Simulium (Simulium) taichungense, Takaoka & Huang, 2018

Takaoka, Hiroyuki & Huang, Yao-Te, 2018, A new black fly species of Simulium (Simulium) (Diptera: Simuliidae) from Taiwan, Zootaxa 4422 (1), pp. 141-150 : 142-147

Simulium (Simulium) taichungense sp. nov.

Female. Body length 2.8 mm. Head. Slightly narrower than thorax. Frons dark brown, shiny, with bluish reflection when illuminated at certain angles, with several dark stout hairs along lateral margins; frontal ratio 1.3:1.0:1.1; frons:head ratio 1.0:3.6. Fronto-ocular area well developed, short, directed laterally, and pointed apically. Clypeus dark brown, white pruinose when illuminated at certain angles, moderately covered with dark-brown medium-long hairs (though mediolongitudinal portion of upper half widely bare). Labrum 0.83 times length of clypeus. Antenna composed of scape, pedicel and nine flagellomeres; scape, pedicel and base of first flagellomere yellow, rest medium to dark brown, when viewed dorsally (first flagellomere entirely yellow or ochreous when viewed ventrally); first to eighth flagellomeres each with pit-like depressions with many sensilla on inner and outer sides.

Maxillary palp with five segments, light to medium brown; proportional lengths of third, fourth, and fifth segments 1.0:1.0:2.4; third segment ( Fig. 1A ) with medium-sized ellipsoidal sensory vesicle (0.3 times length of third segment) having medium-sized opening. Maxillary lacinia with 13 inner and 15 or 16 outer teeth. Mandible with 29 inner and 11–13 outer teeth. Cibarium ( Fig. 1B ) with 46 minute processes near posterodorsal margin. Thorax. Scutum brownish black except anterolateral calli ochreous, shiny and grayish pruinose except large submedian area on each side not shiny and nonpruinose when illuminated posterodorsally and viewed dorsally, moderately covered with whitishyellow recumbent short hairs interspersed with several dark-brown long upright hairs on prescutellar area. Scutellum dark brown, covered with dark-brown upright long hairs and yellow short hairs. Postnotum brownish black, bare. Pleural membrane bare. Katepisternum dark brown, longer than deep, bare, and slightly shiny when illuminated at certain angles. Legs. Foreleg: coxa whitish yellow; trochanter and femur yellow; tibia whitish except apical cap dark brown; tarsus brownish black to black, with moderate dorsal hair crest; basitarsus greatly dilated, 5.1 times as long as its greatest width. Midleg: coxa dark brown except posterolateral surface brownish black; trochanter and femur yellow; tibia white to yellowish white except apical cap yellow; tarsus dark brown except basal half of basitarsus yellow (though its border not well defined). Hind leg: coxa medium to dark brown; trochanter yellow; femur yellow except apical cap medium brown; tibia white to whitish yellow except apical cap medium brown; tarsus dark brown except basal two-thirds of basitarsus and basal two-fifths of second tarsomere dark yellow; basitarsus ( Fig. 1C ) nearly parallel-sided, 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. 1C ) moderately developed, slightly shorter than its basal width, and 0.37 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 1C ) well developed. Claw simple, without basal or subbasal tooth. Wing. Length 2.4 mm. Costa with dark spinules and hairs; subcosta haired except near apex bare; basal section of radius bare; R1 with dark-brown spinules and hairs; R2 with dark-brown hairs; hair tuft on base of radius dark brown; basal cell absent. Halter . White except basal portion darkened. Abdomen. Basal scale medium brown, with fringe of lightbrown hairs. Dorsal surface of abdomen medium to dark brown except basal half of segment 2 yellow; tergite 2 shiny and white pruinose when illuminated at certain angles and tergites 6–9 shiny. Ventral surface light brown except segments 2–4 white; segment 7 with large median sternal plate. Terminalia . Sternite 8 ( Fig. 1D ) with 11 dark-brown medium-long to long stout hairs and five or six yellow short hairs on each lateral surface. Ovipositor valve ( Fig. 1D ) wide, somewhat thick except areas along inner and posterior margins thin and transparent, somewhat rounded ventrally, densely covered with microsetae (except transparent portions along inner and posterior margins bare) interspersed with 16–18 yellow short hairs; inner margins somewhat concave, moderately separated from each other. Genital fork ( Fig. 1E ) 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. 1F ) nearly quadrate, with 25–30 short to medium-long hairs on lateral and ventral surfaces, and with anterior surface strongly sclerotized and pigmented with seven or eight short sensilla; paraproct in lateral view ( Fig. 1G ) 0.8 times as long as wide, and protruding ventrally beyond ventral margin of cercus. Cercus in lateral view ( Fig. 1G ) short, rectangular, 0.6 times as long as wide, with numerous short to medium-long hairs. Spermatheca ( Fig. 1H ) nearly ovoid, 1.36 times as long as greatest width, well sclerotized except ducts and small portion of junction with duct unpigmented, with faintly defined reticulate surface patterns; internal setae present; accessory ducts unpigmented, subequal in thickness to each other, and twice as thick as major duct.

Male. Body length 3.0 mm. Head. As wide as thorax. Upper eye medium brown, with large facets in 18 or 19 vertical columns and in 20 horizontal rows. Clypeus brownish black, thickly white pruinose, covered with darkbrown hairs along lateral margins and near ventral margin (medial portion widely bare). Antenna composed of scape, pedicel and nine flagellomeres, medium to dark brown except scape, basal half of pedicel and base of first flagellomere yellow; first flagellomere elongate, 1.7 times as long as second one. Maxillary palp light to medium brown except segments 1 and 2 lighter; proportional lengths of third, fourth, and fifth segments 1.0:1.2:2.9–3.0; third segment ( Fig. 2A ) of moderate size; sensory vesicle ( Fig. 2A ) small, ellipsoidal (0.22–0.24 times as long as third segment), and with small opening. Thorax. Scutum black, with white pruinose pattern, i.e., anterior pair of large spots on shoulders extending posteriorly along lateral margins connected near base of wings to large transverse posterior spot entirely covering prescutellar area; these pruinose areas silvery iridescent when illuminated at certain angles; scutum uniformly and moderately covered with yellow recumbent short hairs interspersed with medium-brown long upright hairs on prescutellar area. Scutellum brownish black, with several medium-brown long upright hairs and yellow short hairs. Postnotum brownish black to black, white pruinose when illuminated at certain angles and bare. Pleural membrane bare. Katepisternum longer than deep, brownish black, white pruinose when illuminated at certain angles, and bare. Legs. Foreleg: coxa whitish yellow; trochanter whitish yellow with some lateral portions light brown; femur yellow with apical cap medium brown; tibia widely white on outer surface except extreme base light brown and apical one-fourth dark brown, though light brown medially, medium brown on base, and apical cap dark brown on inner surface; tarsus dark brown to brownish black, with moderate dorsal hair crest; basitarsus greatly dilated, 5.1 times as long as its greatest width. Midleg: coxa dark brown except posterolateral surface brownish black; trochanter light to medium brown except base yellowish white; femur yellow with apical tip dark yellow; tibia yellowish white to yellow with apical tip dark yellow; tarsus medium brown except basal three-fifths of basitarsus yellow. Hind leg: coxa dark brown; trochanter yellow; femur yellow except apical cap dark brown; tibia dark brown except base whitish yellow; tarsus ( Fig. 2B ) medium to dark brown except basal half of basitarsus yellow (though extreme base darkened) and basal half of second tarsomere yellow; basitarsus ( Fig. 2B ) much enlarged, gradually widened from base to apical one-third or little more, then narrowed to apex, 4.3 times as long as its greatest width, and 0.90 and 0.87 times as wide as greatest widths of hind tibia and femur, respectively; calcipala ( Fig. 2B ) small, nearly as long as wide, 0.27 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 2B ) well developed. Halter . White except basal portion darkened. Wing. Length 2.3 mm. Other features as in female except subcosta bare. Abdomen. Basal scale brownish black, with fringe of dark long hairs. Dorsal surface of abdomen dark brown to brownish black except basal one-third of segment 2 yellow, with dark short hairs; segments 2 and 5–7 each with pair of silvery iridescent spots dorsolaterally, those on segment 2 broadly connected in middle to each other. Ventral surface yellow except sternites 3–8 medium brown. Genitalia. Coxite in ventral view ( Fig. 2C ) quadrate, nearly as long as wide. Style in ventral view ( Fig. 2C ) elongate, 1.8 times as long as coxite, widest near base, tapered toward apical two-fifths, then slightly widened to near round apex, and without apical spine; style in ventrolateral view ( Fig. 2D ) tapered near basal one-third, nearly parallelsided medially, then slightly widened toward near apex, with round apex; style in medial view ( Fig. 2E ) with elongate triangular basal projection having several small spines on anterior surface; style in caudal view ( Fig. 2F ) with elongate narrow projection having pointed apex. Ventral plate in ventral view ( Fig. 2C ) well sclerotized, with body nearly flat, rounded posteriorly, 0.7 times as long as wide, and covered with many minute setae medially; arms divergent outward; ventral plate in lateral view ( Fig. 2G ) covered with many microsetae medially; ventral plate in end view ( Fig. 2H ) with body triangular. Median sclerite in lateral view ( Fig. 2G ) arising slightly anterior to anterior margin of body of ventral plate, directed posteriorly; median sclerite in ventral view ( Fig. 2I ) plate-like, nearly parallel-sided in middle, then somewhat widened apically. Paramere in caudal view ( Fig. 2J ) with enlarged basal portion and with several distinct hooks and several smaller ones. Aedeagal membrane ( Fig. 2J ) moderately covered with minute setae, and with moderately pigmented dorsal plate in form of horizontal bar ( Fig. 2K ). Abdominal segment 10 ( Fig. 2L, M ) without distinct hairs on ventral surface. Cercus ( Fig. 2L, M ) small, rounded, with 10 distinct hairs.

Pupa. Body length (excluding gill filaments) 3.1–3.5 mm. Head. Integument ochreous to medium brown except ventral surface yellow and bare: frons ( Fig. 3A ) with two bifid medium-long trichomes on each side, though one female pupa with additional unbranched trichome between frontal trichomes and facial one on left side; face with bifid medium-long trichome ( Fig. 3A ) on each side. Thorax ( Fig. 3B, C ). Integument ochreous except anterior narrow portion medium brown, with large anterolateral ridge on each side, and bare except small portion near base of gill on each side densely covered with tubercles, and posterior half of dorsal surface sparsely or moderately covered with small tubercles; thorax with three quadrifid or quinquefid (rarely trifid) anterodorsal trichomes, two quadrifid or quinquefid anterolateral trichomes, one unbranched or bifid mediolateral trichome, and three ventrolateral trichomes (three bifid, or two bifid and one unbranched), on each side; all trichomes long or mediumlong. Gill ( Fig. 3B, C ) with six slender short thread-like filaments in pairs arising from base; dorsal and ventral pairs short stalked and middle pair almost sessile; all filaments unpigmented, subequal in length (1.0 mm or little shorter), slightly widened for short distance from base, nearly parallel-sided up to more or less basal one-third, then gradually tapered toward apex, and most of apical half flattened; outer filament of dorsal pair and outer filament of ventral pair divergent basally at angle of 160 degrees when viewed laterally; cuticular surface with well-defined annular ridges and furrows throughout their length except apical portions less distinct, covered with minute tubercles. Abdomen. Dorsally, entire surface of segment 1 and anterior one-third of segment 2 light brown, other segments unpigmented; segment 1 smooth (without tubercles), with one unbranched slender medium-long seta on each side; segment 2 smooth, with one unbranched slender short seta, five unbranched short setae, of which four are stout, on each side; segments 3 and 4 each with four unbranched hooked spines and one unbranched short seta on each side; segments 7–9 each with distinct spine-combs in transverse row on each side; segments 5–9 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 hooks submedially and few unbranched short setae on each side; segments 6 and 7 each with pair of unbranched inner and outer hooks widely spaced and few unbranched short setae on each side; segments 4–8 each with comb-like groups of minute spines. Cocoon ( Fig. 3D ). Wall-pocket-shaped, thickly woven, with several small open spaces anterolaterally, ochreous, not extended ventrolaterally; individual threads invisible; 3.5 mm long by 2.0 mm wide.

Mature larva. Unknown.

Type material. HOLOTYPE: Female (with its associated pupal exuviae and cocoon) in 80% ethanol, reared from a pupa collected from a stream (24°15'46.3" N, 121°15'54.9" E), Fuxing Road, Heping District, Taichung City, Taiwan, 4-X-2013, by Y.- T. Huang . PARATYPE: One male (with its associated pupal exuviae and cocoon) in 80% ethanol, same data as those of the holotype. These type specimens are deposited at Institute of Biological Sciences , Faculty of Science, University of Malaya .

Biological notes. The pupae of this new species were collected from grasses trailing in the water of a moderately flowing stream (width 2 m, water temperature 20.5˚C, partially shaded, elevation 958 m above sea level). The associated species was S. sakishimaense Takaoka.

Distribution. Taiwan.

Etymology. The species name taichungense refers to the city, Taichung, where this new species was collected.

Remarks. Simulium taichungense sp. nov. is assigned to the S. crocinum species-group of the subgenus Simulium , defined by Takaoka (2017), based on the female cibarium without a median process ( Fig. 1B ), claw simple, ovipositor valve broad, triangular and thick, with bare and transparent portions along the inner and posterior margins ( Fig. 1D ); the male style with a long basal protuberance ( Fig. 2E ), ventral plate with its body nearly quadrate and flat, and lacking teeth on its posterior margin ( Fig. 2C ); and the pupal gill with six filaments ( Fig. 3B, C ) and pupal abdomen without terminal hooks.

This new species is characterized by the pupal gill with six unpigmented filaments and pupal abdomen with distinct spine-combs on the dorsal surface of segments 7–9, by which it is easily distinguished from all 21 species (except S. vietnamense Takaoka, Sofian-Azirun & Chen from Vietnam, of which the pupa is unknown) in the S. crocinum species-group including S. serenum and S. ufengense , both from Taiwan ( Huang and Takaoka, 2009a, b; Takaoka, 1979). The pupae of the known species in this species-group have the gill with six filaments, of which at least two or three are pigmented, and spine-combs only on segment 8 or on segments 7 and 8.

This new species is distinguished from S. ufengense in the female by the mid tibia entirely yellow (yellow except the apical cap light brown in S. ufengense ) and in the male by the fore femur yellow except the apical cap medium brown (entirely yellow in S. ufengense ); and from S. (S.) serenum in the female by the fore femur and mid tibia entirely yellow (yellow with the apical cap medium brown or light brown in S. serenum ) and in the male by the fore basitarsus 5.1 times as long as its greatest width (6.0–6.5 times in S. serenum ).

The female of S. vietnamense is readily distinguished from this new species by the scutum covered with brassy short recumbent hairs, basal portion of the radial vein with hairs on the apical half to three-fourths, and hind tibia darkened on the apical three-fifths of the outer surface ( Takaoka et al., 2014).

Figures

FIGURE 1. Female of Simulium taichungense sp. nov. (A) Third segment of maxillary palp with sensory vesicle (right 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) & (G) Paraprocts and cerci (F, ventral view; G, lateral view). (H) Spermatheca. Scale bars: 0.1 mm for C; 0.02 mm for A, B and D–H.

FIGURE 2. Male of Simulium taichungense sp. nov. (A) Third segment of maxillary palp with sensory vesicle (right side; front view). (B) Hind basitarsus and second tarsomere showing calcipala and pedisulcus (right side; outer view). (C) Coxites, styles and ventral plate (ventral view). (D)–(F) Styles (right side; D, ventrolateral view; E, medial view; F, caudal view). (G) Ventral plate and median sclerite (lateral view). (H) Ventral plate (caudal view). (I) Median sclerite (ventral view). (J) Paramere and aedeagal membrane (left side; caudal view). (K) Dorsal plate (ventral view). (L) and (M) Abdominal segment 10 and cerci (right half; L, lateral view; M, caudal view). Scale bars: 0.1 mm for B; 0.02 mm for A and C–M.

FIGURE 3. Pupa of Simulium taichungense sp. nov. (A) Frons and upper part of face showing trichomes (frontal view). (B) and (C) Anterior half of thorax showing anterolateral ridge, gill filaments and trichomes (B, right side, lateral view; C, left side; dorsal view). (D) Cocoon (lateral view). Scale bars: 1.0 mm for D; 0.1 mm for A–C.