A Biosystematic Study of the Subspecies of Frullania tamarisci (L.)

• Published in: The Bryologist 1987-12, Vol.90 (4), p.287-308
• Main Authors: Crandall-Stotler, Barbara, Stotler, Raymond E., Geissler, Patricia
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biological taxonomies; Bracts; Bryophyta; Capsules; Cilia; Fundamental and applied biological sciences. Psychology; Ocelli; Plant cytology, morphology, systematics, chorology and evolution; Plant reproduction; Sinuses; Spores; Taxa; Terpenoids
• ISSN: 0007-2745; 1938-4378
• DOI: 10.2307/3243091

Frullania tamarisci (L.) Dum. has been recognized to comprise four rather distinct, geographically separated subspecies, namely, F. tamarisci ssp. tamarisci, F. tamarisci ssp. moniliata (Reinw., Blume & Nees) Kamim., F. tamarisci ssp. asagrayana (Mont.) Hatt. and F. tamarisci ssp. nisquallensis (Sull.) Hatt. Despite some character overlap, these infraspecific taxa can be distinguished from each other, morphologically. Whether their morphological discontinuities are reflections of species level genetic divergence or are environmentally induced subspecific modifications has, however, never been tested. To evaluate the evolutionary relationships among the subspecies, both vegetative and reproductive characters were studied in herbarium specimens, and the stability of the less variable characters were evaluated by placing the taxa in controlled, parallel growing conditions. Structural differences in both control and experimental groups were recorded in scanning electron micrographs. Variations in phosphoglucoisomerase (PGI) zymograms as well as flavonoid and terpenoid profiles were also determined. Both morphological and biochemical data sets showed that taxon distinctions are genetically fixed and that genetic distance is greater than that expected for subspecific categories. In addition to the morphological markers used by earlier authors, we found that the form of the first branch underleaf and spore wall architecture are different for each taxon. Unique flavonoid profiles and a considerable level of terpenoid and PGI dissimilarity further suggest substantial intrinsic divergence. We, therefore, propose that the taxa be recognized as discrete species.