Twenty-one new species of the Simulium (Gomphostilbia) asakoae species group (Diptera, Simuliidae) in Thailand, with their genetic relationships Author Takaoka, Hiroyuki Tropical Infectious Diseases Research and Education Centre (TIDREC), University of Malaya, 50603, Kuala Lumpur, Malaysia Author Srisuka, Wichai Entomology Section, Queen Sirikit Botanic Garden, P. O. Box 7, Maerim, Chiang Mai 50180, Thailand Author Fukuda, Masako Institute for Research Promotion, Oita University, Idaigaoka 1 - 1, Hasama, Yufu City, Oita, 879 - 5593, Japan Author Saeung, Atiporn Center of Insect Vector Study, Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand https://orcid.org/0000-0003-3550-5992 atisaeung.noi@gmail.com text ZooKeys 2020 950 51 152 http://dx.doi.org/10.3897/zookeys.950.51298 journal article http://dx.doi.org/10.3897/zookeys.950.51298 1313-2970-950-51 3E805885D3354FB3AE8DFA443FAD82AE 7F08092C01585A70A7948EA57A2A8E2E Simulium (Gomphostilbia) maehongsonense Takaoka, Srisuka & Saeung sp. nov. Figs 14 , 25P Material examined. Holotype : Male (with its associated pupal exuviae and cocoon) (in 80% ethanol) labeled as "Holotype: Simulium maehongsonense male, QSBG col. no. 107, Thailand, 12-VII-2017, by W. Srisuka", collected from a stream (width 120 cm, depth 2 cm, bed sandy, fast flow, pH 7.6, 21.2 °C, partially shade, elevation 1,034 m, 19°36'58.5"N , 97°59'48.2"E ), at Pha Peung, Muang District, Mae Hong Son Province, Thailand, 12-VII-2017, by W. Srisuka (Coll. No. 107). Paratypes : Two females (thorax of one female for DNA analysis), seven males (thorax of one male for DNA analysis) (with their associated pupal exuviae and cocoons), and six mature larvae (one mature larva for DNA analysis) (in 80% ethanol), same data as for holotype. Diagnosis. Female: short sensory vesicle and mandible lacking distinct outer teeth (Fig. 14A ). Male: number of upper-eye facets in 13 vertical columns and 14 horizontal rows. Pupa: relatively shorter gill filaments (longest 2.1-2.3 mm long) (Fig. 14G ) and relatively wider terminal hooks (Fig. 14H ). Larva: postgenal cleft 1.4-2.2 times as long as the postgenal bridge (Fig. 14J ) and abdominal segment 1 light grey (Fig. 25P ). Figure 14. Female, male, pupa and larva of S. maehongsonense sp. nov. A female B-F male G-I pupa J larva. 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 (left side; lateral view) H terminal hooks (caudal view) I cocoon (dorsal view) J head capsule (ventral view). Scale bars: 1.0 mm ( I ); 0.1 mm ( B, G, J ); 0.02 mm ( C-F ); 0.01 mm ( A, H ). Description. Female ( N = 2). Body length 1.9 mm. Head. Frontal ratio 1.9:1.0:2.1; frons:head ratio 1.0:4.2. Labrum 0.52 times length of clypeus. Maxillary palpus: proportional length of third, fourth and fifth palpal segments 1:1.1:2.2; sensory vesicle medium-long (0.26 times length of third palpal segment. Lacinia with 9-11 inner and 11-13 outer teeth. Mandible (Fig. 14A ) with 23 inner teeth and lacking distinct outer teeth (though three vestigial teeth present at some distance from tip). Legs. Foreleg: tibia yellowish white except apical three-tenths brownish black; basitarsus moderately dilated, 5.5 times as long as its greatest width. Midleg: tarsus dark brown though basal half of basitarsus yellow (its border not well defined). Hind leg: coxa light brown; tibia yellowish white on basal two-thirds and light brown to brownish black on rest; basitarsus 6.7 times as long as wide, and 0.6 and 0.5 times as wide as greatest widths of tibia and femur, respectively; calcipala 0.5 times as wide as greatest width of basitarsus; claw with large basal tooth 0.46 times length of claw. Wing. Length 1.9 mm. Abdomen. Dorsal surface of abdomen medium to dark brown except most of segment 2 ochreous (though narrow portion along posterior margin somewhat darkened). Terminalia. Sternite 8 bare medially, with 20-22 medium-long to long hairs together with two or three slender short hairs on each side. Ovipositor valves each moderately covered with microsetae interspersed with two or three short hairs. Paraproct in lateral view 0.6 times as long as wide, with 18 medium-long to long hairs on ventral and lateral surfaces. Spermatheca ellipsoid, 1.3 times as long as its greatest width. Male ( N = 8). Body length 2.0-2.4 mm. Head. Slightly wider than thorax. Upper eye dark brown, consisting of large facets in 13 vertical columns and 14 horizontal rows on each side. Maxillary palpus: proportional lengths of third, fourth, and fifth palpal segments 1.0:1.2:2.8; sensory vesicle 0.17 times length of third palpal segment. Legs. Foreleg: tibia yellowish white except l apical one-third dark brown, and inner and lateral surfaces of subbasal portion light brown; basitarsus moderately dilated, 6.5-7.3 times as long as its greatest width. Hind leg: coxa light brown; tibia dark brown to brownish black except little less than basal half yellowish white; tarsus dark brown except little less than basal half of basitarsus and basal one-third of second tarsomere yellowish; basitarsus (Fig. 14B ) 3.8-3.9 times as long as wide, and 1.0 and 1.0 times as wide as greatest width of tibia and femur, respectively; calcipala (Fig. 14B ) 0.32 times as wide as greatest width of basitarsus. Wing. Length 1.9-2.0 mm. Subcosta with four to nine hairs in four males but bare in four males. Genitalia. Coxite in ventral view (Fig. 14C ) 1.8 times as long as its greatest width. Style in ventral view (Fig. 14C ) with round apex; style in ventrolateral view (Fig. 14D ) slightly tapered toward apex, with round apex. Ventral plate in ventral view (Fig. 14C ) with basal arms of moderate length, nearly parallel- sided, then convergent apically; ventral plate in caudal view (Fig. 14F ) with ventral margin nearly straight or slightly concave. Cercus with 14 hairs. Pupa ( N = 10). Body length 2.5-2.7 mm. Head. Integument yellow. Thorax. Integument yellow. Thorax. Gill (Fig. 14G ) composed of eight slender thread-like filaments, arranged as (3+3) +2 or [3+(1+2)]+2 from dorsal to ventral; common basal stalk 0.5-0.7 times length of interspiracular trunk; dorsal triplet with extremely short stalk; stalk of ventral pair of filaments 0.9-1.5 times length of common basal stalk, and 0.5-0.8 times length of interspiracular trunk; primary stalk of dorsal triplet lying against that of lower pair at angle of 70° when viewed laterally; filaments of dorsal triplet subequal in length (1.1-1.3 mm) and thickness to one another; filaments of middle triplet subequal in length (1.5-1.7 mm) and thickness to one another; two filaments of ventral pair subequal in length (2.1-2.3 mm) and thickness to each other and 1.6 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. 14H ), of which outer margin 3.3-4.0 times length of inner margin and crenulated when viewed caudally. Cocoon (Fig. 14I ). Pale yellow, slipper-shaped, roughly to moderately woven, moderately extended ventrolaterally; anterior margin thickly woven medially, without bulge or short projection; 3.0-3.5 mm long by 2.0-2.9 mm wide. Mature larva ( N = 5). Body length 4.5-5.5 mm. Body light ochreous with following color markings: thoracic segment 1 encircled with distinct greyish band (though disconnected ventromedially), thoracic segment 2 greyish and thoracic segment 3 ochreous on ventral surface; abdominal segment 1 light grey, abdominal segments 5 and 6 each with distinct reddish brown spot of various size and shape dorsomedially, and dorsal and dorsolateral surface of abdominal segments 4-8 faintly to moderately covered with pinkish to reddish brown pigments (Fig. 25P ). Head. Head spots moderately positive. Antenna: proportional lengths of first, second, and third articles 1.0:0.8:0.7-0.9. Labral fan with 38-40 primary rays. Hypostoma with four to six hypostomal bristles per side lying nearly parallel to lateral margin. Postgenal cleft (Fig. 14J ) medium sized, 1.4-2.2 times length of postgenal bridge. Abdomen. Posterior circlet with 88-96 rows of hooklets with up to 14 or 15 hooklets per row. Etymology. The species name, maehongsonense , refers to the province, Mae Hong Son, where this species was collected. Distribution. Thailand (Mae Hong Son). Discussion. The male of this new species is similar to S. phulocense from Vietnam ( Takaoka et al. 2015 ) by having the same number of upper-eye large facets, but is distinguished by the fore basitarsus 6.5-7.3 times as long as its greatest width (8.3 times in S. phulocense ), and ventral plate trapezoidal ventrally (Fig. 14F ) when viewed posteriorly (rounded ventrally in S. phulocense ) and in the pupa by the cocoon without an anterodorsal projection (Fig. 14I ) (with an anterodorsal projection in in S. phulocense ).