AbstractThe new species, Anemonia alicemartinae (Actiniidae), is described from rocky shores of north and central Chile. Its members' abundance, occurrence in exposed positions, and bright red colour make it one of the most eye-catching species of northern Chile. The description is based on 74 specimens collected between 1975 and 2001, and on live observations of several hundred animals in their habitats and in aquaria. The natural microhabitats are positions exposed to currents but protected from surge surf, ranging from tide pools down to depths of 16 m. In 1998, the southern distribution limit was 37 °S, the southernmost extent of the southerly Chile Coastal Countercurrent. The species is similar to Anemonia natalensis and Pseudactinia varia from South Africa. The most distinctive features of A. alicemartinae n. sp. are its bipartite acrorhagi on the margin, uniform red colour, and marks from frequent longitudinal fission. Bud-like structures were observed in two specimens. Evidence of frequent fission and the absence of fertile males in the sample indicate a predominance of asexual reproduction in the population. The fact that such a conspicuous species was not reported in previous surveys of Chilean sea anemones suggests that it has been increasing in abundance and/or expanding its range during the last 50 years. Reasons for this may be human impact on benthic communities or recent introduction of this species into the area.