Simulium (Gomphostilbia) nanthaburiense 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) nanthaburiense Takaoka, Srisuka & Fukuda sp. nov. Fig. 11

Material examined.

Holotype: Male (with its associated pupal exuviae and cocoon) (in 80% ethanol) labeled as "Holotype: Simulium nanthaburiense male, QSBG col. no. 60, Thailand, 25-VII-2017, by W. Srisuka", collected from a stream (width 80 cm, depth 2.5 cm, moderate flow, pH 7.2, 20.1 °C, partially shaded, elevation 1,157 m, 19°11'10.3"N, 101°04'41.7"E), Nam Dan Village, Pua District, Nan Province, Thailand, 25-VII-2017, by W. Srisuka (Coll. No. 60).

Paratypes: One female (thorax for DNA analysis) and 10 males (thorax of one male for DNA analysis) (with their associated pupal exuviae) (in 80% ethanol), same date and data as the holotype; one female (thorax for DNA analysis) (with their associated pupal exuviae) (in 80% ethanol) collected from a stream (width 120 cm, depth 10 cm, bed sandy, moderate flow, pH 6.63, 17.1 °C, partially shaded, elevation 1,154 m, 19°03'36.8"N, 99°19'15.7"E), Huai Mor Nuea Village, Doi Saket, Chiang Mai Province, northern Thailand, 2-II-2019, by W. Srisuka and A. Saeung (Coll. No. 49).

Diagnosis.

Female: mandible with two distinct teeth on the outer margin (11A). Male: small number of upper-eye facets in 12 vertical columns and 13 or 14 horizontal rows.

Description.

Female (N = 2). Body length 2.0 mm.

Head. Frontal ratio 1.7:1.0:2.1; frons:head ratio 1.0:4.3. Labrum 0.64 times length of clypeus. Maxillary palpus: proportional lengths of third, fourth, and fifth palpal segments 1.0:1.1:2.4; sensory vesicle 0.26-0.29 times length of third palpal segment. Maxillary lacinia with ten or eleven inner and 13 or 14 outer teeth. Mandible (Fig. 11A ) with 22 inner teeth and two outer teeth at some distance from tip.

Legs. Foreleg: coxa and trochanter whitish yellow; femur dark yellow to light brown with apical cap medium brown (though extreme tip yellowish); tibia yellowish white except little less than apical three-tenths brownish black; basitarsus moderately dilated, 6.0 times as long as its greatest width. Midleg: tarsus dark brown to brownish black though basal half or little less of basitarsus dark yellow (its border not well defined). Hind leg: coxa light brown with apical one-third yellow; tibia yellowish white on basal two-thirds and brownish black on rest; basitarsus 6.2 times as long as wide, and 0.65 and 0.53 times as wide as greatest widths of tibia and femur, respectively; calcipala slightly longer than width at base, and 0.56 times as wide as greatest width of basitarsus; claw with large basal tooth 0.45 times length of claw.

Wing. Length 2.0 mm.

Abdomen. Dorsal surface of abdomen medium to dark brown except most of segment 2 ochreous.

Terminalia. Sternite 8 with 22 or 23 medium-long to long hairs together with three to six slender short hairs on each side. Paraproct in ventral view with three or four sensilla on anteromedial surface; paraproct in lateral view 0.6 times as long as wide, with 27-29 medium-long to long hairs on ventral and lateral surfaces. Cercus in lateral view 0.5 times as long as wide. Spermatheca 1.6 times as long as its greatest width.

Male (N = 11). Body length 2.0-2.3 mm.

Head. Somewhat wider than thorax. Upper eye dark brown, consisting of large facets in 12 vertical columns and 13 or 14 horizontal rows. Antenna light to medium brown except scape, pedicel and base of first flagellomere yellowish white; first flagellomere elongate, 1.8 times length of second. Maxillary palp light brown, with five palpal segments, proportional lengths of third, fourth, and fifth palpal segments 1.0:1.1.2:2.3; sensory vesicle 0.19 times length of third palpal segment.

Legs. Foreleg: trochanter yellow to dark yellow; tibia whitish except apical three-tenths dark brown and subbasal portion dark yellow to light brown (though outer surface whitish); basitarsus moderately dilated, 6.8-7.4 times as long as its greatest width. Midleg: tarsus dark brown except basal one-fourth to one-third of basitarsus dark yellow to light brown (border not well defined). Hind leg: coxa light brown; tarsus (Fig. 11B ) brownish black except basal half to two-fifths of basitarsus and basal one-third of second tarsomere yellow; basitarsus (Fig. 11B ) 3.8-4.1 times as long as wide, and 0.9 and 1.0 times as wide as greatest width of tibia and femur, respectively; calcipala (Fig. 11B ) slightly shorter than basal width, and 0.33 times as wide as greatest width of basitarsus.

Wing. Length 1.9-2.0 mm. Subcosta with 1-10 hairs, though no hair in two males.

Genitalia. Coxite in ventral view (Fig. 11C ) 1.6 times as long as its greatest width. Style in ventral view (Fig. 11C ) with round apex. Ventral plate in caudal view (Fig. 11F ) with ventral margin nearly straight. Cercus small, rounded, with 12 or 13 hairs.

Pupa (N = 13). Body length 2.5-2.7 mm.

Head. Integument yellow. Thorax. Integument yellow, moderately covered with round tubercles except dorsolateral surface of posterior half sparsely covered with tubercles. Gill (Fig. 11G ) composed of eight slender thread-like filaments, arranged as (3+3)+2 or [3+(1+2)]+2 or [(2+1)+(1+2)]+2 or [(2+1)+3]+2) from dorsal to ventral; common basal stalk 0.6-0.8 times length of interspiracular trunk; stalk of ventral pair of filaments short, 0.6-0.9 times length of common basal stalk, and 0.4-0.7 times length of interspiracular trunk; primary stalk of dorsal triplet lying against that of lower pair at angle of 70-90° when viewed laterally; filaments of dorsal triplet subequal in length (1.9-2.0 mm) and thickness to one another; filaments of middle triplet subequal in length (2.0-2.3 mm) and thickness to one another; two filaments of ventral pair subequal in length (2.9-3.0 mm) and thickness to each other and 1.5-1.7 times as thick as six other filaments of dorsal and middle triplets when compared basally; all filaments light brown (rarely dark brown).

Abdomen. Dorsally, all segments light yellowish; segments 1 and 2 without minute tubercles; segment 9 with pair of wide flat terminal hooks (Fig. 11H ), of which outer margin 1.9-2.1 times length of inner margin and crenulated when viewed caudally.

Cocoon (Fig. 11I ). Pale yellow, slipper-shaped, moderately woven, moderately extended ventrolaterally; anterior margin thickly woven medially, often with bulge; individual threads visible or not; 3.0-3.3 mm long by 1.8-2.5 mm wide.

Mature larva. Unknown.

Etymology.

The species name, nanthaburiense , refers to the historical name of Nan Province, Nanthaburi, where this species was collected.

Distribution.

Thailand (Nan).

Discussion.

This new species is similar to S. brinchangense described from Peninsular Malaysia ( Takaoka et al. 2014b), in having a similar number of male upper-eye facets, but is distinguished by the relative length of the stalk of the ventral pair of filaments against the common basal stalk, which is 0.6-0.9 in this new species but 1.1-1.2 in S. brinchangense , and relative length of the outer margin against the inner margin of the pupal terminal hooks, which is 1.9-2.1 in this new species but 3.0-3.6 in S. brinchangense .

Figures

Figure 11. Female, male and pupa of S. nanthaburiense sp. nov. A female B-F male G-I pupa. A mandible (right side) B hind basitarsus and second tarsomere (left side; lateral view) C coxites, styles and ventral plate (ventral view) D style (right side; ventrolateral view) E ventral plate and median sclerite (lateral view) F ventral plate (caudal view) G gill filaments (right side; lateral view) H terminal hooks (caudal view) I cocoon (dorsal view). Scale bars: 1.0 mm (I); 0.1 mm (B, G); 0.02 mm (C-F); 0.01 mm (A, H).