Phycological Observations-III. ON THE OCCURRENCE OF GENUS ACTINOTRICHIA IN THE PHILIPPINES

Abstract

The phytogeographical distribution of Actinotrichiafragilis (Forsskal) Boergesen (Chaetangiaceae, RHODOPHYTA), a monotypic alga, is presented. The writer suggests that the center of divergence for this plant is the tropical part of western Pacific, following that of Galaxaura, its closest relative among the members of family Chaetangiaceae. This supposition is based on the fact that the number of species of genus Galaxaura decreases on Oceanic islands in the Pacific and at localities in the Indian Ocean. The western-most boundary of Actinotrichia is Madagascar, the eastern-most Tahiti, the southern-most, North Australia (above the Tropic of Capricorn), and the northern-most, in Sado Island, Central Japan. Likewise, notes on its morphology and brief nomenclatural history are included in this paper.