http://www.eje.cz cused on chromosomal races of the obligatory parthenogenetic species Pycnoscelus surinamensis (Linnaeus, 1758) and its bisexual ancestor Pycnoscelus indicus (Fabricius, 1775) (Matthey, 1945(Matthey, , 1948Roth, 1967;Roth & Cohen, 1968) and the description of chromosome numbers and spermatogenesis in other species of cockroaches (Piza, 1958). Signifi cant attention was also given to chromosomal mutations resulting in formation of autosomal multivalents in