On the Anatomy and Systematic Position of the Mathildidae (Mollusca, Allogastropoda)

The anatomy of two mathildid species, Opimilda maoria Powell, 1940 and Gegania valkyrie Powell, 1971 has been investigated using serial sections. The mathildid anatomy strongly resembles that of the Architectonicidae, and therefore both families are included in the superfamily Architectonicoidea. The buccal system of Gegania valkyrie is the most primitive of all Allogastropoda (Architectonicoidea and Pyramidelloidea) so far investigated. Reproductive features within with Architectonicoidea vary. Certain species ( Gegania valkyrie ) are hermaphrodites, whilst others ( Opimilda maoria ) appear to be gonochorists; in these species males also possess a (sperm‐filled) receptaculum seminis. Similar genital and reproductive features are found in the prosobranch relict species Campanile symbolicum Iredale, 1917, the systematic position of which is discussed briefly.