Simulium

Phasuk, J., Chanpaisaeng, J., Adler, P. H. & Courtney, G. W., 2005, Chromosomal and morphological taxonomy of larvae of Simulium (Gomphostilbia) (Diptera: Simuliidae) in Thailand, Zootaxa 1052, pp. 49-60 : 55-57

Simulium sp. A

The arrangement of gill filaments of this species is similar to that of S. varicorne from West Malaysia ( Takaoka and Davies 1995), but the adults differ by having antennae with 11 flagellomeres. The larva has minute, dark, scalelike setae with 3–6 branches on abdominal segments IV–VIII ( Fig. 2 E). The dorsal and middle groups of the gill, each with three filaments, share a short stalk, and the ventral group of two filaments arises from an independent stalk ( Fig. 3 B). The larva is characterized by a deep postgenal cleft, 4.7– 7.0 times as long as the postgenal bridge ( Fig. 4 F).

The chromosomal quality of the slide preparations for this species was poor. Two of 12 larvae were analyzed for major landmarks. The IIS arm has the bulge near the subterminal ring of Balbiani ( Fig. 1 F).

Figures

FIGURE 1. Idiograms of chromosome arm IIS for 12 Simulium species in subgenus Gomphostilbia from Khao Yai National Park, showing relative locations of Ce, centromere; RB, ring of Balbiani; Bu, bulge; Sh, shoestring. A, Simulium angulistylum. B, S. decuplum. C, S. dentistylum. D, S. gombakense. E, S. siamense. F, S. sp. A. G, S. asakoae. H, S. sheilae. I, S. sp. nr. sheilae. J, S. novemarticulatum. K, S. sp. B. L, S. sp. C.

FIGURE 2. Photographs of setae on abdominal cuticle of Simulium species in subgenus Gomphostilbia. A, Simulium angulistylum. B, S. decuplum. C, S. dentistylum. D, S. siamense. E, S. sp. A. F, S. asakoae. G, S. sheilae. H, S. sp. nr. sheilae. I, S. novemarticulatum. J, S. sp. B.

FIGURE 3. Photographs of gill filaments of Simulium species in subgenus Gomphostilbia. A, Simulium angulistylum. B, S. sp. A. C, S. novemarticulatum. D, S. siamense. E, S. sheilae. F, S. sp. nr. sheilae.

FIGURE 4. Photographs of postgenal clefts of Simulium species in subgenus Gomphostilbia. A, Simulium asakoae. B, S. gombakense. C, S. sheilae. D, S. dentistylum. E, S. sp. nr. sheilae. F, S. sp. A.