New karyotypes and C-banding patterns of the subterranean rodents of the genus Ctenomys (Caviomorpha, Octodontidae) from Argentina

Evolutionary relationships of Ctenomys (Rodentia: Octodontidae) from Argentina, based on penis morphology

“…This main division into two groups agrees with data on chromosome banding patterns of heterochromatin (Reig et al 1992) and shape of sperm (Feito and Gallardo 1982, Vitullo et al 1988, Ortells 1990, Vitullo and Cook 1991. Within the group of spike-bearing species, C. australis, C. azarae, and C. porteoisi also share a heterochromatin pattern type III (full arm type 3 C-bands present in most extensions of short arms in 50 to 75% of the chromosomes) and asymmetric type of sperm (Reig et al 1992).…”

“…In the group of species exhibiting spiny bulbs, C. dorbignyi, C. pearsoni, C. roigi and Ctenomys sp. from Curuzu Laurel and San Roque, also share a heterochromatin pattern I (C-bands fully negative n most chromosomes) and symmetric type of sperm (Reig et al 1992). Ortells and Barrantes (1994) also recognize a similar assemblage in the species from Corrientes province using allozyme data.…”

“…Within the group of spike-bearing species, C. australis, C. azarae, and C. porteoisi also share a heterochromatin pattern type III (full arm type 3 C-bands present in most extensions of short arms in 50 to 75% of the chromosomes) and asymmetric type of sperm (Reig et al 1992). In the group of species exhibiting spiny bulbs, C. dorbignyi, C. pearsoni, C. roigi and Ctenomys sp.…”

“…4). Ctenomys talarum also has high variability in diploid and autosomal number of chromosomes (2n = 46-50, FN = 73-86) and in heterochromatin banding patterns (Reig et al 1992). Analysis of sperm morphology indicates within population variation and an irregular symmetric spermatozoa (Vitullo et al 1988).…”

“…One sign of the high variability in this genus is its karyotypic heterogeneity, with diploid numbers ranging from 10 to 70 (Reig et al 1990). The high rate of diversification in Ctenomys, its variability in chromosome numbers, patterns of heterochromatin banding, presence of highly repetitive DNA sequences, and other cytogenetic traits (Reig et al 1992) suggests that chromosomal evolution has accelerated the rate of speciation in the genus (Ortells 1990, Reig et al 1990, Ortells and Barrantes 1994, Ortells 1995. Morphological variation within the genus, evidenced by the large range in body size (from 100 to 1100 g in weight), has not been thoroughly studied, and the extent to which it parallels karyotypic variability remains largely unknown.…”