Comparative cytogenetics of the primitive frog, Leiopelma archeyi (Anura, Leiopelmatidae)

Publisher Website
Google Scholar
Abstract
Chromosomally, Leiopelma archeyi is extremely similar to L. hamiltoni, a closely related species. Both have 2n = 18 chromosomes. Contrary to a previous report, the nucleolar organizer region and secondary constriction in L. archeyi are near the telomere of the smallest, telocentric chromosome, as in L. hamiltoni. The arm-length ratios of all chromosomes are virtually identical in the two species, expect for chromosomes 2 and 3, which show evidence of a past translocation. However, L. archeyi has much less heterochromatin than does L. hamiltoni, and, unlike L. hamiltoni, heteromorphic sex chromosomes are not discernable. These frogs demonstrate two stages in the evolution of sex-chromosome differentiation related to the extent of heterochromatin accumulation.