Simulium (Simulium) crassimanum Edwards, 1933

Takaoka, Hiroyuki, Sofian-Azirun, Mohd, Ya’Cob, Zubaidah, Chen, Chee Dhang, Lau, Koon Weng, Fernandez, Kevin & Lardizabal, Maria Lourdes, 2015, Revision of the Simulium (Simulium) melanopus species-group (Diptera: Simuliidae) in Sabah, Malaysia, Zootaxa 3985 (1), pp. 1-30 : 2-8

Simulium (Simulium) crassimanum Edwards, 1933

Simulium crassimanum Edwards, 1933: 256 (Female) .

Simulium (Simulium) liewi Takaoka, 2007: 296 –300 (Female and pupa). New synonym.

This species was originally described on the basis of females collected at Kamborangah in the Kinabalu National Park, Sabah ( Edwards 1933). Smart and Clifford (1969) redescribed the female of this species based on the holotype specimen. The paratype female of this species was examined and its genitalia were illustrated by Takaoka (1983).

In the present study, the holotype and paratype pinned females were examined. The female is redescribed, and the male and pupa are described for the first time.

Female. Body length 2.0– 2.4 mm. Head. Narrower than width of thorax. Frons ( Fig. 1 A) black, shiny, with several dark stout hairs along each lateral margin, few similar or shorter hairs submedially, and three to five shorter hairs near lower margin on each side; frontal ratio 1.15–1.19:1.00:0.83–0.89; frons-head ratio 1.00:3.60–3.80. Fronto-ocular area ( Fig. 1 A) shallow, rounded or triangular laterally. Clypeus ( Fig. 1 A) black, whitish-gray pruinose, shiny when illuminated at certain angles, moderately covered with dark stout long hairs and yellow shorter hairs, though mediolongitudinal area moderately bare in one female. Labrum 0.73–0.83 times length of clypeus. Antenna composed of scape, pedicel and nine flagellomeres, brownish black except scape and pedicel medium brown. Maxillary palp light brown except third segment dark brown, composed of five segments, proportional lengths of third, fourth, and fifth segments 1.00:0.99–1.18:1.78–2.10; third segment ( Fig. 1 B) slightly enlarged; sensory vesicle ( Fig. 1 B) ellipsoidal, 0.22–0.27 times length of third segment, with small round opening. Maxillary lacinia with 9 inner and 11–13 outer teeth. Mandible with 22–24 inner and 12–14 outer teeth. Cibarium ( Fig. 1 C) with 65–70 minute round processes medially; cornuae somewhat enlarged. Thorax. Scutum black, thinly whitish-gray pruinose and shiny when illuminated at certain angles, moderately covered with medium-brown short hairs interspersed with dark-brown long upright hairs on prescutellar area. Scutellum brownish-black, with darkbrown upright long and short hairs. Postnotum brownish-black, whitish-gray pruinose and shiny when illuminated at certain angles, and bare. Pleural membrane bare. Katepisternum longer than depth, black, thinly whitish-gray pruinose and shiny when illuminated at certain angles and bare. Legs. Foreleg: coxa, trochanter and femur brownish black; tibia dark brown except apical cap brownish black, and outer surface widely white and sheeny when illuminated at certain angles; tarsus brownish-black to black, with thick dorsal crest of short hairs; basitarsus greatly dilated, 3.8–4.0 times as long as its greatest width. Midleg: coxa, trochanter, femur and tibia brownish black; tibia widely white sheeny on posterior surface when illuminated at certain angles; basitarsus ( Fig. 1 D) yellowish white except apical tip light brown, second to fourth tarsomeres ( Fig. 1 D) light brown except basal twothirds of second tarsomere and basal half of third tarsomere yellowish white, and fifth tarsomere dark brown. Hind leg: coxa and trochanter dark brown; femur dark brown except apical cap brownish black; tibia ( Fig. 1 E) dark brown except apical cap brownish-black, and subbasal portion yellow, tibia with whitish sheen widely on posterior surface when illuminated at certain angles; tarsus ( Fig. 1 F) dark brown except basal three-fifths of basitarsus (though base dark brown) and basal one-third of second tarsomere yellowish white; basitarsus nearly parallelsided, 6.00–6.13 times as long as its greatest width, 0.67 and 0.64 times as wide as greatest widths of hind tibia and femur, respectively; calcipala nearly as long as width at base, 0.44–0.50 times as wide as basitarsus; pedisulcus well developed; claw ( Fig. 1 G) with small basal tooth much shorter than its basal width and 0.36 times length of claw. Wing. Length 2.1 mm. Costa with dark spinules and hairs. Subcosta haired except apical one-third or onefourth bare. Basal section of vein R bare; R1 with dark spinules and hairs; R2 with dark hairs only. Hairs at base of radial vein dark brown. Basal cell absent. Halter . White with base darkened. Abdomen. Basal scale dark brown, with fringe of yellow long hairs though bases of hairs darkened. Dorsal surface of abdomen medium to dark brown except base of second segment yellowish, moderately covered with dark brown hairs; tergite 2 with pair of large silvery iridescent dorsolateral spots broadly connected medially to each other; tergites 6–8 shiny. Ventral surface medium brown except segment 2 ochreous; abdominal segment 7 with large sternal plate medially. Terminalia . Sternite 8 ( Fig. 1 H) well sclerotized, moderately depressed medially, moderately covered with three to five long dark stout hairs and 10–12 short to medium-long unpigmented hairs on each side; ovipositor valves tapered posteriorly with transparent bare apex, slightly to moderately bent ventrally ( Fig. 1 H), moderately covered with minute setae, interspersed with 32–41 short to medium-long unpigmented hairs on ventral surface; inner margins well sclerotized, concave medially, moderately separated from each other. Genital fork ( Fig. 1 I) of inverted-Y form; stem slender and well sclerotized, with enlarged flat round apex; arms slender, each with strongly-sclerotized angulate lateral ridge. Paraproct in lateral view ( Fig. 1 J) much produced ventrally, covered with five or six medium-long or long stout hairs and numerous short fine hairs on lateral surface; paraproct anteromedially with thin elongate moderately-sclerotized plate having round apical tip and 11–16 short setae scattered on its surface. Cercus in lateral view ( Fig. 1 J) short, with posterior margin nearly straight, 5.6 times as wide as its greatest length, and moderately covered with short to medium-long hairs. Spermatheca ( Fig. 1 K) ovoidal, 1.2 times as long as greatest width, well sclerotized except duct and area of junction with duct unsclerotized, without reticulate surface patterns; minute internal setae present; both accessory ducts subequal in diameter to each other, and also to that of main duct.

Male. Body length 2.5 mm. Head. Slightly wider than thorax. Upper eye consisting of large facets in 19 or 20 vertical columns and in 20 or 21 horizontal rows on each side. Clypeus brownish-black, whitish-pruinose, shiny and iridescent when illuminated at certain angles, moderately covered with dark-brown long hairs. Antenna composed of scape, pedicel and nine flagellomeres, dark-brown to brownish-black except base of first flagellomere narrowly dark yellow to light brown; first flagellomere elongate, 1.88 times length of second one. Maxillary palp light brown, composed of five segments, proportional lengths of third, fourth, and fifth segments 1.00:1.33:2.33; third segment ( Fig. 2 A) of normal size; sensory vesicle small, globular or ellipsoidal, 0.19–0.24 times length of third segment, and with small opening. Thorax. Scutum ( Fig. 2 B) black, with whitish-gray pruinose (bluish iridescent when illuminated at certain angles) pattern composed of anterior pair of spots on shoulders, and large transverse band covering prescutellar area, which is connected to anterior pair of spots by broad band along lateral margins; anterior pair of spots short, directed medially, with blunt apices, widely separated in middle from each other, and widely separated from posterior transverse spot; anterior or posterior half of spot on each shoulder disappearing depending on angles of light; scutum densely covered with dark (brassy when illuminated at certain angles) fine short hairs interspersed with dark-brown long upright hairs on prescutellar area. Other features similar to those of female. Legs. Color pattern almost similar to that of female except second tarsomere of midleg, basitarsus and second tarsomere of hind leg all yellowish white on little less than basal half, and hind tibia brownish black except basal tip dark yellow or light brown; sheen on posterior surface of mid and hind tibiae indistinct. Fore basitarsus greatly dilated, 4.53 times as long as its greatest width. Hind basitarsus ( Fig. 2 C) greatly enlarged, gradually widened toward apical one-third, then roundly narrowed, 3.0 times as long as its greatest width, 1.0 and 1.07 times as wide as greatest widths of hind tibia and femur, respectively; calcipala nearly as long as its basal width, and 0.25 times as wide as greatest width of basitarsus; pedisulcus well developed. Wing. Length 2.0 mm; other features as in female except subcosta entirely bare. Halter . White except base darkened. Abdomen. Basal scale brownish-black, with fringe of dark long hairs. Dorsal surface of abdomen dark brown, with dark hairs; segments 2 and 4–7 each with pair of silvery iridescent dorsolateral spots; ventral surface of segments 2–4 ochreous and those of other segments medium brown. Genitalia. Coxites, styles and ventral plate in ventral view as in Fig. 2 D. Coxite in ventrolateral view ( Fig. 2 E) subquadrate, 0.84 times as long as wide. Style in medial view ( Fig. 2 F) flattened dorsoventrally, gradually narrowed toward apical one-third, and without basal or subbasal protuberance; style in ventrolateral view ( Fig. 2 G) elongate, 1.71 times length of coxite, 2.32 times as long as its greatest width at basal one-fifth, sinuous, widened from base to basal one-fifth, slightly narrowed toward middle, slightly widened toward apical one-third, then somewhat narrowed toward apex, and with round apex having stout spine. Ventral plate in ventral view ( Fig. 2 D) with body nearly rectangular, having ventrally produced median process that is bare except parts of lateral and anterior surfaces covered with minute setae, and is furnished with several teeth in vertical row on each posterolateral margin; basal arms short, stout and divergent; ventral plate in lateral view ( Fig. 2 H) with body and its ventrally produced process having rounded ventral apex, dentate posterior margin, and covered with minute setae anteriorly and anterolaterally; ventral plate in caudal view ( Fig. 2 I) with body and ventrally produced median process slightly narrowed from base to basal one-third, abruptly widened, then gradually tapered toward apex, bare, with several teeth in vertical row on each lateral margin of basal twothirds. Median sclerite in lateral view ( Fig. 2 H) moderately sclerotized, folded backward and then curved dorsally, and in caudal view ( Fig. 2 J) plate-like, nearly parallel-sided, with concave apex. Paramere ( Fig. 2 K) wide basally and with several parameral hooks apically. Aedeagal membrane ( Fig. 2 L) moderately covered with minute setae, with weakly sclerotized dorsal plate ( Fig. 2 M). Ventral surface of tenth abdominal segment ( Fig. 2 N, O) without distinct hairs. Cercus ( Fig. 2 N, O) slightly rounded, with eight or nine distinct hairs.

Pupa. Body length (excluding gill filaments) 2.6 mm. Head. Integument yellowish, except frons and part of face medium brown and antennal sheaths light brown, bare on frons but sparsely covered with round tubercles on face: frons with two unbranched short trichomes ( Fig. 3 A) on each side; face with one unbranched medium-long trichome ( Fig. 3 B) on each side; frontal trichomes much shorter than facial ones. Thorax. Integument medium brown, though posterior half somewhat lighter, except wing sheaths yellowish, moderately covered with round tubercles or cone-shaped smaller tubercles except dorsal surface of anterior half almost bare, and lateral surface near base of gill densely covered with round tubercles; thorax with two long stout anterodorsal trichomes ( Fig. 3 C), two anterolateral trichomes (one medium-long and slender, one long and stout) ( Fig. 3 D), one medium-long stout mediolateral trichome ( Fig. 3 E), and three ventrolateral trichomes (two long and stout, one short and slender) ( Fig. 3 F), on each side; all unbranched. Gill ( Fig. 3 G) with six slender thread-like filaments in pairs; all pairs short stalked; upper filament of dorsal pair longest (1.4–1.5 mm), lower filament of ventral pair shortest (0.8 mm), and other filaments intermediate in length, though slightly decreasing in length from dorsal to ventral; relative thickness of filaments from dorsal to ventral when compared basally 1.00:0.75–0.88:0.88:0.69–0.75: 0.68– 0.85:0.68–0.85; upper filament of each pair always slightly thicker than counter lower filament, though two filaments of ventral pair often subequal in thickness; each filament light to medium brown, of similar thickness from base to middle, then gradually tapered toward apex; stalks of dorsal and ventral pairs at angle of 90 degrees when viewed laterally; cuticular surface with furrows in irregular intervals but neither distinct ridges nor resulting reticulate patterns throughout their length, covered with minute tubercles. Abdomen. Dorsally, segment 1 light brown, posterior surface of segment 9 yellowish, other segments unpigmented; segment 1 with 4–15 minute tubercles near lateral margin and with one unbranched short slender seta ( Fig. 3 H) on each side; segment 2 with one unbranched short slender seta and five unbranched minute setae ( Fig. 3 I) on each side; segments 3 and 4 each with four unbranched hooked spines and one unbranched minute seta on each side; segments 5, 6 and 9 without spine-combs; segments 7 and 8 each with spine-combs in transverse row (though those on segment 7 ranging from zero to six in number) and comb-like groups of minute spines in transverse row on each side; segments 6 and 9 each rarely with comb-like groups of minute spines in transverse row on each side; segment 9 without terminal hooks. Ventrally, all segments unpigmented; segment 4 with one unbranched minute seta on each side; segment 5 with pair of bifid hooks submedially and one unbranched minute seta on each side; segments 6 and 7 each with pair of bifid inner and unbranched or bifid outer hooks widely spaced and one unbranched minute seta on each side. Grapnel-like hooklets absent. Cocoon ( Fig. 3 J, K). Wall-pocket-shaped or shoe-shaped (anterolateral margins approaching anteroventrally and narrowly connected to each other or not), thickly woven, ochreous, not extended ventrolaterally; individual threads invisible; 2.7–3.0 mm long by 1.1–1.2 mm wide.

Specimens examined. Two females, one male (all reared from pupae), one pharate female, one pharate male, one pupal exuviae, collected from a small stream (width 1.0 m, depth 7–10 cm, streambed rocky, water temperature 16.1˚C, shaded, altitude 1,890 m, 06˚01.870’ N/116˚32.834’ E), slow flowing in a natural forest, downstream of Carson Waterfall, Timpohon, Mt. Kinabalu, Sabah, 4-II-2015, by K. Fernandez; one male, same data as above except date, 8-I-2015; one pharate male, collected from the same small stream as above but different site (width 1.2 m, depth 12 cm, streambed pebbles, water temperature 16.3˚C, shaded, altitude 1,808 m, 06˚01.446’ N/116˚32.648’ E), moderately flowing in a natural forest, downstream of Carson Waterfall, Timpohon, Mt. Kinabalu, Sabah, 18-I- 2015, by K. Fernandez; one pharate male, collected from a small stream (width 0.2 m, depth 2–3 cm, streambed sandy, water temperature 16.4˚C, shaded, altitude 1,728 m, 06˚01.397’ N/116˚32.661’ E), slow flowing in a natural forest, Timpohon, Mt. Kinabalu, Sabah, 24-X-2014 by C.D. Chen, K.W. Lau & K. Fernandez.

Ecological notes. The pupae of this species were collected from plastic sheets and trailing grasses in the water. Associated species were S. (G.) borneoense , S. (S.) nigripilosum and S. (S.) cheedhangi .

Distribution. Sabah.

Remarks. The holotype was in good condition and the following characteristics were confirmed: antenna entirely dark brown, fore coxa dark brown, fore tibia dark brown with a wide white area on the outer surface, mid tibia entirely dark brown to black, mid basitarsus yellowish on basal three-fourths, hind tibia dark brown to black with the base yellow, hind basitarsus whitish on basal three-fifths, basal portion of radial vein entirely bare and tergite 2 silvery iridescent. The paratype female showed similar characteristics except the antenna, which is dark brown with the scape, pedicel and the base of the first flagellomere yellow. The basal portion of the radial vein and tergite 2 were erroneously noted to be haired and not iridescent, respectively, in the redescription by Smart and Clifford (1969).

The pupa of S. (S.) crassimanum is characterized by the bare frons, bare dorsal surface of the anterior half of the thorax, six gill filaments without annular ridges ( Fig. 3 G), and cocoon of the wall-pocket-shape or shoe-shape with low anteroventral collar ( Fig. 3 J, K).

The female and pupa of S. (S.) liewi described from a female reared from a pupa collected in the same stream in Timpohon (Takaoka 2007) are morphologically indistinguishable from those of S. (S.) crassimanum except the frons: head ratio and the genital fork. The frons:head ratio is 1.00: 3.27 in S. (S.) liewi and 1.00: 3.60–3.80 in S. (S.) crassimanum . The genital fork has an expanded tip on the stem ( Fig. 1 I) in S. (S.) crassimanum but is absent in S. (S.) liewi . More females of S. (S.) liewi are needed to determine if these two differences are interspecific or intraspecific variation. In this study, S. (S.) liewi is treated as a junior synonym of S. (S.) crassimanum .

Figures

FIGURE 1. Female of Simulium (Simulium) crassimanum. (A) Head (front view). (B) Third segment of maxillary palp with sensory vesicle (right side; front view). (C) Cibarium. (D) Tarsus of midleg (left side; outer view). (E) Hind tibia (left side; outer view). (F) Basitarsus and second tarsomere of hind leg (left side; outer view). (G) Claw. (H) Sternite 8 and ovipositor valves (ventral view). (I) Genital fork (ventral view). (J) Posterior tip of abdomen showing ovipositor valve directed posteroventrally, genital fork, paraproct and cercus (right side; lateral view). (K) Spermatheca. Scale bars. 0.1 mm for A and D – F; 0.02 mm for B, C and H – K; 0.01 mm for G.

FIGURE 2. Male of Simulium (Simulium) crassimanum. (A) Third segment of maxillary palp with sensory vesicle (right side; front view). (B) Scutum showing pruinose pattern (dorsal view). (C) Basitarsus and second tarsomere of hind leg (left side; outer view). (D) Coxites, styles and ventral plate (ventral view). (E) Coxite (right side; ventrolateral view). (F) and (G) Styles (right side; F, medial view; G, ventrolateral view). (H) Ventral plate and median sclerite (lateral view). (I) Ventral plate (caudal view). (J) Median sclerite (caudal view). (K) Paramere (left side; caudal view). (L) Aedeagal membrane (left half; caudal view). (M) Dorsal plate (ventral view). (N) and (O) Tenth abdominal segments and cerci (right side; N, lateral view; O, caudal view). Scale bars. 0.1 mm for C; 0.02 mm for A and D – O.

FIGURE 3. Pupa of Simulium (Simulium) crassimanum. (A) Frontal trichomes. (B) Facial trichome. (C) – (F) Thoracic trichomes (C, anterodorsal; D, anterolateral; E, mediolateral; F, ventrolateral). (G) Anterior half of thorax and gill filaments (left side; outer view). (H) Slender short seta on dorsal surface of abdominal segment 1. (I) Slender short seta and minute seta on dorsal surface of abdominal segment 2. (J) and (K) Cocoons (J, dorsal view; K, lateral view). Scale bars. 1.0 mm for J and K; 0.1 mm for G; 0.02 mm for A – F, H and I.