Simulium (Gomphostilbia) puaense Takaoka, Srisuka & Saeung, 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) puaense Takaoka, Srisuka & Saeung sp. nov. Fig. 4

Material examined.

Holotype: Male (together with its associated pupal exuviae and cocoon) (in 80% ethanol) labeled as "Holotype: Simulium puaense male, QSBG col. no. 60, Thailand, 25-VII-2017, by W. Srisuka" reared from a pupa collected from a small waterfall (width 80 cm, depth 3 cm, flast flow, pH 7.2, 20.1 °C, exposed to the sun, elevation 1,157 m, 19°11'10.3"N, 101°04'41.7"E), Nam Dan Village, Pua District, Nan Province, northern Thailand, 25-VII-2017, by W. Srisuka (Coll. No.60).

Paratypes: One female (thorax for DNA analysis) (together with its associated pupal exuviae and cocoon) (in 80% ethanol), reared from a pupa collected from a stream (width 30 cm, depth 5 cm, bed sandy, moderate running, pH 6.3, 22.6 °C, exposed to the sun, elevation 1,097 m, 18°50'03.7"N, 99°22'32.2"E), at Pa Meing Village, Muang Pan District, Lampang Province, northern Thailand, 9-VIII-2016, by W. Srisuka (Coll. No. 86); three males (thorax of one male for DNA analysis) (together with their associated pupal exuviae and cocoons) (in 80% ethanol), same data as for holotype.

Diagnosis.

Female: small sensory vesicle 0.24 times as long as the third palpal segment (Fig. 4A ) and relatively shorter labrum against the clypeus. Male: small number of upper-eye (large) facets in nine or ten vertical columns and 12 horizontal rows, and hind basitarsus 3.2-3.6 times as long as its greatest width and 0.9-1.1 and 1.1-1.2 times as wide as the hind tibia and femur, respectively.

Description.

Female (N = 1). Body length 2.1 mm.

Head. Frontal ratio 1.9:1.0:2.4 frons:head ratio 1.0:4.4. Labrum 0.56 times length of clypeus. Maxillary palpus: proportional lengths of third, fourth, and fifth palpal segments 1.0:1.1:2.0; sensory vesicle (Fig. 4A ) 0.24 times length of third palpal segment. Lacinia with ten or eleven inner and 12 or 13 outer teeth. Mandible (Fig. 4B ) with 20 inner teeth and two or three 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 more than apical one-fourth brownish black; basitarsus moderately dilated, 5.8 times as long as its greatest width. Midleg: tarsus dark brown to brownish black though basal half of basitarsus dark yellow (its border not well defined). Hind leg: coxa light brown; tibia yellowish white on little more than basal half and light brown to brownish black on rest; basitarsus 5.9 times as long as wide, and 0.7 and 0.5 times as wide as greatest widths of tibia and femur, respectively; claw with large basal tooth 0.47 times length of claw.

Wing. Length 2.0 mm.

Abdomen. Dorsal surface of abdomen medium to dark brown except anterior two-thirds of segment 2 ochreous.

Terminalia. Sternite 8 with 20 medium-long to long hairs together with two or three slender short hairs on each side. Paraproct in ventral view with four or five sensilla on anteromedial surface; paraproct in lateral view 0.6 times as long as wide, with 21-23 medium-long to long hairs on ventral and lateral surfaces.

Male (N = 4). Body length 2.1-2.4 mm.

Head. Slightly wider than thorax. Upper eye dark brown, consisting of large facets in nine or ten vertical columns and 12 horizontal rows on each side. Antenna: first flagellomere 1.5-1.6 times length of second. Maxillary palpus light brown, with five palpal segments, proportional lengths of third, fourth, and fifth palpal segments 1.0:1.0:2.0; sensory vesicle 0.13-0.18 times length of third palpal segment.

Legs. Foreleg: basitarsus moderately dilated, 6.6-7.2 times as long as its greatest width. Hind leg: tibia dark brown to brownish black except basal half whitish yellow; tarsus (Fig. 4C ) brownish black except basal half or little less of basitarsus and basal one-third of second tarsomere whitish yellow; basitarsus (Fig. 4C ) enlarged, 3.2-3.6 times as long as wide, and 0.9-1.1 and 1.0-1.2 times as wide as greatest width of tibia and femur, respectively; calcipala (Fig. 4C ) slightly shorter than basal width, and 0.28 times as wide as greatest width of basitarsus.

Wing. Length 2.0-2.1 mm. Subcosta with two to five hairs (though subcosta bare in one male).

Genitalia. Coxite in ventral view (Fig. 4D ) nearly rectangular, 1.7-2.2 times as long as its greatest width. Style in ventrolateral view (Fig. 4E, F ) gradually tapered toward apex or nearly parallel-sided from basal one-third to apical one-fourth, with truncated apex. Ventral plate in ventral view (Fig. 4D ) with basal arms of moderate length, nearly parallel-sided; ventral plate in caudal view (Fig. 4H ) with ventral margin nearly straight. Cercus with 11-14 hairs.

Pupa (N = 5). Body length 2.6-3.0 mm.

Thorax. Gill (Fig. 4I ) composed of eight slender thread-like filaments, arranged as [3+(1+2)]+2 from dorsal to ventral; common basal stalk 0.6-0.7 times length of interspiracular trunk; dorsal and middle triplets sharing short stalk, and dorsal triplet mostly composed of three individual filaments arising at same level from extremely short stalk, middle triplet mostly composed of one individual and two paired filaments with extremely short secondary stalk; stalk of ventral pair of filaments variable in length, 0.8-1.3 times length of common basal stalk, and 0.6-0.8 times length of interspiracular trunk; primary stalk of dorsal triplet lying against that of lower pair at angle of 40-60° when viewed laterally; filaments of dorsal triplet subequal in length (1.5-1.8 mm) and thickness to one another; filaments of middle triplet subequal in length (1.7-2.0 mm); two filaments of ventral pair subequal in length (2.3-2.6 mm) and thickness to each other and 1.5 times as thick as six other filaments of dorsal and middle triplets when compared basally; all filaments light brown.

Abdomen. Dorsally, all segments light yellowish; segments 1 and 2 without minute tubercles; segment 9 with pair of wide flat terminal hooks (Fig. 4J ), of which outer margin is 2.0 times length of inner margin and crenulated when viewed caudally (terminal hooks abnormally formed in one pupa, Fig. 4K ).

Cocoon (Fig. 4L ). Slipper-shaped, light yellow, moderately woven, moderately extended ventrolaterally; anterior margin thickly woven medially, rarely with small bulge; individual threads not visible; 3.0-3.5 mm long by 2.2-2.5 mm wide.

Mature larva. Unknown.

Etymology.

The species name, puaense , refers to the district, Pua, one of the two localities where this species was collected.

Distribution.

Thailand (Lampang and Nan)

Discussion.

This new species is similar to S. vinhphucense Takaoka & Low from Vietnam ( Takaoka et al. 2017a) by having a small number of brown male upper-eye (large) facets, but is distinguished from the latter species by the relative length of the male fore basitarsus against its greatest width (6.6-7.2 in this new species versus 8.2 in S. vinhphucense ) and relative width of the male hind basitarsus against the hind femur, which is 1.1-1.2 in this new species versus 1.5 in S. vinhphucense ), and ventral plate in caudal view trapezoidal (Fig. 4H ) (rounded ventrally in S. vinhphucense ).

This new species is also similar to S. thungchangense sp. nov. and S. chaudinhense from Vietnam ( Takaoka et al. 2017a) in having a small number of male upper-eye (large) facets, but is barely distinguished from the two latter species by the upper-eye (large) facets medium brown (vermilion in the two latter species) and dorsum of pupal abdominal segments 1 and 2 bare (with minute tubercles in in the two latter species).

Figures

Figure 4. Female, male and pupa of S. puaense sp. nov. A, B female C-H male I-L pupa. A sensory vesicle (left side; anterior view) B mandible (left side) C hind basitarsus and second tarsomere (left side; lateral view) D coxites, styles and ventral plate (ventral view) E, F styles (right side; ventrolateral view E gradually tapered toward apex F nearly parallel-sided) G ventral plate and median sclerite (lateral view) H ventral plate (caudal view) I gill filaments (left side; lateral view) J, K terminal hooks (caudal view J normal K right hook abnormal) L cocoon (dorsal view). Scale bars: 1.0 mm (L); 0.1 mm (C, I); 0.02 mm (A, D-H); 0.01 mm (B, J, K).