Cytogenetic Studies on Siberian Spiders

Karyotypes are reported for 24 spider species, of which 1 is represented by juveniles, from Western Siberia (environs of Novosibirsk). Chromosome counts (2n) are as follows: Lycosidae–‐Pardosa agrestis, P. lugubris, P. palustris, and P. plumipes, 28 (males); Hygrolycosa rubrofasciata, 20 (males) and 22 (females); Xerolycosa miniata and X. nemoralis, 22 (males). Thomisidae–‐Misumenops tricuspidatum and Xysticus sp., 23 (males). Linyphiidae–‐Erigone atra, Bolyphantes alticeps, Helophora insignis, and Taranucnus setosus, 24 (males); Neriene clathrala, 25 (males). Tetragnathidae–‐Pachygnatha clercki, 24 (males) and 26 (females); P. listeri, 24 (males). Clubionidae–‐Clubiona stagnatilis, 24 (males). Araneidae–‐Singa hamata, 24 (males). Theridiidae–‐Steatoda grossa, 22 (males) and 24 (females). Some uncommon peculiarities were observed:(1) one specimen of P. lugubris showed the region‐specific chromatin decondensation visible at diakinesis only; (2) tetraploid pachytene and diakinetic cells were found in a male Xysticus sp.; (3) all nuclei of P. listeri contained two trivalents. An analysis of the synaptonemal complexes of three species (Pardosa sp., Tibellus sp., and Steatoda grossa) was also performed.