flattened dorsoventrally, with short basal protuberance directed dorsomedially, with several cone-like spines along its anterior margin; style in dorsomedial view ( Fig. 4F ) with short basal protuberance with well sclerotized, saw-like ragged anterior margin. Ventral plate in ventral view ( Fig. 4C ) with body broad, bearing prominent median process sharply narrowed to round tip; body covered with minute setae medially; arms short, stout, divergent from base; ventral plate in lateral view ( Fig. 4G ) with median process abruptly bent ventrally at nearly right angle; ventral plate in caudal view ( Fig. 4H ) in form of equilateral triangle, and bare. Median sclerite in ventral view ( Fig.4C ) weakly sclerotized, wide, nearly parallel-sided on posterior 2/3, with its base arising in front of anteroventral margin of ventral plate. Paramere in caudal view ( Fig. 4I ) wide, moderately sclerotized, with several short to medium-long hooks near apex. Aedeagal membrane in caudal view ( Fig. 4I ) sparsely covered with minute setae; dorsal plate indistinct. Abdominal segment 10 ( Fig. 4J, K ) with 5–10 distinct hairs on ventral and posterolateral surface near each posterolateral corner. Cercus ( Fig. 4J, K ) small, rounded, with 14–17 distinct hairs.

Pupa. Body length 3.1–3.5 mm. Head. Integument yellow to dark yellow, moderately covered with relatively large tubercles interspersed with small ones near lateral margins; large tubercles round and lacking secondary projections ( Fig. 5A ); frons with 2 pairs of short trichomes with uncoiled apices ( Fig. 5B ); face with pair of long trichomes with uncoiled apices ( Fig. 5C ), 1.3–1.9 times length of frontal trichomes. Thorax. Integument yellow to dark yellow, moderately covered with relatively large tubercles except lateral surfaces and dorsal surface of posterior 1/2 of thorax moderately covered with small tubercles; thorax on each side with 3 bifid or trifid long trichomes with uncoiled apices) anterodorsally ( Fig. 5D ), 2 trichomes (1 bifid or trifid long with uncoiled apex, 1 unbranched medium-long with uncoiled apex) anterolaterally ( Fig. 5E ), 1 unbranched or bifid medium-long trichome with uncoiled apex mediolaterally ( Fig. 5F ), and 3 trichomes with uncoiled apices (2 unbranched or bifid long, 1 unbranched or bifid short) ventrolaterally ( Fig. 5G ). Gill ( Fig. 5H ) with 10 thread-like filaments arranged as 2+(1+2)+(2+1)+2 or 2+(1+2)+(1+1+1)+2 filaments from dorsal to ventral (exceptionally 2+2+1+(1+1+1)+2 filaments in left gill of one pupa –– Fig. 5I ); dorsal and ventral pairs with short stalk, two middle triplets with short stalk and short to medium-long secondary stalk when arranged as 1 individual and 2 paired filaments; dorsalmost filament shortest (1.0– 1.3 mm long), 1 or 2 filaments of lower middle triplet longest (1.3–1.7 mm long) and other filaments intermediate in length; proportional thickness of 10 filaments from dorsal to ventral 1.4–1.6:1.4–1.6:1.2–1.3:1.2:1.0–1.1:1.4–1.8:1.3–1.7:1.2–1.5:1.1–1.2:1.0 when compared basally; all filaments medium brown, covered with annular ridges and furrows and densely covered with minute tubercles, relatively larger ones on ridges and smaller one on interridges. Abdomen. Dorsally, nearly transparent except segment 1 grayish; segment 1 without tubercles, with 1 short seta on each side; segment 2 without tubercle, with 1 short seta and 5 short spinous setae, of which 1 is much smaller than others, on each side; segments 3 and 4 each with 4 distinct hooks and 1 short spinous seta on each side; all setae and hooks unbranched; segments 5, 6, 7 and 9 lacking spine-combs; segment 8 with distinct spine-combs in transverse row; segments 6–9 each with comb-like groups of minute spines on each side; segment 9 with pair of cone-like terminal hooks ( Fig. 5J ). Ventrally, segments 4–9 transparent, each with comb-like groups of minute spines; segment 5 with pair of bifid stout hooklets submedially and few unbranched short setae on each side; segments 6 and 7 each with pair of bifid inner and unbranched outer stout hooklets somewhat separated from each other and few unbranched short setae on each side. Grapnel-shaped hooklets absent on each side of segment 9. Cocoon ( Fig. 5K ). Medium-brown, shoe-shaped, with several small to large open spaces anterolaterally on each side (shape and size of open spaces are variable by cocoons), moderately woven; posterior half with floor; individual threads visible; 3.9–4.3 mm long by 1.5 mm wide.

Mature larva. Body length 5.2–6.2 mm. Body grayish light-brown, or dark gray, or light to medium brown, or grayish green. Abdomen in lateral view gradually widened from segment 1 to segment 7, then narrowed to segment 9. Thorax and abdomen with pair of cone-like dorsolateral protuberance on each segment ( Fig. 6A ), though those on thoracic segments 1 and 2 and abdominal segment 8 tiny, often overlooked. Cephalic apotome whitish-yellow on anterior 1/2, yellow on posterior 1/2, darkened widely along each lateral margin and narrowly along posterior margin; mediolongitudinal spots faintly positive but other spots usually indistinct though posterior1/2 of mediolateral spots distinct in some larvae; lateral surface of head capsule yellow or yellowish-brown to medium brown, except eyespot region whitish and wide areas above and anterior to and posterior to eyespot region medium brown; spots near posterior margin indistinct or somewhat negative; ventral surface of head capsule yellow or yellowish-brown or light brown; elongate spots on each side of postgenal cleft indistinct or negative. Antenna composed of 3 articles and apical sensillum, slightly longer than stem of labral fan; length ratio of 3 articles (from base to tip) 1.0:1.3–1.5:0.7–0.8. Labral fan with 36–44 main rays. Mandible ( Fig. 6B ) with serrations composed of 2 teeth (1 large, 1 small); main tooth at right angle against mandible on apical side; comb-teeth composed of 4 or 5 teeth, gradually decreased in length from first to third; supernumerary serrations absent. Hypostoma ( Fig. 6C ) with 9 anterior teeth, of which each corner tooth longest, followed by median tooth and outer tooth of 3 intermediate teeth on each side; lateral margins serrate apically; 4–6 hypostomal bristles divergent posteriorly from lateral border on each side. Postgenal cleft ( Fig. 6D ) large, rounded, 4.7–5.6 times length of postgenal bridge; subesophageal ganglion pigmented or unpigmented. Cervical sclerites composed of pair of light brown pieces, not fused to occiput. Histoblast of pharate pupal gill with 10 thread-like slender filaments. Thoracic cutilce almost bare except dorsolateral and lateral area on segment 3 sparsely covered with minute colorless setae. Abdominal cuticle sparsely covered with minute colorless setae which appear to be widened apically and divided into two or three apices ( Fig. 6A ) when viewed anterodorsally, and moderately covered with short colorless setae on each side of anal sclerite. Rectal scales absent. Rectal organ of 3 lobes, each with 12–15 finger-like secondary lobules. Anal sclerite X-shaped, with short broad anterior arms 0.7–0.8 times length of posterior ones and with forked apices; 4–6 sensilla posterior to posterior arms. Last abdominal segment not bulged laterally and lacking ventral papillae. Posterior circlet with 92–98 rows of hooklets with up to 18 hooklets per row.

Type specimens. Holotype. Male (with its associated pupal exuviae and cocoon, preserved in 80% ethanol), collected from an irrigation channel (width 0.5–1.0 m, bed muddy, water temperature 21 ˚C, exposed to sun, altitude 283 m, N21˚26’014’’/E105˚36’808’’), flowing slowly to moderately in a grassland near the bank of a big river, Tay Thien, Vinh Phuc Province, Vietnam, 12-XI-2013, by M. Sofian-Azirun, Z. Ya’cob and H. Takaoka . Paratypes. Two females, three males (all reared from pupae and preserved with their associated pupal exuviae and cocoons in vials with 80% ethanol), six pupae and 10 mature larvae (all preserved in vials with 80% ethanol), same data and date as holotype .

Biology. The pupae and larvae of this new species were collected from grass leaves trailing in water. Associated species were S. (N.) aureohirtum and S. (S.) nodosum .

Etymology. The species name taythienense refers to the locality name, Tay Thien, where this new species was collected.

Remarks. S. (S.) taythienense sp. nov. is assigned to the Simulium striatum species-group by the unique shapes of the female ovipositor valves ( Fig. 3E ) and the male ventral plate ( Fig. 4C ). This new species is characterized by having the haired basal portion of the female radial vein and the pupal gill with 10 slender filaments of almost the same thickness ( Fig. 5H ). In having these characters, this new species is similar to S. (S.) grisescens Brunetti from India ( Brunetti 1911; Puri 1932), S. (S.) quinquestriatum (Shiraki) from Taiwan ( Shiraki 1935; Takaoka 1979), S. (S.) pingtungense Huang & Takaoka also from Taiwan ( Huang & Takaoka 2008) and S. (S.) wuzhishanense Chen from China (Chen 2003).

This new species is distinguished in the male from S. (S.) grisescens by the color and relative size of the hind basitarsus, which is yellowish on the basal 3/5 or little less and 0.2 times as wide as its length in this new species, but is yellowish on the basal 1/2 and 0.3 times as wide as its length in S. (S.) grisescens , and from the other three species by the number of upper-eye enlarged facets, which are in 17 or 18 vertical columns and 17 or 18 horizontal rows in this new species but in 16 horizontal rows in S. (S.) quinquestriatum , in 19 vertical columns and 20 horizontal rows in S. (S.) pingtungense and in 12 vertical columns and 14 horizontal rows in S. (S.) wuzhishanense ). This new species differs from S. (S.) quinquestriatum and S. (S.) wuzhishanense by the brassy short hairs on the male scutum (cf., yellow short hairs in S. (S.) quinquestriatum and S. (S.) wuzhishanense ) and from S. (S.) pingtungense and S. (S.) wuzhishanense by the presence of paired dorsal protuberances on the larval abdomen (cf., such protuberances absent in the latter two species).

This new species is distinguished from S. (S.) saccatum Rubtsov from Siberia ( Rubtsov 1956) by the nearly parallel-sided style and ventral plate not produced posteriorly (cf., style narrowed from basal 1/3 toward apex and ventral plate produced posteriorly in S. (S.) saccatum ). The color of short hairs on the scutum and the number of upper-eye facets of the male of S. (S.) saccatum are unknown.

Figures

FIGURE 3. Female of S. (S.) taythienense sp. nov. A, third segment of right maxillary palp with sensory vesicle (front view); B, upper portion of cibarium (front view); C, tibia of left hind leg (outer view); D, basitarsus with calcipala and second tarsomere with pedisulcus of left hind leg (outer view); E, sternite 8 and ovipositor valve (only right half shown; ventral view); F, genital fork (ventral view); G & H, right paraprocts and cerci (G, ventral view; H, lateral view); I, spermatheca. Scale bars = 0.1 mm for C & D, 0.02 mm for A, B & E–I.

FIGURE 4. Male of S. (S.) taythienense sp. nov. A, third segment of right maxillary palp with sensory vesicle (front view); B, basitarsus with calcipala and second tarsomere with pedisulcus of left hind leg (outer view); C, coxites, styles, ventral plate and median sclerite (ventral view); D, right coxite and style (ventrolateral view); E & F, right styles (E, medial view; F, dorsolateral view); G & H, ventral plates (G, lateral view; H, caudal view); I, left paramere and aedeagal membrane (caudal view); J & K, tenth abdominal segments and cerci (right side; J, lateral view; K, caudal view). Scale bars = 0.1 mm for B, and 0.02 mm for A & C–K.

FIGURE 5. Pupa of S. (S.) taythienense sp. nov. A, tubercles on frons; B, frontal trichomes; C, facial trichome; D–G, thoracic trichomes (D, anterodorsal; E, anterolateral, F, mediolateral; G, ventrolateral); H & I, gill filaments (H, right gill; I, left gill of one pupa showing different arrangement); J, terminal hooks; K, cocoon (lateral view). Scale bars = 1.0 mm for K, 0.2 mm for H & I, and 0.02 mm for A–G & J.

FIGURE 6. Mature larva of S. (S.) taythienense sp. nov. A, protuberance and minute colorless setae on abdominal segment 4; B, mandible; C, hypostoma; D, ventral surface of head capsule showing postgenal cleft and pigmented subesophageal ganglion. Scale bars = 0.1 mm for D, 0.05 mm for C, and 0.02 mm for A & B.