Penial glands of the Patagonian red snail Odontocymbiola magellanica (Neogastropoda, Volutidae).

BIGATTI, G.; ALFREDO JUAN CASTRO VAZQUEZ

San Juan

Congreso; 2° Reunión Conjunta de las Sociedades de Biología de la República Argentina; 2011

Phylogenetic reconstructions of the Caenogastropoda have paid particular attention to the external morphology of copulatory organs. However, the internal structures (spermiduct, epithelial cover and glands, irrigation and innervations, etc.) are largely unknown, and may be also significant for phylogenetic as well for functional studies. We have recently examined the copulatory organs of two caenogastropod species, Trophon geversianus (Neogastropoda, Muricidae) and Pomacea canaliculata (Architaenioglossa, Ampullariidae) and have found marked differences in the structural plans of these taxa, which are considerably apart in a phylogenetical perspective. In the current study, O. magellanica (Neogastropoda, Volutidae) showed a structural plan similar to that of T. geversianus, in that the penis is an outgrowth of the right side of the neck, which bends rearwards and culminates in a small but distinct genital papilla. It showed, however, two distinct superficial glands, named the ‘distal’ and ‘paradistal’ glands, extending the first through the distal region of the dorsal aspect of the penis, while the second extends close to the internal border of this organ, separated from the distal gland by the sulcus from which the spermiduct was originated. It should be noted that these are ductless glands similar to those found in the penial sheath of P. canaliculata, but which are totally absent in T. geversianus. The richness of morphological characters found in the glands of both P. canaliculata and O. magellanica suggests its usefulness for phylogenetic studies.