Simulium (Eusimulium) jomsomense Takaoka & Shrestha, 2010

Takaoka, Hiroyuki & Shrestha, Suchitra, 2010, New species of black flies (Diptera: Simuliidae) from Nepal 2731, Zootaxa 2731, pp. 1-62 : 8-15

Simulium (Eusimulium) jomsomense Takaoka & Shrestha sp. nov.

Description. Female. Body length 3.2 mm. Head. Slightly narrower than width of thorax. Frons brownishblack, thinly whitish-gray pruinose, not shiny, densely covered with yellow recumbent short hairs interspersed with several dark brown hairs along each lateral margin; frontal ratio 1.66:1.00:2.15. Frons-head ratio 1.00:4.50. Fronto-ocular area ( Fig. 4A) directed laterally and upward, deep, pointed apically. Clypeus brownish-black, thinly whitish-gray pruinose, not shiny, densely covered with yellow short to long hairs. Labrum 0.58 times as long as clypeus. Antenna composed of scape, pedicel, and 9 flagellomeres, medium to dark brown except scape and pedicel yellow. Maxillary palp composed of 5 segments, light to medium brown except segments 1 and 2 ochreous, proportional lengths of 3rd, 4th, and 5th segments 1.00:0.79:2.23; sensory vesicle ( Fig. 4B) greatly enlarged, ellipsoidal, 0.50–0.55 times as long as 3rd segment, and with medium-sized opening medially. Maxillary lacinia with 8–10 inner and 16 outer teeth. Mandible with 18 (left side) or 22 (right side) inner teeth and lacking outer teeth. Cibarium smooth. Thorax. Scutum brownish-black except anterolateral calli dark brown, thinly gray pruinose and shiny on shoulders, lateral surface along lateral margins and on prescutellar area when illuminated at certain angle of light, densely covered with whitish-yellow to yellow recumbent short hairs. Scutellum brownish-black, covered with whitish-yellow short and long hairs. Postnotum brownish-black, gray pruinose, and with submedian patch of whitish-yellow short hairs on each side. Pleural membrane bare. Katepisternum dark brown, longer than deep, shiny when illuminated at certain angle of light, and bare. Legs. Foreleg: coxa and trochanter whitish-yellow; femur whitish-yellow except apical cap medium brown (though yellow on basal 1/2 of outer surface and dark yellow on rest of outer surface from middle to basal edge of apical cap); tibia yellowish-white except base light brown and apical cap medium brown; tarsus dark brown; basitarsus somewhat dilated, 6.58 times as long as its greatest width. Midleg: coxa dark brown; trochanter whitish-yellow; femur whitish-yellow to yellow except apical tip dark brown (though somewhat darker on small portion of posterior surface anterior to apical cap); tibia whitishyellow except apical cap dark brown; tarsus dark brown except little less than basal 1/2 light to medium brown. Hind leg: coxa medium brown; trochanter dark yellow; femur yellow except apical cap dark brown (though light brown on small portion of posterior and outer surface anterior to apical cap); tibia yellow on basal 2/3, light brown on basal 1/2 of rest and dark brown on apical cap; basitarsus yellow to dark yellow except base light brown and apical 1/5 or little more dark brown; rest of tarsus medium to dark brown except basal 1/2 of 2nd tarsomere whitish-yellow; basitarsus ( Fig. 4C) slender, nearly parallel-sided on basal 1/2, then slightly narrowed toward apex, 5.78 times as long as wide, and 0.78 and 0.64 times as wide as tibia and femur, respectively; calcipala ( Fig. 4C) well developed, 0.69 times as long as basal width, and 0.43 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 4C) moderately developed. Claw ( Fig. 4D) with large basal tooth 0.48 times as long as claw. Wing. Length 2.8 mm. Costa with dark brown spinules and light brown hairs except basal portion with patch of yellow hairs. Subcosta with light brown hairs except near apex bare. Hair tuft on stem vein yellow. Basal portion of radial vein fully haired. R 1 with dark brown spinules and light brown hairs. R 2 with light brown hairs only. Basal cell and basal median cell absent. Abdomen. Basal scale medium brown, with fringe of yellow long hairs; dorsal surface of abdominal segments medium to dark brown except tergal plate of segment 2 ocherous; all segments moderately to densely covered with whitishyellow short hairs, interspersed with dark brown short to medium-long hairs dorsally and dorsolaterally on few posterior segments; tergites 8 and 9 slightly shiny when illuminated at certain angle of light; segment 7 with large sternal plate medially. Genitalia. Sternite 8 ( Fig. 4E) weakly to moderately sclerotized except anterior margin well sclerotized (except medial portion), bare medially, and with 37–42 short to long hairs on each side. Ovipositor valves ( Fig. 4E) roughly triangular, rounded medioposteriorly, thin, membranous, densely covered with microsetae interspersed with 15 or 16 short to medium-long hairs; inner margin very weakly sclerotized and narrowly darkened only along basal 1/2. Genital fork ( Fig. 4F) of usual inverted-Y-form, stem slender and well sclerotized; arms of moderate width, with wide apical plate strongly folded anteriorly, bearing small slightly sclerotized projection on anteriror margin. Paraproct in ventral view ( Fig. 4G) short, with anterior surface strongly sclerotized and with almost transparent flat anteroventral surface, of which anteromedial margin rimmed with 14 or 15 medium-long hairs; paraproct in lateral view ( Fig. 4H) slightly produced ventrally beyond ventral margin of cercus, covered with microsetae interspersed with 3 or 4 short hairs on lateral surface. Cercus in ventral view ( Fig. 4G) much longer than paraproct, and strongly curved inward; cercus in lateral view ( Fig. 4H) subquadrate, 0.75 times as long as its basal width, and with numerous fine and stout short to medium-long hairs. Spermatheca ( Fig. 4I) ovoid, well sclerotized, with nipple-like well sclerotized extension at base of duct, with many fissures on surface; internal setae absent; both accessory ducts subequal in diameter to each other, and also to main duct.

Male. Body length 3.3 mm. Head. Somewhat wider than thorax. Upper eye consisting of 18 vertical columns and 20 horizontal rows of large facets. Face brownish-black, gray pruinose. Clypeus brownish-black, gray pruinose, moderately covered with yellow long hairs. Antenna composed of scape, pedicel and 9 flagellomeres, dark brown except scape, pedicel, and extreme base of 1st flagellomere yellow; 1st flagellomere somewhat elongate, 1.80 times as long as 2nd one. Maxillary palp composed of 5 segments, light to medium brown, proportional lengths of 3rd, 4th, and 5th segments 1.00:0.95:2.22; sensory vesicle ( Fig. 5A) medium-sized, globular or ellipsoidal, 0.29 times as long as 3rd segment, with very small opening. Thorax. Scutum black, thinly gray pruinose and shiny on shoulders, along lateral margins and on prescutellar area when illuminated at certain angle of light, densely covered with yellow short recumbent hairs interspersed with yellow long upright hairs on prescutellar area. Scutellum dark brown to brownish-black, with yellow short and long hairs. Postnotum brownish-black, bare. Pleural membrane and katepisternum as in female.

Legs. Foreleg: coxa yellow; trochanter light to medium brown; femur medium brown except apical cap dark brown; tibia light to dark brown except median large portion on outer surface yellowish-white; tarsus dark brown; basitarsus slightly dilated, 8.32 times as long as its greatest width. Midleg: coxa dark brown; trochanter light to medium brown; femur light brown except apical cap dark brown; tibia yellow on basal 1/2 (though base somewhat dark), light to dark brown on apical 1/2 (gradually darkened toward apex) (border of light and dark areas not well defined); tarsus medium to dark brown. Hind leg: coxa dark brown; trochanter medium brown; femur medium brown except apical cap dark brown; tibia yellow on basal 1/3 or little more (though extreme base medium brown) and medium to dark brown on rest; tarsus medium brown except little less than basal 1/2 of 2nd tarsomere yellow; basitarsus ( Fig. 5B) enlarged, spindle-shaped, 4.76 times as long as its greatest width, and 0.80 and 0.83 times as wide as greatest width of hind tibia and femur, respectively; calcipala ( Fig. 5B) well developed, short, 0.75 times as long as its basal width, and 0.29 times as wide as greatest width of basitarsus; pedisulcus ( Fig. 5B) well developed. Wing. As in female except length 2.5 mm and subcosta with 1–3 hairs. Abdomen. Basal scale dark brown, with fringe of yellow long hairs. Dorsal surface of abdominal segments medium brown to brownish-black, moderately covered with yellow short to long hairs interspersed with light to medium brown short hairs on few posterior segments; segments 2 and 5– 8 each with pair of shiny whitish-gray pruinose dorsolateral or lateral spots when illuminated at certain angle of light. Genitalia. Coxite in ventral view ( Fig. 5C) large, rectangular (though tapered near posterior end), 1.46 times as long as greatest width, and moderately covered with distinct hairs on posterior 2/5 of ventral surface; coxite in lateral view ( Fig. 5D) large and rounded; coxite in dorsal view ( Fig. 5E) densely covered with distinct hairs medially. Style in ventral view ( Fig. 5C) and in medial view ( Fig. 5F) short, 0.54 times as long as coxite, tapered toward apex, with single spine subapically, and covered with several short to long distinct hairs mainly on ventrolateral surface; style in lateral view ( Fig. 5D) and in posterolateral view ( Fig. 5G) falcate, markedly curved dorsally in middle, with apex truncated. Ventral plate in ventral view ( Fig. 5C) roughly Y-shaped, with hairy narrow median keel directed posteroventrally, and hairy wide membranous flanges extending along basal arms; basal arms well sclerotized, stout, widely diverged laterally, with dilated apex; ventral plate in lateral view ( Fig. 5H) with wide hairy median keel with round apex; ventral plate in end view ( Fig. 5I) roughly inverted T-shaped, with hairy narrow median keel and hairy membranous flanges extending laterally along posterior margin of basal arms. Median sclerite in lateral view ( Fig. 5H) arising near anterior margin of ventral plate, markedly bent dorsally near apex; median sclerite in end view ( Fig. 5J) well sclerotized, narrow, nearly parallel-sided, though slightly narrowed apically. Paramere in dorsal view ( Fig. 5K) narrow, with 1 long hook directed posterolaterally. Aedeagal membrane ( Fig. 5L,M) transparent, moderately covered with small stout cone-shaped spines as well as comb-like spines; dorsal plate in end view ( Fig. 5M) weakly sclerotized, horizontally spindle-shaped. Abdominal segment 10 without distinct hairs on each side. Cercus ( Fig. 5N,O) well developed, moderately produced posteriorly, with 12 or 13 medium-long to long distinct hairs.

Pupa. Body length (excluding gill filaments) about 3.5 mm. Head. Integument yellowish-brown, moderately covered with round tubercles; antennal sheath almost bare; frons with 2 simple or bifid very long trichomes (1 with coiled apex, 1 with uncoiled apex) ( Fig. 6A) on each side; face with 1 very long simple or bifid trichome with coiled or uncoiled apex ( Fig. 6B) on each side. Thorax. Integument yellowish-brown, moderately (more sparsely on some parts on dorsal surface than on frons) covered with round tubercles, and with 3 very long simple trichomes with coiled apices ( Fig. 6C) mediodorsally, 2 simple trichomes (1 very long with coiled apex, 1 long with uncoiled apex) ( Fig. 6D) anterolaterally, 1 long simple or bifid trichome with uncoiled apex ( Fig. 6E) mediolaterally, and 3 simple trichomes (1 long with coiled or uncoiled apex, 1 long with uncoiled apex, 1 short with uncoiled apex) ( Fig. 6F) ventrolaterally, on each side. Gill ( Fig. 6G,H) with 4 slender thread-like filaments, longer than pupal body, arranged vertically in dorsal and ventral pairs arising from very short common basal stalk; common basal stalk with transparent portion ventrally; stalk of dorsal pair short, nearly as long as common basal stalk, 1.1–1.2 times as thick as interspiracular trunk; ventral pair almost sessile; 2 filaments of dorsal pair lying at vertical plane, subequal in length (5.1 mm including common basal stalk) to each other, 2 filaments of ventral pair lying at oblique plane, subequal in length to each other (4.1 mm including common basal stalk) (measurements based only on 2 intact filaments of male pupal exuviae since apices of all other filaments were cut off); relative thickness of 4 filaments from dorsal to ventral 1:00:1.00:0.88: 0.88 in female pupal exuviae and 1.00:0.94:0.77: 0.82 in male pupal exuviae; dorsalmost filament first directed upward and bent forward, diverging basally from lowermost filament at angle of 90 degrees or little more when viewed laterally; all filaments yellowish-brown, gradually tapered toward apex, furnished with distinct annular ridges and furrows, and densely covered with minute tubercles on outer surface. Abdomen. Dorsally, segments 1 and 2 almost entirely weakly-sclerotized, light yellowishbrown except posterior 1/5 of segment 2 not pigmented, and densely or moderately covered with minute tubercles; segment 1 with 1 medium-long slender simple seta on each side; segment 2 with 1 short simple or bifid seta and 5 short spinous setae (1 of which is somewhat shorter than others) on each side; segments 3 and 4 weakly sclerotized and light brown on anterior 1/5 to 1/4, each with 4 dark stout hooks and 1 short spinous seta on each side; segment 5 slightly darkened along anterior margin, with 1 dark short spinous seta and without spine-combs and comb-like groups of minute spines on each side; segments 6–8 each with spinecombs and comb-like groups of minute spines lying transversely along anterior margin on each side, though distinct spines in spine-combs vary in number between sides and sexes, and among segments, i.e., 1 or 2 on segment 6, 2 or 3 on segment 7 and 2 or 5 on segment 8 in female pupal exuvae, 2 or 3 on segment 6, 6 or 8 on segment 7 and 6 or 7 on segment 8 in male pupal exuviae, and distinct spines also vary in shape from simple or bifid or trifid in male pupal exuviae ( Fig. 6I); segment 9 weakly sclerotized, yellow, with comb-like groups of minute spines on each side and pair of cone-shaped terminal hooks ( Fig. 6J), though those of male pupal exuviae appearing to be somewhat smaller than those of female pupal exuviae. Ventrally, segments 3–8 nearly transparent, segment 9 weakly sclerotized and yellowish-brown; segment 3 with 2 short slender simple setae on each side; segment 4 with 4 short dark simple spinous setae on each side; segment 5 with 2 dark bifid hooks and few short simple spinous setae (dark in female pupal exuviae) on each side; segments 6 and 7 each with 1 dark bifid inner hook and 1 dark simple outer hook, and few short simple spinous setae (dark in female pupal exuviae) on each side; segments 4–8 each with comb-like groups of minute spines. Segment 9 without grapnel-shaped hooklets on each lateral side. Cocoon ( Fig. 6K,L). Simple, wall-pocket-shaped, neatly (in female cocoon) or somewhat roughly (in male cocoon) woven, thin except anterior margin somewhat thickly woven in female cocoon, and not extending ventrolaterally; floor woven on posterior 2/5; individual threads usually visible; 3.5–4.5 mm long by 1.4 mm wide.

Mature larva. Unknown.

Type specimens. Holotype female (with its associated pupal exuviae and cocoon) (preserved in 80% ethanol), reared from pupa collected from a moderately-flowing stream (water temperature 10.0˚C, exposed to the sun, altitude 2,745 m, 28˚78’67.3” N, 83˚73’38.7” E), Jomsom , Mustang, Nepal, 23. IX. 2009 . Paratype: 1 male (with its associated pupal exuviae and cocoon) (preserved in 80% ethanol), same data as those of the holotype .

Biological notes. The pupae of this new species were collected from stalks of grasses trailing in water. No other species was collected.

Etymology. The species name jomsomense refers to the locality name, Jomsom, where this new species was collected.

Remarks. Simulium (E.) jomsomense sp. nov. is assigned to the subgenus Simulium (Eusimulium) , redefined by Adler et al. (2004) by having the female postnotum bearing a patch of hairs on each side, the spermatheca typically with a sclerotized neck ( Fig. 4I), the male ventral plate not lamellate, with a narrow body bearing a haired median keel and elongate stout arms ( Fig. 5C), the style small, short and with an apical spine ( Fig. 5C–G), the paramere with a single hook ( Fig. 5K), the cercus enlarged ( Fig. 5N,O), and the pupal gill with four slender filaments ( Fig. 6G).

This new species is characterized by the combination of the following male characteristics: postnotum without a patch of hairs on each side, hind basitarsus somewhat enlarged and spindle-shaped ( Fig. 5B), ventral plate with a large round median lobe directed ventrally ( Fig. 5C) and hairy membranous flange along the posterior margin of each arm ( Fig. 5I), and aedeagal membrane with relatively large spines as well as comb-like groups of minute spines ( Fig. 5L,M).

The subgenus Eusimulium includes 36 named species which are very similar in adult females, males and pupae to one another. This subgenus is mainly distributed in the Holarctic Region though a few to several species are known in the Neotropical, Ethiopian and Oriental Regions ( Adler & Crosskey 2010).

In the Oriental Region, four species of this subgenus are known ( Adler & Crosskey 2010): S. (E.) angustipes Edwards , widely distributed from western Europe to Kazakhstan, Siberia and Hebei, China (Crosskey et al. 1989), S. (E.) weiningense Chen and Zhang from Guizhou, China ( Chen & Zhang 1997), S. (E.) taipei (Shiraki) from Taiwan ( Shiraki 1935), and S. (E.) satsumense Takaoka from the Nansei Islands, Japan ( Takaoka 1976). The present new species is easily distinguished from S. (E.) angustipes by the enlarged, spindle-shaped male hind basitarsus (c.f., male hind basitarsus is narrow and parallel-sided in S. (E.) angustipes according to Davies (1966)), from S. (E.) weiningense by the female genital fork with a small projection directed anteriorly from each lateral plate, the darker male legs, and the pupal abdominal segment 5 without spine-combs on the dorsal surface, from S. (E.) taipei by the brownish-black female scutum (c.f., reddish brown in S. (E.) taipei according to the original description), and from S. (E.) satsumense by the female ovipositor valve with 15 or 16 short to medium-long hairs and the bicolored male legs (c.f., ovipositor valve is covered with a few long hairs and the male legs are almost entirely black in S. (E.) satsumense ).

In Simla and its surrounding hills, northwestern India, one species was also recorded under the name of S. (E.) aureum Fries , a type species of this subgenus, originally described from western Europe ( Puri 1933). This species appears to be very similar to the present new species in that the ventral plate has hairy membranous flanges along the basal arms and a large round median lobe directed ventrally, and the male hind basitarsus is enlarged. The present new species is barely distinguished from this Indian species by the yellow fore coxa and the hind tibia which is yellow on the basal 1/3 and medium to dark brown on the rest (c.f., the fore coxa is brownish-black and the hind tibia is yellow on the basal 1/2 and brownish-black on the rest according to the description by Puri (1933)). The identification of this Indian species is probably wrong, because S. (E.) aureum has a narrow, parallel-sided male hind basitarsus and a narrow body of the ventral plate when viewed laterally ( Davies 1966). Datta (1985) recorded S. (E.) aureum from Kashimir, northwestern India, while noting that this might be a new species which might prove to be closer to S. (E.) latizonum Rubtsov or S. (E.) rubzovianum (Sherban) , both of which were synonymized as S. (E.) angustipes and S. (E.) velutinum (Santos Abreu) , respectively ( Adler & Crosskey 2010). Simulium (E.) velutinum , a species described from Canary Islands and widespread in the circum-Mediterranean area differs from the present new species by lacking a dark sclerotized nipple-like extension from the spermatheca at the base of the spermathecal duct ( Crosskey 1988).

It is noteworthy that S. (E.) azorense Carlson from Azores Archipelago has the ventral plate with hairy membranous flanges as well as the enlarged male hind basitarsus ( Crosskey 1986), suggesting a close similarity to the present new species. However, S. (E.) azorense apparently differs by having the basal fringe of the male abdomen entirely black.

Simulium (E.) nigrofusipes Rubtsov from Tadzhikistan and Armenia ( Rubtsov 1989) appears to be similar to this new species in having the enlarged, spindle-shaped male hind basitarsus, the female ovipositor valve furnished with numerous hairs, and the female genital fork with a small projection directed from each lateral plate. However, there are differences in the ventral plate between the two species: e.g., S. (E.) nigrofusipes lacks hairy membranous flanges extending along the basal arms.