Simulium (Gomphostilbia) phapeungense Takaoka, Srisuka & Fukuda, 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) phapeungense Takaoka, Srisuka & Fukuda sp. nov. Figs 10 , 25N

Material examined.

Holotype: Male (thorax for DNA analysis) (with its associated pupal exuviae and cocoon) (in 80% ethanol) labeled as "Holotype: Simulium phapeungense 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).

Paratype: One male (thorax for DNA analysis) (with its associated pupal exuviae and cocoon) (in 80% ethanol), same data as for holotype; five mature larvae (one mature larva for DNA analysis) (in 80% ethanol), collected from a stream (width 80 cm, depth 2.5 cm, moderate flow, pH 7.2, 20.1 °C, partially shaded, elevation 1,157 m, 19°11'10.3"N, 101°04'41.7"E), Nam Dan Village, Pua District, Nan Province, Thailand, 25-VII-2017, by W. Srisuka (Coll. No. 60).

Diagnosis.

Male: small number of brown upper-eye (large) facets in eleven vertical columns and 13 horizontal rows, and widened hind basitarsus (Fig. 10A ) 1.2 times as wide as the hind femur. Pupa: dorsum of pupal abdominal segments 1 and 2 without minute tubercles. Larva: abdominal segments 1, 3, 4, and 5 light grey (Fig. 25N ).

Description.

Male (N = 2). Body length 2.2 mm.

Head. Somewhat wider than thorax. Upper eye dark brown, consisting of large facets in eleven vertical columns and 13 horizontal rows on each side. Antenna: first flagellomere elongate, 1.5 times length of second. Maxillary palpus: proportional lengths of third, fourth, and fifth palpomeres 1.0:1.3:2.7; sensory vesicle ellipsoidal, 0.18-0.21 times length of third palpomere.

Legs. Foreleg: tibia whitish except apical three-tenths dark brown; basitarsus somewhat dilated, 6.9 times as long as its greatest width. Midleg: tarsus dark brown except basal one-third of basitarsus dark yellow (border not well defined). Hind leg: coxa light brown; tibia light to dark brown except little less than basal half whitish; tarsus (Fig. 10A ) dark brown except basal half of basitarsus and basal one-third of second tarsomere whitish to yellowish white; basitarsus (Fig. 10A ) enlarged, 3.5 times as long as wide, and 1.0 and 1.2 times as wide as greatest width of tibia and femur, respectively; calcipala (Fig. 10A ) 0.27 times as wide as greatest width of basitarsus.

Wing. Length 2.0 mm. Subcosta with five hairs.

Genitalia. Style in ventral view (Fig. 10B ) bent inward, with round apex. Ventral plate in ventral view (Fig. 10B ) with basal arms nearly parallel-sided, then convergent apically; ventral plate in caudal view (Fig. 10E ) with ventral margin nearly straight or slightly concave. Cercus with 12 or 13 hairs.

Pupa (N = 2). Body length 2.5 mm.

Head. Integument yellow.

Thorax. Integument yellow, moderately covered with round tubercles except dorsal surface of posterior two-thirds sparsely covered with tubercles and dorsolateral surfaces of posterior two-thirds almost bare. Gill (Fig. 10F ) composed of eight slender thread-like filaments, arranged as (3+3)+2 from dorsal to ventral; common basal stalk 0.7-0.8 times length of interspiracular trunk; dorsal and middle triplets each composed of three individual filaments arising at same level; stalk of ventral pair of filaments variable in length, 0.9-1.3 times length of common basal stalk, and 0.7-1.0 times length of interspiracular trunk; primary stalk of dorsal triplet lying against that of lower pair at angle of 50-60° when viewed laterally; filaments of dorsal triplet subequal in length (1.9-2.0 mm) and thickness to one another; filaments of middle triplet subequal in length (2.0-2.2 mm) and thickness to one another; two filaments of ventral pair, of which apical tips were lost, probably ca. 2.5 mm long and 1.3-1.8 times as thick as six other filaments of dorsal and middle triplets when compared basally.

Abdomen. Dorsally, all segments light yellowish except bases of spine-combs of segments 6-8 yellow; segments 1 and 2 without minute tubercles; segment 9 with pair of wide flat terminal hooks (Fig. 10G ), of which outer margin 2.5-2.6 times length of inner margin and crenulated when viewed caudally.

Cocoon (Fig. 10H ). Pale yellow or medium brown, slipper-shaped, roughly or moderately woven, somewhat extended ventrolaterally; anterior margin thickly woven medially, often with small bulge; individual threads visible; 2.8-3.3 mm long by 2.0 mm wide.

Mature larva (N = 4). Body length 4.8-5.2 mm. Body creamy white to light ochreous with following color markings: thoracic segment 1 encircled with distinct grey band (though disconnected ventromedially), thoracic segments 2 and 3 grey on ventral surface; abdominal segments 1, 3, 4, and 5 light grey, abdominal segment 4 with reddish brown small spots dorsolaterally in one larva, abdominal segments 5 and 6 each with distinct reddish brown, W-shaped, transverse band dorsally (though that on abdominal segment 6 partially faded, leaving one round dorsomedial spot and two lateral spots of various size and shape), dorsal and dorsolateral surface of abdominal segments 7 and 8 faintly greyish partially, overlaid by reddish brown pigment (Fig. 25N ).

Head. Head capsule yellow except narrow portion along posterior margin moderately darkened connected to dark posterolateral spots; head spots faintly to moderately positive. Antenna: proportional lengths of first, second, and third articles 1.0:0.8:0.8. Labral fan with 30-33 primary rays. Hypostoma: lateral margin with four to six hypostomal bristles per side. Postgenal cleft (Fig. 10I, J ) rounded (in three larvae) or somewhat pointed (in two larvae), 1.0-2.0 times length of postgenal bridge.

Abdomen. Rectal organ compound, each of three lobes with 11-14 finger-like secondary lobules. Posterior circlet with 85-87 rows of hooklets with up to 14 or 15 hooklets per row.

Female. Unknown.

Etymology.

The species name, phapeungense , refers to the name of the village, Pha Peung, where this species was collected.

Distribution.

Thailand (Mae Hong Son and Nan).

Discussion.

Simulium phapeungense sp. nov. is similar to S. loeiense sp. nov. described above by having the small number of brown upper-eye (large) facets in eleven vertical columns and 13 horizontal rows and a widened hind basitarsus (Fig. 10A ) 1.2 times as wide as the hind femur. However, this new species is readily distinguished from the latter species by the dorsum of pupal abdominal segments 1 and 2 without minute tubercles and larval abdominal segments 1, 3, 4, and 5 light grey (Fig. 25N ).

Figures

Figure 10. Male, pupa and larva of S. phapeungense sp. nov. A-E male F-H pupa I, J larva A hind basitarsus and second tarsomere (left side; lateral view) B coxites, styles and ventral plate (ventral view) C style (right side; ventrolateral view) D ventral plate and median sclerite (lateral view) E ventral plate (caudal view) F gill filaments (right side; lateral view) G terminal hooks (caudal view) H cocoon (dorsal view) I head capsule showing postgenal cleft (ventral view) J postgenal cleft (ventral view). Scale bars: 1.0 mm (H); 0.1 mm (F, I, J); 0.02 mm (A-E); 0.01 mm (G).

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).