Aglaothamnion priceanumsp. nov. (Ceramiaceae, Rhodophyta) from the North-Eastern Atlantic: Morphology and life history of Parasporangial plants

Abstract

Aglaothamnion priceanum sp. nov. (Ceramiaceae, Rhodophyta) is described from Clare Island, Co. Mayo, Ireland (type locality), Scotland, the Faeroes, and north-western France, where it occurs in the subtidal of wave-exposed sites as a small epiphyte on species of Laminaria, on the red alga Merdithia microphylla, and on the tubes of serpulid polychaetes. The species was previously included with Callithamnion decompositum J. Agardh, but the holotype of C. decompositum is a plant related to Compsothamnion and does not correspond with any of the entities previously included under the name Callithamnion decompositum. Parasporangial plants collected from the type locality, and at Gjogv, Faeroes, gave rise in culture to further plants forming parasporangia. Although paraspores from the Clare Island first-generation cultured plants developed into healthy plants, no further parasporangia were produced under a range of temperature and daylength conditions. Optimal growth of the Faeroese strain was obtained at 12–17°...