Occurrence of Asparagopsis armata Harv. on the Scilly Isles

Abstract

The red alga, Asparagopsis armata Harv., was originally found in Australia, where it is very abundant along the south coast; it occurs also in New Zealand and Tasmania1. It was first recorded in the northern hemisphere in 1925 by Sauvageau2. Its naturalization along the European and North African coasts has been followed and described by J. Feldmann and G. Feldmann3 and shown to be coincident with that of Falkenbergia rufolanosa Harv., the tetrasporic generation of A. armata. No occurrences were recorded north of the coast of Brittany. Since that account, however, Asparagopsis has been found at two stations on the coast of Co. Galway, west Ireland, by de Valera4 in July and October 1941; it has also been found in Cornwall by Drew5 on the Lizard Peninsula, where it was well established in August 1950, and she has found specimens of Falkenbergia cast ashore on the Lizard and at Falmouth, in August 1950. It is not without interest, therefore, to note the presence of Asparagopsis armata on the Scilly Isles. Several plants were found growing tangled among Chondrus crispus (L.) Stackh. and Laurencia pinnatifida (Gmel.) Lamour, on a boulder which projected from the sandy shore at the south end of Pentle Bay, Tresco, at extreme low water, spring tide, on March 24, 1951. The specimens have the characteristic reflexed barbs on otherwise bare branches; the fronds are up to four inches long, and these specimens show neither cystocarps nor spermatangial branches. I am grateful to Dr. Mary W. Parke for her kindness in identifying the specimens and for the loan of literature.