ULTRASTRUCTURE OF MINCHINIA SP SPORES FROM SHIPWORMS (TEREDO SPP) IN THE WESTERN NORTH-ATLANTIC, WITH A DISCUSSION OF TAXONOMY OF THE HAPLOSPORIDIIDAE

Electron microscopy of haplosporidan spores from Teredo navalis and T. furcifera revealed 4 distinct membrane‐bound extensions, 1 apical extension opposite the opercular hinge, 1 terminal and 2 opposing lateral extensions. These extensions were not continuous with the spore wall, but contained microtubule‐like structures and degrading epispore cytoplasm. No other known species in the family Haplosporidiidae is characterized by spores possessing four epispore extensions. There are currently two genera in this family, Minchinia and Haplosporidium. The genus Minchinia includes spores such as those of M. chitonis which bear two epispore cytoplasm extensions. Spores of the genus Haplosporidium have been characterized by spore wall derived filaments. A 3rd group of haplosporidan species with spores ornamented by wrappings have traditionally also been assigned to the genus Haplosporidium. Based on the presence of epispore cytoplasm extensions rather than spore wall filaments, the haplosporidan of Teredo spp. can be placed in the genus Minchinia. Copyright © 1990, Wiley Blackwell. All rights reserved