Simulium (Montisimulium) xinzhouense Chen and Zhang

Han-Bin, Chen, Guo-Sheng, Lian & Chun-Lin, Zhang, 2011, A faunal summary of Simulium (Montisimulium) with descriptions of five new species from China (Diptera: Simuliidae), Zootaxa 3017, pp. 51-68 : 54-55

Simulium (Montisimulium) xinzhouense Chen and Zhang , sp. nov.

( Figs. 1–13 )

Female. Body length about 3.5 mm. Wing length 3.0 mm.

Head. Narrower than thorax. Frons and clypeus dark brown, with golden yellowish hairs as well as sparse black ones; frontal ratio 7.6:4.7:7.9; frons-head ratio 7.6:32.7. Antenna composed of 2 +9 segments, brown except scape yellowish brown. Maxillary palp greyish brown, with proportional length of 3rd to 5th segments 5.2:5.8:15.9; 3rd segment somewhat enlarged, with elongated sensory vesicle, ca. 0.65X length of respective segment. Maxilla with 12 outer teeth and 9 inner ones. Mandible with 24 inner teeth and no outer ones. Cibarium unarmed.

Thorax. Scutum brownish black, covered densely with golden pubescence as well as sparse erect black hairs on prescutellar area. Scutellum grayish with sparse golden pubescence and black erect hairs. Postscutellum brown and bare. Pleural membrane and katepisternum bare. Legs: All coxae and trochanters brown except fore trochanter pale. All femora pale with distal 1/3 brownish black. All tibiae brown, except for large pale medial portions of outer surface. All tarsi brown except hind basitarsus and basal 2/5 of second tarsomere pale. Fore basitarsus slen- der, about 8.0 times as long as wide. Hind basitarsus nearly parallel-sided, about 7.5 times as long as wide. Calcipala enlarged, pedisulcus developed. Each claw with large basal tooth ca. 1/ 3X length of claw. Wing. Costa with spinules as well as hairs. Subcosta hairy. Basal section of radius full haired. Hair tuft at stem vein brown.

Abdomen. Basal scale grayish brown with a fringe of brownish yellow hairs. Terga brownish black with dark hairs. Genitalia: Sternite 8 with about 40 long black hairs on each side. Anterior gonapophyses tongue-shaped, inner margins narrowly sclerotized and posterior borders rounded. Genital fork with sclerotized slender stem; arms moderately wide and each with strongly sclerotized posterolateral margin but devoid of projection directed forwards. Spematheca nearly globular in shape, sclerotized with reticulate pattern. Paraproct and cercus of moderate size.

Male. Body length about 4.0 mm. Wing length about 3.2 mm.

Head. Width equal to that of thorax. Upper-eye consisting of 17 vertical and 18 horizontal rows of large facets. Clypeus black grey with sparse brownish black hairs. Antenna composed of 2+9 segments, all brown except for pale scape; 1st flagellomere about 2.0 times as long as next one. Maxillary palp with 5 segments, sensory vesicle small, about 0.23 times as long as 3rd segment.

Thorax. Nearly as in female except hind basitarsus somewhat inflated, about 4.0 times as long as wide, and subcosta of wing bare.

Abdomen. As in female. Genitalia: Gonocoxite subconical, about 1.4 times as long as wide. Gonostylus small, about 0.6 length of gonocoxite, abruptly narrowed apically and with apical spine; when viewed ventrolaterally, gonostylus with a directed outwards subapical rounded projection which has 4 or 5 small stout teeth. Ventral plate lamellate, much wider than long, with a distal margin concave and proximal margin convex medially; lateral margin each having horn-like subapical process; basal arms about 0.6 length of plate body and converging apically. Parameres each with 5 or 6 strong parameral teeth. Median sclerite slender.

Pupa. Body length about 4.0 mm.

Head and thorax. Integument pale brown, densely covered with small tubercles. Trichomes simple and very minute. Gill organ with 8 filaments arranged in following way: from fairly short stalk 2 branches arise in upper and lower groups; upper one divided into 2 branches (2+3) and lower one divided again into 2 braches (2+1). All 8 filaments on either side uniformly covered with numerous black conical tubercles.

Abdomen. Terga 1–2 tuberculate; tergum 2 with 5 short slender setae and 1 longer seta on each side; terga 3 and 4 each with 4 hooked spines on each side; terga 5–8 each with spine-combs per side; tergum 9 with pair of well-developed terminal hooks. Sternum 5 with pair of bifid hooks submedially; Sterna 6–7 each with pair of bifid hooks widely spaced on each side. Cocoon: Wall-pocket-shaped, tightly woven, slightly extending ventrolaterally, with small anterodorsal projection.

Mature larva. Body length about 6.5–7.0 mm. Cephalic apotome yellowish brown with faint positive head spots. Antenna with 3 segments and terminal sensory organ; proportional lengths of 3 segments = 5.1:6.3:4.8; much longer than stem of labral fan. Labral fan with about 30 main rays. Mandible with comb teeth unequal in length, first tooth longer than others, 2nd and 3rd subequal in length. Mandibular serrations composed of one large and one small tooth, lacking supernumerary serrations. Hypostomal teeth 9 in number, corner and median teeth strongly prominent and intermediate ones smallest; 7 hypostomal setae on each side lying subparallel to lateral margins; lateral serrations weakly developed. Thoracic and abdominal integument bare. Rectal gill compound, each with 6–11 finger-like secondary lobes. Anal sclerite X-shaped with anterior arms about 0.6 times as long as posterior ones. Posterior circlet with about 88 rows of up to 16 hooklets per row. Ventral papillae well developed.

Type materials. Holotype Ƥ, reared from pupa, slide-mounted, was collected on a stone in a fast-flowing small stream from Wutaishan (113°25ʹE, 38°73ʹN, 2600 m), Xinzhou City, Shanxi Province, China, 22 July 2007, by Lian Guo-Sheng. Paratypes: 1033, 28 pupae and 4 larvae, all slide-mounted, same date as holotype.

Distribution. Shanxi Province, China.

Remarks. This new species seems to fall into the subgenus Montisimulium of the genus Simulium by the shape of the genitalia of both sexes, as defined by Rubtsov (1974). It is characterized by having 8 pupal filaments. This character is also shared by several known Montisimulium species, such as S. (M.) brachystylum , S. (M.) ocreastylum , S. (M.) octofiliatum from Tajikistan and S. (M.) sonkulense from Kirghizia. The new species, however, can be separated from all the related species mentioned above by features of the genitalia in both sexes, such as the shape of the female spermatheca and the male gonostylus, ventral plate and median sclerite.

Etymology. The specific name was given for its type locality.

Figures

FIGURES 1 – 13. S. (M.) xinzhouense Chen and Zhang, sp. nov. 1. Female genitalia; 2. Female cibarium; 3. Female sensory vesicle; 4. Claw of female; 5. Gonocoxite and gonostylus of male; 6. Ventral plate; 7. Median sclerite; 8. Paramere; 9. Cocoon in dorsal view; 10. Filaments; 11. Larval head capsule in ventral view; 12. Larval mandible; 13. Larval anal sclerite.