Callistochiton pulchellus (Gray 1828)

Animal of small size, up to 11.5 mm in examined specimens, elongate oval, moderately elevated, color of tegmentum creamy white or bright white. Head valve semicircular, sculpture with 10–15 low rounded, equally spaced, nodulose, annulate, radial ribs, becoming obsolete towards the apex, the posterior ribs being strongest and more nodulose. Intermediate valves rectangular, lateral areas well defined, sculptured with two strong radial ribs. Central area with two series of equally spaced, diagonal lirae, forming rounded depressions in the interspaces. Tail valve semi-oval, slightly less wide than head valve, sculptured like head valve, with 8–11 weaker radial ribs. Girdle rather wide, yellowish white, dorsally covered with small, oval, imbricating scales (After Kaas and Van Belle 1994).

This species has records from Islay (17°03’S; 72°06’W), Peru to Chanavayita cove, 54 km south of Iquique, Chile (20°42’S; 70°09’W), with records also in the Galápagos Islands (01°40’N; 92°01 W), Ecuador (Aguilera 2005a). The present record (at 27°S) is now the southernmost record for this species. Distribution range of taxa considered in this work. Species Distribution References Acanthopleura echinata (Barnes, 1824) Talara, Peru (04°34’S; 81°16’W) to Punta Tumbes, Bahía de Concepción, Chile (36°49’S; 73°03’W). Ferreira 1986 Callistochiton pulchellus (Gray, 1828) Islay (17°03’S; 72°06’W), Peru to Ramada Beach, Caldera (26°56’S; 70°47’W). Aguilera 2005a and this study. Calloplax vivipara (Plate, 1902) Pozo Toyo, South of Iquique (20°25’S; 70°10.5’W) to Valparaiso (33°02’S; 71°38’W), Chile. Plate 1902; Ferreira 1978 and this work Chaetopleura (Chaetopleura) peruviana (Lamarck, 1819) Cape San Lorenzo, Ecuador (01°04’S; 80°55’60”W) to the Chonos Archipelago, Chile (45°00’S; 74°00’W). Kaas and Van Belle (1983) Chiton (Chiton) cumingsii Frembly, 1827 Paita, Peru (05°05’34”S; 81°06’07”W) to Puerto Montt (41°28’S; 72°56’W), Chile. Marincovich (1973). Chiton (Chiton) granosus Frembly, 1827 Paita, Peru (05°05’34”S; 81°06’07”W) to Boca de Guafo (43°39’S; 74°00’W), Region of Aysén, Chile. Marincovich (1973) and Osorio et al. (2005). Chiton (Chiton) magnificus Deshayes, 1827 San Lorenzo Island, Peru (12°05’23”S; 77°13’26”W) south to Bahía Tictoc, Chiloé Province, Chile. (43°36’40”S; 72°57’15”W). Bullock (1988) Enoplochiton niger (Barnes, 1824) Talara, Peru (04°34’S; 81°16’W) to Coquimbo Bay, Chile (29°58’S; 71°21’W). Ferreira 1986 Radsia barnesii (Gray, 1828) Ramada Beach, Caldera (26°56’S; 70°47’W) to the Chonos Archipelago (45°0’0”S; 74°0’0”W), Chile. Bullock (1988) and this study Tonicia atrata (Sowerby II, 1840) Playa Mansa, Caldera (27°03’58”S; 70°49’36”W) to Tierra del Fuego (54°S), Chile. Reid and Osorio (2000) and this study Tonicia chilensis (Frembly, 1827) Peru (12°S) to Chile (54°S). Reid and Osorio (2000).