Systematic implications of isozymes in Halophila section Halophila

Abstract

Isozymes in seven enzyme systems were studied by gel electrophoresis for clues to the taxonomic relationships of species in Halophila section Halophila. As presented in den Hartog's (1970) original treatment, the section included four species, H. ovalis (R.Br.) Hook. f. with four subspecies (ssp. bullosa (Setchell) den Hartog, ssp. hawaiiana (Doty & Stone) den Hartog, ssp. australis (Doty & Stone) den Hartog and ssp. linearis (den Hartog) den Hartog, H. ovata Gaud., H. decipiens Ostenfeld and H. stipulacea (Forsk.) Aschers. Other systematic studies have suggested that H. minor (Zoll.) den Hartog should replace H. ovata and include H. ovalis ssp. bullosa and that H. ovalis ssp. hawaiiana be recognized as a distinct species. The isozyme comparisons of three populations of H. ovalis from the Indian and Pacific Oceans showed little variation but indicated patterns that were distinct from those of H. minor, H. hawaiiana, H. decipiens and H. stipulacea. Plants from the Indian River of Florida that had been included in H. decipiens showed a difference in isozymes that support their recognition as a distinct species, H. johnsonii Eiseman. Further studies are needed to determine the status of other populations of the pantropical H. decipiens and for clarification of the status of H. ovalis ssp. bullosa and ssp. australis.