Cytogenetic studies of three Lycosidae species from Argentina (Arachnida, Araneae)

Abstract

Cytogenetic studies of the family Lycosidae (Arachnida: Araneae) are scarce. Less than 4% of the described species have been analyzed and the male haploid chromosome numbers ranged from 8+X1X2 to 13+X1X2. Species formerly classified as Lycosa were the most studied ones. Our aim in this work was to perform a comparative analysis of the meiosis in "Lycosa" erythrognatha Lucas, "Lycosa" pampeana Holmberg and Schizocosa malitiosa (Tullgren). We also compared male and female karyotypes and characterized the heterochromatin of "L." erythrognatha. The males of the three species had 2n = 22, n = 10+X1X2, all the chromosomes were telocentric and there was generally a single chiasma per bivalent. In "Lycosa" pampeana, which is described cytogenetically for the first time herein, the bivalents and sex chromosomes showed a clustered arrangement at prometaphase I. The comparison of the male/female karyotypes (2n = 22/ 24) of "Lycosa" erythrognatha revealed that the sex chromosomes were the largest of the complement and that the autosomes decreased gradually in size. The analysis of the amount, composition and distribution of heterochromatin with C-banding and staining with DAPI- and CMA3- showed that "Lycosa" erythrognatha had little GC-rich heterochromatin in the pericentromeric region of all chromosomes. In addition, the actual occurrence of the genus Lycosa in the Southern Hemisphere is discussed.