Simulium (Gomphostilbia) lemborense Takaoka & Sofian-Azirun

Takaoka, Hiroyuki, Sofian-Azirun, Mohd, Chen, Chee Dhang, Lau, Koon Weng, Halim, Muhammad Rasul Abdullah, Low, Van Lun, Ya’Cob, Zubaidah, Abdullah, Nurul Ashikin & Suana, I. Wayan, 2017, Simulium (Gomphostilbia) lemborense, a new black fly species (Diptera: Simuliidae) from Flores, Indonesia, Zootaxa 4236 (1), pp. 149-156 : 150-156

Simulium (Gomphostilbia) lemborense Takaoka & Sofian-Azirun sp. nov.

Female. Body length 2.0 mm. Head. Nearly as wide as width of thorax. Frons brownish black, and densely covered with yellowish-white scale-like recumbent short hairs interspersed with few dark longer hairs near vertex; frontal ratio 1.67–1.68:1.00:3.20–3.27; frons:head ratio 1.00:6.24–6.30. Fronto-ocular area well developed, narrow, directed dorsolaterally. Clypeus brownish black, densely covered with yellowish-white scale-like hairs interspersed with several dark longer hairs on each side. Labrum 0.59–0.69 times length of clypeus. Antenna composed of scape, pedicel and nine flagellomeres, light to medium brown except scape, pedicel and basal onethird to one-half of first flagellomere whitish yellow when viewed dorsally (flagellomeres 1 and 2 yellowish on ventral surface when viewed ventrally in some females). Maxillary palp composed of five segments, light to medium brown, proportional lengths of third, fourth, and fifth segments 1.00:1.08:2.44–2.63; third segment ( Fig. 1 A) somewhat widened apically; sensory vesicle ( Fig. 1 A) medium sized, ellipsoidal (0.30–0.40 times length of third segment), with medium-sized opening. Maxillary lacinia with 9–12 inner and 13 outer teeth. Mandible with 22 or 23 inner teeth and 10 or 11 outer teeth. Cibarium ( Fig. 1 B) medially forming small sclerotized plate folded forward from posterior margin, with weakly sclerotized mediolongitudinal ridge having narrow, well sclerotized apical portion. Thorax. Scutum dark brown to brownish black and faintly with three blackish longitudinal vittae (one median, two submedian), thinly pruinose and shiny when illuminated at certain angles, densely covered with white to yellowish-white scale-like recumbent short hairs. Scutellum dark brown, covered with yellow short hairs and dark-brown long upright hairs along posterior margin. Postnotum dark brown, slightly shiny when illuminated at certain angles, and bare. Pleural membrane bare. Katepisternum longer than deep, dark brown, shiny when illuminated at certain angles, moderately covered with fine short hairs. Legs. Foreleg: coxa yellow (though anterior surface slightly darkened in some females); trochanter light brown; femur light brown with apical cap medium brown; tibia medium brown except median large areas on outer surface light brown and base somewhat pale, and covered with white fine hairs on basal four-fifths; tarsus brownish black, with moderate dorsal hair crest; basitarsus moderately dilated, 5.45–5.90 times as long as its greatest width. Midleg: coxa dark brown except posterolateral surface brownish black; trochanter light brown except basal half of outer surface yellowish white; femur light brown with apical cap medium brown; tibia light brown except base white and apical cap dark brown, covered with whitish fine hairs on posterior surface of basal three-fourths; tarsus brownish black except basal half of basitarsus white. Hind leg: coxa medium brown; trochanter whitish yellow with anterior surface somewhat darkened; femur medium brown with apical cap dark brown; tibia ( Fig. 1 C) light brown except base yellowish white, subbasal triangular spot medium brown and apical one-third brownish black, covered with whitish fine hairs on outer and posterior surfaces of little more than basal three-fourths; tarsus brownish black except basal two-thirds (though base light brown) and basal half of second tarsomere yellowish white; basitarsus ( Fig. 1 D) narrow, nearly parallelsided though slightly narrowed apically, 6.33–6.58 times as long as wide, and 0.55–0.60 and 0.50–0.55 times as wide as greatest widths of tibia and femur, respectively; calcipala ( Fig. 1 D) slightly longer than width at base, and 0.42 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 1 D) well developed; claw ( Fig. 1 E) with large basal tooth 0.52 times length of claw. Wing. Length 1.9 mm. Costa with dark spinules and hairs except basal patch of hairs yellow. Subcosta bare (though subcosta with three and four hairs on each side in one female, and subcosta with one hair on left side in one female). Hair tuft on base of radius dark brown. Basal portion of radius fully haired; R1 with dark spinules and hairs; R2 with hairs only. Basal cell absent. Halter . White except basal portion darkened. Abdomen. Basal scale light brown, with fringe of whitish-yellow hairs. Dorsal surface of abdomen medium to brownish black, moderately covered with dark short to long hairs; tergites of segments 2 and 6–9 shiny when illuminated at certain angles. Ventral surface of segment 2 white, those of other segments medium to dark brown; sternal plate on segment 7 undeveloped. Terminalia . Sternite 8 ( Fig. 1 F) bare medially, with 8–16 mediumlong to long hairs together with few slender short hairs on each side. Ovipositor valves ( Fig. 1 F) triangular (though posteromedial corners rounded), thin, membranous, moderately covered with microsetae interspersed with one or two short hairs; inner margins sinuous, somewhat sclerotized, and moderately separated from each other. Genital fork ( Fig. 1 G) of usual inverted-Y form, with slender stem; arms of moderate width, moderately folded dorsally, with lobe directed posteromedially. Paraproct in ventral view ( Fig. 1 H) pointed medially, with four sensilla on anteromedial surface; paraproct in lateral view ( Fig. 1 I) slightly produced ventrally beyond ventral tip of cercus, 0.76 times as long as wide, with 11–19 medium-long to long hairs on ventral and lateral surfaces. Cercus in lateral view ( Fig. 1 I) short, rounded posteriorly, 0.50 times as long as wide. Spermatheca ( Fig. 1 J) ellipsoidal, 1.55–1.57 times as long as its greatest width, well sclerotized except duct and small area near juncture with duct unsclerotized, and with many fissures on outer surface; internal setae absent; both accessory ducts slightly thicker in diameter than major one.

Male. Body length 2.0 mm. Head. Somewhat wider than thorax. Upper eye medium brown, consisting of large facets in 13 vertical columns and 13 horizontal rows. Face brownish black, white pruinose. Clypeus brownish black, whitish pruinose, moderately covered with golden-yellow medium-long hairs interspersed with several darkbrown longer hairs along each lateral margin. Antenna composed of scape, pedicel and nine flagellomeres, yellowish on scape and pedicel, dark yellow to light brown on flagellomeres 1–3 (except basal one-third of flagellomere 1 whitish yellow), and medium to dark brown on flagellomeres 4–9; first flagellomere elongate, 1.66 times length of second one. Maxillary palp light to medium brown, with five segments, proportional lengths of third, fourth, and fifth segments 1.00:1.27:3.00; third segment ( Fig. 2 A) widened apically; sensory vesicle ( Fig. 2 A) small, globular or ellipsoidal (0.19–0.23 times length of third segment), and with medium-sized opening. Thorax. Scutum dark brown to brownish black, shiny and thinly white pruinose on shoulders, lateral area along each lateral margin and prescutellar area, when illuminated at certain angles, and densely covered with whitishyellow scale-like recumbent short hairs. Scutellum dark brown, covered with yellow short hairs and dark-brown long upright hairs along posterior margin. Postnotum dark brown, slightly shiny and white pruinose when illuminated at certain angles, and bare. Pleural membrane bare. Katepisternum dark brown, longer than deep, shiny when illuminated at certain angles, moderately covered with fine short hairs. Legs. Color almost same as that of female, though somewhat darker so that subbasal dark spot on hind tibia not well defined in male ( Fig. 2 B). Fore basitarsus moderately dilated, 6.35–6.95 times as long as its greatest width. Hind basitarsus ( Fig. 2 C) nearly parallel-sided, 5.92–6.42 times as long as wide, and 0.50–0.60 and 0.52–0.56 times as wide as greatest widths of tibia and femur, respectively; calcipala ( Fig. 2 C) as wide as or slightly shorter than basal width, and 0.58 times as wide as greatest width of basitarsus. Pedisulcus ( Fig. 2 C) well developed. Wing. Length 1.5–1.6 mm. Other characters as in female except subcosta with three hairs. Halter . White except dorsal surface and basal stem darkened. Abdomen. Basal scale dark brown, with fringe of light-brown hairs. Dorsal surface of abdomen medium brown to brownish black, covered with dark-brown short to long hairs; segments 2 and 5–8 each with pair of shiny dorsolateral or lateral patches; ventral surface of segment 2 whitish, those of segments light to medium brown. Genitalia. Coxite in ventral view ( Fig. 2 D) nearly rectangular, 1.67 times as long as its greatest width. Style in ventral view ( Fig. 2 D) bent inward, with blunt apex having single spine; style in ventrolateral view ( Fig. 2 E) 0.86 times length of coxite, with wide basal portion about half as wide as length, moderately tapered toward middle, then slightly toward apex, with rounded or blunt apex. Ventral plate in ventral view ( Fig. 2 D) with body transverse, 0.62 times as long as wide, with anterior margin produced anteromedially, posterior margin somewhat concave medially, and lateral margins narrowed posteriorly, and densely covered with microsetae on ventral surface; basal arms of moderate length, nearly parallel-sided; ventral plate in lateral view ( Fig. 2 F) moderately produced ventrally; ventral plate in caudal view ( Fig. 2 G) rounded ventrally, densely covered with microsetae on posterior surface. Median sclerite ( Fig. 2 H) weakly sclerotized, plate-like and wide. Parameres ( Fig. 2 I) of moderate size, each with three or four distinct long and medium-long stout hooks, and without minute setae on outer surface of basal arm. Aedeagal membrane ( Fig. 2 I) moderately setose; dorsal plate not defined. Ventral surface of abdominal segment 10 ( Fig. 2 J, K) somewhat sclerotized on anterior half, without distinct hairs near posterolateral corners. Cercus ( Fig. 2 J, K) small, rounded, with 12 or 13 hairs.

Pupa. Body length 2.2–2.3 mm. Head. Integument yellow, moderately covered with small round tubercles except antennal sheaths and ventral surface almost bare; antennal sheath without any protuberances; frons with three unbranched long trichomes with straight apices ( Fig. 3 A), arising close together on each side; face with one unbranched long trichome with straight apex ( Fig. 3 B) on each side, which is as long as or slightly shorter than frontal ones. Thorax. Integument yellow, moderately covered with round tubercles, and with three long dorsomedial trichomes of different lengths (anterior trichome longest, posterior one shortest) with coiled apices ( Fig. 3 C), two anterolateral trichomes (anterior trichome medium-long, posterior one long) with straight apices ( Fig. 3 D), one short mediolateral trichome with straight apex ( Fig. 3 E), and three short ventrolateral trichomes with straight apices ( Fig. 3 F) on each side; all trichomes unbranched. Gill ( Fig. 3 G) composed of eight slender threadlike filaments, arranged as (2+1)+(1+2)+2 filaments, of which two triplets arising close together from dorsal surface of common basal stalk, and directed upwards, with short common basal stalk having somewhat swollen transparent basal fenestra at base; common basal stalk 0.19 times length of interspiracular trunk; two triplets not sharing stalk, and composed of one individual and two paired filaments with extremely short stalk, or of three individual filaments arising at same level, with extremely short stalk; stalk of ventral pair of filaments nearly as long as interspiracular trunk; filaments of triplets subequal in length (0.5–0.7 mm) and thickness to one another; two filaments of ventral pair subequal in length (2.2–2.4 mm) and thickness to each other, gradually tapered toward apex; cuticle of all filaments with annular ridges and furrows though becoming less marked apically, densely covered with minute tubercles. Abdomen. Dorsally, segments 1 and 2 almost entirely dark gray, segments 3 and 4 dark gray narrowly along anterior margin or unpigmented, and segment 9 yellow, and other segments unpigmented; segment 1 with one unbranched slender short hair-like seta ( Fig. 3 H) on each side; segment 2 with one minute seta ( Fig. 3 I) submedially near anterior margin, and one unbranched slender short hair-like seta and five minute setae ( Fig. 3 J) near posterior margin, on each side; segments 3 and 4 each with one minute seta (similar to Fig. 3 I) submedially near anterior margin, four hooked spines and one minute seta near posterior margin, on each side; segment 5 with or without spine-combs in transverse row (though spine-combs, if present, consisting of one spine or two) and comb-like groups of minute spines on each side; segments 6–9 each with spine-combs in transverse row and comb-like groups of minute spines on each side; segment 5 with four minute setae near posterior margin on each side; segments 6 and 7 each with two minute setae near posterior margin on each side; segment 8 with one minute seta near posterior margin on each side; segment 9 with pair of conical terminal hooks ( Fig. 3 K). Ventrally, segment 4 with one unbranched or bifid hook (somewhat smaller in size to those on segments 5–7) and few minute setae on each side; segment 5 with pair of bifid hooks submedially and few minute setae on each side; segments 6 and 7 each with pair of bifid inner and unbranched outer hooks somewhat spaced from each other and few minute setae on each side; segments 4–8 each with comb-like groups of minute spines. Each side of segment 9 with three grapnel-shaped hooklets. Cocoon ( Fig. 3 L). Wall-pocket-shaped, moderately woven, moderately or widely extended ventrolaterally; anterior margin somewhat thickly woven medially, without anterodorsal projection, though slightly bulged in one cocoon; posterior three-fifths with floor roughly woven; individual threads visible; 2.3–2.4 mm long by 1.5–2.1 mm wide.

Mature larva. Body length 3.8–4.0 mm. Body creamy white, thoracic segments 1–3 and abdominal segments 1–4 each with reddish-brown annular bands though disconnected dorsomedially and those of abdominal segments 1–4 less distinct ventromedially in some larvae; abdominal segments 5–9 each with broad reddish-brown transverse band dorsally and dorsolaterally, though that on segment 7 usually disconnected dorsomedially; abdominal segments 5–7 each with reddish-brown markings ventrally; thoracic segments 1–3 and abdominal segments 1–4 grayish ventrally in some larvae. Head capsule yellow, moderately covered with minute setae dorsally (sparsely laterally and ventrally); head spots faintly to moderately positive; lateral surface of head capsule yellow except eye-spot region white, with faint small round spot below eye-spot region, and one or two small and two relatively larger spots near posterior margin; eyebrow faintly defined; ventral surface of head capsule yellow, with positive spot on each side of postgenal cleft. Antenna composed of three segments and apical sensillum, longer than stem of labral fan; proportional lengths of first, second, and third segments 1.00:0.80–0.84:0.92–0.93. Labral fan with 36–40 primary rays. Mandible ( Fig. 4 A) with three comb-teeth decreasing in length from first tooth to third; mandibular serration composed of two teeth (one medium-sized, one small); major tooth at acute angle against mandible on apical side; supernumerary serrations absent. Hypostoma ( Fig. 4 B) with row of nine apical teeth, of which median tooth is longer than each corner tooth; three intermediate teeth on each side shorter than corner tooth; lateral margin smooth; four or five hypostomal bristles per side, lying nearly parallel to lateral margin. Postgenal cleft ( Fig. 4 C) bullet-shaped, long, 2.58–2.93 times length of postgenal bridge. Cervical sclerites composed of pair of small yellow rod-like pieces. Thoracic proleg without hairs; thoracic and abdominal segments 1–8 sparsely covered with unbranched colorless minute setae; abdominal segments 5–9 moderately covered with dark unbranched and bifid setae ( Fig. 4 D) on dorsal and dorsolateral surfaces; last abdominal segment densely covered with unbranched colorless minute setae on dorsolateral and lateral surfaces of each side of anal sclerite and on each lateral surface even down to base of ventral papilla; thorax and abdomen without dorsal protuberances. Rectal scales minute and colorless. Rectal organ compound, each of three lobes with five or six finger-like secondary lobules. Anal sclerite of usual X-form, with anterior arms nearly as long as or slightly shorter than posterior ones, broadly sclerotized at base; no sensilla on broad base and posterior to posterior arms; accessory sclerite absent. Last abdominal segment with pair of large conical ventral papillae. Posterior circlet with 69–79 rows of hooklets with up to 13 or 14 hooklets per row.

Type material. HOLOTYPE: Female (with associated pupal exuviae) (preserved in ethanol), reared from a pupa, collected from a slow-flowing stream (width 20–30 m, depth 30–40 cm, bottom rocky, water temperature 23.0˚C, exposed to the sun, altitude 53 m, 08˚39’57.337’’S/ 120˚07’49.693’’E), Wae Loagge, Lembor, Flores Island, Indonesia, 27-II-2 0 16, by M. Sofian-Azirun, C.D. Chen, K.W. Lau & I.W. Suana; five females, 10 males, three pupae and four mature larvae, same data as the holotype .

Biological notes. The pupae and larvae of this new species were collected from fallen leaves and grasses tailing in the water. The only associated species was S. (S.) timorense Takaoka, Hadi & Sigit.

Distribution. Flores Island.

Etymology. The species name lemborense refers to the place name, Lembor, where this new species was collected.

Remarks. This new species is assigned to the Simulium batoense species-group of the subgenus Gomphostilbia , redefined by Takaoka (2012), by having the antenna with nine flagellomeres, bare pleural membrane, dark hair tuft on the base of the radius, dark tibiae of the female and male ( Fig. 1 C and Fig. 2 B), and slender male hind basitarsus ( Fig. 2 C).

This new species is characterized by the pupal gill with eight thread-like filaments, of which two filaments of the ventral pair are three to four times as long as the six other filaments ( Fig. 3 G). Hence it is further assigned to the S. duolongum subgroup within the S. batoense species-group, defined by Takaoka (2012). The arrangement and relative length of the pupal gill filaments of this new species are almost identical to those of S. (G.) singgihi Takaoka , described from Sulawesi ( Takaoka, 2003). However, this new species is distinguished from S. (G.) singgihi in the female by the narrow frons (the frons:head ratio is 1: 6.24–6.34 in this new species but 1: 4.9 in S. (G.) singgihi ), in the male by the style with a wide base (the length:width ratio is 1: 0.53 in this new species but 1: 0.47 in S. (G.) singgihi ), and in the larva by the relatively shorter postgenal cleft (the ratio of the postgenal cleft against the postgenal bridge is 2.58–2.98 in this new species but 5.0 in S. (G.) singgihi ) and presence of dark minute setae dorsally on a few posterior segments of the abdomen (absent in S. (G.) singgihi ).

This new species is distinguished from other species of the S. batoense species-group, except S. (G.) friederichsi Edwards , from Java and Sumatra, which is known only from the male ( Edwards, 1934), by a combination of the narrow female frons relative to the width of the head, smaller number of male upper-eye large facets, and two long filaments of the ventral pair of the pupal gill relative to the six other filaments ( Fig. 3 G). The male of S. (G.) lemborense sp. nov. is distinguished from that of S. (G.) friederichsi by the difference in the scutal color pattern, which in S. (G.) lemborense sp. nov. is composed of dark non-pruinose areas in the form of an inverted T in the middle, white pruinose areas on each shoulder, a narrow area along each lateral margin and a wide prescutellar area, but in S. (G.) friederichsi is composed of a dark non-pruinose median longitudinal vitta, two dark non-pruinose oblong spots on each side, and white pruinose areas on the rest of the scutum ( Takaoka, 1991).

This new species represents the most eastern distribution record for the S. batoense species-group.

Figures

FIGURE 1. Female of Simulium (Gomphostilbia) lemborense sp. nov. (A) Third segment of maxillary palp with sensory vesicle (right side; front view). (B) Cibarium (front view). (C) Hind tibia (left side; outer view). (D) Hind basitarsus and second tarsomere (left side; outer view). (E) Claw. (F) Sternite 8 and ovipositor valve (right side only; ventral view). (G) Genital fork (ventral view). (H) & (I) Paraprocts and cerci (H, ventral view; I, lateral view). (J) Spermatheca. Scale bars. 0.1 mm for C and D; 0.02 mm for A, B and F – J; 0.01 mm for E.

FIGURE 2. Male of Simulium (Gomphostilbia) lemborense sp. nov. (A) Third segment of maxillary palp with sensory vesicle (right side; front view). (B) Hind tibia (left side; outer view). (C) Hind basitarsus and second tarsomere (left side; outer view). (D) Coxites, styles and ventral plate (ventral view). (E) Style (right side; ventrolateral view). (F) Ventral plate and median sclerite (lateral view). (G) Ventral plate (caudal view). (H) Median sclerite (caudal view). (I) Paramere and aedeagal membrane (left side; caudal view). (J) & (K) Abdominal segment 10 and cerci (right side; J, lateral view; K, caudal view). Scale bars. 0. 1 mm for B and C; 0.02 mm for A and D – K.

FIGURE 3. Pupa of Simulium (Gomphostilbia) lemborense sp. nov. (A) Frontal trichomes. (B) Facial trichome. (C) – (F) Thoracic trichomes (C, mediodorsal; D, anterolateral; E, mediolateral; F, ventrolateral); (G) Gill filaments (left side; outer view). (H) Hair-like seta on dorsum of abdominal segment 1. (I) Minute seta near anterior margin of dorsum of abdominal segment 2. (J) Hair-like seta and minute seta near posterior margin of dorsum of abdominal segment 2. (K) Terminal hooks (caudal view). (L) Cocoon (dorsal view). Scale bars. 1.0 mm for L; 0.1 mm for G; 0.02 mm for A – F, H, J and K; 0.01 mm for I.

FIGURE 4. Larva of Simulium (Gomphostilbia) lemborense sp. nov. (A) Apical tip of mandible. (B) Hypostoma. (C) Head capsule showing postgenal cleft (ventral view). (D) Dark minute setae on dorsum of abdominal segment 7. Scale bars. 0.1 mm for C; 0.02 mm for A, B and D.