Parasitology, Harold W. Manter Laboratory of
Date of this Version
1982
Abstract
Apparent common architectural constraints in the structure of the bothridia of both species of Dioecotaenia permit testing of a number of models for the evolution of the scolex of Dioecotaenia from that found in other tetraphyllidean cestodes. Although presently known species of Dioecotaenia exhibit bothridialloculi in the shape of hexagons, derivation of those bothridia from an ancestor possessing a single central hexagonal bothridium with marginal loculi would not produce total bothridialloculi numbers consistent with those known. A more feasible derivation involves an ancestral form exhibiting three linear loculi. If the loculi are arranged vertically, as in species of Rhinebothrium, orientation of the bothridia would have undergone a 90° shift in orientation at some point to achieve the orientation seen today in Dioecotaenia spp. If the bothridialloculi were arranged horizontally, simple addition of rows of three loculi, with subsequent modification of their shape into hexagons permitting closer packing, would account for the observed bothridial morphology. Tritaphros retzii, a parasite of European rajiform elasmobranchs, exhibits three bothridialloculi arranged horizontally.
Comments
Published in Proceedings of the Helminthological Society of Washington 49(1), 1982, pp. 56-61