The red algal genus Callithamniella (Rhodophyta, Ceramiaceae) in Australia, including two new species, C. cygnora and C. carolyniae
HUISMAN, J.M., MCLAY, T.G.B. AND METTI, Y.
Callithamniella Feldm.-Maz. comprises five currently accepted species characterised by a filamentous, uncorticated thallus with prostrate and erect axes, each with at most only a single vegetative lateral branch per cell. The genus is widely distributed but seemingly rarely encountered, and the only known reproductive structures are tetrasporangia, spermatangia and carpogonial branches. Post-fertilization development has not been recorded. Callithamniella flexilis Baardseth is currently the only species of this genus recognised in Australia, recorded from north of Coffs Harbour in New South Wales. The present study was prompted by the collection of an unknown species from the Swan Estuary, Perth, Western Australia, here named as C. cygnora Huisman, McLay & Metti. Additionally, an unnamed taxon from the south coast distinguished by the presence of relatively large vesicular cells, is also confirmed as distinct and named C. carolyniae Huisman, McLay & Metti. DNA sequence analyses of C. cygnora confirm the inclusion of Callithamniella in the Dohrnielleae tribe of the Ceramiaceae, closely related to Antithamnionella Lyle. An updated description for C. flexilis is provided along with a key to the Australian species of the genus.
