Simulium (Simulium) malayense Takaoka & Davies, 1995

Takaoka, Hiroyuki, Ya’Cob, Zubaidah & Sofian-Azirun, Mohd, 2018, Classification, annotated list and keys for the black flies (Diptera: Simuliidae) of Peninsular Malaysia, Zootaxa 4498 (1), pp. 1-65 : 49-51

53. Simulium (Simulium) malayense Takaoka & Davies, 1995

Simulium (Simulium) malayense Takaoka & Davies, 1995: 120 –123 (Female, pupa and larva).

This species was described from females, pupae and larvae collected from Fraser’s Hill (Takaoka and Davies, 1995). It is characterized in the female by the bare basal section of the radial vein, and in the pupa by the absence of tubercles on the frons and the anterodorsal surface of the thorax and the wall-pocket shaped cocoon without windows anterolaterally, and abdominal segment 1 dark gray.

The aquatic stages of this species inhabit small to medium-sized streams at low to high elevations (220–1,400 m) in Cameron Highlands (Ya’cob et al., 2016b).

This species was also recorded from Thailand ( Kuvangkadilok and Takaoka, 2000) and Vietnam ( Pham, 1998, 1999).

The male of this species is described below.

Male. Body length 2.9–3.0 mm. Head. Width slightly wider thorax. Upper eye medium brown, consisting of large facets in 15 or 16 vertical columns and 17 horizontal rows. Clypeus black, thickly white pruinose, silvery or bluish, shiny when illuminated at certain angle of light, moderately covered with dark brown stout setae along and near lateral margins (mediolongitudinal portion bare). Antenna composed of scape, pedicel and nine flagellomeres, medium to dark brown except scape and base of first flagellomere yellow, and pedicel dark yellow to light brown; first flagellomere elongate, 2.0 times as long as second one. Maxillary palp grayish to dark brown, composed of five segments with proportional lengths of third, fourth, and fifth segments 1.0:1.1–1.2:2.5–2.6; third segment ( Fig. 12A ) of normal size; sensory vesicle ( Fig. 12A ) small (0.2 times as long as third segment), ellipsoidal, and with small opening. Thorax. Scutum brownish black to black, with white pruinose pattern, i.e., anterior pair of rectangular spots on shoulders extending posteriorly along lateral margins and connected to large transverse spot entirely covering prescutellar area; these pruinose areas shiny when illuminated at certain angles; scutum uniformly and densely covered with golden-yellow recumbent short pubescence interspersed with dark brown long upright setae on prescutellar area. Scutellum brownish black, with several dark long upright setae as well as golden-yellow short pubescence. Postnotum brownish black, white pruinose when illuminated at certain angles, bare. Pleural membrane bare. Katepisternum longer than deep, dark brown to brownish black, bare. Legs. Foreleg: coxa yellow; trochanter light brown; femur light to medium brown with apical cap dark brown; tibia light to medium brown with apical cap dark brown on inner surface, though widely white on outer surface except apical cap dark brown, and with white sheen when illuminated at certain angles; tarsus brownish black, with moderate dorsal hair crest; basitarsus greatly dilated, 4.6–4.7 times as long as its greatest width. Midleg: coxa brownish black; trochanter medium brown except base light brown; femur medium brown with apical cap dark brown; tibia white on basal half or little more and medium to dark brown on rest of lateral surface, though white on basal twothirds to three-fourths and dark brown on rest of anterior and posterior surfaces; tibia with white sheen on posterior surface of basal two-thirds when illuminated at certain angles; tarsus dark brown except basal half of basitarsus yellowish. Hind leg: coxa dark brown; trochanter yellow; femur dark brown except base yellow and apical cap brownish black; tibia dark brown with basal tip white and apical cap brownish black; tarsus ( Fig. 12B ) dark brown except little less than basal half of basitarsus and basal half of second tarsomere whitish yellow; basitarsus ( Fig. 12B ) much enlarged, wedge-shaped, gradually widened from base to apical one-third, then somewhat narrowed to apex, 3.6–3.9 times as long as its greatest width, and 0.9–1.0 and 1.0–1.1 times as wide as greatest widths of hind tibia and femur, respectively; calcipala ( Fig. 12B ) small, nearly as long as width at base, 0.2–0.3 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 12B ) well marked. Wing. Length 2.2–2.5 mm; costa with dark spinules and hairs; subcosta bare; basal section of radial vein bare; R1 with dark spinules and hairs; R2 with hairs; hair tuft on stem vein dark brown; basal cell absent. Abdomen. Basal scale brownish black, with fringe of dark long hairs. Dorsal surface of abdomen dark brown to black, with dark short hairs; segments 2 and 5–7 each with pair of silvery or bluish iridescent spots dorsolaterally, those on segment 2 connected broadly to each other in middle.

Genitalia. Coxite in ventral view ( Fig. 12C ) nearly quadrate, covered with many stout hairs on posterior half. Style in ventral view ( Fig. 12C ) elongate, 1.6 times as long as coxite, gradually tapered to middle and nearly parallelsided or slightly widened apically, with subapical spine (no spine in one male); style in ventrolateral view ( Fig. 12D ) elongate, nearly parallel-sided from base to basal one-fourth to one third, tapered to middle, then nearly parallel-sided or slightly widened toward apex; style in medial view ( Fig. 12E ) spatulate dorsoventrally, with long horn-like basal protuberance pointed dorsally, which has several small cone-like spines on anterior surface. Ventral plate in ventral view ( Fig. 12C ) Y-shaped, with body nearly rectangular (though somewhat narrowed basally, and rounded on each posterolateral corner), having several teeth on each posterolateral margin and median process with bare round apex; arms divergent from each other; ventral plate in lateral view ( Fig. 12F ) with body serrated along posterior margin and moderately covered with microsetae on each anterolateral surface, and bare median process lying at about 60 degrees against dorsal margin; ventral plate in caudal view ( Fig. 12G ) with body having several ridges in two irregular vertical rows on posterior surface and median process elliptical and smooth. Median sclerite ( Fig. 12F, H ) plate-like, widened from base toward near apex, with round apex, brown basally, but not so well pigmented apically. Paramere ( Fig. 12I ) with three hooks and few small ones. Aedeagal membrane ( Fig. 12J ) moderately covered with minute fine setae; dorsal plate ( Fig. 12K ) in form of horizontal bar, well pigmented except median wide portion weakly pigmented or unpigmented. Abdominal segment 10 ( Fig. 12L, M ) without any distinct hair on ventral and lateral surface. Cercus ( Fig. 12L, M ) small, rounded, with 5 to 11 distinct hairs.

Specimens examined. Three males reared from pupae from a stream rapidly flowing in natural forest (width 1.0-4.0 m, water temperature 20.0˚C, shaded, elevation 750 m), Perak State, crossing the road to Cameron Highlands, Pahang State, 29-I-2011, by H. Takaoka.

Remarks. The male of S. (S.) malayense is distinguished from those of two Malaysian related species, S. (S.) hirtinervis and S. (S.) kisapense , by the following characters (those of the other species in parentheses): from S. (S.) hirtinervis by upper-eye large facets in 15 or 16 vertical columns and 17 horizontal rows (14 vertical columns and 13 horizontal rows), hind tibia dark brown except the basal tip white (brownish black except the basal one-third white), and ventral plate in caudal view with a median process 0.56 times as wide as the body (0.4 times as wide as the body); and from S. (S.) kisapense by the ventral plate in caudal view with a median process 0.56 times as wide as the body (0.38 times as wide as the body), ventral plate in lateral view with the posterior margin serrated on the basal half (serrated on basal four-fifths); ventral plate in ventral view with arms widely divergent, the distance between the tips of arms 2.5 times as wide as the greatest width of the body of the ventral plate (somewhat divergent, 1.36 times).

Figures

FIGURE 12. Male of Simulium (Simulium) malayense. (A) Third maxillary palpal segment with sensory vesicle (right side; front view). (B) Basitarsus and second tarsomere of hind leg (left side; outer view). (C) Coxites, styles and ventral plate (ventral view). (D) and (E) Styles (right side; D, ventrolateral view; E, medial view). (F) Ventral plate with median sclerite (lateral view). (G) Ventral plate (caudal view). (H) Median sclerite (caudal view). (I) Paramere (left side; caudal view). (J) Aedeagal membrane (caudal view). (K) Dorsal plate (ventral view). (L) and (M) Abdominal segment 10 and cerci (right side; L, lateral view; M, caudal view). Scales. 0.1 mm for B; 0.02 mm for A and C–M.