Preliminary studies of the chromosomes of twelve cockroach species (Blattaria: Blattidae, Blattellidae, Blaberidae).

A preliminary survey of mitotic and meiotic cells from 12 cockroach species was made. Cells were obtained from embryonic and testicular tissues and were prepared by the squash technique. Haploid and diploid numbers were either established or confirmed for each species. Diploid numbers ranged from 20 in Supella to 74 in Blaberus , with numbers of 24 and 28 being common to several species. Chromosome size appeared to vary inversely with chromosome number. The XO sex determination mechanism was confirmed, and the X chromosome was identified in at least 2 species. Observations on centromere location and on certain unusual chromosome situations are also presented.