TAXA DELIMITATION IN REBOULIA INVESTIGATED WITH MORPHOLOGICAL, CYTOLOGICAL, AND ISOZYME MARKERS

Taxa delimitation in Reboulia is investigated with morphological analy ses, chromosome counts, and variation in isozyme patterns. The formerl y single, polymorphic species attributed to the genus, Reboulia hemisp haerica, recently subdivided into several taxa, is shown to comprise f our genetically distinct entities, one polyploid and three haploids. G enetic similarity coefficients between the haploid electrophoretic gro ups were below 0.550. the polyploid was formerly described as Reboulia queenslandica or R. hemisphaerica var. australis from Australia and N ew Zealand. It is suspected to have originated from an intercross betw een two of the haploid groups, as inferred from allelic constitution. One of the putative haploid progenitors is widespread in Europe, Asia, Africa, and America and fits the definition of Reboulia hemisphaerica in the strict sense. A morphologically indistinct sibling component o f this latter taxon has been detected in the western Mediterranean are a. The other putative haploid progenitor is distributed in Japan and c orresponds morphologically to R. hemisphaerica var. orientalis. Uncert ainty as to the priority of names precludes at present conclusive stat ements on the nomenclatual status of these genetic entities. Gene dive rsity statistics were calculated only for Reboulia hemisphaerica in th e strict sense, confirming that marchantialean liverworts are less pol ymorphic than mosses.