MOLLUSCA OF SOUTHERN CHILE 



115 



with radiating flecks of black and turquoise; girdle profusely covered 

 with long (to 7 mm), brown, corneous hairs, with dense minute 

 spicules beneath. 



Habitat. Under rocks in lowest eulittoral, on moderately exposed 

 shores. It has been recorded from throughout the tidal zone and to a 

 depth of 40 m (Leloup, 1956; Kaas & Van Belle, 1987). It appears to 

 be scarce on the shores of central and northern Chile (Guiler, 1959a; 

 Marincovich, 1973; Otafza & Santelices, 1985). 



RECORDS. Stations 12, 17. Kaas & Van Belle (1987) gave a range 

 from Cape San Lorenzo (Ecuador) to the Chonos Archipelago, and 

 our records are therefore at the southern extreme. However, Leloup 

 (1956) mentioned occurrence in the Magellan Strait (53°S), but 

 without details. Range: 1-46°S. 



Remarks. Both Kaas & Van Belle (1987) and Ferreira (1983) 

 mentioned that the girdle hairs characteristically protrude from the 

 sutures between the valves, but this was not the case in our material. 

 Dell (1971) also noted the lack of sutural hairs in some specimens 

 from Punta Pulga (42°S), and suggested that this might be due to 

 exposure. 



Family ISCHNOCHITONIDAE 



Ischnochiton (Ischnochiton) stramineus (Sowerby, in 

 Broderip & Sowerby, 1 832) 



(Figure 6B, D) 



Chiton stramineus Sowerby, in Broderip & Sowerby, 1832: 104. 

 Ischnochiton (Ischnochiton) stramineus - Kaas & Van Belle, 1990: 



173-176, fig. 78, map 38 (synonymy). 

 Ischnochiton stramineus - Kaas & Van Belle, 1998: 178. 

 Ischnochiton imitator E.A. Smith, 1881 -Leloup, 1956: 42^13, fig. 



22. 



Description. Valve area to 12.0 by 5.6 mm, maximum width of 

 girdle 1.0 mm; valves rather flattened; lateral triangles not raised or 

 differentiated; sculpture of fine, quincuncially arranged granules; 

 shell colour cream to fawn, sometimes stained with black deposits; 

 girdle cream to fawn, densely covered with short, imbricating 

 scales, each with about 6 ribs, converging towards recurved top of 

 scale (Fig. 6D); gills throughout pallial groove (holobranchial). 



Habitat. Understones andcobbles resting on silt, in large sheltered 

 rock pool, 0.3-0.5 m below low water of spring tide. Leloup ( 1 956) 

 recorded it throughout the intertidal zone and to a depth of 22 m. 



Records. Station 14. Elsewhere from Islay (Peru) to Tierra del 

 Fuego and Magellan Strait (Kaas & Van Belle, 1990). Range: 17- 

 54°S. 



REMARKS. Compare with Leptochiton medinae. 



Ischnochiton (Haploplax) pusio (Sowerby, in Broderip & 



Sowerby, 1832) 



(Figures 2D, 6E) 



Chiton pusio Sowerby, in Broderip & Sowerby, 1832: 105. 

 Ischnochiton pusio - Leloup, 1956: 44-45, fig. 23. 

 Ischnochiton (Haploplax) pusio - Kaas & Van Belle, 1994: 67-69, 

 fig. 27, map 18 (synonymy). Kaas & Van Belle, 1998: 153-154. 



Description. Valve area to 15.7 by 8.4 mm, maximum width of 

 girdle 1.7 mm; valves smooth, very fine quincuncial granulation 

 visible at high magnification; shell colour brown to blackish brown, 



usually with radiating flecks of white or turquoise; girdle rather wide, 

 brown to black, often banded, covered with relatively large, stout, 

 smooth, glossy, imbricating scales with square base, scales becoming 

 smaller towards inner and outer margins of girdle (Fig. 6E). 



Habitat. Under stones on gravel in shallow tidal channel, just 

 sublittoral; 10-15 m depth in sheltered bay, on substrate of cobbles 

 encrusted with calcareous red algae. This species has been reported 

 to be common intertidally, and to a depth of 90 m (Leloup, 1956; 

 Dell, 1971; Brattstrom, 1990; Kaas & Van Belle, 1994). 



RECORDS. Stations 7, 15. Elsewhere Tumbes (Peru) to Tierra del 

 Fuego (Kaas & Van Belle, 1994). Range: 12-54°S. 



Remarks. This is superficially similar to small specimens of 

 Chiton magnificus bowenii, but in that species the valves are glossy, 

 the girdle shows a definite inner zone of smaller scales and the scales 

 do not become smaller at the outer margin. 



Family MOPALHDAE 



Plaxiphora (Plaxiphora) aurata (Spalowsky, 1795) 



(Figure 2B) 



Chiton auratus Spalowsky, 1795: 88, pi. 13, figs 6a, b. 

 Plaxiphora aurata - Leloup, 1956: 25-26. Kaas & Van Belle, 1998: 



26. 

 Plaxiphora (Plaxiphora) aurata - Kaas & Van Belle, 1994: 266- 



269, fig. 108, maps 5, 28, 41 (synonymy). 

 Plaxiphora carmichaelis (Gray, 1 828) - Ferreira, 1982: 43-45, figs 



1-8 (synonymy). 



Description. Valve area to 75 by 30 mm, maximum width of 

 girdle 16 mm; valves frequently eroded: jugal and pleural areas 

 smooth; lateral triangles defined by two nodulose radiating ribs, one 

 diagonal and one posterior; shell colour purple black with radiating 

 lines and stripes of pink or turquoise; girdle wide, fleshy, brown, 

 with minute spicules and sparse tufts of long (to 8 mm) corneous 

 hairs, frequently fouled with algae. 



Habitat. On and under rocks in low eulittoral, on sheltered and 

 sometimes muddy shores; in Macrocystis holdfasts, 3-5 m depth; 

 tolerant of reduced salinity (range 1 5-3 \%c). Leloup (1956) recorded 

 this species from throughout the intertidal zone, Brattstrom (1990) 

 in its lowest part and Dell ( 1 97 1 ) noted it also to a depth of 1 2 m. At 

 an intertidal estuarine site in Argentina it was reported to occur only 

 on shaded vertical rock walls, reaching densities of 7-12 per m 2 

 (Lopez-Gappa & Tablado, 1997); in contrast, it was generally scarce 

 in the present study area. 



RECORDS. Stations 1, 7, 14, 20, 22, 25, 26. Elsewhere Valparaiso 

 to Tierra del Fuego and Magellan Strait (Leloup, 1956; Dell, 1971; 

 Kaas & Van Belle, 1994), and outside the Chilean region on the 

 subantarctic islands and South Island, New Zealand (Kaas & Van 

 Belle, 1994). Range: 31-54°S. 



REMARKS. This and Leptochiton medinae were the only chitons to 

 be found in the areas of significantly reduced salinity in the Golfo 

 Elefantes. 



Family CHITONIDAE 



Chiton (Amaurochiton) magnificus bowenii King & 

 Broderip, 1832 



(Figures 2C, 6F) 



