The shallow-water chitons (Mollusca, Polyplacophora) of Caldera, Region of Atacama, northern Chile

Abstract

The Molluscan species of the northern littoral of Chile have been sparsely studied. This work reviews for the first time the diversity of polyplacophoran molluscs around the port of Caldera, in the Region of Atacama (26°45’49”S; 70°45’17”W to 27°20’23”S; 70°56’46”W), northern Chile. Eleven species were found in this study: Acanthopleura echinata (Barnes, 1824); Callistochiton pulchellus (Gray, 1828); Calloplax vivipara (Plate, 1899), Chaetopleura peruviana (Lamarck, 1819); Chiton cumingsii Frembly, 1827; Chiton granosus Frembly, 1827; Chiton magnificus Deshayes, 1827; Enoplochiton niger (Barnes, 1824), Radsia barnesii (Gray, 1828), Tonicia atrata (G. B. Sowerby II, 1840) and Tonicia chilensis (Frembly, 1827). All of the species occurring in the area have distributions in the southeastern Pacific Ocean, from Ecuador to central Chile, and three of them are species endemic to the Chilean coasts (Calloplax vivipara, Radsia barnesii, and Tonicia atrata). This diversity of species is comparable to that of better surveyed faunas of central and southern Chile or Patagonia. Of the eleven species recorded, the geographic distribution records for Callistochiton pulchellus, Radsia barnesii and Tonicia atrata are extended, and Calloplax vivipara is found alive again after 40 years, filling a gap in its known distribution. Illustrations of living specimens in their habitat, distribution records and a taxonomic key for all the studied taxa are also provided.