Taxa delimitation in Reboulia investigated with morphological, cytological, and isozyme markers

Taxa delimitation in Reboulia is investigated with morphological analyses, chromosome counts, and variation in isozyme patterns. The formerly single, polymorphic species attributed to the genus, Reboulia hemisphaerica, recently subdivided into several taxa, is shown to comprise four genetically distinct entities, one polyploid and three haploids. Genetic similarity coefficients between the haploid electrophoretic groups were below 0.550. the polyploid was formerly described as Reboulia queenslandica or R. hemisphaerica var. australis from Australia and New Zealand. It is suspected to have originated from an intercross between 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 of this latter taxon has been detected in the western Mediterranean area. The other putative haploid progenitor is distributed in Japan and corresponds morphologically to R. hemisphaerica var. orientalis. Uncertainty as to the priority of names precludes at present conclusive statements on the nomenclatual status of these genetic entities. Gene diversity statistics were calculated only for Reboulia hemisphaerica in the strict sense, confirming that marchantialean liverworts are less polymorphic than mosses.