Abstract
The merits of morphological characters, isozyme patterns and random amplified polymorphic DNA (R.A.P.D.) markers for bryophyte species delimitation were investigated using European species of Porella. Isozymes and R.A.P.D. markers allow rapid detection of genetic differences in morphologically highly-variable groups of organisms. Twenty-two clones of the European Porella species (eight species are currently recognised: P. arborisvitae, P. baueri, P. canariensis, P. cordaeana, P. obtusata, P. pinnata, P. platyphylla, P. platyphylloidea) were investigated together with three populations of Canadian P. platyphylloidea. Isozyme patterns of esterase, glutamate-oxaloacetate transaminase, peroxidase and malate enzyme were studied by electrophoresis. R.A.P.D. fingerprints were made using the polymerase chain reaction and six primers. Data were also obtained for 39 morphological characters scored for ten or more individuals of each population. Eight distinct isoenzyme patterns were obtained corresponding to the seven species and aberrant population 267. These results were supported by the R.A.P.D. analysis which showed population 267 to be close to P. platyphylla but also to possess affinities with P. platyphylloidea. The analysis allowed a reassessment of relationships between the European Porella species and the definition of improved morphological character sets for discriminating the taxa.