Haplodiploidy in Aspiculuris tetraptera (Nitzch) (Heteroxynematidae) and Syphacia obvelata (Rudolphi) (Oxyuridae), nematode (Oxyurida) parasites of Mus musculus

Abstract

Cytological aspects of gametogenesis are studied in the common oxyuroid (Nematoda) parasites of Mus musculus, Syphacia obvelata (Oxyuridae) and Aspiculuris tetraptera (Heteroxynematidae). Both species are shown to be haplodiploid: males develop from unfertilized eggs and are haploid and females develop from fertilized eggs and are diploid. In female A. tetraptera there are 12 chromosomes in oogonial divisions; meiosis is normal and six bivalents were observed in ova. There are two maturation divisions and embryos in eggs in utero contain 6 or 12 chromosomes. In males, there are six chromosomes in spermatogonial divisions; there is a single maturation division and all spermatozoa have six chromosomes. Gametogenesis was similar in Syphacia obvelata but the chromosome numbers are four in males and eight in females.