Simulium (Simulium) nigrogilvum Summers, 1911

Takaoka, Hiroyuki, Sofian-Azirun, Mohd, Ya’Cob, Zubaidah, Chen, Chee Dhang, Lau, Koon Weng, Low, Van Lun, Pham, Xuan Da & Adler, Peter H., 2017, The black flies (Diptera: Simuliidae) of Vietnam, Zootaxa 4261 (1), pp. 1-165 : 96-100

Simulium (Simulium) nigrogilvum Summers, 1911

Simulium nigrogilvum Summers, 1911: 586 –588 (Female).

Simulium (Himalayum) nigrogilvum: Takaoka & Suzuki, 1984: 22 –27 (Female, male, pupa and larva). Simulium (Simulium) nigrogilvum: Otsuka et al., 2003: 113 –120.

Distribution. Thailand and Vietnam.

Remarks. This species was assigned to the subgenus Himalayum Lewis ( Takaoka and Suzuki 1984) but later transferred to the subgenus Simulium ( Otsuka et al. 2003) . The females of this species are known to be anthropophilic (Choochote et al. 2005) and to transmit an unknown filarial parasite in Thailand (Fukuda et al. 2003). This species was recorded from Vietnam by Crosskey and Howard (1997). However, data including the material collected and its locality were not given.

Simulium (Simulium) turgidum Takaoka & Pham sp. nov.

Female. Body length 3.3 mm. Head. Nearly as in female of S. (S.) laocaiense sp. nov. except following characters: Frontal ratio 1.2:1.0:1.0, frons:head ratio 1.0:4.3. Labrum 0.7 times length of clypeus. Antenna: first flagellomere 1.36 times length of second one. Maxillary palp: proportional lengths of third, fourth, and fifth segments 1.0:1.3:3.4; third segment ( Fig. 41 A) with apex somewhat produced medially, with medium-sized ellipsoidal sensory vesicle (0.4 times length of third segment) having large or medium-sized opening. Maxillary lacinia with12–13 inner and 13 or 14 outer teeth. Mandible with 25 inner and 12 or 13 outer teeth. Cibarium ( Fig. 41 B) with 38 minute processes near posterodorsal margin. Thorax, Legs, Wing and Halter . As in female of S. (S.) laocaiense sp. nov. except following characters: Scutum covered with yellow short hairs. Fore tibia whitish yellow except apical one-fifth brownish black, and little more than apical two-fifths of inner surface light brown to brownish black. Fore basitarsus greatly dilated, 5.8 times as long as its greatest width. Mid tarsus light to medium brown except basal one-third to one-half of basitarsus yellow (though its border not well defined). Hind basitarsus ( Fig. 41 C) gradually widened toward apical one-third, then slightly narrowed toward apex, 5.6 times as long as wide, and 0.8 and 0.7 times as wide as greatest widths of hind tibia and femur, respectively; calcipala ( Fig. 41 C) moderately developed, 0.7 times as long as wide, and 0.5 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 41 C) well developed. Wing length 3.1 mm. Subcosta haired except near apex bare. Abdomen. Basal scale medium brown to brownish black, with fringe of yellowish hairs. Dorsal surface of abdomen medium brown to black; tergite 2 shiny and white pruinose when illuminated at certain angles and tergites 6–9 shiny. Ventral surface light brown except basal portion of segment 2 white; sternal plate on segment 7 indistinct. Terminalia . Sternite 8 ( Fig. 41 D) with 11 or 12 dark-brown medium-long to long stout hairs and three to six yellow short hairs on each lateral surface. Ovipositor valve ( Fig. 41 D) wide, somewhat thick except narrow areas along inner and posterior margins thin and transparent, somewhat rounded ventrally, densely covered with microsetae (except narrow transparent portions along inner and posterior margins bare) interspersed with 22–25 yellow short hairs; inner margins somewhat separated from each other. Genital fork ( Fig. 41 E, F) of inverted-Y form, with narrow well sclerotized stem; arms of moderate width, each with heavily sclerotized lateral portion, with short projection directed anterodorsally. Paraproct in ventral view ( Fig. 41 G) nearly quadrate, 1.2 times as long as its width, with 23 or 24 short to medium-long hairs on lateral and ventral surfaces; anterior surface strongly sclerotized and pigmented, and with four or five short sensilla; paraproct in lateral view ( Fig. 41 H) 0.7 times as long as wide, and protruding ventrally beyond ventral margin of cercus. Cercus in lateral view ( Fig. 41 H) short, rectangular, 0.6 times as long as wide, with numerous short to medium-long hairs. Spermatheca ( Fig. 41 I) globular, 1.1 times as long as greatest width, well sclerotized except small portion of junction with duct unsclerotized, with faintly defined reticulate surface patterns; internal setae present; accessory ducts subequal in thickness to each other, and slightly thicker than major duct.

Male. Unknown.

Pupa. Body length (excluding gill filaments) 4.0 mm. Head. Integument dark brown except ventral surface ochreous, and bare, without tubercles (though surface appearing to have micro-sculptures formed by numerous fine ridges); frons with two bifid medium-long trichomes ( Fig. 42 A); face with one bifid or trifid medium-long trichome on each side ( Fig. 42 B). Thorax. Integument dark brown except wing sheaths ochreous, and bare except dorsal surface of posterior half sparsely to moderately covered with round tubercles and basal portions of gills densely covered with tubercles having minute secondary projections (though bare surface appearing to have microsculptures formed by numerous fine ridges); thorax with three long anterodorsal trichomes with four to six branches ( Fig. 42 C), two long or medium-long anterolateral trichomes with four branches (anterior one little shorter than posterior one) ( Fig. 42 D), one unbranched or bifid medium-long mediolateral trichome ( Fig. 42 E), and three ventrolateral trichomes (two unbranched medium-long, one bifid in left side ( Fig. 42 F); one unbranched medium-long, one quadrifid medium-long, and one unbranched short ( Fig. 42 G) in right side), on each side. Gill ( Fig. 42 H) with six somewhat inflated filaments in pairs; common basal stalk short, with small basal fenestra ventrally; all pairs almost sessile; outer filament of dorsal pair longest (1.8 mm long), followed by inner filament of dorsal pair and outer filament of middle pair (1.4 mm long), inner filament of middle pair and outer filament of ventral pair (1.1 mm long), and inner filament of ventral pair (1.0 mm long); each filament widened from base to basal one-fifth to one-third, then tapered toward apex; relative thickness of six filaments from dorsal to ventral when widest portion compared 1.0:0.9:0.9:0.8:0.7:0.6; all filaments dark brown, gradually tapered toward apex; outer filament of dorsal pair and inner filament of ventral pair divergent basally at angle of 60 degrees; cuticular surface with well-defined annular ridges and furrows throughout their length forming definite reticulate surface patterns, covered with minute tubercles. Abdomen. Dorsally, entire surface of segment 1 and anterior half of segment 2 light brown, other segments unpigmented; segment 1 sparsely covered with minute spines laterally, with one unbranched slender medium-long seta ( Fig. 42 I) on each side; segment 2 covered with comb-like groups of minute spines submedially, with one unbranched slender short seta and five unbranched minute setae, of which four are stout ( Fig. 42 J), on each side; segments 3 and 4 each with four unbranched hooked spines and one unbranched minute seta on each side; segments 7 and 8 each with spine-combs in transverse row on each side; segments 6–9 each with comb-like groups of minute spines; segment 9 without terminal hooks. Ventrally, all segments unpigmented; segment 4 with one unbranched hook and few short setae on each side; segment 5 with pair of unbranched or bifid hooks submedially and few unbranched short seta on each side; segments 6 and 7 each with pair of bifid inner and unbranched outer hooks widely spaced and few unbranched short seta on each side; segments 3–8 each with comb-like groups of minute spines. Grapnel-like hooklets absent. Cocoon ( Fig. 42 K, L). Wall-pocket-shaped, thickly woven, with anterolateral windows, ochreous, not extended ventrolaterally; individual threads invisible; 4.0– 4.2 mm long by 1.6–1.8 mm wide.

Mature larva. Body length 6.7–7.5 mm. Body ochreous or partially reddish brown, mottled to varying extent with grayish-black to black pigment except ventral surface of abdominal segments 3–9 unpigmented. Head. Cephalic apotome ( Fig. 43 A) whitish yellow on little more than anterior half and light to medium brown on rest (though small medial area in front of posterior margin dark brown); posterior spot of mediolongitudinal spots and posterior half of each mediolateral spot dark brown, anterior spot of mediolongitudinal spots light brown, and other spots indistinct, merged into dark background, or anterior spot of posterolateral spots on each side faintly negative. Lateral surface of head capsule light to medium brown except eye-spot region, eyebrow and median small area along anterior margin yellowish white, with faint or distinct negative spots except one small spot below eye-spot region light brown. Ventral surface of head capsule ( Fig. 43 B) light to medium brown except postgenal bridge lighter medially, and elongate spot on each side of cleft indistinct, merged into dark background. Antenna ( Fig. 43 C) composed of three articles and apical sensillum, slightly longer than stem of labral fan; antenna yellowish white except third segment dark brown; length ratio of articles (from base to tip) 1.0:1.2–1.3:0.5. Labral fan with 49–51 primary rays. Mandible ( Fig. 43 D) with mandibular serration composed of two teeth (one medium-sized and one small); major tooth at obtuse angle apically against mandible; comb-teeth decreasing in length from first to third; supernumerary serrations absent. Hypostoma ( Fig. 43 E) with nine anterior teeth, of which median tooth slightly longer than each corner tooth; lateral margins weakly serrate apically; seven or eight hypostomal bristles divergent posteriorly from lateral border on each side. Postgenal cleft ( Fig. 43 B) medium-long, triangular, 1.4 times length of postgenal bridge; sheath of subesophageal ganglion well pigmented, wine-glass-shaped. Cervical sclerites on each side composed of one light-brown elliptical piece, not fused to occiput. Thorax and Abdomen. Thoracic and abdominal cuticle bare except last segment of abdomen moderately covered with short colorless setae on each side of anal sclerite. Rectal scales present. Rectal organ compound, each of three lobes with 23–25 fingerlike secondary lobules. Anal sclerite X-shaped, with broadened anterior arms 0.7–0.9 times length of posterior ones; no sensilla on base of anal sclerite and 12 sensilla posterior to posterior arms. Last abdominal segment bulged laterally but lacking ventral papillae. Posterior circlet with 104–110 rows of hooklets with up to 17 or 18 hooklets per row.

Type material. HOLOTYPE: Female (with its associated pupal exuviae and cocoon) in 80% ethanol, labeled in a vial as [ UMSRP: Vietnam 0 36, Holotype, Simulium (S.) turgidum , Female, coll. Vietnam, 20-XII-2014, Takaoka et al.], reared from a pupa collected from a stream (width 0.5–2.5 m, bottom rocky, water temperature 10.0˚C, exposed to the sun, elevation 1,812 m, 22˚21’27.450”N/103˚46’35.743”E) moderately flowing in a forest, Sapa , Lao Cai Province, northern Vietnam , 20-XII-2014, by H. Takaoka, M. Sofian-Azirun, Z. Ya’cob, C.D. Chen & K.W. Lau. PARATYPES: One pupa in 80% ethanol, labeled in a vial as [ UMSRP: Vietnam 0 36, Paratype, Simulium (S.) turgidum , Pupa, coll. Vietnam, 20-XII-2014, Takaoka et al.], collected from a stream (width 0.5 m, bottom rocky, water temperature 11.0˚C, exposed to the sun, elevation 1,750 m, 22˚21’43.110”N/ 103˚47’19.221”E) moderately flowing in a secondary forest, Sapa , Lao Cai Province, northern Vietnam , 20-XII- 2014, by H. Takaoka, M. Sofian-Azirun, Z. Ya’cob, C.D. Chen & K.W. Lau; one mature larva, same data as those of the holotype .

Biological notes. The pupae of S. (S.) turgidum were collected from trailing grasses. Associated species were S. (M.) nigrofilum sp. nov., S. (N.) laichauense sp. nov., S. (S.) sapaense sp. nov., S. (S.) giayense sp. nov., S. (S.) sp. ( S. multistriatum species-group) and S. (S.) sp. ( S. variegatum species-group).

Distribution. Vietnam (Lao Cai).

Etymology. The species name turgidum refers to the inflated gill filaments of this new species. The Latin adjective ‘turgidus’ means ‘inflated’.

Remarks. As for S. (S.) laocaiense sp. nov., S. (S.) turgidum sp. nov. also is placed in the S. griseifrons species-group based on the similarity of the female enlarged ovipositor valve ( Fig. 41 D) to that of S. (S.) rudnicki , which is a member of the S. griseifrons species-group.

In having inflated pupal gill filaments ( Fig. 42 H), this new species is similar to S. (S.) tumidilfilum Luo, Yang & Chen described from Hubei, China ( Luo et al. 2010), and S. (S.) waterfallum Zhang, Yang & Chen described from Hainan, China (Zhang et al. 2003), both of which were wrongly placed in the S. multistriatum species-group. However, this new species is distinguished in the female from the latter two species by the ovipositor valve which is triangular with 22–25 short hairs (tongue-like with 5–8 short hairs in S. (S.) tumidilfilum and S. (S.) waterfallum ), and in the pupa from S. (S.) tumidilfilum by each inflated filament slightly narrowed at its base (much narrowed in S. (S.) tumidilfilum ), and from S. (S.) waterfallum by abdominal segments 7 and 8 each with spine-combs (abdominal segments 6–8 each with spine-combs in S. (S.) waterfallum ).

Figures

FIGURE 41. Female of Simulium (Simulium) turgidum sp. nov. A, Third segment of maxillary palp with sensory vesicle (left side; front view); B, Cibarium (front view); C, Hind basitarsus and second tarsomere (left side; outer view). D, Sternite 8 and ovipositor valve (right side only; ventral view); E, Genital fork (ventral view); F, Arm of genital fork showing anterodorsal triangular projection; G & H, Paraprocts and cerci (G, ventral view; H, lateral view). I, Spermatheca. Scale bars. 0.1 mm for C; 0.02 mm for A, B and D – I.

FIGURE 42. Pupa of Simulium (Simulium) turgidum sp. nov. A, Frontal trichome; B, Facial trichome; C – G, Thoracic trichomes (C, anterodorsal; D, anterolateral; E, mediolateral; F & G, ventrolateral); H, Anterior part of thorax and gill filaments (right side; outer view); I, Hair-like seta and minute seta on dorsal surface of abdominal segment 1; J, Hair-like seta, minute seta and stout seta on dorsal surface of abdominal segment 2; K & L, Cocoons (K, dorsal view; L, lateral view). Scale bars. 1.0 mm for K and L; 0.1 mm for H; 0.02 mm for A – G, I and J.

FIGURE 43. Larva of Simulium (Simulium) turgidum sp. nov. A & B, Head capsules (A, dorsal view; B, ventral view); C, Antenna; D, Mandible; E, Hypostoma. Scale bars. 0.1 mm for A and B; 0.05 mm for C and E; 0.02 mm for D.