Simulium (Nevermannia) bachmaense Takaoka, Sofian-Azirun

Takaoka, Hiroyuki, Sofian-Azirun, Mohd, Ya’Cob, Zubaidah, Chen, Chee Dhang, Lau, Koon Weng & Pham, Xuan Da, 2014, Three new species of Simulium (Nevermannia) (Diptera: Simuliidae) from Vietnam, Zootaxa 3866 (4), pp. 555-571 : 566-570

Simulium (Nevermannia) bachmaense Takaoka, Sofian-Azirun & Ya’cob sp. nov.

( Fig. 6 & 7 )

Female. Body length 3.0 mm. Similar to that of S. (N.) langbiangense sp. nov. except following characters. Head. Frontal ratio 1.36:1.00:2.22. Frons:head ratio 1.0:5.2. Labrum 0.99 times length of clypeus. Maxillary palp: proportional lengths of third, fourth, and fifth segments 1.0:0.8:1.6; third segment ( Fig. 6 A) much enlarged; sensory vesicle ( Fig. 6 A) elongate, 0.61–0.66 times length of third segment, with rounded opening of moderate size; opening appearing to be narrowed by some substance adhering to inside brim of opening. Maxillary lacinia with 7 or 8 inner and 12 or 13 outer teeth. Mandible with 21 inner teeth and lacking outer teeth. Cibarium with 25 minute conical processes with pointed apices and numerous minute spinous processes near lower margin. Legs. Foreleg: femur yellow to light brown with apical cap dark brown, though inner surface yellow; basitarsus slender, slightly dilated, 8.7 times as long as its greatest width. Midleg: coxa light brown except posterolateral surface dark brown. Hind leg: coxa light brown though median large portion yellow; trochanter yellow; femur yellow except apical cap dark brown; tarsus dark brown except basal two-thirds of basitarsus dull yellow (though base dark brown), and basal half of second tarsomere yellow; basitarsus nearly parallel-sided, 5.7 times as long as its greatest width, and 0.87 and 0.74 times as wide as hind tibia and femur, respectively; calcipala well developed, 1.4 times as long as width at middle, and 0.5 times as wide as greatest width of basitarsus. Claw with large basal tooth 0.46 times length of claw. Wing. Length 2.7 mm. Subcosta with light-brown hairs except near apex bare. Abdomen. Basal scale light brown, with fringe of whitish-yellow long hairs. Dorsal surface of abdomen dark brown to brownish-black except segment 2 light brown though tergite medium brown. Genitalia. Sternite 8 furnished with 14–16 long hairs and few short hairs on each side. Ovipositor valves densely covered with microsetae interspersed with 4 short hairs. Genital fork ( Fig. 6 B): lateral plate of each arm bearing slightly pigmented triangular projection with pointed apex posteromedially and distinct triangular projection directed anterodorsally. Paraproct in ventral view: anteromedial surface with five or six sensilla; paraproct in lateral view with 32 or 33 short to long hairs on ventral and lateral surfaces. Cercus in lateral view 0.6 times as long as basal width. Spermatheca ( Fig. 6 C) ellipsoidal, 1.37 times as long as its greatest width.

Male. Body length 3.0 mm. Similar to male of S. (N.) langbiangense sp. nov. except following characters. Head. Upper eye consisting of large facets in 16 vertical columns and 17 horizontal rows. Antenna yellow except pedicel and little less than apical half of first flagellomere somewhat dark yellow to light brown, and base of first flagellomere whitish yellow; first flagellomere elongate, 2.4 times length of second one. Maxillary palp: proportional lengths of third, fourth, and fifth segments 1.0:1.0:1.8; third segment ( Fig. 6 ) of moderate size; sensory vesicle ( Fig. 6 D) small, ellipsoidal, 0.26–0.28 times length of third segment, with opening of moderate size. Legs. Fore trochanter yellow except outer surface light brown; hind basitarsus mostly light brown though base medium brown and apical half somewhat darkened; basal half of hind second tarsomere grayish; fore basitarsus slender, 9.7 times as long as greatest width; hind basitarsus enlarged, spindle-shaped (similar to Fig. 2 B), 4.4 times as long as its greatest width, and 1.1 and 0.9 times as wide as greatest widths of hind tibia and femur, respectively. Wing. Subcosta with four hairs. Genitalia. Coxite in ventral view rectangular, 2.2 times as long as its greatest width. Style in ventral view short, 0.6 times length of coxite. Ventral plate in ventral view ( Fig. 6 D) lamellate, well sclerotized except anteromedian portion not sclerotized, thus anterior margin of ventral surface not well defined, with posterior margin concave medially. Paramere (similar to Fig. 5 G) with six hooks decreasing in length toward apex. Cercus small, rounded and encircled by 10 or 11 unbranched hairs.

Pupa. Body length 3.2 mm. Similar to pupa of S. (N.) langbiangense sp. nov. except following characters. Head. Integument moderately covered with round tubercles; frons with two short setae (one seta about twice length of other) ( Fig. 7 A); face with one long unbranched somewhat stout trichome with coiled apex ( Fig. 7 B) on each side. Thorax. Integument moderately covered with round tubercles, with three long somewhat stout trichomes with coiled apices, decreasing in length from anterior to posterior ( Fig. 7 C) mediodorsally, two trichomes (one long, somewhat stout, with coiled apex, and one medium-long, slender, with uncoiled apex) ( Fig. 7 D) anterolaterally, one medium-long somewhat stout trichome with uncoiled apex ( Fig. 7 E) mediolaterally, and three short slender trichomes with uncoiled apices ( Fig. 7 F) ventrolaterally on each side; all trichomes unbranched. Gill ( Fig. 7 G) with six long thread-like slender filaments, arranged as four filaments in dorsal group and two filaments in ventral group; four filaments of dorsal group arising close together, and lying nearly horizontally, and arranged as 1+2+1 filaments (similar to Fig. 5 K) or 2+1+1 filaments from outside to inside; medial or outer pair with very short stalk; and ventral pair with medium-long stalk nearly as long as interspiracular trunk; common basal stalk short, 0.7 times length of interspiracular trunk and with basal fenestra of moderate size; all filaments tapered toward apex, four filaments of dorsal group nearly subequal in length (4.5–5.1 mm) and thickness to one another, and slightly longer and thicker than two filaments of ventral pair (3.5–4.0 mm long). Abdomen. Dorsally, all segments pigmented (segments 1 and 2 grayish brown, and others yellowish); segment 5 without spine-combs. Cocoon ( Fig. 7 H). Wallpocket-shaped, compactly woven without open spaces in web, thin, with anterior margin somewhat thickly woven, with or without small bulge on anterodorsal margin, and extending ventrolaterally; individual threads invisible; 4.0 mm long by 3.2–3.8 mm wide.

Mature larva. Similar to larva of S. (N.) langbiangense sp. nov. except following characters. Body length 7.0 mm. Body whitish yellow, though parts of thoracic segments and abdominal segments 1–4 light grayish, with color markings as follows: thoracic segment 1 encircled with vermilion transverse band though disconnected dorsomedially and ventromedially; thoracic segments 1–3 each faintly with vermilion spot on ventral surface (though segment 1 only posterior to proleg); abdominal segments 1 and 3–6 each with purplish brown markings though on segments 5 and 6 somewhat lighter: segment 2 with tiny spot on each ventrolateral surface, segment 3 with pair of large dumbbell-like spots somewhat divergent posteriorly on dorsal surface, little smaller spot on each lateral surface and tiny spot on each ventrolateral surface; segment 4 with similar dumbbell-like spots on dorsal surface and tiny spot on each lateral surface (spot on each ventrolateral surface absent), segment 5 with pair of small round spots slightly separated in middle from each other and lying near anterior margin and pair of small elliptical spots broadly separated in middle from each other near posterior margin, segment 6 with similar spots as those on segment 5 except spots near posterior margin small and rounded, and segments 5–8 each with faint vermilion area of irregular patterns on each dorsolateral surface, and segment 6 with two small round spots lying tandem on ventral surface. Antenna consisting of three segments and apical sensillum, much longer than stem of labral fan; proportional lengths of first, second, and third segments 1.0:0.6:0.8. Labral fan with 34 main rays. Hypostoma: lateral margin with few weakly developed teeth apically; six hypostomal bristles lying slightly divergent posteriorly from lateral margin on each side. Postgenal cleft ( Fig. 7 I) small, rounded, 0.46 times length of postgenal bridge. Rectal organ: not observable because the rectal organ was withdrawn). Anal sclerite of usual Xform, with anterior arms subequal in length to posterior ones. Posterior circlet with 88 rows of up to 17 hooklets per row.

Type specimens. HOLOTYPE: Female (with associated pupal exuviae and cocoon) (preserved in 80% ethanol), reared from pupa, collected from a small stream (width 0.2–0.3 m, depth 2–3 cm, water temperature 17.0˚C, shaded, altitude 1,414 m, 16˚11’41.099” N/107˚51’47.675” E), slowly flowing from a natural forest, near the top of Bach Ma National Park, Phu Loc, Thua Thien-Hue Province, Vietnam, 23-II-2014, by H. Takaoka, M. Sofian-Azirun and Z. Ya’cob. PARATYPES: One male (with associated pupal exuviae and cocoon) (preserved in 80% ethanol), reared from pupa, and one mature larva (preserved in acetic alcohol), same data as those of holotype.

Biological notes. The pupae and larva of this new species were collected from dead tree leaves in the water. Associated species were S. (G.) sp. ( S. gombakense species-group).

Etymology. The species name bachmaense refers to the name of the national park, Bach Ma, where this new species was collected.

Remarks. Simulium (N.) bachmaense sp. nov. is assigned to the S. feuerborni species-group based on the combination of the following characteristics: male genitalia with a simple lamellate ventral plate ( Fig. 6 D), a short inwardly-twisted style, a simple narrow median sclerite and several parameral hooks; the pupal gill with six long thread-like filaments per side ( Fig. 7 G); and the larval head with a small short postgenal cleft ( Fig. 7 H).

The female of S. (N.) bachmaense sp. nov. is distinctive among the members of the S. feuerborni species-group in having the genital fork with a triangular lobe-like projection pointed medioposteriorly in each arm ( Fig. 6 B). The lobe-like projections of the genital fork in most known species of the S. feuerborni species-group are rounded medioposteriorly, as shown in Fig. 1 F and Fig. 5 C.

This new species is similar to S. (N.) fruticosum Takaoka & Choochote from Thailand ( Takaoka & Choochote 2005) and S. (N.) chitoense Takaoka from Taiwan (Takaoka 1979) in many characters including the number of enlarged upper-eye male facets, male genitalia, arrangement of the pupal gill filaments, and simple wall-pocketshaped cocoon. However, this new species is distinguished from both known species by the female genital fork having a triangular lobe-like projection with pointed apex ( Fig. 6 B), ellipsoidal spermatheca ( Fig. 6 C), almost yellowish male antennae and small postgenal cleft whichi is 0.46 times the length of the postgenal bridge ( Fig. 7 I). This new species is also distinguished from S. (N.) fruticosum by having the greater number (25) of minute processes on the middle of the cibarium (cf., 11 in S. (N.) fruticosum ), pupal head integument moderately covered with tubercles (cf., densely covered in S. (N.) fruticosum ) and anterolateral trichomes, of which the shorter one is about half the length of the longer one ( Fig. 7 D) (cf., the shorter one about one-third the length of the longer one in S. (N.) fruticosum ), and from S. (N.) chitoense by the yellowish-brown female scutum (cf., brownish-black scutum in S. (N.) chitoense ), and larval posterior circlet consisting of 88 rows of up to 17 hooks per row (cf., 70 rows of up to 12 hooks in S. (N.) chitoense ).

Figures

FIGURE 1. Female of Simulium (Nevermannia) langbiangense sp. nov. A, third segment of right maxillary palp with sensory vesicle bearing enlarged opening (front view); B, middle portion of cibarium with numerous minute processes; C, basitarsus and second tarsomere of left hind leg (outer view); D, claw; E, eighth sternite and ovipositor valve (ventral view; left half); F, genital fork (ventral view); G & H, right paraprocts and cerci (G, ventral view; H, lateral view); I, spermatheca. Scale bars 0.1 mm for C; 0.02 mm for A, B & E – I; 0.01 mm for D.

FIGURE 2. Male of Simulium (Nevermannia) langbiangense sp. nov. A, third segment of left maxillary palp with sensory vesicle (front view); B, basitarsus and second tarsomere of left hind leg (outer view); C, coxites, styles and ventral plate (ventral view); D & E, right styles (D, medial view; E, ventrolateral view); F, right coxite and style (caudal view); G, ventral plate and median sclerite (lateral view); H, ventral plate (caudal view): I, median sclerite (ventral view); J, left paramere with four distinct hooks and three small hooks (mediocaudal view); K, aedeagal membrane and dorsal plate (caudal view); L & M, right half of tenth abdominal segments with cerci (L, lateral view; M, caudal view). Scale bars. 0.1 mm for B; 0.02 mm for A & C – M.

FIGURE 5. Female, male and pupa of Simulium (Nevermannia) phami sp. nov. A – C, female; D – G, male; H – M, pupa. A, third segment of maxillary palpal segment with sensory vesicle (right side; front view); B, basitarsus and second tarsomere of left hind leg (outer view); C, genital fork (ventral view); D & E, basitarsi and second tarsomeres of left hind legs (outer view; D, basitarsus parallel-sided; E, basitarsus spindle-shaped); F, style (right side; dorsolateral view); G, paramere (left side; caudal view); H, two short setae on frons (left side; front view); I, basal portion of five gill filaments and anterior portion of thorax with interspiracular trunk shown in broken line (right side; lateral view); J – L, basal portions of five gill filaments with different arrangements (dorsal view; J & K, left side; L, right side); M, cocoon (dorsal view). Scale bars. 1.0 mm for M; 0.1 mm for B, D, E & I – L; 0.02 mm for A, C, F & G; 0.01 mm for H.

FIGURE 6. Female and male of Simulium (Nevermannia) bachmaense sp. nov. A – C, female; D & E, male. A, third segment of maxillary palpal segment with sensory vesicle (right side; front view); B, genital fork (ventral view); C, spermatheca; D, third segment of maxillary palpal segment with sensory vesicle (right side; front view); E, ventral plate (ventral view). Scale bars. 0.02 mm for A – E.

FIGURE 7. Pupa and larva of Simulium (Nevermannia) bachmaense sp. nov. A – H, pupa; I, larva. A, two minute setae on frons (left side); B, facial trichome (right side); C – F, thoracic trichomes (C, dorsomedial; D, anterolateral; E, mediolateral, F, ventrolateral); G, left gill filaments (outer view); H, cocoon (dorsal view); I, head capsule with hypostoma and postgenal cleft (ventral view). Scale bars. 1.0 mm for H; 0.2 mm for G; 0.1 mm for I; 0.02 mm for A – F.