An electron microscope study of the karyotypes of two wolf spiders

Abstract

Meiosis in two species of wolf spiders, Lycosa georgicola Walckenaer and Lycosa rabida Walckenaer, has been analyzed by light and electron microscopy. Both karyotypes comprise 13 autosomal pairs + X1X2, all except one pair of which are telocentric. The autosomes show a gradual increase in size ranging from 5.6 to 9.9% of the total genome length. The two X chromosomes of L. rabida are not significantly different in length. In both species, the two X chromosomes are loosely aligned at prophase, but never synapse in the true sense; they do not form synaptonemal complexes. This supports the evidence that X1 and X2 are not homologous. In L. georgicola, one of the X's is associated at prophase with one autosomal pair, but this association does not persist to prometaphase.