Acta Protozool. (2006) 45: 301 - 312 New Data to the Shell Ultrastructure and the Biometry of the Marine Interstitial Testate Amoebae (Rhizopoda: Testaceafilosia) Vassil GOLEMANSKY and Milcho TODOROV Institute of Zoology, Bulgarian Academy of Sciences, Sofia, Bulgaria Summary. The data about the shell ultrastructure of 6 interstitial testate amoebae: Chardezia caudata, Psammonobiotus balticus, P. golemanskyi, Corythionella minima, C. pontica and Micramphora pontica is presented for the first time. A biometric analysis of all of them, found in rich populations in the North-Eastern Black Sea littoral, is also accomplished. On the basis of the present investigations some morphometric descriptions and taxonomic diagnoses of the studied interstitial testate amoebae are supplemented and corrected. The summarized data on their geographical distribution so far in the World Ocean is given, too. Key words: biometry, distribution, shell ultrastructure, taxonomy, testate amoebae. INTRODUCTION The marine interstitial testate amoebae form a spe- cific taxocenose in the underground waters of the marine sand supralittoral. They became a subject of more detailed investigations only in the last four de- cades. The morphological descriptions and taxonomic diagnoses of most of the taxa reported so far have been performed mainly by light microscopy. Because of that, the information about some essential details of the shell morphology, the structure and the character of the idiosomes and xenosomes, forming the shells, is scanty and incomplete. As a result the taxonomic status of some of the established taxa and their phylogenetic relations with close genera and species are still unclear. Eighty psammobiotic interstitial testate amoebae from the marine sand supralittoral have been established so far, but more detailed information about their structure and ultra-morphology has been given only for 26 of them (Golemansky and Ogden 1980; Golemansky and Coûteaux 1982; Ogden and Coûteaux 1986, 1989; Ander- son et al. 1996; Golemansky and Todorov 1996, 2004). Further investigations on the ultra-morphology of other taxa of this group (especially of genera and species with problematic systematic status) are necessary, so that, the taxonomic problems with the marine interstitial testate amoebae and their relations with the freshwater testate amoebae can be solved and explained. Address for correspondence: Vassil Golemansky, Institute of Zoology, Bulgarian Academy of Sciences, 1 Tsar Osvoboditel Blvd., 1000 Sofia; Fax: (3592) 9888-28-97; E-mail: golemansky@zoology.bas.bg; mtodorov@zoology.bas.bg