Simulium (Simulium) xuandai 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 : 361-364

4. Simulium (Simulium) xuandai Takaoka, Sofian-Azirun & Ya’cob sp. nov.

Male. Body length 3.0 mm. Head. Slightly wider than thorax. Upper eye consisting of large facets in 20 vertical columns and 20 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 composed of scape, pedicel and 9 flagellomeres, dark brown except scape, pedicel and base of first flagellomere yellow and rest of first flagellomere and second and third flagellomeres dark yellow; first flagellomere elongate, 1.6 times length of second one. Maxillary palp with 5 segments, medium-brown except first and second segments ochreous and fifth segment grayish light-brown; proportional lengths of third, fourth, and fifth segments 1.0:1.0:2.4; third segment ( Fig. 7A ) of normal size; sensory vesicle ( Fig. 7A ) globular or ellipsoidal, 0.2 times length of third segment, and with small opening. Thorax. Similar to that of male of S. (S.) taythienense sp. nov. except scutum uniformly and moderately covered with whitish-yellow recumbent short hairs interspersed with dark-brown short hairs near anterior margin and dark-brown long upright hairs on prescutellar area, and scutellum dark brown, with dark-brown long upright hairs and yellow short hairs. Legs. Foreleg: coxa yellowishwhite; trochanter yellow, with lower surface somewhat darkened; femur yellow except apical tip on inner surface, dark yellow with apical tip light brown on outer surface; tibia brownish-black to black except basal tip light brown; tarsus black, with moderate dorsal hair crest; basitarsus greatly dilated, 6.1 times as long as its greatest width. Midleg: coxa brownish-black; trochanter brownish-black except base whitish; femur brownish-black except apical cap black; tibia dark-brown to brownish-black except base yellowish-white, and with whitish sheen widely on posterior surface when illuminated at certain angles; tarsus medium brown except basal 3/4 to2/3 of basitarsus and basal tip of second tarsomere yellowish-white. Hind leg: coxa brownish-black; trochanter yellowish-white; femur dark brown except base whitish-yellow and apical cap brownish-black; tibia brownish-black except base yellowish-white; tarsus brownish-black except little more than basal 1/2 of basitarsus and basal 1/2 of second tarsomere whitish-yellow; basitarsus ( Fig. 7B ) somewhat enlarged, slightly widened toward apical 1/3, then slightly narrowed, 4.1–4.3 times as long as wide, and 0.8 and 0.8 times as wide as greatest width of hind tibia and femur, respectively; calcipala ( Fig. 7B ) developed, small, little shorter than its basal width, and 0.3 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 7B ) well developed. Wing. Length 2.3 mm. Other characters as in male of S. (S.) taythienense sp. nov. except right subcosta bare and left subcosta with two hairs. Abdomen. As in male of S. (S.) taythienense sp. nov. Genitalia. Coxite in ventral view ( Fig. 7C ) nearly quadrate, little longer than wide; coxite in ventrolateral view ( Fig. 7D ) rectangular, 0.7 times as long as wide. Style in ventral view ( Fig. 7C ) elongate, slightly narrowed toward middle, nearly parallel-sided to apical 1/3, then slightly narrowed to apex, inner margin gently concave, with subapical spine; style in ventrolateral view ( Fig. 7D ) 1.9 times length of coxite, 3.4 times as long as greatest width near apex; style in medial view ( Fig. 7E ) somewhat flattened dorsoventally, with short basal protuberance directed dorsomedially, with several cone-like spines along its anterior margin; style in dorsomedial view ( Fig. 7F ) with short basal protuberance with well sclerotized, saw-like ragged anterior margin. Ventral plate in ventral view ( Fig. 7C ) with body broad, with lateral margins gently convex, anterior margin deeply concave, and posterior margin nearly straight; body 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. 7G ) with median process abruptly bent ventrally at nearly right angle; ventral plate in caudal view ( Fig. 7H ) in form of equilateral triangle, and bare. Median sclerite, paramere, aedeagal membrane, abdominal segment 10 and cercus nearly as in those of S. (S.) taythiensense sp. nov. except cercus with 14 distinct hairs.

Pupa. Body length 3.2 mm. Head. Integument light ochreous, moderately covered with relatively large tubercles having few to several secondary projections of which some are sharply pointed on frons ( Fig. 8A ), and moderately with round or cone-like small ones without secondary projections on face; frons with two pairs of unbranched or bifid long trichomes with coiled or uncoiled apices ( Fig. 8B ); face with pair of unbranched or bifid long trichomes with coiled or uncoiled apices ( Fig. 8C ), subequal in length to frontal trichomes. Thorax. Integument light ochreous, moderately covered with relatively large tubercles (similar to those on frons) except lateral surfaces and dorsal surface of posterior 1/2 of thorax moderately covered with relatively smaller round or cone-like tubercles; thorax on each side with 3 long trichomes with 4 or 5 branches ( Fig. 8D ) anterodorsally, 2 long trichomes with 4 or 5 branches (similar to Fig. 8D ) anterolaterally, 1 medium-long trichome with 3 or 4 branches ( Fig. 8E ) mediolaterally, and 3 trichomes with uncoiled apices (2 bifid or quadrifid long, 1unbranched or bifid medium-long) ( Fig. 8F ) ventrolaterally. Gill ( Fig. 8G ) with 10 thread-like filaments arranged as 2+(2+1)+(2+1)+2 filaments from dorsal to ventral; dorsal and ventral pairs with short stalk, two middle triplets with short stalk; all filaments subequal in length (about 1.0 mm) and thickness, though filaments of middle triplets slightly thinner than those of dorsal and ventral pairs (relative thickness of filaments from dorsal to ventral when compared basally 1.0:1.0:0.8:0.8:0.9:0.8:0.8:0.8:1.0:1.0); all filaments medium brown, covered with sharply-defined 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 light ochreous; segment 1 without tubercles, with 1 bifid medium-long seta on each side; segment 2 without tubercle, with 1 bifid medium-long seta and 5 short spinous setae, of which 1 is much smaller than others, on each side; other characters as in S. (S.) taythienense sp. nov. except right inner hook of ventral surface of segment 6 trifid. Cocoon ( Fig. 7I ). Light ochreous, shoe-shaped, with several small to large open spaces anterolaterally on each side; posterior half with floor; posterior half thickly woven and individual threads almost invisible; 3.9 mm long by 1.5 mm wide.

Female and mature larva. Unknown.

Type specimen. Holotype. Male (reared from a pupa and preserved with its associated pupal exuviae and cocoon in a vial with 80% ethanol), collected from a moderately-flowing forest stream (width 4–5 m, depth 10–15 cm, bed gravelly, stony and rocky, water temperature 18.0˚C, shaded, altitude 700 m, N21˚27’054”/E105˚38’470”), behind the Tam Dao Resort Hotel, Tam Dao, Vinh Phuc Province, Vietnam, 9-XI-2013, by H. Takaoka.

Biology. The pupa of this new species was collected from a plastic tape trailing in water. Associated species were S. (S.) tani and Simulium (S.) sp. ( Simulium multistriatum species-group).

Etymology. The species name xuandai is in honor of Dr. Pham Xuan Da, director general, National Institute of Food Control, Ministry of Health, Vietnam, for his contribution as a pioneer in faunal studies of black flies in Vietnam.

Remarks. S. (S.) xuandai sp. nov. is assigned to the striatum species-group by the unique shape of the male ventral plate ( Fig. 7C ). This new species is characterized by having the male scutum covered with yellow short hairs and the pupal gill with 10 slender filaments of almost the same thickness, arranged as 2+(2+1)+(2+1)+2 filaments from dorsal to ventral ( Fig. 8G ). In having these characters, this new species is similar to S. (S.) lineothorax Puri, S. (S.) pallidum Puri, both from India ( Puri 1932), S. (S.) consimile Puri from India and Sri Lanka ( Puri 1932; Davies & Györkös 1992), S. (S.) quinquestriatum (Shiraki) from Taiwan ( Shiraki 1935; Takaoka 1979), and S. (S.) wuzhishanense Chen from China (Chen 2003).

This new species is distinguished in the male from S. (S.) lineothorax by the absence of longitudinal vittae on the scutum, from S. (S.) pallidum by the darker legs (e.g., the mid tibia is dark-brown to brownish-black except base yellowish-white in this new species but is entirely yellow in S. (S.) pallidum), and from the other three species by the number of upper-eye enlarged facets, which are in 20 vertical columns and 20 horizontal rows in this new species but in 16 vertical columns and 15 or 16 horizontal rows in S. (S.) consimile, in 16 horizontal rows in S. (S.) quinquestriatum and in 12 vertical columns and 14 horizontal rows in S. (S.) wuzhishanense .

S. (S.) xuandai sp. nov. is readily distinguished from S. (S.) taythienense sp. nov. in the male by the yellowish short hairs on the scutum, and in the pupa by the relatively large tubercles having secondary projections on the head and thoracic integument ( Fig. 8A ), and branched trichomes on the frons ( Fig. 8B ).

Figures

FIGURE 7. Male of S. (S.) xuandai 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 and ventral plate (ventral view); D, right coxite and style (ventrolateral view); E & F, left styles (E, dorsolateral view; F, medial view); G, ventral plate and median sclerite (lateral view); H, ventral plate (caudal view). Scale bars = 0.1 mm for B, and 0.02 mm for A & C–H.

FIGURE 8. Pupa of S. (S.) xuandai sp. nov. A, tubercles on frons; B, frontal trichomes; C, facial trichomes; D–F, thoracic trichomes (D, mediodorsal; E, mediolateral; F, ventrolateral); G, right gill filaments (outer view); H, seta on dorsal surface of abdominal segment 1; I, cocoon (lateral view). Scale bars = 1.0 mm for I, 0.2 mm for G, and 0.02 mm for A–F & H.