Simulium (Gomphostilbia) tanahrataense Takaoka, Sofian-Azirun

Takaoka, H., Sofian-Azirun, M., Ob, Z. Ya’C & Hashim, R., 2014, Two new species of Simulium (Gomphostilbia) (Diptera: Simuliidae) from Cameron’s Highlands, Peninsular Malaysia, with keys to 21 species of the Simulium asakoae species-group, Zootaxa 3765 (1) : -

Simulium (Gomphostilbia) tanahrataense Takaoka, Sofian-Azirun & Ya’cob sp. nov.

Male. Body length 2.4–2.6 mm. Head. Nearly as wide as thorax. Upper eye medium brown, consisting of 14 vertical columns and 15 horizontal rows of large facets. Face dark brown, grayish-white pruinose. Clypeus brownish-black, whitish pruinose, densely covered with golden yellow scale-like medium-long hairs (mostly directed upward) interspersed with several dark brown simple longer hairs. Antenna composed of scape, pedicel and 9 flagellomeres, dark brown except scape and pedicel light brown and base of first flagellomere yellow; first flagellomere elongate, 2.11 times length of second one. Maxillary palp light to medium brown, with 5 segments, proportional lengths of third, fourth, and fifth segments 1.00:1.10:2.60; third segment ( Fig. 3 A) slightly widened apically; sensory vesicle ( Fig. 3 A) ellipsoidal, small (0.16–0.18 times length of third segment), with small opening. Thorax. Scutum dark brown to black, shiny and thinly grayish-white pruinose on each shoulder, on broad area along each lateral margin and on prescutellar area when illuminated at certain angles; scutum densely covered with golden-yellow recumbent short hairs. Scutellum dark brown, with golden-yellow short hairs and dark brown long upright hairs along posterior margin. Postnotum dark brown and bare. Pleural membrane bare. Katepisternum dark brown, moderately covered with fine hairs. Legs. Foreleg: coxa yellow though anterior surface slightly darkened; trochanter light brown except base yellow; femur light brown with apical cap medium brown; tibia light brown except median large portion on outer surface whitish and apical 1/4 dark brown, and with white sheen on outer surface of basal 3/4; tarsus brownish-black; basitarsus moderately dilated, 7.50–7.69 times as long as its greatest width. Midleg: coxa medium brown except posterior surface brownish-black; trochanter light brown except basal 1/2 yellow; femur light brown except apical cap medium brown (though extreme tip yellow); tibia dark brown except basal 1/4 or little more yellow; tarsus dark brown though little less than basal 1/2 of basitarsus dark yellow to light brown. Hind leg: coxa medium brown; trochanter yellow; femur medium brown with base yellow and apical cap dark brown (though extreme tip yellow); tibia ( Fig. 3 B) dark brown to brownish-black except little more than basal 1/3 yellow; tarsus ( Fig. 3 C) medium to dark brown except little less than basal 1/2 of basitarsus and little less than basal 1/2 of second tarsomere yellowish; basitarsus ( Fig. 3 C) enlarged, gradually widened to little more than middle, then nearly parallel-sided or slightly narrowed toward apex, 3.76–3.79 times as long as wide, and 0.89–0.90 and 0.99–1.00 times as wide as greatest width of tibia and femur, respectively; calcipala ( Fig. 3 C) slightly shorter than basal width, and 0.32 times as wide as greatest width of basitarsus. Pedisulcus ( Fig. 3 C) well defined. Wing. Length 2.2 mm. Costa with dark brown spinules as well as dark brown hairs except basal portion with patch of yellowish hairs. Subcosta with 6–12 hairs. Hair tuft on base of radial vein yellow. Basal portion of radius fully haired; R1 with dark spinules and hairs; R2 with hairs only. Basal cell absent. Halter . Grayish-white except basal stem darkened. Abdomen. Basal scale dark brown, with fringe of light to medium brown hairs. Dorsal surface of abdomen medium brown to brownish-black except anterior and dorsolateral areas of segment 2 light brown, and moderately covered with dark brown short to long hairs; segments 2 and 5–7 each with pair of shiny dorsolateral patches; ventral surface of segments 2 and 3 white except sternal plate of segment 3 light brown, those of other segments medium to dark brown. Genitalia. Coxite in ventral view ( Fig. 3 D) nearly rectangular, 1.86 times as long as its greatest width. Style in ventral view ( Fig. 3 D) bent inward, slightly tapered from base toward apical 1/3, then nearly parallel-sided, rounded apically and with apical spine; style in ventrolateral view ( Fig. 3 E) moderately tapered from base toward apex and with truncate apex; style in medial view ( Fig. 3 F) shorter than coxite (0.76 times length of coxite), gently bent inward, nearly parallel-sided, with apical spine. Ventral plate in ventral view ( Fig. 3 D) with body transverse, 0.55 times as long as wide, widened posteriorly, with anterior margin produced anteromedially, and posterior margin slightly concave medially, densely covered with microsetae on ventral surface; basal arms of moderate length, directed forward, then slightly convergent apically; ventral plate in lateral view ( Fig. 3 G) moderately produced ventrally; ventral plate in end view ( Fig. 3 H) trapezoidal, densely covered with microsetae on posterior surface except portion near each lateral tip somewhat widely bare. Median sclerite ( Fig. 3 D) thin, plate-like, wide. Parameres of moderate size, each with 3 distinct long and stout hooks and several smaller ones. Aedeagal membrane moderately setose, slightly sclerotized at base but dorsal plate not well defined. Ventral surface of abdominal segment 10 without distinct hairs near posterior margin. Cercus in lateral view ( Fig. 3 I) small, rounded, with 11–14 hairs.

Pupa. Body length 2.5–2.7 mm. Nearly as in pupa of S. (G.) brinchangense sp. nov. except for the following characteristics. Thorax. Gill ( Fig. 3 J) composed of 8 slender thread-like filaments, arranged as [(1+2)+(1+2)]+2 filaments from dorsal to ventral; common basal stalk medium-long, 0.69–0.70 times length of interspiracular trunk; stalk of ventral pair of filaments medium-long, 1.13–1.17 times length of common basal stalk (though that of left gill of 1 pupa is short, 0.75 times length of common basal stalk); stalk of ventral pair 1.15 and 1.18 times as thick as primary stalks of middle and dorsal triplets, respectively, but 0.86 times as thick as common stalk of middle and dorsal triplets; dorsal triplet composed of 1 individual and 2 paired filaments bearing short primary and secondary stalks; 3 filaments of dorsal triplet subequal in length (1.6–1.8 mm long including their own stalks and common basal stalk) and thickness to one another; middle triplet composed of 1 individual and 2 paired filaments and bearing short to medium-long primary stalk and short secondary stalk; 3 filaments of middle triplet subequal in length (1.8–2.2 mm long including their own stalks and common basal stalk) and thickness to one another; 2 filaments of ventral pair subequal in length (2.5–2.6 mm long including their own stalk and common basal stalk) and thickness to each other, and 1.36 and 1.51 times as thick as those of middle and dorsal triplets, respectively, when compared basally; (tips of all filaments are lost, actual length of filaments probably slightly longer than those shown above). Abdomen. Dorsally, segments 5–9 each with spine-combs in transverse row (though those on segments 5 and 9 slightly smaller than those on segment 8, and those on segment 5 composed of 2 spines on left side and 3 spines on right side) and comb-like groups of minute spines on each side (though segment 5 lacking spine-combs and comb-like groups of minute spines in 1 pupal exuviae); segment 9 with pair of triangular flat terminal hooks, of which outer margin 2.69–2.81 times as long as inner margin and crenulated ( Fig. 3 K). Cocoon. Wall-pocket-shaped, thinly and moderately woven, widely extended ventrolaterally; anterior margin with dorsal portion gently rounded when viewed dorsally and somewhat produced anteriorly; 3.6–3.9 mm long by 2.9–3.1 mm wide.

Female and larva. Unknown.

Type specimens. HOLOTYPE: Male (with associated pupal exuviae and cocoon) (preserved in 80% ethanol) reared from pupa, collected from a stream (width 3–5 m, water temperature 16.0˚C, exposed to the sun, altitude 1,470 m) moderately flowing in front of the gate of Forest Department, Tanah Rata, Cameron’s Highlands, Pahang, Malaysia, 28.I.2011, by H. Takaoka and A. Takaoka. Paratype: 1 male with associated pupal exuviae and cocoon (preserved in 80% ethanol), same data as those of the holotype.

Biological notes. The pupae of this new species were collected from grass leaves trailing in the water. Associated species were S. (G.) sofiani , S. (N.) feuerborni , S. (S.) tani Takaoka & Davies, 1995 and S. (S.) hackeri Edward, 1928 .

Etymology. The species name tanahrataense refers to the name of the town, Tanah Rata, where this new species was collected.

Remarks. The male of S. (G.) tanahrataense sp. nov. is similar to those of S. (G.) sofiani and S. (G.) lurauense in having a similar number of enlarged upper-eye facets, a dark scutum without longitudinal vittae and a similar shape of the ventral plate, but is clearly distinguished from the latter two species by the bicolored, much widened hind basitarsus ( Fig. 3 C) [cf., the hind basitarsi are not so widened and nearly entirely darkened in S. (G.) sofiani and S. (G.) lurauense ( Takaoka et al. 2011a, b)]. The larger number of enlarged male upper-eye facets separates S. (G.) tanahrataense sp. nov. from S. (G.) brinchangense sp. nov. and the remaining four known species of the asakoae species-group reported from Peninsular Malaysia [i.e., S. (G.) asakoae , S. (G.) hoiseni , S. (G.) izuae and S. (G.) roslihashimi ], all of which have enlarged male upper-eye facets in 10–13 vertical columns and 13 or 14 horizontal rows ( Takaoka & Davies 1995; Takaoka 2008; Takaoka et al. 2011b, 2013b).

The pupa of S. (G.) tanahrataense sp. nov. is indistinguishable from that of S. (G.) roslihashimi , and is also similar to those of S. (G.) brinchangense sp. nov. and S. (G.) lurauense in the arrangement of the gill filaments ( Fig. 3 J), but is distinguished from S. (G.) brinchangense sp. nov. by the anterodorsal margin of the cocoon lacking a median bulge, and from S. (G.) lurauense by the relatively longer outer margin of the terminal hooks ( Fig. 3 K) [i.e., the length of the outer margin relative to that of the inner margin is 2.69–2.81 in this new species but 1.15–2.43 in S. (G.) lurauense ].

Simulium (G.) tanahrataense sp. nov. is distinguished from 13 known species of the asakoae species-group from other countries as shown in the key.

Figures

FIGURE 3. Male and pupa of Simulium (Gomphostilbia) tanahrataense sp. nov. A – I, male; J & K, pupa. A, third segment of maxillary palp with sensory vesicle (right side and front view); B, hind tibia (left side and outer view); C, basitarsus and second tarsomere of hind leg showing calcipala and pedisulcus (left side and outer view); D, coxites, styles, ventral plate and median sclerite (ventral view); E & F, styles (right side, E, ventrolateral view and F, medial view); G, ventral plate and median sclerite (lateral view); H, ventral plate (end view); I, abdominal segment 10 and cercus (right side and outer view); J, gill filaments (apical tips of all filaments lost) (right side and outer view); K, terminal hooks (caudal view). Scale bars. 0.1 mm for B, C and J; 0.02 mm for A, D – I and K.