PLEUROCLADIA LACUSTRIS IN ARCTIC AMERICA(1)

Several large populations of Pletirocladia lacustris A. Br. were found at Devon Island, N.W.T., Canada, in an intermittently marine habitat. The morphology, cytology, and ecology of this species were described from living material from two habitats, the limestone and granite shores. The genus Kolderupia Lund ivas found synonymous with Pleurocladia; consequently Kolderupia maritima and K. lucifuga were lectotypified, characterized, and transferred to Pleurocladia. The genus Pleurocladia should be regarded as a member of the Ectocarpaceae until life history studies show a need for reclassification. In the Ectocarpaceae, Pleurocladia is probably most closely related to Protectocarpus Kuckuck. The distribution of P. lacustris indicated that the species, if not extremely rare, is uncommon.