The equine parasites which have so far been classified as belonging to the single species Parascaris equorum (Goeze) have been shown to belong to two distinct species on the basis of morphological and karyological characters, and of the electrophoretic study of 27 enzyme loci. The name Parascaris univalens is proposed for the species with distally truncated spicula and karyotype 2 n = 2. The name “univalens” was used by Hertwig in 1890 to indicate horse ascarids with this karyotype. A complete description...
The karyotypes of the two sibling species Parascaris equorum and P. univalens are illustrated, as well as their chromosome morphology. The chromosomes are characterized by heteropycnotic extremities and the absence of a well-defined centromerical zone. Furthermore in P. equorum one chromosome pair appears distinctly longer than the other, which would exclude the evolution of this species by a simple process of tetraploidization; this is also ruled out by the electrophoretic data. The electrophoretic...
The taxonomy of the genus Bulinus is re-examined on the basis of morphology and of electrophoretic study of 20 gene-enzyme systems. The genus is at present divided into two subgenera: Bulinus and Physopsis. According to Mandahl-Barth the first subgenus is made up of three groups of species (the tropicus, truncatus and forskalii groups), while the species of the second subgenus are united in a fourth group (africanus). We have studied various species and subspecies belonging to the two subgenera...
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