Simulium (Gomphostilbia) longlanhense Takaoka

Takaoka, Hiroyuki, Sofian-Azirun, Mohd, Ya’Cob, Zubaidah, Chen, Chee Dhang, Lau, Koon Weng & Pham, Xuan Da, 2015, The black flies (Diptera: Simuliidae) from Thua Thien Hue and Lam Dong Provinces, Vietnam, Zootaxa 3961 (1), pp. 1-96 : 41-48

Simulium (Gomphostilbia) longlanhense Takaoka & Ya’cob sp. nov.

( Figs. 17 A–20F)

Female. Body length 1.7–2.0 mm. Head. Slightly narrower than thorax. Frons brownish-black, densely covered with yellow scale-like recumbent short hairs; frontal ratio 1.47:1.00:1.58; frons:head ratio 1.0:4.1. Fronto-ocular area well developed, narrow, directed dorsolaterally. Clypeus brownish-black, slightly shiny when illuminated at certain angles, and densely covered with yellowish-white recumbent hairs interspersed with four dark longer hairs on each side of lower portion. Labrum 0.63 times as long as clypeus. Antenna composed of scape, pedicel and nine flagellomeres, dark brown except scape, pedicel and basal extreme of first flagellomere yellow. Maxillary palp composed of five segments, light brown except segments 1 and 2 ochreous and segment 3 dark brown, proportional lengths of third, fourth, and fifth segments 1.0:1.1:2.2; third segment ( Fig. 17 A) of moderate size; sensory vesicle ( Fig. 17 A) of moderate size, 0.33–0.37 times length of third segment and with medium-sized opening. Maxillary lacinia with 10 or 11 inner and 17 outer teeth. Mandible with 37 inner teeth and two to four minute outer teeth at some distance from apex (tiny and rudimentary outer teeth can be overlooked). Cibarium ( Fig. 17 B) with dorsal margin having short plate produced forward and downward, and with weakly sclerotized mediolongitudinal stripe bearing well sclerotized U-shaped apex. Thorax. Scutum brownish-black except anterolateral calli ochreous, shiny when illuminated at certain angles, densely covered with yellow scale-like recumbent hairs. Scutellum dark brown, covered with yellow short hairs and dark-brown long upright hairs. Postnotum brownish-black, bare. Pleural membrane bare. Katepisternum longer than deep, dark brown, shiny when illuminated at certain angles, moderately covered with pale and dark short hairs. Legs. Foreleg: coxa and trochanter light brown; femur light brown with apical cap medium brown (though extreme tip yellow); tibia dark yellow except base whitish-yellowish, subbasal band light brown and apical one-third brownish black; tibia moderately covered with yellow hairs (brightly shiny when illuminated) on basal four-fifths; tarsus black, with moderate dorsal hair crest; basitarsus much dilated, 5.4 times as long as its greatest width. Midleg: coxa medium brown except posterolateral surface dark brown; trochanter light brown except base yellow; femur light brown except basal portion of inner surface yellow and apical cap medium brown (though extreme tip yellow); tibia light brown except base yellow and apical cap brownish-black, and with whitish-yellow short hairs (brightly shiny when illuminated) on outer and posterior surfaces of basal four-fifths; tarsus dark brown except basal half of basitarsus light to medium brown. Hind leg: coxa medium brown; trochanter yellow; femur light brown except base yellow and apical cap dark brown (though extreme tip yellow); tibia ( Fig. 17 C) light brown (gradually darkened toward apex) except base yellow, and apical cap dark brown; tibia moderately covered with whitish-yellow short hairs (brightly shiny when illuminated) on outer and posterior surfaces of basal four-fifths; tarsus ( Fig. 17 D) dark brown except basal two-thirds of basitarsus (though base light brown) and basal half of second tarsomere yellow; basitarsus ( Fig. 17 D) narrow, nearly parallelsided, 6.0 times as long as wide, and 0.63 and 0.50 times as wide as greatest widths of tibia and femur, respectively; calcipala ( Fig. 17 D) well developed, slightly longer than wide, and 0.5 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 17 D) well developed; claw ( Fig. 17 E) with large basal tooth 0.5 times length of claw. Wing. Length 1.6 mm. Costa with dark brown spinules and light-brown hairs except basal patch of yellow hairs. Subcosta haired except near apex bare. Hair tuft on base of radial vein yellow. Basal portion of radius fully haired. Basal cell absent. Halter . Clear white except basal portion darkened. Abdomen. Basal scale creamy, with fringe of yellowish-white hairs. Dorsal surface of abdomen light to medium brown except segment 2 creamy, segment 3 creamy to ochreous though tergal plate and dorsolateral narrow portions dark brown, and segment 4 ochreous though tergal plate and dorsolateral wide portions dark brown, and 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 creamy, those of other segments creamy to ochreous except sternite 8 dark brown; sternal plate on segment 7 undeveloped. Genitalia. Sternite 8 ( Fig. 17 F) bare medially, with 16–18 medium-long to long hairs together with few slender short hairs on each side. Ovipositor valves ( Fig. 17 F) triangular (though posteromedial corners appearing truncated), thin, membranous, moderately covered with microsetae interspersed with three or four short hairs; inner margins rounded ventrally, gently concave, moderately sclerotized, and somewhat separated from each other. Genital fork ( Fig. 17 G, H) of usual inverted-Y form, with slender stem; arms of moderate width, with wide lateral plate. Paraproct in ventral view ( Fig. 17 I) with anteromedial margin somewhat darkened, slightly raised ventrally, with anteromedial surface slightly sclerotized having two or three sensilla; paraproct in lateral view ( Fig. 17 J) much produced ventrally, 0.47 times as long as wide, with 13 medium-long to long hairs on ventral and lateral surfaces. Cercus in lateral view ( Fig. 17 J) short, rounded posteriorly, 0.45 times as long as wide. Spermatheca ( Fig. 17 K) ellipsoidal, 1.55 times as long as 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 slender, subequal in diameter to major one.

Male. Body length 2.1–2.4 mm. Head. Slightly wider than thorax. Upper eye medium brown, consisting of 15 vertical columns and 16 horizontal rows of large facets. Face black, whitish-gray pruinose when illuminated at certain angles. Clypeus black, whitish-gray pruinose when illuminated at certain angles, and moderately covered with yellow short hairs interspersed with dozen of dark-brown longer hairs on each side. Antenna composed of scape, pedicel and nine flagellomeres, brownish-black except scape and pedicel light to medium brown; first flagellomere elongate, 1.7 times length of second one. Maxillary palp with five segments, light brown except third segment dark brown, proportional lengths of third, fourth, and fifth segments 1.0:1.2:2.5; third segment ( Fig. 18 A) somewhat widened apically; sensory vesicle ( Fig. 18 A) globular or ellipsoidal, small, 0.19 times length of third segment, and with small opening. Thorax. Scutum black, shiny on lateral portions along lateral margins when illuminated at certain angles, densely covered with golden-yellow short hairs. Scutellum brownish-balck, with golden-yellow short hairs and dark-brown long upright hairs. Postnotum black and bare. Pleural membrane bare. Katepisternum longer than deep, brownish-black, thinly pruinose and shiny when illuminated at certain angles, moderately covered with pale hairs. Legs. Foreleg: coxa and trochanter medium brown; femur medium brown with apical cap dark brown; tibia medium brown except apical cap dark brown, and with yellow short hairs (brightly shiny when illuminated at certain angles) on outer surface of basal five-sixths: tarsus brownish-black; basitarsus somewhat flattened, 6.9 times as long as greatest width. Midleg: coxa dark brown except posterolateral surface brownish-black; trochanter medium brown; femur medium brown with apical cap dark brown (though extreme tip somewhat paler); tibia medium brown except base yellow and apical cap dark brown, and with golden-yellow short hairs on posterior surface of basal one-third; tarsus dark brown to brownish-black. Hind leg: coxa medium brown; trochanter light brown; femur medium brown with apical cap dark brown (though extreme tip yellow); tibia ( Fig. 18 B) medium to brownish-black except base yellow, and covered with golden-yellow short hairs on lateral and posterior surfaces of basal two-thirds; tarsus brownish-black except little more than basal two-thirds of basitarsus and basal half of second tarsomere yellow; basitarsus ( Fig. 18 C) narrow, nearly parallel-sided, 6.0 times as long as wide, and 0.6 and 0.6 times as wide as greatest widths of tibia and femur, respectively; calcipala ( Fig. 18 C) well developed, slightly longer than width at base, and 0.48 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 18 C) well developed. Wing. Length 1.5 mm. Other features as in female except subcosta bare and hair tuft of base of radial vein dark brown though apical one-third golden yellow. Halter . Grayish with basal portion darkened. Abdomen. Basal scale brownish-black, with fringe of dark-brown long hairs. Dorsal surface of abdomen dark brown to brownish-black, covered with light-brown short to long hairs; segments 2, 6 and 7 each with pair of shiny dorsolateral patches, when illuminated at certain angles. Genitalia. Coxite in ventral view ( Fig. 18 D) nearly rectangular, 1.57 times as long as its greatest width. Style in ventral view ( Fig. 18 D) slender, curved inward, tapered toward middle, with apical spine (in one male, both styles with fine apical spine, as in Fig. 18 F); style in ventrolateral view ( Fig. 18 E) tapered from base to basal one-third, then slightly narrowed toward apex, with round apex; style in medial view ( Fig. 18 F) gently curved inward, tapered from base to basal two-fifths, then nearly parallel-sided. Ventral plate in ventral view ( Fig. 18 D) transverse, 0.69 times as long as greatest widths at base, with body nearly parallel-sided, though posterolateral corners rounded, with anterior margin produced anteromedially, posterior margin nearly straight, and densely covered with microsetae on ventral surface except anterolateral areas bare; basal arms of moderate length, somewhat divergent; ventral plate in lateral view ( Fig. 18 G) with posterior portion of body not produced ventrally; ventral plate in caudal view ( Fig. 18 H) rounded ventrally (width:height ratio 1.00:0.41), moderately covered with microsetae on medial one-third of posterior surface. Median sclerite ( Fig. 18 G, I) plate-like, arising from level just above anteromedial tip of body of ventral plate, and directed dorsally. Paramere ( Fig. 18 J) with three to five distinct hooks. Aedeagal membrane ( Fig. 18 J) moderately covered with microsetae, and with no sclerotized dorsal plate. Ventral surface of abdominal segment 10 ( Fig. 18 K, L) with or without distinct hair near posterior margin on each side. Cercus ( Fig. 18 K, L) rounded, somewhat produced ventrally, with 12–18 hairs.

Pupa. Body length 2.0– 2.4 mm. Head. Integument yellow, moderately covered with small round tubercles except most of ventral surface of face bare; antennal sheath with 10 round protuberances, each with 2–12 tubercles ( Fig. 19 A); frons with three pairs of unbranched long trichomes with uncoiled apices; face with pair of unbranched long trichomes with uncoiled apices; three frontal trichomes on each side arising close together, subequal in length to one another and nearly as long as or somewhat longer than facial one. Thorax ( Fig. 19 B). Integument yellow, moderately covered with small cone-like and round tubercles, with three long anterodorsal trichomes with coiled or uncoiled apices, two anterolateral trichomes with uncoiled apices (one long, one medium-long or short), one medium-long mediolateral trichome with uncoiled apex, and three ventrolateral trichomes with uncoiled apices (one long, one medium-long, one short) on each side; all trichomes unbranched. Gill ( Fig. 19 B) composed of eight slender thread-like filaments, arranged as 2+1+(1+2)+2 filaments or 2+1+3+2 filaments from dorsal to ventral, with short common basal stalk having somewhat swollen basal fenestra at base; dorsal paired filaments arising upward, with short stalk; dorsal single filament arising near base of dorsal pair; middle triplet group consisting of one individual filament and two paired filaments with extremely short or short primary and secondary stalks, or three individual filaments arising from short stalk at same level; ventral paired filaments with short stalk; all filaments light brown, slightly tapered toward apices, and subequal in length to one another (0.8–1.0 mm long); cuticle of all filaments with well-defined annular ridges and furrows, and densely covered with minute tubercles. Abdomen. Dorsally, all segments nearly unpigmented except segment 9 yellowish; segment 1 without tubercles and with one unbranched slender medium-long hair-like seta on each side; segment 2 with one unbranched slender medium-long or short hair-like seta and five short somewhat spinous setae submedially near posterior margin on each side; segments 3 and 4 each with four hooked spines and one short somewhat spinous seta near posterior margin on each side; segments 5–8 each with two or three unbranched short setae near posterior margin on each side; segments 6–9 each with spine-combs in transverse row (spine-combs absent on segment 9 in some pupae) and comb-like groups of minute spines near anterior margin on each side; segment 9 with pair of cone-like terminal hooks ( Fig. 19 C). Ventrally, segment 4 with one unbranched hook and few unbranched short setae on each side; segment 5 with pair of bifid hooks submedially and few unbranched short slender 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 unbranched short slender setae on each side; segments 4–8 with comb-like groups of minute spines. Each side of segment 9 with three grapnel-shaped hooklets. Cocoon ( Fig. 19 D). Wall-pocket-shaped, moderately woven, extended ventrolaterally; anterior margin thickly woven, without anterodorsal bulge or projection; posterior half with floor roughly or moderately woven; individual threads visible; 2.4–3.0 mm long by 1.5–2.2 mm wide.

Mature larva. Body length 3.3–3.5 mm. Body creamy except thoracic segment 1 encircled by light reddishbrown band along anterior margin though disconnected ventromedially, anterior and posterior surfaces of thoracic proleg light gray, ventral surface of thoracic segments 2 and 3 light gray and light reddish-brown, and abdominal segments 1–4 (at least ventral surface) faintly light gray though intersegmental areas between thoracic segment 3 and abdominal segment 5 unpigmented. Head capsule moderately covered with unpigmented minute spinous setae except head spots, eye-spot regions, narrow areas along posterior margin of lateral surface, and narrow areas along lateral margins of postgenal cleft bare. Cephalic apotome whitish yellow; head spots indistinct or faintly positive. Lateral surface of head capsule whitish yellow except eye-spot region whitish; eyebrow faintly defined; two relatively large spots and one small spot near posterior margin indistinct; one or two small spots below eye-spot region indistinct. Ventral surface of head capsule whitish yellow except darkened area near posterior margin on each side of postgenal cleft; one elongate spot and one round spot on each side of postgenal cleft indistinct. Antenna composed of three segments and apical sensillum, nearly as long as or slightly longer than stem of labral fan; length ratio of three segments (from base to tip) 1.0:1.1:1.0–1.1. Labral fan with 30–32 main rays. Mandible ( Fig. 20 A) with three comb-teeth decreasing in length from first tooth to third; serrations composed of two teeth (one medium-sized, one small); major tooth at acute angle against mandible on apical side; supernumerary serrations absent. Hypostoma ( Fig. 20 B) with row of nine apical teeth, of which median tooth subequal in length to each corner tooth; lateral margin smooth except apical portion often having few serrations; four hypostomal bristles per side lying parallel to lateral margin. Postgenal cleft ( Fig. 20 C) deep, reaching posterior margin of hypostoma. Cervical sclerites composed of pair of small yellow rod-like pieces, not fused to occiput, widely separated medially from each other. Thoracic proleg without hairs; thoracic cuticle moderately covered with dark flat setae with thin unpigmented apical portions (apical margin not well discerned) ( Fig. 20 D) except ventral surface bare; abdominal cuticle of segments 1–4 moderately covered with similar dark flat setae except intersegmental areas and ventral surface bare, and that of segments 5–9 moderately or densely covered with similar dark and flat setae of various sizes except ventral surface almost bare, though relatively larger ones only on dorsal surface ( Fig. 20 E); last abdominal segment moderately covered also with unbranched colorless setae on each side of anal sclerite; when viewed dorsally, abdomen remarkably constricted between abdominal segment 4 and segment 5, and anterolateral surface of segment 5 with 14–19 relatively longer dark unbranched or branched setae in addition to dark flat setae ( Fig. 20 F); thorax and abdomen without dorsal protuberances. Rectal scales present. Rectal organ compound, each of three lobes with eight thumb-like or finger-like secondary lobules. Anal sclerite of usual X-form, with anterior arms 0.9 times length of posterior ones, broadly sclerotized at base; accessory sclerite absent. Last abdominal segment expanded ventrolaterally forming double bulges on each side, visible as large conical ventral papilla when viewed from side. Posterior circlet with 70–72 rows of hooklets with up to 12 or 13 hooklets per row.

Type material. HOLOTYPE. Female, reared from a pupa collected from a small stream (width 4–6 m, water temperature 18.0˚C, exposed to the sun, altitude 1,452 m, 12˚10’56.408” N/108˚40’48.152” E), moderately flowing in open land, Long Lanh, Lac Duong District, Lam Dong Province, southern Vietnam, 24-IV-2014, by H. Takaoka, M. Sofian-Azirun, Z. Ya’cob, C.D. Chen & K.W. Lau. PARATYPES: Two females, three males, one pupa and four mature larvae, same data as those of the holotype.

Biological notes. The pupae and larvae of this new species were collected from grass leaves trailing in the water. Associated species were S. (G.) breviflagellum sp. nov., S. (G.) hongthaii , S. (G.) thituyenae sp. nov., and S. (S.) xuandei sp. nov.

Etymology. The species name longlanhense refers to the area name, Long Lanh, where this new species was collected.

Remarks. This new species is assigned to the S. batoense species-group of the subgenus Gomphostilbia , defined by Takaoka (2012), based on the antenna with nine flagellomeres, pleural membrane bare, hind tibiae mostly darkened ( Fig. 17 C), spermatheca without sclerotized neck ( Fig. 17 K), male hind basitarsus slender and parallel-sided ( Fig. 18 C), and ventral plate slightly produced ventrally (its ratio of the height against the greatest width is 0.41) ( Fig. 18 H).

Among six subgroups of the S. batoense species-group (Takaoka 2012), S. (G.) longlanhense sp. nov. is placed in the S. parahiyangum subgroup (nine species included) by having the pupal gill with eight short slender filaments of almost the same length ( Fig. 19 B).

Two of the nine species of this subgroup, i.e., S. (G.) bhutanense Takaoka & Somboon and S. (G.) chuzargangense Takaoka & Somboon , both from Bhutan, were described from females ( Takaoka and Somboon 2008). The females of (G.) bhutanense and S. (G.) chuzargangense differ from this new species by having the tarsal claws each with a small basal tooth and the bare subcosta, respectively. The arrangement of eight gill filaments, i.e., 2+1+(1+2)+2 filaments or 2+1+3 +2 filaments from dorsal to ventral, and the short common basal stalk of the gill of this new species separate this new species from the other seven species, of which the pupa is known, except S. (G.) dentistylum Takaoka & Davies described from Peninsular Malaysia, which has a similar arrangement of the pupal gill and the short common basal stalk ( Takaoka and Davies 1995). This new species is distinguished from S. (G.) dentistylum in the male by the greater number of upper-eye facets in 15 vertical columns and 16 horizontal rows (cf., in 14 vertical columns and 14 horozontal rows in S. (G.) dentistylum ), abdominal segments 2, 6 and 7 each with a pair of shiny dorsolateral patches (cf., abdominal segments 2, 5, 6 and 7 each with a pair of shiny dorsolateral patches in S. (G.) dentistylum ), in the pupa by the frons mostly covered with round tubercles, which are lower than the basal width (cf., cone-shaped tubercles which are higher than the basal width in S. (G.) dentistylum ), and in the larva by the labral fan with 30–32 main rays (cf., about 40 main rays in S. (G.) dentistylum ).

Figures

FIGURE 17. Female of Simulium (Gomphostilbia) longlanhense sp. nov. A, third segment of maxillary palp (right side; front view); B, cibarium (front view); C, tibia of hind leg (left side; outer view); D, basitarsus and second tarsomere of hind leg (left side; outer view); E, claw; F, sternite 8 and ovipositor valve (right half; ventral view); G & H, genital forks (G, ventral view; H, lateral view); I & J, paraprocts and cerci (right side; I, ventral view; J, lateral view); K, spermatheca. Scale bars. 0.1 mm for C and D; 0.02 mm for A, B and F – K; 0.01 mm for E.

FIGURE 18. Male of Simulium (Gomphostilbia) longlanhense sp. nov. A, third segment of maxillary palp (left side; front view); B, tibia of hind leg (left side; outer view); C, basitarsus and second tarsomere of hind leg (left side; outer view); D, coxites, styles and ventral plate (ventral view); E & F, styles (right side; E, ventrolateral view; F, medial view); G, ventral plate and median sclerite (lateral view); H, ventral plate (caudal view); I, median sclerite (ventral view); J, paramere and aedeagal membrane (right half; caudal view); K & L, tenth abdominal segments and cerci (right side; K, lateral view; L, caudal view). Scale bars. 0.1 mm for B and C; 0.02 mm for A and D – L.

FIGURE 19. Pupa of Simulium (Gomphostilbia) longlanhense sp. nov. A, antennal sheath (left side; lateral view); B, anterior half of thorax and gill filaments (right side; outer view); C, terminal hooks (caudal view); D, cocoon (dorsal view). Scale bars. 1.0 mm for D; 0.1 mm for B; 0.04 mm for A; 0.02 mm for C.

FIGURE 20. Mature larva of Simulium (Gomphostilbia) longlanhense sp. nov. A, mandible; B, hypostoma (ventral view); C, head capsule with postgenal cleft (ventral view); D, dark flat setae on dorsal surface of thorax (front view); E, dark flat setae on dorsal surface of abdominal segment 8 (front view); F, dark longer setae together with dark flat setae on anterolateral surface of abdominal segment 5 (lateral view). Scale bars. 0.1 mm for C; 0.02 mm for B, D, E and F; 0.01 mm for A.