Cytogenetic studies in three Lycosidae species from Argentina (Arachnida: Araneae)

CHEMISQUY, M. A.; RODRÍGUEZ GIL, S. G.; SCIOSCIA, C. L.; MOLA, L. M.

GENETICS AND MOLECULAR BIOLOGY

Año: 2008 vol. 31 p. 857 - 867

1415-4757

Cytogenetic research on family Lycosidae (Arachnida: Araneae) is scarce, and has involved less than 4% of the described species, with the male haploid chromosome numbers ranging from 8+X1X2 to 13+X1X2. Species formerly placed in Lycosa are the more studied ones. The objectives of this work are to analyse and compare the meiotic behaviour of “Lycosa” erythrognatha Lucas, “Lycosa”pampeana Holmberg and Schizocosa malitiosa (Tullgren); and to compare male and female karyotypes together with the characterization of the heterochromatin of “L.” erythrognatha. The males of the three species have 2n=22, n=10+X1X2, telocentric chromosomes, and generally a single chiasma per bivalent. In “Lycosa” pampeana, which is described cytogenetically for the first time, the bivalents and sex chromosomes show a particular clustered arrangement at prometaphase I. The comparison of the male/female karyotypes (2n=22/24) of “Lycosa” erythrognatha revealed that the sex chromosomes are the largest of the complement and that the autosomes decrease gradually in size. The analysis of the heterochromatin amount, composition and distribution with C-, DAPI- and CMA3- banding allowed to characterise the latter species as having scanty, GC-rich heterochromatin in the pericentromeric region of all chromosomes. In addition, the actual occurrence of the genus Lycosa in Southern Hemisphere is discussed.