Avrainvillea rotumensis sp. nov. (Bryopsidales, Chlorophyta), a peltate species from the South Pacific

A new species of Avrainvillea was found on the South Pacific island of Rotuma, Fiji. Avrainvillea rotumensis sp. nov. occurs 1.5-3.0 m deep in a high energy current area of the Hoféa Passage, one of the few openings in the fringing reef that surrounds the island. The distinctive peltate growth habit of A. rotumensis is unique for the genus and facilitates quick and accurate field identification. The peltate blade (7–9 cm in diameter at maturity) is unusually thick (34 mm) tapering toward a short (up to 6 cm in length), thick (1.5-2.0 cm in diameter) stipe

<i>Halimeda pygmaea</i> and <i>Halimeda pumila</i> (Bryopsidales, Chlorophyta): two new dwarf species from fore reef slopes in Fiji and the Bahamas

Halimeda pygmaea and Halimeda pumila, two diminutive calcified green algal species, are described from material collected on Fijian and Bahamian reef slopes, respectively. The species resemble Halimeda cryptica in having a single siphon traversing the nodes between subsequent calcified segments and living in sheltered fore-reef slope habitats. They differ from H. cryptica by their diminutive size and various anatomical features. Molecular sequence data (tufA) underpin the identity of H. pygmaea and reveal its phylogenetic position as a sister taxon to H. cryptica in the Halimeda section Micronesicae

A multi-locus time-calibrated phylogeny of the siphonous green algae

The siphonous green algae are an assemblage of seaweeds that consist of a single giant cell. They comprise two sister orders, the Bryopsidales and Dasycladales. We infer the phylogenetic relationships among the siphonous green algae based on a five-locus data matrix and analyze temporal aspects of their diversification using relaxed molecular clock methods calibrated with the fossil record. The multi-locus approach resolves much of the previous phylogenetic uncertainty, but the radiation of families belonging to the core Halimedineae remains unresolved. In the Bryopsidales, three main clades were inferred, two of which correspond to previously described suborders (Bryopsidineae and Halimedineae) and a third lineage that contains only the limestone-boring genus Ostreobium. Relaxed molecular clock models indicate a Neoproterozoic origin of the siphonous green algae and a Paleozoic diversification of the orders into their families. The inferred node ages are used to resolve conflicting hypotheses about species ages in the tropical marine alga Halimeda