Tonicia lebruni, ROCHEBRUNE, 1884

TONICIA LEBRUNI ROCHEBRUNE, 1884 View in CoL

( FIG. 4 View Figure 4 )

Tonicia lebruni Rochebrune, 1884: 35 View in CoL . – Leloup, 1956: 78, figs 47–49 (bibliography and synonymy). – Kaas et al., 2006: 309, fig. 126, map 55 (bibliography). – Sirenko, 2006a: 84, fig. 5. – Schwabe, 2009: 413.

Type material repository: Natural History Museum Paris ( MNHN) .

Type locality: Punta Arenas , Chile .

Description of T. lebruni

Medium-sized body measuring ≤ 40 mm ( Table 2); moderately or highly elevated (dorsal elevation 0.33– 0.40), subcarinated; valves not beaked. Tegmentum pale reddish brown, greenish roseate, greyish blue and violaceous. Head valve semi-circular; tegmentum smooth except for some growth lines and sparsely and irregularly scattered small pustules. Intermediate valves broadly rectangular; anterior margin sinuose. Posterior margin strait except for the small pointed apex. Lateral areas minimally raised and sculptured like the head valve. Central area smooth, except for the growth lines. Tail valve about as wide as the head valve. Mucro central; antemucronal area sculptured like the central area. Postmucronal area sculptured like the head valve. Articulamentum brown; sutural laminae rather short, rounded, and connected across the narrow jugal sinus by a short dentate plate. Slit formula 8–9/1/9–12. Slits equidistant and slit rays absent. Teeth deeply pectinated on the upper side and outer edge. Girdle moderately wide and nude to the naked eye; dorsal side in live specimens bonded with yellow, greenish-olive or yellow with lilac patches; colours disappear after fixation in alcohol. Girdle dorsally covered with oval to conical brown spicules that are embedded in the cuticle. Spicules of different forms and sizes, up to 82 µm × 28 µm; very short obsolete bristles. Marginal spicules elongate and bluntly pointed. Ventral side of the girdle covered with radiating rows of subquadrancular scales. Major lateral tooth of the radula with a unicuspid roundish head. Gills spanning from valve II to valve VIII; 36 in a specimen with body length of 35 mm.

Remarks

Tonicia lebruni differs from other congeneric species by having brown apophyses. Also, it has a practically smooth tegmentum, with rare scattered pustules on the head valve, lateral and postmedian areas.

Distribution: Tonicia lebruni inhabits southern South America from the Chubut Province and Falkland Islands in the Atlantic Ocean (~ 43°S) to the Magellan region, where it is found in Tierra del Fuego and Isla de los Estados (~ 54°S), inhabiting the intertidal zone to depths of 36 m. This species is known to brood eggs in its pallial groove until juveniles with a fully developed foot and eight shell valves emerge ( Ituarte & Arellano, 2015).