Simulium (Simulium) sansahoense Takaoka & Chen

Takaoka, Hiroyuki, Sofian-Azirun, Mohd, Ya’Cob, Zubaidah, Chen, Chee Dhang, Lau, Koon Weng, Low, Van Lun, Pham, Xuan Da & Adler, Peter H., 2017, The black flies (Diptera: Simuliidae) of Vietnam, Zootaxa 4261 (1), pp. 1-165 : 82-89

Simulium (Simulium) sansahoense Takaoka & Chen sp. nov.

Female. Body length 2.5 – 2.6 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 and few to several yellow fine hairs near antennal bases; frontal ratio 1.3:1.0:0.9–1.1; frons:head ratio 1.0:3.3–3.5. Fronto-ocular area well developed, short, directed laterally, and rounded or pointed apically. Clypeus black, shiny and white pruinose when illuminated at certain angles, moderately covered with dark-brown medium-long hairs mixed with yellow fine hairs (though mediolongitudinal portion somewhat widely bare on upper half to three-fifths). Labrum 0.6 times length of clypeus. Antenna composed of scape, pedicel and nine flagellomeres, dark brown, except scape, pedicel and first flagellomere yellow when viewed ventrally, but dark brown except scape, pedicel and basal one-third of first flagellomere yellow when viewed dorsally. Maxillary palp with five segments, medium brown except third segment dark brown; proportional lengths of third, fourth, and fifth segments 1.0:1.2:2.7; third segment ( Fig. 34 A) of moderate size, with medium-sized ellipsoidal sensory vesicle (0.3 – 0.4 times length of third segment) having medium-sized opening. Maxillary lacinia with 11 or 12 inner and 13 – 15 outer teeth. Mandible with 29 inner and 12 outer teeth. Cibarium ( Fig. 34 B) with 30 or 31 minute processes near posterodorsal margin. Thorax. Scutum black, shiny and white pruinose with three faint dark vittae (one median, two submedian) when illuminated at certain angles, moderately covered with yellow short fine hairs interspersed with several dark-brown long upright hairs on prescutellar area. Scutellum brownish black, covered with dark-brown upright long and yellow short hairs. Postnotum brownish black, shiny and white pruinose when illuminated at certain angles, and bare. Pleural membrane bare. Katepisternum longer than deep, brownish black, shiny and white pruinose when illuminated at certain angles, and bare. Legs. Foreleg: coxa and trochanter whitish yellow; femur yellow with apical cap light brown; tibia whitish yellow except apical cap dark brown, with median outer surface widely white and with bright white sheen when illuminated at certain angles; tarsus black, with moderate dorsal hair crest; basitarsus greatly dilated, 5.8 – 5.9 times as long as its greatest width. Midleg: coxa dark brown; trochanter whitish yellow with apical portion partially light brown; femur yellow except apical cap light brown; tibia whitish yellow except apical tip light brown, and with whitish sheen widely on posterior surface when illuminated at certain angles; tarsus medium brown except basal four-fifths of basitarsus whitish yellow. Hind leg: coxa medium to dark brown; trochanter yellowish white; femur yellow except apical cap light brown; tibia white on posterior surface of basal half and yellow on rest except apical cap medium brown, and with whitish sheen widely on posterior surface when illuminated at certain angles; tarsus medium brown except little more than basal two-thirds of basitarsus (though base light brown) and basal half of second tarsomere yellowish white; basitarsus ( Fig. 34 C) nearly parallel-sided, 6.2 – 6.3 times as long as wide, and 0.8 and 0.7 times as wide as greatest widths of hind tibia and femur, respectively; calcipala ( Fig. 34 C) moderately developed, nearly as long as wide, and 0.4 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 34 C) well developed; claw ( Fig. 34 D) with small subbasal tooth. Wing. Length 2.5 – 2.7 mm. Costa with dark spinules and hairs; subcosta haired except apical one-fifth to half bare; basal section of radial vein bare; R1 with dark-brown spinules and hairs; R2 with dark-brown hairs; hair tuft on base of radius dark brown; basal cell absent. Halter . White except base darkened. Abdomen. Basal scale dark brown, with fringe of yellow hairs. Dorsal surface of abdomen medium brown to brownish black, with dark short hairs; tergite 2 shiny and silvery iridescent when illuminated at certain angles and tergites 6–9 shiny when illuminated at certain angles. Ventral surface light to medium brown; segment 7 without sternal plate. Terminalia . Sternite 8 ( Fig. 34 E) well sclerotized and bare medially, covered with 6–10 long and medium-long stout hairs and three or four short fine hairs on each side. Ovipositor valves ( Fig. 34 E) nearly tongue-like, rounded posteromedially, membranous, each densely covered with microsetae together with five to eight short to medium-long hairs; inner margin deeply concave medially. Genital fork ( Fig. 34 F) of inverted-Y form; stem slender and well sclerotized; arms of moderate width, each with strongly sclerotized apical portion having distinct projection directed anterodorsally. Paraproct in ventral view ( Fig. 34 G) nearly quadrate, with anteromedian portion depressed and moderately sclerotized having eight or nine sensilla on its surface; paraproct in lateral view ( Fig. 34 H) somewhat produced ventrally, 0.7 times as long as wide, covered with 15–19 short to medium-long hairs and numerous microsetae on lateral and ventral surfaces. Cercus in lateral view ( Fig. 34 H) short, rounded posteriorly, 0.56 times as long as its greatest width, and covered with medium-long and short hairs. Spermatheca ( Fig. 34 I) ovoidal, 1.2 times as long as wide, sclerotized except duct and narrow area of juncture with duct unsclerotized, without discernible reticulate surface patterns; minute internal setae present; accessory ducts subequal in thickness to each other and slightly thicker than main duct.

Male. Body length 2.6–3.0 mm. Head. Slightly wider than thorax. Upper eye medium brown, with large facets in 21 or 22 vertical columns and in 21–23 horizontal rows. Clypeus black, thickly white pruinose, silvery or bluish, shiny when illuminated at certain angles, covered with dark-brown hairs along lateral margins and near ventral margin (medial portion widely bare). Antenna composed of scape, pedicel and nine flagellomeres, medium brown to brownish black except base of first flagellomere dark yellow; first flagellomere elongate, 1.7 times as long as second one. Maxillary palp grayish to dark brown, composed of five segments with proportional lengths of third, fourth, and fifth segments 1.0:1.3:2.9; third segment ( Fig. 35 A) of moderate size; sensory vesicle ( Fig. 35 A) small, ellipsoidal (0.3 times as long as third segment), and with small opening. Thorax. Scutum black, with white pruinose pattern, i.e., anterior pair of crescent spots on shoulders extending posteriorly along lateral margins connected near base of wings to large transverse posterior spot entirely covering prescutellar area; these pruinose areas silvery or bluish iridescent when illuminated at certain angles; scutum uniformly and moderately covered with yellow recumbent short hairs interspersed with dark-brown long upright hairs on prescutellar area. Scutellum brownish black, with several dark-brown long upright hairs and yellow short hairs. Postnotum black, white pruinose when illuminated at certain angles and bare. Pleural membrane bare. Katepisternum longer than deep, black, white pruinose when illuminated at certain angles, and bare. Legs. Foreleg: coxa whitish yellow; trochanter light brown except base whitish yellow; femur light brown with apical cap medium brown, though inner surface of basal half yellowish; tibia medium brown except median large portion widely white on outer surface, and with bright white sheen widely on outer surface when illuminated at certain angles; tarsus brownish-black to black, with moderate dorsal hair crest; basitarsus greatly dilated, 6.6–6.8 times as long as its greatest width. Midleg: coxa brownish black; trochanter medium brown except base yellowish white; femur light brown with apical cap medium brown; tibia light brown except basal one-third yellow and apical cap medium brown; tibia with white sheen on posterior surface of basal one-third when illuminated at certain angles; tarsus medium to dark brown except basal half or little more of basitarsus whitish yellow. Hind leg: coxa dark brown; trochanter whitish yellow; femur medium brown except base whitish yellow and apical cap dark brown; tibia medium brown except apical cap brownish black and basal tip yellowish white; tarsus ( Fig. 35 B) medium to dark brown except basal half or little more of basitarsus whitish yellow (though extreme base darkened) and basal half of second tarsomere yellowish white; basitarsus ( Fig. 35 B) much enlarged, gradually widened from base to apical one-third, then slightly narrowed to apex, 4.1–4.9 times as long as its greatest width, and 0.7–0.8 and 0.9 times as wide as greatest widths of hind tibia and femur, respectively; calcipala ( Fig. 35 B) small, slightly shorter than wide, 0.3 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 35 B) well developed. Wing. Length 2.6–2.7 mm. Other features as in female except subcosta bare. Halter . White except basal portion darkened. Abdomen. Basal scale brownish black, with fringe of dark long hairs. Dorsal surface of abdomen dark brown to brownish black, with dark short hairs; segments 2, 5, 6 and 7 each with pair of silvery or bluish iridescent spots dorsolaterally, those on segment 2 broadly connected in middle to each other. Genitalia. Coxites, styles and ventral plate in ventral view as in Fig. 35 C. Coxite in ventrolateral view ( Fig. 35 D) 0.8 times as long as wide. Style in ventrolateral view ( Fig. 35 E) elongate, 2.9 times as long as its greatest width near base, nearly parallel-sided from base to little more than basal one-third, then tapered toward middle, and nearly parallel-sided or slightly widened to apex, and with distinct apical spine; style in medial view ( Fig. 35 F) 1.4 times as long as coxite, widened from base to basal one-fourth, tapered to little less than apical one-third, then nearly parallel-sided to apex. Ventral plate in ventral view ( Fig. 35 C) well sclerotized, with narrow body having ventrally produced process posteriorly, which bears toothed posterolateral margins and is covered with many minute setae on anterolateral surface; arms divergent outward, then convergent apically; ventral plate in lateral view ( Fig. 35 G) with posterior margin serrated from base to apical tip and with anterolateral surfaces covered with many microsetae; ventral plate in end view ( Fig. 35 H) elliptical, with both lateral margins gently rounded, and each with several teeth. Median sclerite in lateral view ( Fig. 35 G) arising from anterior margin of body of ventral plate, directed dorsally; median sclerite in caudal view ( Fig. 35 I) plate-like, nearly parallel-sided to apex, with round apex, brown basally, but not so well sclerotized apically. Paramere in caudal view ( Fig. 35 J) with enlarged basal portion and with several distinct hooks and several smaller ones. Aedeagal membrane densely covered with minute setae, and with moderately sclerotized dorsal plate in form of horizontal bar ( Fig. 35 K). Abdominal segment 10 ( Fig. 35 L, M) with three or five hairs on ventral surface and three to five hairs on lateral surface on each side. Cercus ( Fig. 35 L, M) small, rounded, with 10 or 11 distinct hairs.

Pupa. Body length 3.0– 3.2 mm. Head. Integument ochreous except ventral and lateral surfaces whitish yellow and antennal sheaths yellow, densely covered with small round tubercles; frons with two pairs of unbranched short slender trichomes ( Fig. 36 A), arising close together; face with pair of unbranched medium-long somewhat stout trichomes ( Fig. 36 B). Thorax. Integument light brown except wing sheaths yellow, moderately covered with small round tubercles; thorax with three medium-long stout anterodorsal trichomes (one posterior trichome somewhat narrower than two anterior ones) ( Fig. 36 C), two medium-long stout anterolateral trichomes (anterior trichome shorter and more slender than posterior one) ( Fig. 36 D), one medium-long stout mediolateral trichome ( Fig. 36 E), and three ventrolateral trichomes (one anterior trichome short and slender, two other trichomes medium-long and stout) ( Fig. 36 F), on each side; all unbranched. Gill ( Fig. 36 G) with eight slender thread-like filaments arranged as (2+2)+(2+2) from dorsal to ventral, arising from short common basal stalk; all pairs short-stalked except second pair from above almost sessile; length of filaments variable: upper filaments of first and second pairs from above shortest (0.84 mm long), two filaments of fourth pair from above longest (1.2–1.3 mm long), and other filaments intermediate in length (1.0– 1.1 mm long); all filaments subequal in thickness to one another, though two filaments of fourth pair slightly thicker than others; all filaments dark brown, slightly tapered toward apices, with annular furrows (annular ridges not well developed), and densely covered with minute tubercles. Abdomen. Dorsally, all segments unpigmented except segments 1 and 2 entirely light brown, and also segment 3 occasionally with wide darkened area anteriorly; segment 1 with one unbranched short hair-like seta ( Fig. 36 H) on each side; segment 2 with one unbranched short hair-like seta and five minute setae, of which three or four are stout ( Fig. 36 I), on each side; segments 3 and 4 each with four distinct hooks and one unbranched minute seta on each side; segment 5–7 lacking spine-combs; segment 8 with distinct spine-combs in transverse row on each side; segments 6–9 each with comb-like groups of minute spines on each side; segment 9 with pair of small conical terminal hooks ( Fig. 36 J). Ventrally, segments 3–8 unpigmented, each with comb-like groups of minute spines; segment 4 with few minute setae on each side; segment 5 with pair of bifid hooks submedially and few minute setae on each side; segments 6 and 7 each with pair of bifid inner and unbranched outer hooks somewhat separated from each other, and few minute setae on each side. Grapnel-shaped hooklets absent on each side of segment 9. Cocoon ( Fig. 36 K, L). Corbicular, moderately woven, ochreous, not extended ventrolaterally, and with several large open spaces anteriorly; individual threads invisible; 3.5–4.2 long by 1.0– 1.3 mm wide.

Mature larva. Body length 5.3–6.0 mm. Body vermilion to ochreous (though intersegmental areas from thoracic segment 3 to abdominal segment 5 paler) except ventral surface of thorax and abdominal segments 1–4 light grayish-green, and that of abdominal segments 5–9 unpigmented. Head. Cephalic apotome ( Fig. 37 A) variable in color patterns: e.g., some cephalic apotome whitish yellow to yellow though medial portion narrowly darkened along posterior margin, with faint or moderate positive head spots; some others whitish yellow on anterior three-fifths, with faint anterior spot of mediolongitudinal spots, and light to dark brown on posterior twothirds with faint to moderate negative or obscure spots; some others light to medium brown on anterior one-third, medium to dark brown on posterior two-thirds, with faintly or moderately negative spots, and medial portion between dark areas yellow, with obscure or faintly positive anterior spot of mediolongitudinal spots; some others widely yellowish except narrow area along posterior margin darkened and somewhat light brown medially, with obscure or negative head spots. Lateral surface of head capsule light to medium brown except eye-spot region whitish and anterior portion near anterior margin and area below eye-spot region yellowish to varying extent, with spots near posterior margin obscure or faintly or moderately negative, and isolated spot below eye-spot region often positive; eyebrow distinct. Ventral surface of head capsule ( Fig. 37 B) light to medium brown except anterior area near hypostoma and both lateral areas yellowish to varying extent; long spot on each side of postgenal cleft obscure or faintly positive or negative. Head capsule sparsely covered with minute colorless setae. Antenna composed of three articles and apical sensillum, much longer than stem of labral fan; length ratio of three articles (from base to tip) 1.0:1.3 – 1.4:0.6. Labral fan with 52–56 primary rays. Mandible ( Fig. 37 C) with mandibular serration composed of two teeth (one medium-sized, one small); main tooth at obtuse angle against mandible on apical side; supernumerary serrations absent; comb-teeth decreasing in length from first to third. Hypostoma ( Fig. 37 D) with nine anterior teeth, of which median tooth is slightly longer than corner teeth, and intermediate teeth on each side shortest; lateral margins serrate apically; six or seven hypostomal bristles per side lying divergent posteriorly from lateral margin. Postgenal cleft ( Fig. 37 B) rounded, 4.0 times length of postgenal bridge; sheath of subesophageal ganglion weakly pigmented. Cervical sclerites on each side composed of one light-brown rod-like piece and one light-brown elliptical piece, not fused to occiput. Thorax and Abdomen. Histoblast of pharate pupal gill with eight short filaments. Thoracic cuticle sparsely covered with minute colorless setae dorsally. Abdominal segments 1 – 5 each with pair of small protuberances ( Fig. 37 E) dorsally; abdominal cuticle sparsely or moderately covered with minute colorless setae dorsally and dorsolaterally; last abdominal segment moderately covered with short colorless setae on each side of anal sclerite. Rectal scales present. Rectal organ compound, each lobe with 14 – 18 finger-like secondary lobules. Anal sclerite X-shaped, with short broad anterior arms 0.7 times length of posterior ones; one to five sensilla on base of anal sclerite; four to six sensilla posterior to posterior arms. Last abdominal segment somewhat swollen laterally but lacking ventral papillae. Posterior circlet with 84 – 86 rows of hooklets with up to 16 – 19 hooklets per row.

Type material. HOLOTYPE: Female (with its associated pupal exuviae and cocoon) in 80% ethanol, labeled in a vial as [ UMSRP: Vietnam 0 34, Holotype, Simulium (S.) sansahoense , Female, coll. Vietnam, 20-XII-2014, Takaoka et al.], reared from a pupa collected from a river (width 6.0 m, depth 12 cm, water temperature 10.0˚C, exposed to the sun, elevation 1,194 m, 22˚19’44.349”N/103˚49’49.930”E), moderately flowing from a natural forest, San Sa Ho , Sapa , Lao Cai Province, northern Vietnam , 20-XII-2014, by H. Takaoka, M. Sofian-Azirun, Z. Ya’cob, C.D. Chen & K.W. Lau. PARATYPES: Four females, six males (all reared from pupae), two pupae and 10 mature larvae, in 80% ethano,l same data as those of the holotype, labeled in each vial as [ UMSRP: Vietnam 0 34, Paratype, Simulium (S.) sansahoense , coll. Vietnam, 20-XII-2014, Takaoka et al.].

Biological notes. The pupae and larvae of this new species were collected from plastic plates in the current. The associated species were S. (S.) daoense sp. nov. and S. (S.) phuluense sp. nov.

Distribution. Vietnam (Lao Cai).

Etymology. The species name sansahoense refers to the name of the locality, San Sa Ho, where this new species was collected.

Remarks. Simulium (S.) sansahoense sp. nov. is assigned to the S. argentipes species-group of the subgenus Simulium , defined by Takaoka and Saito (2007), based on the female terminalia ( Fig. 34 E), pupal gill with eight filaments ( Fig. 36 G) and corbicular cocoon ( Fig. 36 K, L).

This new species is similar to S. (S.) bidentatum (Shiraki) from Japan ( Takaoka 1976) and S. (S.) tanae from Yunnan Province, south China ( Xue 1992) by having yellowish legs. However, this new species is distinguished from S. (S.) bidentatum in the female by the length ratio of the labrum against the clypeus 0.6 (0.7 in S. (S.) bidentatum ), ovipositor valve covered with five to eight short to medium-long hairs (12 or 13 short to medium-long hairs in S. (S.) bidentatum ); in the male by the scutum covered with yellow fine hairs (brassy fine hairs in S. (S.) bidentatum ), and fore and mid femora that are light brown except the apical cap medium-brown (yellow except the apical cap light to medium-brown in S. (S.) bidentatum ). Morphological data of S. (S.) bidentatum used here were based on specimens collected from Oita, Japan, in May, 2015 by Dr. M. Fukuda.

This new species is distinguished from S. (S.) tanae by the following characters (those of S. (S.) tanae in parentheses): female body length 2.5–2.6 mm (3.0– 3.4 mm), female frons with the ratio of the greatest width against the height 1.3–1.4 (2.0), spermatheca ellipsoidal ( Fig. 34 I) (globular), male abdominal segments 2 and 5–7 each with a pair of iridescent dorsolateral spots (segments 2, 6 and 7 each with such spots).

Five other species of the S. argentipes species-group, viz., S. (S.) arboreum Takaoka from the Philippines, S. (S.) argentipes Edwards from Peninsular Malaysia, S. (S.) beludense Takaoka from Sabah and Sarawak, S. (S.) canlaonense Delfinado from the Philippines, and S. (S.) minangkabaum Takaoka & Sigit from Sumatra, Indonesia, differ from this new species by having much darker female legs ( Takaoka 1983, 1996, 2006, Takaoka and Davies 1995, Takaoka and Sigit 1997).

Figures

FIGURE 34. Female of Simulium (Simulium) sansahoense sp. nov. A, Third segment of maxillary palp with sensory vesicle (right side; front view); B, Cibarium (front view); C, Hind basitarsus and second tarsomere (left side; outer view). D, Claw; E, Sternite 8 and ovipositor valve (right side only; ventral view); F, Genital fork (ventral view); G & H, Paraprocts and cerci (G, ventral view; H, lateral view). I, Spermatheca. Scale bars. 0.1 mm for C; 0.02 mm for A, B and E – I; 0.01 mm for D.

FIGURE 35. Male of Simulium (Simulium) sansahoense sp. nov. A, Third segment of maxillary palp with sensory vesicle (left side; front view); B, Hind basitarsus and second tarsomere (left side; outer view); C, Coxites, styles and ventral plate (ventral view); D, coxite (right side; ventrolateral view); E & F, Styles (right side; E, ventrolateral view; F, medial 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, Dorsal plate (caudal view); L & M, Abdominal segment 10 and cerci (right side; L, lateral view; M, caudal view). Scale bars. 0.1 mm for B; 0.02 mm for A and C – M.

FIGURE 36. Pupa of Simulium (Simulium) sansahoense sp. nov. A, Frontal trichome; B, Facial trichome; C – F, Thoracic trichomes (C, anterodorsal; D, anterolateral; E, mediolateral; F, ventrolateral); G, Anterior part of thorax and gill filaments (left side; outer view); H, Hair-like seta and minute seta on dorsal surface of abdominal segment 1; I, Hair-like seta, minute seta and stout seta on dorsal surface of abdominal segment 2; J, Terminal hooks (caudal view); K & L, Cocoons (K, dorsal view; L, lateral view). Scale bars. 1.0 mm for K and L; 0.1 mm for G; 0.02 mm for B – F and J; 0.01 mm for A, I and H.

FIGURE 37. Larva of Simulium (Simulium) sansahoense sp. nov. A & B, Head capsules (A, dorsal view; B, ventral view); C, Mandible; D, Hypostoma; E, Protuberance and minute setae on dorsal surface of abdominal segment 5. Scale bars. 0.1 mm for A and B; 0.05 mm for D; 0.02 mm for C and E.