Simulium (Gomphostilbia) kiewfinense Takaoka, Srisuka & Fukuda, 2020

Takaoka, Hiroyuki, Srisuka, Wichai, Fukuda, Masako & Saeung, Atiporn, 2020, Twenty-one new species of the Simulium (Gomphostilbia) asakoae species group (Diptera, Simuliidae) in Thailand, with their genetic relationships, ZooKeys 950, pp. 51-152 : 51

Simulium (Gomphostilbia) kiewfinense Takaoka, Srisuka & Fukuda sp. nov. Fig. 19

Material examined.

Holotype: Male (with its associated pupal exuviae and cocoon) (in 80% ethanol) labeled as "Holotype: Simulium kiewfinense male, QSBG col. no. 36, Thailand, 6-IV-2018, by W. Srisuka", collected from a stream (width 1.1 m, depth 12 cm, bed sandy, moderate flow, pH 6.9, 18.3 °C, partially shaded, elevation 1,446 m, 18°51'38.8"N, 99°22'15.2"E), at Kiew Fin, Muang Pan District, Lampang Province, Thailand, 6-IV-2018, by W. Srisuka (Coll. No. 36).

Paratypes: Two males (thorax of one male for DNA analysis) (with their associated pupal exuviae and cocoons) (in 80% ethanol), same data as for holotype.

Diagnosis.

Male: greater number of upper-eye facets in 16 or 17 vertical columns and 16 or 17 horizontal rows one each side.

Description.

Male (N = 3). Body length 2.0-2.1 mm.

Head. Somewhat wider than thorax. Upper eye medium brown, consisting of large facets in 16 or 17 vertical columns and 16 or 17 horizontal rows. Antenna composed of scape, pedicel and nine flagellomeres, medium to dark brown except scape, pedicel, and base of first flagellomere yellow; first flagellomere elongate, 1.8 times length of second. Maxillary palpus light brown, with five palpal segments, proportional lengths of third, fourth, and fifth palpomeres 1.0:1.0:2.6; sensory vesicle 0.19 times length of third palpal segment.

Legs. Foreleg: tibia whitish except apical three-tenths dark brown and subbasal portion light brown; basitarsus moderately dilated, 6.6-7.1 times as long as its greatest width. Midleg: tarsus dark brown except basal one-third of basitarsus dark yellow to light brown (border not well defined). Hind leg: coxa light brown; tarsus (Fig. 19A ) brownish black except basal two-fifths to little less than basal half of basitarsus and basal one-third of second tarsomere yellow; basitarsus (Fig. 19A ) 3.7-3.8 times as long as wide, and 0.9 and 1.0 times as wide as greatest width of tibia and femur, respectively; calcipala (Fig. 19A ) slightly shorter than basal width, and 0.33 times as wide as greatest width of basitarsus.

Wing. Length 1.9-2.0 mm. Subcosta bare.

Genitalia. Coxite in ventral view (Fig. 19B ) nearly rectangular, 1.8 times as long as its greatest width. Style in ventral view (Fig. 19B ) with round apex. Ventral plate in ventral view (Fig. 19B ) with basal arms nearly parallel-sided, then convergent apically; ventral plate in caudal view (Fig. 19E ) with ventral margin nearly straight. Cercus with 14 or 15 hairs.

Pupa (N = 3). Body length 2.5-2.7 mm.

Head. Integument yellow.

Thorax. Integument yellow, moderately covered with round tubercles except dorsolateral surface of posterior half almost bare. Gill (Fig. 19F ) composed of eight slender thread-like filaments, arranged as [3+(1+2)]+2 from dorsal to ventral; common basal stalk 0.7-0.8 times length of interspiracular trunk; stalk of ventral pair of filaments 0.9-1.2 times length of common basal stalk, and 0.7-0.9 times length of interspiracular trunk; primary stalk of dorsal triplet lying against that of lower pair at angle of 70-80° when viewed laterally; filaments of dorsal triplet subequal in length (1.5-2.1 mm) and thickness to one another; filaments of middle triplet subequal in length (2.0-2.5 mm) and thickness to one another; two filaments of ventral pair subequal in length (3.0-3.5 mm) and thickness to each other and 1.3-1.5 times as thick as six other filaments of dorsal and middle triplets when compared basally.

Abdomen. Dorsally, all segments light yellowish; segments 1 and 2 without minute tubercles; segment 9 with pair of wide flat terminal hooks (Fig. 19G ), of which outer margin 2.3-2.7 times length of inner margin and crenulated when viewed caudally.

Cocoon (Fig. 19H ). Pale yellow, slipper-shaped, moderately woven, moderately extended ventrolaterally; anterior margin thickly woven medially, often with bulge; 3.0-3.3 mm long by 2.2 mm wide.

Female and mature larva. Unknown.

Etymology.

The species name, kiewfinense , refers to the local name, Kiew Fin, where this species was collected.

Distribution.

Thailand (Lampang).

Discussion.

This new species is similar to S. junkumae sp. nov. described above and S. hongthaii from Vietnam ( Takaoka et al. 2014a) in having the greater number of male upper-eye facets. However, it is distinguished from both species by the relative length of the fore basitarsus against its greatest width (6.6-7.1 in this new species versus 7.8-8.1 in S. junkumae sp. nov. and 7.5-8.4 in S. hongthaii ), also from S. junkumae sp. nov. by the male subcosta bare (subcosta with hairs in S. junkumae sp. nov.) and from S. (G.) hongthaii by the relative length of the coxite against its greatest width (1.8 in this new species and 2.2 in S. hongthaii ).

Figures

Figure 19. Male and pupa of S. kiewfinense sp. nov. A-E male F-H pupa. A hind basitarsus and second tarsomere (left side; lateral view) B coxites, styles and ventral plate (ventral view) C style (right side; ventrolateral view) D ventral plate and median sclerite (lateral view) E ventral plate (caudal view) F gill filaments (left side; lateral view) G terminal hooks (caudal view) H cocoon (dorsal view). Scale bars: 1.0 mm (H); 0.1 mm (A, F); 0.02 mm (B-E); 0.01 mm (G).