Simulium undecimum, Takaoka, Srisuka & Saeung, 2018

Adler, Peter H., Srisuka, Wichai, Low, Van Lun, Takaoka, Hiroyuki & Saeung, Atiporn, 2019, High-Elevation Chromosomal Diversity of Black Flies (Diptera: Simuliidae) in Thailand, Insect Systematics and Diversity 3 (2019), No. 1, pp. 1-10 : 2-3

Simulium undecimum

The banding patterns of all 54 chromosomally prepared larvae ( 28 females and 26 males) were fully analyzed, including two females infected with mermithid nematodes. The patterns corresponded precisely with the banding sequence of S. malayense cytoform B described by Thaijarern et al. (2018) as having the following fixed inversions: IIS-1, IIS-2, IIS-3, IIL-1, IIIL-3, IIIL-5, IIIL-6, and IIIL- 10. Among the nuclei in individual larvae, ectopic pairing was absent or expressed among any or all combinations of the thick, darkly staining centromere bands. Homologs were 98–100% paired along their lengths. We found a small, glassy band, not previously reported,

a Identification confirmed by association of gill histoblasts from one mature larva with two pupal exuviae.

b The larva of this species is undescribed; identification was made based on the gill histoblast of one mature larva. in section 66 of IIL in all larvae ( Fig. 2C ), possibly reflecting enhanced polytenization or nucleotide content. Sex chromosomes were microscopically undifferentiated (X 0 Y 0) and polymorphisms were absent.

Figures

Fig. 2. Species-specific chromosomal sequences of species from Doi Inthanon,Thailand. (A) IS base of Simulium tenebrosum cytospecies B (female larva), with bracket indicating limits of IS-33; C, centromere. (B) IIIL end of S. kiewmaepanense (male larva), showing IIIL-1 sequence (bracketed). (C) IIL distal half of S. undecimum (male larva) with bracket indicating limits of IIL-1 and enhanced, glassy band (+). (D) IIS of S. kiewmaepanense (male larva) showing IIS-1, IIS-2, IIS-3 sequence.The sequence involves two coincident breakpoints.Thus, for the hypothesis shown, inverting IIS-3 will create the e/g junction representing the IIS-1 break proximal to the centromere; when IIS-2 is then inverted, it creates the h/f junction representing the IIS-1 break distal to the centromere.The Simulium subgeneric standard sequence is, thus, obtained by alphabetically ordering the fragments indicated by the letters a–h; bu, bulge; C, centromere; RoB, ring of Balbiani.