Simulium angulistylum Takaoka and Davies 1995

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 : 51

Simulium angulistylum Takaoka and Davies 1995

This species was originally described based on the female, male, pupa, and mature larva from West Malaysia ( Takaoka and Davies 1995). The gill has eight short, slender filaments arranged in groups of 3 + 3 + 2 from dorsal to ventral ( Fig. 3 A). Larvae can be identified by the presence of delicate setae with 5–12 (mostly 8–10) branches on abdominal segments V–VIII ( Fig. 2 A).

The polytene chromosomes of this species were figured by Kuvangkadilok et al. (2003), although chromosomes II and III were reversed. In the present study, 15 of 62 larvae were analyzed for major landmarks. The centromere regions of chromosomes I and II are slightly expanded, but the centromere region of chromosome III is not expanded. In the IIS arm, the bulge is central and the ring of Balbiani subterminal ( Fig. 1 A).

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.