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Two species of sea anemones with a conspicuous marginal ruff of frond-like structures encompassing the tentacular crown occur on the Chilean coast. Oulactis concinnata (= Isoulactis chilensis) (Drayton in Dana, 1846) is re-described in detail and further information is provided for Oulactis coliumensis (Riemann- Zürneck & Gallardo, 1990) (= Saccactis coliumensis) (both Actiniidae). The distribution of O. concinnata from Playa Las Salinas, Perú (9°19’10’’S, 78°26’30’’W), to the region of Valdivia, Chile (39°47’S, 73°21’W), lies within a zoogeographical unit known as the Peruvian Province. Re-description of O. concinnata is based on examination of 10 specimens collected between 1975 and 2003, and on observations of about 50 living anemones in their habitat and in aquaria. Specimens of this species occur in the intertidal zone and to depths of 15 m in crevices filled with sand, broken shells or pebbles. The most distinctive and conspicuous features of O. concinnata are its large size, the lobed and often colourful oral disc and the column with adhesive verrucae. Towards the margin these become smaller and compound and, on the upper margin, form the ruff of frond-like papillae. The structure of the marginal ruff is described in detail and its possible function is considered. The hypothesis is presented that the frond-like structures of the ruff are derived from verrucae. Oulactis concinnata is unusual in possessing special fighting tentacles with batteries of large basitrichs but lacking holotrichs. The genera Isoulactis Carlgren, 1959, Isocradactis Carlgren, 1924, and Saccactis Lager, 1911, are synonymized with the genus Oulactis Milne Edwards & Haime, 1851. The diagnoses of two other genera with a marginal ruff, Actinostella Duchassaing, 1850, and Onubactis López-González, den Hartog & García-Gómez, 1995, are provided. The diagnoses of the genera Oulactis and Actinostella are amended, their distinguishing features and cnidae compared and the described species listed. A lo largo de la costa chile |
