Chiton (Chiton) magnificus Deshayes, 1827

Araya, Juan Francisco & Araya, Marta Esther, 2015, The shallow-water chitons (Mollusca, Polyplacophora) of Caldera, Region of Atacama, northern Chile, Zoosystematics and Evolution 91 (1), pp. 45-58 : 45

Taxon classification Animalia Chitonida Chitonidae

Chiton (Chiton) magnificus Deshayes, 1827 Table 2

Chiton (Chiton) magnificus Deshayes, 1827: 454. Chiton magnificus : Pilsbry 1893: 160, pl. 30, figs 23, 24; Chiton (Amaurochiton) magnificus magnificus: Bullock 1988: 163, figs 52-54, 57, 58, 64, 65, 68, 72, 73 and 76. Chiton magnificus : Schwabe et al. 2006: 9, figs 7, 8 and 15. A more detailed bibliography and synonymy can be found in Bullock (1988: 163).

Description.

Animal of large size, reaching 115 mm in examined specimens. Body dark bluish-grey, broad-oval, slightly carinated, rather flat. Valves flattened to moderately carinated. Anterior valve sligthtly convex, semicircular, with wide V-shaped to straight posterior margin unnotched in middle, with numerous radially arranged, shallow ribs; intermediate valves rectangular with slightly concave posterior margin at both sides of faintly protruding apex, lateral areas slightly elevated, sculptured with up to 5 radial ribs between a wider diagonal ridge and a very wide posterior rib; tail valve semicircular with an anterior mucro; post-mucronal area with same sculpture as head valve and lateral areas (After Schwabe et al. 2006). According to Osorio (2002), this species can reach a maximum length of 174 mm.

Material examined.

Specimens found in Aguas Verdes, Sur de Playa Ramada and in Playa Chorrillos, in subtidal areas attached to large boulders.

Distribution.

Bullock (1988) gives a distribution for this species from Isla San Lorenzo, Peru south to Bahía Tictoc (43°36 ’40” S; 72°57 ’15” W), Chiloé Province, southern Chile. This species can be found in rock pools and boulder fields with strong water exchange, from the intertidal down to a maximum of 30.5 m depth at the Comau Fjord (42°23'S; 72°27'W), Region of Aysén ( Schwabe et al. 2006). Smith and Ferreira (1977) considered the records of this species from Galapagos Islands as erroneous.

Remarks.

A shiny, large and conspicuous chiton, this species has been overlooked in recent molluscan literature, being cited by Valdovinos (1999) as Chiton latus and by Osorio (2002) as Chiton magnificus boweni. It seems to be an uncommon species, restricted to specific localities along the coast of Chile. Juvenile specimens may be misidentified as Chiton cumingsii , differing from this species in having a wider and flatter body, with smoother sculpture and with bright blue spots on the valves, which are cream white to greenish yellow in color. Apparently, in northern Chile this species is found only in subtidal areas. This is a commercially important species ( Osorio 2002).