Tonicia smithi Leloup, 1980

Schwabe, Enrico, Försterra, Günter, Häussermann, Verena, Melzer, Roland R. & Schrödl, Michael, 2006, Chitons (Mollusca: Polyplacophora) from the southern Chilean Comau Fjord, with reinstatement of Tonicia calbucensis Plate, 1897, Zootaxa 1341, pp. 1-27 : 17

Tonicia smithi Leloup, 1980

(Figures 12)

Tonicia smithi Leloup, 1980: 5 –7, text­figs. 2–5, pl. 1, fig. A.; Kaas & Van Belle 1998: 172; Sirenko & Gallardo 2005: 89; Sirenko 2006b: 85, fig. 9.

Size: Maximum length 56 mm (ZSM Moll 20050456). Body outline: Slender oval, rather flat, subcarinated to carinated. Color: Bright­ to chestnut­brown, mainly with bluish or whitish triangular dots arranged in terminal valves and lateral areas. Valves: Tegmentum smooth, except for growth marks. Head valve semicircular, posterior margin widely Vshaped, unnotched or with small beak in middle. Intermediate valves rectangular, with protruding apex and straight posterior margin (but widely V­shaped). Jugal area anteriorly wider than anterior valve margin. Jugal area not keeled, but clearly elevated, becoming more elevated toward posterior valve. Lateral areas not elevated, but indicated through arrangement of ocellis restricted to anterior half of lateral areas. Tail valve with semicircular posterior margin and backward­directed anterior margin. Mucro swollen, situated in middle of valve. Posterior slope slightly concave, rather flat. Articulamentum: Solid, white with brownish hue in centre, slit formula: 8 / 1 / 11, slit rays present in all valves. Teeth long and with sharp edges. Strongly pectinated outside. Apophyses very large, rectangular or trapezoidal. Connected with a long, strongly sawed jugal plate notched on both sides. Perinotum: Very fleshy, appearing naked, dorsally covered with microscopic fine irregular calcareous corpuscles deeply embedded in cuticle. Isolated randomly arranged hook­like spicules all over the dorsal perinotum. Darker spicule tips sharply pointed. Ventrally, radiating rows of non­imbricating squarish scales, faintly striated, one side straight, obtusely rounded on the other. Thick perinotum bridges between valves; bridges becoming wider with age. Ctenidia (ZSM Moll 20050456, 56 mm body length): 48 ctenidia on each side of foot, groups of largest ctenidia situated under 6th and 7th valves. Radula (same specimen): 15 mm radula length, 3.8 mm account for radula cartilage. 59 teeth rows, 45 already mineralized. Central tooth rather short, slender and rectangular; blade simple and directed inward. First lateral tooth double size of central one; shaft slender and parallel­sided. Blade simple and inward­directed, wider than shaft. Head of second lateral tooth with elongate­oval blade, with simple sharp edge, pointed in middle. Major uncinal tooth spoon­shaped.

Material: One specimen each, from stations 4 and 12, was collected between depths of 19 and 25 m (see Table 1 ).

Distribution: Along the Pacific coast of South America from 38°S southwards via the Straits of Magellan to the Falklands with a bathymetric range of 3–21 m ( Leloup 1980; Sirenko 2006b).