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) muangpanense Takaoka, Srisuka & Fukuda sp. nov. Figs 13 , 25O Material examined. Holotype : Male (with its associated pupal exuviae and cocoon) (in 80% ethanol) labeled as "Holotype: Simulium muangpanense male, QSBG col. no. 86, Thailand, 9-VIII-2016, by W. Srisuka", 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). Paratypes : Three females (thorax of one female for DNA analysis), four males (thorax of one male for DNA analysis) (with their associated pupal exuviae and cocoons), and five mature larvae (one mature larva for DNA analysis) (in 80% ethanol), same data as for holotype. Diagnosis. Female: mandible with two or three outer teeth (Fig. 13A ). Male: number of upper-eye facets in 13 vertical columns and 14 horizontal rows, hind basitarsus (Fig. 13B ) 0.9 times as wide as the hind femur. Larva: abdominal segments 1, 4, 5, 7, and 8 grey at least on dorsal and dorsolateral surface (Fig. 25O ). Figure 13. Female, male, pupa and larva of S. muangpanense sp. nov. A female B-F male G-I pupa J, K 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) K postgenal cleft. Scale bars: 1.0 mm ( I ); 0.1 mm ( B, G, J, K ); 0.02 mm ( C-F ); 0.01 mm ( A, H ). Description. Female ( N = 3). Body length 2.0-2.1 mm. Head. Frontal ratio 1.8:1.0:2.1; frons:head ratio 1.0:4.0. Labrum 0.61 times length of clypeus. Maxillary palpus: proportional lengths of third, fourth, and fifth palpal segments 1.0:1.0:2.5; sensory vesicle medium sized, ellipsoidal (0.29-0.31 times length of third palpal segment), with small opening. Lacinia with nine or ten inner and 14 outer teeth. Mandible (Fig. 13A ) with 20 inner teeth and two or three outer teeth at some distance from tip. Legs. Foreleg: basitarsus moderately dilated, 6.4 times as long as its greatest width. Midleg: femur light brown with basal one-fourth whitish yellow and apical cap medium brown (though extreme tip yellowish); tarsus dark brown to brownish black though little less than basal half of basitarsus yellow (its border not well defined). Hind leg: coxa light brown with apical one-third yellowish white; tibia white to yellowish white on basal two-thirds and light brown to brownish black on rest; basitarsus 6.04 times as long as wide, and 0.76 and 0.58 times as wide as greatest widths of tibia and femur, respectively; calcipala nearly as long as or lightly longer than width at base, and 0.5-0.6 times as wide as greatest width of basitarsus. Wing. Length 2.0 mm. Terminalia. Sternite 8 with 18-21 medium-long to long hairs together with four slender short hairs on each side. Ovipositor valve moderately covered with microsetae interspersed with two or three short hairs. Paraproct in ventral view with four or five or six sensilla on anteromedial surface; paraproct in lateral view 0.6 times as long as wide, with 24-28 medium-long to long hairs on ventral and lateral surfaces. Cercus in lateral view 0.46 times as long as wide. Male ( N = 5). Body length 2.1-2.5 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. Antenna: first flagellomere 1.5-1.7 times length of second. Maxillary palpus: proportional lengths of third, fourth, and fifth palpal segments1.0:1.2:2.9-3.1; sensory vesicle globular or ellipsoidal, 0.15-0.18 times length of third palpal segment. Legs. Foreleg: femur light brown except apical cap medium brown (though apical tip yellowish); tibia light brown on basal one-third (though basal tip yellow and outer surface narrowly yellowish white), yellowish white on middle one-third, and brownish black on apical one-third; basitarsus moderately dilated, 6.7-7.3 times as long as its greatest width. Midleg: femur light brown with base yellowish on inner surface and apical cap medium brown (though apical tip yellowish); tibia medium brown except basal one-third (or little more on posterior surface) yellowish white; tarsus dark brown except base of basitarsus dark yellow to light brown (border not well defined). Hind leg: coxa light brown with apical one-third yellowish; femur light to medium brown with base whitish yellow and apical cap brownish black (though apical tip yellow); tibia dark brown to brownish black except basal half or little less whitish yellow; tarsus dark brown except basal two-fifths of basitarsus and little less than basal half of second tarsomere whitish yellow; basitarsus (Fig. 13B ) 4.0-4.2 times as long as wide, and 0.9 and 0.9 times as wide as greatest width of tibia and femur, respectively; calcipala (Fig. 13B ) slightly shorter than basal width, and 0.33 times as wide as greatest width of basitarsus. Wing. Length 1.6-1.9 mm. Other characters as in female except subcosta with 0-6 hairs. Genitalia. Coxite in ventral view (Fig. 13C ) 1.9 times as long as its greatest width. Style in ventral view (Fig. 13D ) with round apex, and in ventrolateral view (Fig. 13D ) slightly tapered toward apex or nearly parallel-sided from middle to apex, and 0.8 times length of coxite. Ventral plate in ventral view (Fig. 13C ) with basal arms nearly parallel-sided, then convergent apically; ventral plate in caudal view (Fig. 13F ) rounded ventrally, though ventral margin slightly concave medially. Ventral surface of abdominal segment 10 moderately sclerotized along anterior margin. Cercus with 13-16 hairs. Pupa ( N = 8). Body length 2.3-2.6 mm. Thorax. Gill (Fig. 13G ) composed of eight slender thread-like filaments, arranged as [(2+1)+(1+2)]+2 or [3+(1+2)]+2 from dorsal to ventral; common basal stalk 0.6-0.8 times length of interspiracular trunk; stalk of ventral pair of filaments variable in length, 1.0-1.5 times length of common basal stalk, and 0.7-1.0 times length of interspiracular trunk; filaments of dorsal triplet subequal in length to one another (2.0-2.2 mm) and those of middle triplet subequal in length to one another (2.4-2.5); two filaments of ventral pair subequal in length to each other (3.0-3.2 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 pale yellowish; segments 1 and 2 almost bare or sparsely covered with minute tubercles; segment 9 with pair of flat terminal hooks (Fig. 13H ), of which outer margin 2.8-3.1 times length of inner margin and crenulated when viewed caudally. Cocoon (Fig. 13I ). Slipper-shaped, moderately woven, moderately extended ventrolaterally; anterior margin thickly woven medially, rarely with bulge; 3.0-3.4 mm long by 2.0-2.5 mm wide. Mature larva ( N = 4). Body length 4.8-5.0 mm. Body ochreous with following color markings: thoracic segment 1 encircled with grey band (though disconnected ventromedially), thoracic segments 2 and 3 grey on ventral surface (though often faded on segment 3); abdominal segments 1 and 4 entirely grey, abdominal segments 5, 7, and 8 grey on dorsal and dorsolateral surface; abdominal segment 4 with faint narrow reddish brown transverse band on dorsal and dorsolateral surface in one larva; abdominal segment 5 with distinct reddish brown, W-shaped, transverse band dorsally, abdominal segment 6 often with three reddish brown spots (one round dorsomedial spot and two lateral spots of various size and shape), and abdominal segments 7 and 8 distinctly covered with reddish brown pigment usually on dorsolateral surface (Fig. 25O ). Head. Head capsule yellow with narrow area along posterior margin darkened; head spots faintly or moderately positive. Antenna: proportional lengths of first, second, and third articles 1.0:0.7-0.8:0.8-0.9. Labral fan with 31 or 32 primary rays. Hypostoma with five hypostomal bristles per side lying nearly parallel to lateral margin. Postgenal cleft (Fig. 13J, K ) medium-long, 1.2-2.1 times length of postgenal bridge, usually with apical margin round (though angulated in one larva). Thorax and Abdomen. Thoracic and abdominal cuticle almost bare except abdominal segments 5-8 moderately covered with unbranched dark minute setae (though setae rarely bifid) on dorsal and dorsolateral surface. Rectal organ compound, each of three lobes with seven to nine finger-like secondary lobules. Anal sclerite with anterior arms 1.1-1.2 times as long as posterior ones. Posterior circlet with 76-80 rows of hooklets with up to 14 or 15 hooklets per row. Etymology. The species name, muangpanense , refers to the district, Muang Pan, where this species was collected. Distribution. Thailand (Lampang). 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 in the female by the fore basitarsus 5.8 times as long as its greatest width (6.9 times in S. phulocense ), in the male by the fore basitarsus 6.7-7.3 times as long as its greatest width (8.3 times in S. phulocense ), and ventral plate trapezoidal ventrally when viewed posteriorly (rounded ventrally in S. phulocense ) and in the pupa by the cocoon without an anterodorsal projection (with an anterodorsal projection in S. phulocense ). Simulium tanahrataense from Peninsular Malaysia ( Takaoka et al. 2014b ) and S. confertum Takaoka & Sofian-Azirun from Vietnam ( Takaoka et al. 2015 ) have a similar number of male upper-eye facets (in 14 vertical columns and 15 horizontal rows) and a similar shape of the ventral plate (trapezoidal in caudal view), but are barely distinguished from this new species by the male hind basitarsi as wide as the hind femora (0.9 times as wide as the hind femur in this new species) and the length of the ventral paired filaments of the pupa 2.6-2.7 mm (3.0-3.2 mm in this new species). The larva of this new species is almost the same in body color pattern as S. monglaense described from Myanmar ( Takaoka et al. 2017b ) but is barely distinguished from the latter species by the posterior circlet with 76-80 rows (85-93 rows in S. monglaense ). This new species is distinguished from S. monglaense in the female by the mandible with distinct outer teeth and in the male by the relative length of the fore basitarsus against its greatest width (6.7-7.3 in this new species versus 8.0 in in S. monglaense ).