Comparative Studies on Ancylostoma braziliense and Ancylostoma ceylanicum. I. The Adult Stage

Abstract

Laboratory strains of Ancylostoma braziliense Gomes de Faria, 1910, and Ancylostoma ceylanicum Looss, 1911, originally obtained from domestic cats in Malaysia and Taiwan, respectively, were maintained in experimentally infected dogs and cats. Examination of adult worms revealed new morphological differences. When killed in hot water and preserved in 10% formalin, the female worms of A. braziliense usually were sharply flexed ventrally at the level of the vulva whereas those of A. ceylanicum were not, and in A. braziliense both sexes were relatively slender. In addition, the distance between transverse cuticular striations in A. ceylanicum was approximately twice that seen in A. braziliense. Moreover, a small tubercular process on the lateral margin of the buccal capsule in A. braziliense was not found in A. ceylanicum. By these features it was easy to distinguish A. braziliense from A. ceylanicum. Previously the size of the teeth was the only known differential feature in the female. The conclusion of Biocca (1951) that Ancylostoma braziliense Gomes de Faria, 1910, and Ancylostoma ceylanicum Looss, 1911, are distinct species has gained general acceptance among parasitologists (Yoshida, 1965). However, the described differences between these two hookworms are essentially limited to the shape of the teeth and copulatory bursa of the adult worms. Distinctive features of the bursa make species recognition of the male relatively easy, but the shape of the teeth is difficult to differentiate (Velasquez and Cabrera, 1968) and, therefore, the identification of females may be unreliable. The writer and his co-workers have carried out a series of studies to further characterize and differentiate A. braziliense and A. ceylanicum in both the adult and larval stages. The present report describes some new morphological differences in the adult worms.