130 



D.G. REID AND C. OSORIO 



these shells; on sheltered shores it is common even on silty rock 

 surfaces; found at seawater salinities down to 20%o, but also frequent 

 at mouths of streams where salinity must fall to very low levels at low 

 tide or during rain. In northern Chile it is reported to be common in the 

 barnacle zone and also in tidepools throughout the eulittoral (Guiler, 

 1959a; Marincovich, 1973), and is also common over a wide tidal 

 range in the Magellan Strait (Benedetti-Cecchi & Cinelli, 1997). 

 Together with lottiid limpets of the genus Scurria, Siphonaria lessonii 

 is one of the most abundant herbivores of the mid-intertidal zone of 

 southern Chile, reaching densities of 1317 per m 2 and grazing 

 principally on Iridaea fronds (Jara & Moreno, 1984). In a marine 

 reserve this species occured mainly in the mid and upper eulittoral; 

 outside the reserve, where the competing dominant herbivore 

 Fissurella picta is removed by human collection, 5. lessonii was 

 larger and extended its zonation to low tide level (Godoy & Moreno, 

 1989). A detailed study of the ecology of this species has been made 

 in the Mar del Plata, Argentina (Olivier & Penchaszadeh, 1968). 



RECORDS. Stations 1, 6, 8, 10, 11, 12, 14, 20, 21, 25. Elsewhere 

 Paita (Peru) to Magellan Strait and Tierra del Fuego (Hubendick, 

 1946; Marincovich, 1973). Range: 5-54°S. 



Remarks. This is one of the most abundant molluscs in the upper 

 intertidal zone in the study area. It is a pulmonate limpet, recognized 

 by the pneumostome of the mantle to the right side of the foot. It 

 should not be confused with Scurria parasitica which is a symmetri- 

 cally oval limpet, with broader dark rays, and white interior with 

 brown apex; these two limpets frequently occur together in beds of 

 Mytilus. 



Family CHILINIDAE 



Chilina patagonica Sowerby, 1874 



(Figure 41) 



Chilina patagonica Sowerby, 1874: Chilina sp. 11, pi. 3, fig. 11. 

 Strebel, 1907: 166-168, pi. 8, figs 98, 102, 105a^;. Haeckel, 

 1911: 89-136, pis 7-11 (anatomy). Stuardo, 1961: 22 (synonymy). 

 Castellanos & Gaillard, 1981: 34, pi. 5, figs 15, 16 (synonymy). 



Description. Shell to 16 mm; cylindrical with produced spire, 

 apex usually eroded away; shell thin and covered by thick 

 periostracum; columella with one prominent fold; colour yellow 

 brown with more or less distinct axial lines of dark brown which 

 form four conspicuous spiral bands of chevrons or irregular axial 

 marks, columella white. 



Habitat. Common among stones, Enteromorpha and on mud, in 

 sheltered brackish inlet (salinity 5%c) near freshwater stream, also 

 among saltmarsh vegetation on sheltered shores of Laguna San 

 Rafael. Strebel (1907) recorded this species from marine fjords, and 

 Davenport et al. ( 1 995) found it commonly in streams and saltmarsh 

 vegetation in the Laguna San Rafael. In Estero Reloncavi Bratt- 

 strom (1990) recorded Chilina bulloides Sowerby from similar 

 low-salinity habitats. 



Records. Stations 28, 31. Elsewhere Puerto Montt to I. Picton 

 (Strebel, 1907). Range: 41-55°S. 



REMARKS. There are about 36 nominal species of Chilina recorded 

 from Chile (Stuardo, 1961; Ituarte, 1997), mostly from freshwater 

 habitats. Shells are variable in form and coloration, making identifi- 

 cation difficult. A review of the Chilean species based on anatomical 

 and radular characters is in progress (Valdovinos & Stuardo, 1995). 

 Meanwhile, the identification of the present material has been based 



on comparison with dry syntypes (NHM) and on the interpretations 

 of Strebel (1907) and Castellanos & Gaillard (1981). There are 

 several anatomical accounts of Chilina species (Haeckel, 1911; 

 Brace, 1983; Ituarte, 1997) and they are of evolutionary interest as 

 primitive basommatophoran pulmonates. 



Class Bivalvia 



Family NUCULIDAE 



Nucula (Nucula) pisum Sowerby, 1833 

 (Figure 7G) 



Nucula pisum Sowerby, 1833a (January): 6, pi. 3, fig. 23. Sowerby, 



in Broderip & Sowerby, 1833 (March): 198. Dall, 1909: 250. 



Soot-Ryen, 1959: 12, pi. 1, figs 1, 2. 

 Linucula pisum - Dell, 1964: 144, pi. 2, figs 7, 8 (synonymy). 



Ramorino, 1968: 183-185, pi. 1, fig. 4, pi. 4, fig. 2. Osorio & 



Bahamonde, 1970: 187. Maxwell, 1988: 89. 

 Nucula (Linucula) pisum - Bernard, 1983: 10 (synonymy). 

 Nucula (Nucula) pisum - Villarroel & Stuardo, 1998: 129-131. 



Description. Shell to 3.3 mm (to 5.4 mm, NHM); rounded 

 trigonal; hinge taxodont, 9-14 anterior teeth, 5 posterior (Soot- 

 Ryen, 1959); sculpture of strong concentric striae towards margin in 

 larger shells, crossed by apparent radial lines throughout (these are 

 subsurface prisms within outer shell layer) that crenulate the margin, 

 radials on escutcheon are finer and divergent from the rest; colour 

 fawn, stained by ferruginous deposit at umbos, interior nacreous. 



Habitat. Dredged from 10-15 m depth, among cobbles with 

 encrusting calcareous red algae. Recorded from depths of 5-60 m on 

 coarse or fine sand by Soot-Ryen (1959). Villarroel & Stuardo 

 (1998) reported a maximum density of 848 per nr on sandy mud at 

 5 1-80 m in the Bahia de Valparaiso, and gave an overall depth range 

 of 8-200 m; from the same locality Ramorino (1968) recorded 

 densities of up to 4650 per m 2 . 



RECORDS. Station 7 (2 specimens). Elsewhere, the extent of the 

 range is uncertain. Soot-Ryen (1959) gave Valparaiso (the type 

 locality) and recorded specimens from 41^3°S. Dall (1909) gave 

 'Valparaiso to San Bias, Chile' (the latter presumably Estrecho San 

 Bias, 51°S, but mis-quoted as San Bias, Argentina, a locality at 

 40°S, by Carcelles & Williamson, 1951, Soot-Ryen, 1959, and 

 Osorio & Bahamonde, 1970). Carcelles & Williamson (1951) also 

 included the Magellanic region and Falkland Islands. However, Dell 

 ( 1 964) noted possible confusion with Nucula falklandica Preston, 

 1912, in these southern parts of the range. Range: 25-54°S. 



REMARKS. Maxwell (1988) and Villarroel & Stuardo (1998) have 

 discussed the generic allocation of this species. 



Family MALLETIIDAE 



Malletia magellanica (Smith, 1875) 



(Figure 4J, K) 



Solenella magellanica Smith, 1875: 118-119. 



Malletia magellanica - Smith, 1881: 39, pi. 5, fig. 3, 3a. Carcelles, 



1950: 74, pi. 3, fig. 65. Carcelles & Williamson, 1952: 324. 



Osorio & Bahamonde, 1970: 188. Villarroel & Stuardo, 1998: 



155-156. 



