Stoecharthrum monnati sp. nov., a parasite of the bivalve Lucinoma borealis in Brittany, is similar to S. giardi, the type species of the genus, except in being longer and in having more oocytes and more rings of epidermal cells. In Stoecharthrum fosterae sp. nov., found in the bivalve Mytilus trossulus in Puget Sound, Washington, and S. burresoni sp. nov., found in the ascidian Ascidia callosa on San Juan Island, Washington, the oocytes are crowded into the axial mass instead of being arranged in a single row as they are in S. giardi and S. monnati. In addition, their bodies are proportionately less slender and their patterns of ciliation are appreciably different. The definition of the genus Stoecharthrum has therefore been slightly modified. |
