Simulium (Gomphostilbia) inthanonense Takaoka & Suzuki, 1984

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) inthanonense Takaoka & Suzuki, 1984 Figs 24 , 25S, T

Simulium (Gomphostilbia) inthanonense Takaoka & Suzuki, 1984: 18-21 (female, pharate male, pupa, and larva).

Remarks.

This species was described from females, pharate males, pupae and larvae collected from Doi Inthanon National park, Chiang Mai Province ( Takaoka and Suzuki 1984), and was placed in the S. ceylonicum species group ( Takaoka 2012).

This species is here transferred from the S. ceylonicum species group to the S. asakoae species group, based on the male ventral plate emarginated on both sides when viewed ventrally (Fig. 24F ), though the dark tuft hairs on the base of the radial vein of the female and the male depart from the definition of the species group ( Takaoka 2012). An analysis of the COI gene sequences supports this transfer (Fig. 26 ). The descriptions of the female, pupa and larva are revised, and the male is fully described for the first time.

Specimens examined.

Ten females, 10 males (with their associated pupal exuviae and cocoons) (in 80% ethanol), collected from a small stream (width 40 cm, depth 10 cm, bed sandy, moderate flow, pH 7.2, 15.3 °C, partially shaded, elevation 1,314 m, 18°31'01.9"N, 98°28'17.3"E), at Mae Klang Watershed, Doi Inthanon National Park, Mae Cham District, Chiang Mai Province, Thailand, 21-XII-2018, by W. Srisuka (Coll. No. 25); five females and five males and five mature larvae (two mature larvae for DNA analysis) (in 80% ethanol) collected in a stream (width 1.0 m, depth 20 cm, bed sandy, flow moderate, partially shaded, pH 6.8, 14.0 °C, elevation 1,589 m, 18°30'29.8"N, 98°30'37.4"E), at Mae Aum, Doi Inthanon National Park, Chom Thong District, Chiang Mai Province, Thailand, 25-I-2019, by W. Srisuka (Coll. No. 20). One male (thorax for DNA analysis) (with its associated pupal exuviae and cocoon) (in 80% ethanol), collected from a stream (width 70 cm, depth 10 cm, pH 6.5, 13.8 °C, moderate flow, bed sandy, partially shaded, elevation 1,685 m, 18°31'15.4"N, 98°29'59.4"E), before check point 2, Doi Inthanon National parks, Chiang Mai Province, northern Thailand, 20-III-2018, by W. Srisuka (Coll. No. 6).

Diagnosis.

Female and male: darkened hair tuft at the base of the radial vein and relatively long sensory vesicle (Fig. 24A, D ). Female: mandible with several distinct teeth on the outer margin (Fig. 24B ), and hind tibia yellowish on the basal half. Male: greater number of large upper-eye facets in 17 vertical columns and 17 (rarely 18) horizontal rows on each side, subcosta without hairs, and hind basitarsus (Fig. 24E ) narrower than the hind tibia and femur. Pupa: dorsal surface of abdominal segments 1-5 light greyish brown. Larva: postgenal cleft (Fig. 24L ) as long as or little shorter than the postgenal bridge and abdominal segments 1 and 3 (or 1-3) greenish grey (Fig. 25S, T ). Two forms of this species are designated, based on larvae: morph 1 has abdominal segments 1-3 greenish grey (Fig. 25S ) and morph 2 has abdominal segments 1 and 3 greenish grey (Fig. 25T ).

Description.

Female (N = 15). Body length 2.0-2.1 mm.

Head. Frontal ratio 1.6-1.8:1.0:2.3-2.8; frons:head ratio 1.0:4.7-5.1. Labrum 0.55-0.61 times length of clypeus. Maxillary palpus: proportional lengths of third, fourth, and fifth palpal segments 1.0:0.9-1.0:2.1-2.2; sensory vesicle (Fig. 24A ) elongate, 0.58-0.61 times length of third palpal segment. Lacinia with 10-13 inner and 15-17 outer teeth. Mandible (Fig. 24B ) with 28-30 inner teeth and four to six outer teeth at some distance from tip.

Legs. Foreleg: basitarsus moderately dilated, 6.2-6.4 times as long as its greatest width. Hind leg: coxa medium brown; basitarsus 7.1-7.2 times as long as wide, and 0.6-0.7 and 0.5-0.6 times as wide as greatest widths of tibia and femur, respectively; calcipala nearly as long as width at base, and 0.6 times as wide as greatest width of basitarsus; claw with large basal tooth 0.43 times length of claw.

Wing. Length 2.1-2.4 mm. Costa with dark spinules and hairs. Hair tuft on base of radius dark brown.

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

Terminalia. Sternite 8 with 16-25 medium-long to long hairs together with three or four slender short hairs on each side. Ovipositor valves each covered with microsetae interspersed with three or four short hairs. Paraproct with five to eight sensilla on anteromedial surface; paraproct in lateral view with 26-32 medium-long to long hairs on ventral and lateral surfaces. Cercus in lateral view short, slightly rounded posteriorly, 0.5 times as long as wide. Spermatheca (Fig. 24C ) ellipsoidal, 1.4-1.5 times as long as its greatest width, and with many fissures nearly entirely on outer surface in some females.

Male (N = 16). Body length 2.3-2.6 mm.

Head. Slightly wider than thorax. Upper eye medium brown, consisting of large facets in 17 vertical columns and 17 (rarely 18) horizontal rows on each side. Antenna medium to dark brown except scape, pedicel and base of first flagellomere yellow, though apical half or two-thirds of pedicel light brown in some males; first flagellomere 1.7 times length of second. Maxillary palpus: proportional lengths of third, fourth, and fifth palpal segments 1.0:1.2:2.6; third palpomere (Fig. 24D ) somewhat enlarged; sensory vesicle (Fig. 24D ) medium-long, 0.40-0.47 times length of third palpal segment.

Legs. Foreleg: coxa yellow; trochanter light brown; femur medium brown; light brown except apical one-third dark brown and median large portion on outer surface white and shiny; basitarsus moderately dilated, 6.9-7.7 times as long as its greatest width. Midleg: trochanter light brown except base yellow; femur medium brown with base yellowish and apical cap dark brown (though apical tip yellow); tarsus light to dark brown. Hind leg: coxa medium brown; trochanter yellow to dark yellow; tarsus (Fig. 24E ) brownish black except basal two-fifths of basitarsus and basal one-third of second tarsomere dark yellow to light brown; basitarsus (Fig. 24E ) 4.2-4.4 times as long as wide, and 0.8-0.9 and 0.8-0.9 times as wide as greatest width of tibia and femur, respectively; calcipala (Fig. 24E ) slightly shorter than basal width, and 0.35 times as wide as greatest width of basitarsus.

Wing. Length 2.1-2.3 mm. Other characters as in female except subcosta bare. Halter. Light to medium brown except lower portion whitish.

Genitalia. Coxite in ventral view (Fig. 24F ) nearly rectangular, 1.7-1.8 times as long as its greatest width. Style in ventrolateral view slightly tapered toward apex, with round apex. Ventral plate in ventral view (Fig. 24F ) with basal arms nearly parallel-sided, then convergent apically; ventral plate in caudal view (Fig. 24H ) with ventral margin nearly straight. Cercus with 12-14 hairs.

Pupa (N = 31). Body length 2.5-3.0 mm.

Head. Integument yellow.

Thorax. Integument yellow, with two somewhat darkened areas in tandem on dorsal surface of posterior half. Gill (Fig. 24I ) composed of eight slender thread-like filaments, arranged as [(2+1)+(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 composed of one individual and two paired filaments; stalk of ventral pair of filaments 1.3-1.7 times length of common basal stalk, and 0.9-1.1 times length of interspiracular trunk; primary stalk of dorsal triplet lying against that of ventral pair at angle of 80-120° when viewed laterally; filaments of dorsal triplet subequal in length (2.2-3.2 mm) and thickness to one another; those of middle triplets subequal in length (2.8-3.8) and thickness to one another, two filaments of ventral pair subequal in length (3.5-4.2 mm) and thickness to each other and 1.1-1.5 times as thick as six other filaments of dorsal and middle triplets when compared basally.

Abdomen. Dorsally, segments 1-5 light greyish brown, segment 9 and bases of spine-combs of segments 6-8 light yellow; segments 1 and 2 without minute tubercles; segment 9 with pair of triangular terminal hooks (Fig. 24J ), of which outer margin 1.3-1.7 times length of the inner margin and weakly crenulated when viewed caudally.

Cocoon (Fig. 24K ). Yellow to dark brown, slipper-shaped, moderately woven, widely extended ventrolaterally; anterior margin thickly woven medially and with short projection (its length usually 1.0 mm or slightly more); 3.2-3.9 mm long by 1.6-3.0 mm wide.

Mature larva (N = 3). Body length 5.6-6.0 mm. Body light ochreous with following color markings: thoracic segment 1 encircled with distinct reddish brown band (though disconnected ventromedially), thoracic segments 2 and 3 dark ochreous on ventral surface; abdominal segments 1 and 3 (or abdominal segments 1-3) greenish grey; abdominal segments 5 and 6 each with three distinct, reddish brown spots (one round dorsomedial spot and two dorsolateral spots) (Fig. 25S, T ).

Head. Head spots faintly to moderately positive. Antenna: proportional lengths of first, second, and third articles 1.0:1.0-1.1:0.8-0.9. Labral fan with 40 primary rays. Hypostoma with four to six hypostomal bristles per side lying nearly parallel to or slightly diverginf from lateral margin. Postgenal cleft (Fig. 24L ) short, nearly quadrate, as long as or little shorter than postgenal bridge.

Thorax and Abdomen. Thoracic and abdominal cuticle sparsely covered with unpigmented minute setae. Rectal organ compound, each of three lobes with 9-13 finger-like secondary lobules. Anal sclerite with anterior arms nearly as long as posterior ones. Posterior circlet with 82-87 rows of hooklets with up to 15 hooklets per row.

Distribution.

Thailand (Chiang Mai), China and Vietnam.

Figures

Figure 24. Female, male, pupa and larva of S. inthanonense. A-C female D-H male I-K pupa L larva. A, D sensory vesicles (right side; anterior view A female D male) B mandible (right side) C spermatheca E hind basitarsus and second tarsomere (left side; lateral view) F coxites, styles and ventral plate (ventral view) G ventral plate and median sclerite (lateral view) H ventral plate (caudal view) I gill filaments (right side; lateral view) J terminal hooks (caudal view) K cocoon (dorsal view) L head capsule (ventral view). Scale bars: 1.0 mm (K); 0.1 mm (E, I, L); 0.02 mm (A, C, D, F-H); 0.01 mm (B, J).

Figure 25. Schematic illustrations of larval body color patterns (dorsal view). A S. teerachanense sp. nov. B S. pitasawatae sp. nov. C S. sutheppuiense sp. nov. D S. asakoae E S. klonglanense sp. nov. F S. namdanense sp. nov. G S. chaowaense sp. nov. H S. loeiense sp. nov. I S. huaimorense sp. nov. J S. nanoiense sp. nov. K S. junkumae sp. nov. L S. myanmarense M S. maewongense sp. nov. N S. phapeungense sp. nov. O S. muangpanense sp. nov. P S. maehongsonense sp. nov. Q S. thungchangense sp. nov. R S. chiangdaoense S S. inthanonense (morph 1) T S. inthanonense (morph 2).

Figure 26. Neighbor-joining tree of the 26 Thai species of the Simulium asakoae species group based on COI gene sequences (586 positions). The numbers at the nodes mean the bootstrap confidence values after 500 replicates. The bootstrap values above 50 % are shown. The scale bar indicates the distance in substitutions per nucleotide. The symbols in front of the species names are each the collection number (corresponding to those in the text), developmental stages (F, female; M, male; L, larva), and sample number (if two or more samples were examined) in this order.