Holocentric chromosomes of arachnids: Presence of kinetochore plates during meiotic divisions

An ultrastructural study of holocentric chromosomes during meiotic division I and, for the first time, on meiotic division II of three arachnids (the scorpion Tityus bahiensis and the spiders Dysdera crocata and Segestria florentina) is presented. While the results obtained in spiders are similar to those obtained in species previously analyzed, T. bahiensis is an exception to the rule since it shows kinetochore plates during division I. Furthermore, such plates were observed in the three species during division II.