Description:
Analysis of antigenic proteins in populations of terrestrial and aquatic forms of <em>P. endiviifolia</em> and populations from Japan revealed the antigenic differentiation of the examined samples into two distinct groups. <em>Pellia megaspora</em> from the eastern part of the USA also exhibits a significant antigenic devergence and bears the most resemblance to the group of populations of the aquatic form of <em>P. endiviifolia</em> from Poland and samples from Japan. The observed serological distances between terrestrial and aquatic forms of <em>P. endiviifolia</em> are of the same rank as differences between remaining species of the genus <em>Pellia</em>. Clarification of the nature of the detected serological differentiation in the <em>Pellia megaspora-P, endiviifolia</em>complex will require further studies.