Tonicia chilensis (Frembly, 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

Tonicia chilensis (Frembly, 1827) Plate 2, Fig. 4; Table 2

Chiton chilensis Frembly, 1827: 203, pl. 17, fig. 6; Reeve 1847: pl. 4, f. 19. Tonicia elegans Subspecies chilensis: Pilsbry 1893: 196, pl. 41, figs 22-24, pl. 42, figs 31-35. Tonicia chilensis : Gordillo and Schwabe 2009: 269, fig. 2E, F. A more complete synonymy can be found at Kaas and Van Belle (1998: 45).

Description.

Animal of medium to large size, reaching 43 mm in examined specimens. Shell elongate-oval, not much elevated, the dorsal ridge rounded, side-slopes straightened. Color umber-brown at the sides, becoming chestnut in the middle, delicately and peculiarly speckled and blotched and streaked with buff or buff-white. Lateral areas hardly raised, but separated from the central areas by an obtuse diagonal ridge bearing a series of low tubercles, sometimes subobsolete; sculptured with subradiating rows of small granules, and showing a band of irregularly placed black eyes on the forward part. Central area of second valve having in the middle, a keel or a group of lirae; central areas of the other valves having a narrow smooth dorsal band with several longitudinal furrows on each side of it; and at the sides there are longitudinal diverging delicate rows of granules. End valves radially sub-granulate, and crowded with eye-spots subradially arranged (After Pilsbry 1893).

Material examined.

Specimens found on rocks at low tide in Aguas Verdes, Sur de Playa Ramada, Playa Mansa (MPCCL 3072014F, 1 specimen), Sur Bahía de Caldera and in Calderilla.

Distribution.

According to Reid and Osorio (2000) this species distributes in Chile and Peru between latitudes 12° and 54°S. It has a bathymetric range from 0-28 m ( Schwabe et al. 2006).

Remarks.

This species has large and colorful mantles and plates of variable shades, which are similar to the encrusting calcareous algae commonly found in the rocky coasts. Due to the high diversity of forms, several synonyms have been described (see Kaas and Van Belle 1998), and this species needs a complete revision according to Schwabe et al. (2006). This species was found only in the lower intertidal to the subtidal areas, especially in protected locations.