Polypedilum nubiferhas four polytene chromosomes (2n= 8). A standard chromosome map of the polytene chromosomes and the limits of 29 alternative sequences are described. Phylogenies for the sequences on arms C, E and G are proposed. Sequences C4, E3, Fl and G1 are apparently quite ancient, and therefore probably ancestral, because of their occurrence in widely separated populations in Australia and Israel. There were no common sequences in arms A1, B1 and D1 but sequences A1, B1 and D1 are the most widespread in Australia. P.nubiferis female heterogametic, females always being heterozygous for a heterodhromatinized differential segment 41cY-dY on arm G. On the basis of the differing frequencies of some of the arm G sequences, it is likely that the sex determining regions are included within the differential 41c-d ends.