The Great Barrier Reef, a center for Pelagophyceae (Heterokontophyta) diversity, including a new genus and seven new species.

The pelagophytes are a morphologically diverse class of marine heterokont algae defined by deoxyribonucleic acid (DNA) gene sequences, the presence of a multilayered, perforated theca (PT), and the novel role of the Golgi apparatus in the formation and secretion of the PT, as well as materials for the synthesis of the outer extracellular layers (e.g., cell walls and mucilage). We established clonal cultures of sand-dwelling pelagophytes collected from intertidal and subtidal locations at Heron Island on the Great Barrier Reef (GBR), Australia, and established phylogenetic trees based on nuclear 18S rDNA and plastid rbcL, psaA, psaB, psbA, and psbC gene sequences that led to the discovery of seven new species and several interesting range extensions. The new genus and species, Revolvomonas australis, is sister to Pituiglomerulus and Chrysocystis in the Chrysocystaceae (Sarcinochrysidales, Pelagophyceae). Additional new species are Sarcinochrysis kraftii, Sa. guiryi, Arachnochrysis pilardiaziae, A. cassiotisii, Sungminbooa capricornica, and Su. tropica; also identified and cultured from the GBR were Sa. marina, Aureoumbra geitleri, Chrysoreinhardia giraudii, Chrysocystis fragilisi, and the planktonic Pelagomonas calceolata. Revolvomonas was studied in detail and has several unusual features for sand-dwelling pelagophytes. In just three short collecting trips to Heron Island, we were able to isolate and identify over 40% of the pelagophyte genera discovered to date. This study substantiates the diverse nature of pelagophytes and suggests tropical reef sand may be a center for pelagophyte diversity.