Ceramium juliae (Ceramiaceae, Ceramiales), a new red algal species with distinctive spines from eastern Australia

Abstract

Ceramium juliae sp. nov. (Ceramiaceae, Ceramiales, Rhodophyta) is described from subtidal habitats on the southeast coast of Australia. Plants are prostrate on the basal parts of the brown algae Cladostephus spongiosus and Halopteris platycena and the red alga Chondria succulenta and reach lengths of no more than 8 mm. Individual axes grow to widths of 160 µm, are dichotomously to alternately branched and have markedly involute apices. Each axial cell produces six periaxial cells, each of which produces a distinctive spine. The first-formed spine becomes multiseriate, as does the second-formed which lies on the opposite side of the filament. Four uniseriate spines are then formed, two on each side of the axis, to make a total of six spines per cortical node. Tetrasporangia are cut off from the periaxial cells and occur one per cortical segment. Comparisons are made with other spined Ceramium species as are the generic characteristics of the genus Ceramium with relation to Centroceras, Ardreanema, Campylaephora, Corallophila and Reinboldiella.