Open Access

Jan-Peter Frahm

• The habitat as well as the unicellular thallus margins of Aneura maxima lead to the assumption that this species could be a hygromorphosis of A. pinguis. Therefore specimens of A. pinguis were cultivated in water. Even after four months the multicellular thallus margins were retained, which proved to be a stable character to separate A. pinguis from A. maxima. Therefore plants even with a small unistratose border, which are attributed to aquatic forms of A. pinguis, may belong to A. maxima. It is supposed that A. maxima was overlooked in Europe but regarded as aquatic forms of A. pinguis named as fo. rivularis. Such plants show unicellular thallus margins and are regarded as hygrophytic form of A. maxima. The presence viz. absence of an unicellular thallus margin seems to be a sufficient character to separate both species. The discussion about the width of the unistratose thallus margin is useless because the type of A. maxima has only 2-4 rows of unicellular cells and not 6-12 or more as attributed by European hepaticologists. This raises doubts whether the European material is identical with A. maxima rather with A. pellioides from Japan.