Simulium (Gomphostilbia) thituyenae Takaoka & Pham, 2015

Takaoka, Hiroyuki, Sofian-Azirun, Mohd, Ya’Cob, Zubaidah, Chen, Chee Dhang, Lau, Koon Weng, Low, Van Lun, Pham, Xuan Da & Adler, Peter H., 2017, The black flies (Diptera: Simuliidae) of Vietnam, Zootaxa 4261 (1), pp. 1-165 : 49-52

Simulium (Gomphostilbia) thituyenae Takaoka & Pham, 2015

Simulium (Gomphostilbia) thituyenae Takaoka & Pham (in Takaoka et al., 2015a) : 24 –28 (Female and pupa)

Distribution. Vietnam (Lam Dong).

Remarks. This species was described from Lam Dong Province in southern Vietnam ( Takaoka et al. 2015a). The male and larva of this species are still unknown.

Simulium (Gomphostilbia) vinhphucense Takaoka & Low sp. nov.

Male. Body length 2.5 mm. Nearly as in male of S. (G.) sanchayense sp. nov. except following characters. Head. Upper eye medium brown, consisting of large facets in 9 vertical columns and 11 or 12 horizontal rows. Antenna medium brown except scape and pedicel yellow, base of first flagellomere whitish yellow, and rest of first flagellomere and second and third flagellomeres yellow to dark yellow; first flagellomere elongate, 1.7 times length of second one. Maxillary palp: proportional lengths of third, fourth, and fifth segments 1.0:1.1:2.4; third segment ( Fig. 21 A) slender; sensory vesicle ( Fig. 21 A) ellipsoidal, small (0.2 times length of third segment), and with small opening. Thorax. Scutum dark brown except anterolateral calli ochreous, with faint longitudinal vittae (one median and two submedian), shiny and thinly gray pruinose on entire surface. Legs. Fore and mid trochanters and base of mid femur yellow. Fore basitarsus moderately dilated, 8.2 times as long as its greatest width. Hind basitarsus ( Fig. 21 B) enlarged, 3.3 times as long as wide, and 1.1 and 1.5 times as wide as greatest width of tibia and femur, respectively; calcipala ( Fig. 21 B) slightly shorter than basal width, and 0.2 times as wide as greatest width of basitarsus. Wing. Length 2.0 mm. Subcosta with two hairs. Abdomen. Dorsal surface of abdomen medium to dark brown except segment 2 pale though narrow portion along posterior margin somewhat darkened; tergites 3– 6 each with markedly lighter medial portion; ventral surface of abdomen light to medium brown except segment 2– 4 pale though sternites 3 and 4 somewhat darkened. Genitalia. Coxite in ventral view ( Fig. 21 C) nearly rectangular, twice as long as its greatest width. Style in ventral view ( Fig. 21 C) bent inward, bluntly rounded apically and with apical spine; style in ventrolateral view ( Fig. 21 D) 0.8 times length of coxite, gradually tapered from base to apex, and with truncated apex. Ventral plate in ventral view ( Fig. 21 C) with body transverse, 0.5 times as long as wide, with anterior margin produced anteromedially, and posterior margin slightly concave medially, lateral margins nearly straight or slightly emarginated basally, and densely covered with microsetae on ventral surface; basal arms of moderate length, directed forward, then convergent apically; ventral plate in lateral view ( Fig. 21 E) moderately produced ventrally; ventral plate in caudal view ( Fig. 21 F) rounded ventrally, densely covered with microsetae on posterior surface except portion near each lateral tip narrowly bare. Median sclerite plate-like, wide ( Fig. 21 G). Parameres ( Fig. 21 H) of moderate size, each with four distinct long and medium-long stout hooks and several smaller ones. Aedeagal membrane ( Fig. 21 H) moderately setose; dorsal plate not defined. Ventral surface of abdominal segment 10 ( Fig. 21 I, J) without distinct hairs near posterior margin. Cercus ( Fig. 21 I, J) small, rounded, with 12 or 14 hairs.

Pupa. Body length 2.6 mm. Nearly as in pupa of S. (G.) sanchayense sp. nov. except following characters. Head. Frons with three pairs of unbranched long trichomes with straight or coiled apices; face with pair of unbranched long trichomes with straight or coiled apices. Thorax. Three unbranched ventrolateral trichomes (one medium-long with coiled apex, two short with straight apices) on each side. Gill ( Fig. 21 K) composed of eight slender thread-like filaments, arranged as [(1+2)+(1+2)]+2 from dorsal to ventral, with medium-long common basal stalk having somewhat swollen transparent basal fenestra at base; common basal stalk 0.7 times length of interspiracular trunk; dorsal and middle triplets sharing short stalk, and each triplet composed of one individual and two paired filaments and bearing short primary and secondary stalks; stalk of ventral pair of filaments mediumlong, 0.8–1.0 times length of common basal stalk, and 0.6 times length of interspiracular trunk, and 0.8–0.9 times as thick as common stalk of middle and dorsal triplets and 1.2–1.3 times as thick as primary stalks of dorsal and middle triplets; common stalk of dorsal and middle triplets 1.3–2.1 and 0.7–1.1 times lengths of primary stalks of dorsal and middle triplets, respectively; primary stalks of dorsal and middle triplets each much longer than secondary stalk; primary stalk of dorsal triplet lying against that of ventral pair at angle of 6 0–70 degrees when viewed laterally; six filaments of dorsal and middle triplets subequal in length (1.8–2.1 mm) and thickness to one another; two filaments of ventral pair subequal in length (2.6–2.7 mm) and thickness to each other, and 1.7 times as thick as six other filaments when compared basally Abdomen. Dorsally, segment 1 with one unbranched slender medium-long hair-like seta on each side; segment 2 with one unbranched slender medium-long hair-like seta and five somewhat spinous minute setae submedially on each side; segment 9 with pair of wide flat terminal hooks, of which outer margin is 3.0 times length of inner margin and crenulated ( Fig. 21 L) when viewed caudally. Cocoon ( Fig. 21 M). Wall-pocket-shaped, thinly and moderately woven, widely extended ventrolaterally; right submedial portion of anterior margin slightly produced anteriorly; individual threads clearly visible; 3.5 mm long by 2.3 mm wide.

Female and larva. Unknown.

Type material. HOLOTYPE: Male (with its associated pupal exuviae and cocoon) in 80% ethanol, labeled in a vial as [ UMSRP: Vietnam 0 29, Holotype, Simulium (G.) vinhphucense , Male, coll. Vietnam, 8-XI-2013, Takaoka et al.], reared from a pupa collected from a small stream (width 0.5 m, bottom rocky, water temperature 17˚C, shaded, elevation 975 m, 21˚27’501’’N/105˚38’941’’E), slow-flowing in bushes along the road near the Tam Dao National Park , Vinh Phuc Province, northern Vietnam , 8-XI-2013, by H. Takaoka, M. Sofian-Azirun & Z. Ya’cob.

Biological notes. The pupa of this new species was collected from a grass leaf trailing in the current. Associated species were S. (G.) hongthaii , S. (G.) sanchayense sp. nov., S. (N.) sp. ( S. feuerborni species-group) and S. (S.) lowi sp. nov.

Distribution. Vietnam (Vinh Phuc).

Etymology. The species name vinhphucense refers to the province name, Vinh Phuc, where this new species was collected.

Remarks. This new species is assigned to the S. asakoae species-group of the subgenus Gomphostilbia by having the yellow hair tuft on the base of the radius and enlarged male hind basitarsi ( Fig. 21 B), although the lateral margins of the ventral plate are not emarginated when viewed ventrally ( Fig. 21 C).

The male of this new species is characterized by the smaller number of upper-eye (large) facets in 9 vertical columns and 11 or 12 horizontal rows. This smaller number of male upper-eye facets was recorded in S. (G.) mengi Chen, Zhang & Wen , and S. (G.) miaolingense Wen & Chen , both described from Guizhou Province, China, which have the male upper-eye facets in eight and nine horizontal rows, respectively ( Chen and An 2003). This new species is distinguished from S. (G.) mengi and S. (G.) miaolingense by the larger number of horizontal rows of the male upper-eye facets, from the former species by the stalk of the ventral paired pupal gill filaments as long as or shorter than the common basal stalk ( Fig. 21 K) (stalk of the ventral paired filaments longer than the common basal stalk in S. (G.) mengi ), and from the latter species by the shape of the ventral plate not angulated laterally ( Fig. 21 C) (ventral plate basally angulated outward when viewed ventrally in S. (G.) miaolingense ).

Figures

FIGURE 21. Male and pupa of Simulium (Gomphostilbia) vinhphucense sp. nov. A – J, Male and K – M, Pupa. A, Third segment of maxillary palp with sensory vesicle (right side; front view); B, Hind basitarsus and second tarsomere (right side; outer 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, Median sclerite (caudal view); H, Paramere and aedeagal membrane (right side; caudal view); I & J, Abdominal segment 10 and cerci (right side; I, lateral view; J, caudal view); K, Anterior part of pupal thorax and gill filaments (left side; outer view); L, Terminal hooks (caudal view); M, Cocoon (dorsal view). Scale bars. 1.0 mm for M; 0.1 mm for B and K; 0.02 mm for A, C – J and L.