Sex chromosome system

Chromosomal characteristics of a Brazilian whip spider (Amblypygi) and evolutionary relationships with other arachnid orders

E. Paula-Neto, Araujo, D., Carvalho, L. S., Cella, D. M., and Schneider, M. C., Chromosomal characteristics of a Brazilian whip spider (Amblypygi) and evolutionary relationships with other arachnid orders, vol. 12, pp. 3726-3734, 2013.

We analyzed mitotic and meiotic cells of a Brazilian amblypygid, Heterophrynus longicornis, using conventional and molecular cytogenetic techniques (Giemsa staining, C-banding, Ag-NOR, and FISH with rDNA probe). This is the first study that focuses solely on amblypygid chromosomes; it was undertaken to add data on cytogenetic knowledge of this group and contribute to the understanding of chromosome evolution in the Arachnida. We found 2n = 66 for male and female individuals, monocentric chromosomes, and absence of morphologically differentiated sex chromosomes.

Chromosomal characteristics and karyotype evolution of Oxyopidae spiders (Araneae, Entelegynae)

L. M. Stávale, Schneider, M. C., Brescovit, A. D., and Cella, D. M., Chromosomal characteristics and karyotype evolution of Oxyopidae spiders (Araneae, Entelegynae), vol. 10, pp. 752-763, 2011.

We made a cytogenetic analysis of four species of Oxyopidae and compared it with the karyotype data of all species of this family. In Hamataliwa sp, the mitotic cells showed 2n♂ = 26+X1X2 and telocentric chromosomes. The 2n♂ = 28, which has been described for only one oxyopid spider, is the highest diploid number reported for this family. Peucetia species exhibited distinct karyotype characteristics, i.e., 2n♂ = 20+X1X2 in P. flava and 2n♂ = 20+X in P. rubrolineata, revealing interspecific chromosome variability within this genus.

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