Surface Ultrastructure of Spores in Three Genera of Balanosporida, Particularly in Minchinia armoricana Van Banning, 1977. The Taxonomic Significance of Spore Wall Ornamentation in the Balanosporida

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Abstract
The surface ultrastructure of mature spores of M. armoricana was examined and differed from spores of other Balanosporida. Two groups of cylindrical fibers, 32-135 nm diameter, were attached to the main spore wall beneath the operculum and to the posterior end of the spore. The fibers aggregated distally to the points of attachment to form the 2 prominent extensions that typify the genus. The substructure of each fiber consisted of a coiled ribbon, 5.1-8.8 nm diameter, embedded in a granular matrix. Arguments are presented for considering the epispore ornamentation of Balanosporida to be species specific. Using the criterion the validity of the species Urosporidium jiroveci and Haplosporidium cadomensis is questioned. In support of that position, descriptions are presented concerning selected fine structures of the spore walls of Urosporidium sp. from Microphallus sp. in the shrimp, Palaemonetes pugio and Haplosporidium sp. from the mud crab, Panopeus herbstii.