Simulium (Gomphostilbia) maewongense 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) maewongense Takaoka, Srisuka & Saeung sp. nov. Figs 7 , 25M

Material examined.

Holotype: Male (with its associated pupal exuviae and cocoon) (in 80% ethanol) labeled as "Holotype: Simulium maewongense male, QSBG col. no. 80, Thailand, 12-VII-2018, by W. Srisuka", collected from a small stream (width 20 cm, depth 2 cm bed sandy, slow flow, 19.5 °C, partially shaded, elevation 1,322 m, 16°06'02.9"N, 99°06'23.8"E, 98°30'53.0"E), at Chon Yen, Mae Wong National Park, Klong Lan District, Kham Phaeng Phet Province, Thailand, 12-VII-2018, by W. Srisuka (Coll. No. 80).

Paratypes: Three females, four males (thorax of one male for DNA analysis) (with their associated pupal exuviae and cocoons), and 14 mature larvae (two mature larvae for DNA analysis) (in 80% ethanol), same data as for holotype; one female (with its associated pupal exuviae and cocoon). (in 80% ethanol), collected from a stream of Klong Nam Lai (width 1.4 m, depth 13 cm, bed sandy, moderate flow, pH 6.23, 25.8 °C, exposed to the sun, elevation 196 m, 16°12'28.3"N, 99°15'47.8"E), at Klong Lan District, Kham Phaeng Phet Province, Thailand, 27-VI-2013, by W. Srisuka (Coll. No. 144).

Diagnosis.

Female: mandible lacking teeth on the outer margin. Male: upper-eye (large) facets in eleven vertical columns and 13 or 14 horizontal rows. Pupa: thorax bare except the anterior two-fifths or half and small area of the dorsal surface near the posterior margin moderately covered with tubercles, and cocoon with a short anterodorsal projection or bulge (Fig. 7G ). Larva: abdominal segments 1 and 2 greyish (Fig. 25M ), and the postgenal cleft medium-long, 0.9-1.2 times as long as the postgenal bridge.

Description.

Female (N = 4). Body length 2.1-2.2 mm.

Head. Frontal ratio 1.8-2.0:1.0:2.3-3.3. Frons: head ratio 1.0:4.3-5.4. Labrum 0.68 times length of clypeus. Maxillary palpus: proportional length of third, fourth and fifth palpal segments 1.0:1.0-1.1:2.2-2.3; sensory vesicle medium-long, 0.36 times as long as third palpal segment. Lacinia with 8-11 inner and 12 or 13 outer teeth. Mandible with 21-23 teeth on inner margin and lacking teeth on outer margin (though outer margin undulated).

Legs. Fore basitarsus 6.3-6.5 times as long as its greatest width. Hind basitarsus 5.9-6.1 times as long as its greatest width and 0.7 and 0.6 times as wide as greatest width of hind tibia and femur, respectively. Calcipala nearly as long as wide and 0.56 times as wide as greatest width of hind basitarsus.

Wing. Length 2.2-2.3 mm.

Terminalia. Sternite 8 with 17-22 medium to long stout hairs and three to five short slender hairs. Ovipositor valve with one to four short hairs. Paraproct 0.5 times as long as wide, and with 22-25 short to medium-long hairs on outer surface. Cercus 0.4 times as long as wide. Spermatheca ellipsoidal, 1.4 times as long as its greatest width.

Male (N = 5). Body length 2.6 mm.

Head. Upper eye dark brown, consisting of large facets in eleven vertical columns and 13 or 14 horizontal rows on each side. Antenna: first flagellomere 1.6 times as long as second. Maxillary palpus: proportional length of third, fourth and fifth palpal segments 1.0:1.2:2.8; sensory vesicle small, globular or ellipsoidal, 0.19-0.21 times as long as palpal segment 3.

Legs. Foreleg: basitarsus 7.7 times as long as its greatest width. Hind leg: basitarsus (Fig. 7A ) dark brown except little less than basal half yellowish white, and enlarged, 3.5 times as long as its greatest width, and 1.0 and 1.2-1.3 times as wide as greatest width of hind tibia and femur, respectively. Calcipala (Fig. 7A ) as long as wide and 0.3 times as wide as greatest width of hind basitarsus.

Wing. Length 2.2 mm. Subcosta haired except near apex bare.

Genitalia. Ventral plate in ventral view (Fig. 7B ) somewhat emarginated on each lateral margin; ventral plate in caudal view (Fig. 7D ) rounded ventrally. Cercus with 15-17 hairs.

Pupa (N = 9). Body length 3.0 mm.

Thorax. Integument almost bare except anterior two-fifths to half moderately covered with round tubercles and small dorsal area near posterior margin sparsely covered with tubercles. Gill (Fig. 7E ) composed of eight slender thread-like filaments, arranged as [3+(1+2)]+2or [(2+1)+(1+2)]+2 or [(2+1)+3]+2 from dorsal to ventral, with medium-long common basal stalk having somewhat swollen transparent basal fenestra; 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, middle triplet mostly composed of one individual and two paired filaments with extremely short secondary stalk; stalk of ventral pair of filaments, 0.9-1.3 times length of common basal stalk, and 0.6-0.9 times length of interspiracular trunk, and 0.9 times as thick as common stalk of middle and dorsal triplets; primary stalk of dorsal triplet lying against that of lower pair at angle of 60-90° when viewed laterally; filaments of dorsal and middle triplets subequal in length (1.8-2.2 mm) and thickness to one another; two filaments of ventral pair subequal in length (2.8-3.2 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, segments 1 and 2 bare. Terminal hooks (Fig. 7F ) with outer margin 2.0 times as long as inner margin.

Cocoon (Fig. 7G ). Slipper-shaped, moderately woven, widely extended ventrolaterally; anterior margin thickly woven medially, with bulge or short projection; 3.0-4.0 mm long by 2.5-2.8 mm wide.

Mature larva (N = 12). Body length 5.5-6.5 mm. Body creamy white to light ochreous with following color markings: thoracic segment 1 encircled with ochreous or reddish brown band (though disconnected ventromedially), thoracic segments 2 and 3 ochreous on ventral surface; abdominal segments 1 and 2 entirely grey, dorsal and dorsolateral surface of abdominal segment 4 with faint reddish brown band or spot (though completely faded in some larvae), abdominal segments 5 and 6 each with reddish brown, W-shaped, transverse band near posterior margin of dorsal and dorsolateral surface, which is always distinct on abdominal segment 5 but is faded to varying extent on abdominal segment 6 leaving one small round dorsomedial spot and two distinct lateral areas, abdominal segments 7 and 8 distinctly covered with reddish brown pigment on each dorsolateral surface (Fig. 25M ), and ventral surface of abdominal segments 6 and 7 each with two light reddish brown spots (though absent in some larvae).

Head. Head spots faintly (or rarely moderately) positive or indistinct. Antenna: proportional lengths of first, second, and third articles 1.0:0.8:0.7-0.8. Labral fan with 27-29 primary rays. Hypostoma: median tooth little longer than each corner tooth. Postgenal cleft small, rounded, 0.9-1.2 times length of postgenal bridge.

Abdomen. Rectal organ compound, each of three lobes with 6-8 finger-like secondary lobules. Anal sclerite with anterior arms 1.1-1.2 times as long as posterior ones. Posterior circlet with 91-96 rows of hooklets with up to 14 or 15 hooklets per row.

Etymology.

The species name, maewongense , refers to the name of the national park, Mae Wong, where this species was collected.

Distribution.

Thailand (Kham Phaeng Phet).

Discussion.

Among 36 species of the S. asakoae species group, S. gyorkosae Takaoka & Davies from Indonesia ( Takaoka and Davies 1996), S. jianfengense Long et al. from Hainan Island, China ( Long et al. 1994), S. myanmarense from Myanmar ( Takaoka et al. 2017b), S. yunnanense Chen & Zhang from Yunnan, China ( Chen and Zhang 2004), and S. phulocense Takaoka & Chen and S. unii Takaoka & Pham, both from Vietnam ( Takaoka et al. 2015, 2017a), have a similar cocoon with a short anterodorsal projection. However, S. maewongense sp. nov. is distinguished from these six known species by the following characters (those of each related species in parentheses): from S. gyorkosae by the female mandible lacking outer teeth (four or five outer teeth); from myanmarense by the number of male upper-eye facets in eleven vertical columns (15 or rarely 14 vertical columns); from S. jianfengense by the ventral plate produced anteromedially when viewed ventrally (Fig. 7B ) (not produced), and with its ventral margin rounded when viewed posteriorly (Fig. 7D ) (pointed ventrally); from S. yunnanense by the yellow hair tuft of the base of the radial vein (black hair tuft); from S. phulocense by the relative length of the female sensory vesicle against the third palpal segment 0.36 (0.26-0.27) and male upper-eye facets in eleven vertical columns (12 or 13 vertical columns); from S. unii by upper-eye facets in eleven vertical columns (13 or 14 vertical columns), and the ventral plate with its lateral margins emarginated medially (Fig. 7B ) (ventral plate narrowed posteriorly).

The larval body color pattern (Fig. 25M ) of this new species is similar to that of S. tuenense Takaoka from Taiwan ( Takaoka 1979), although S. tuenense differs from this new species by the number of male upper-eye facets in 15 vertical columns and 15 or 16 horizontal rows and cocoon without an anterodorsal projection ( Huang et. al. 2011).

Figures

Figure 7. Male and pupa of S. maewongense sp. nov. A-D male E-G pupa. A hind basitarsus and second tarsomere (left side; lateral view) B coxites, styles and ventral plate (ventral view) C ventral plate and median sclerite (lateral view) D ventral plate (caudal view) E gill filaments (right side; lateral view) F terminal hooks (caudal view) G cocoon (dorsal view). Scale bars: 1.0 mm (G); 0.1 mm (A, E); 0.02 mm (B-D); 0.01 mm (F).

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).