MOLLUSCA OF SOUTHERN CHILE 



123 



(Strebel, 1905a). The bright pink coloration of the shell fades in 

 museum specimens, and this species is then more difficult to separate 

 from the similar Margarella expansa (Sowerby, 1838); when fresh, 

 the latter is usually olive in colour, with a vivid green iridescence on 

 the spire whorls, and the shape is lower-spired with a more expanded 

 final whorl (Strebel, 1905a; Powell, 1951). In a revision of the 

 suprageneric classification of trochoideans, Hickman & McLean 

 ( 1 990) used acombination of gill and radular characters to distinguish 

 the Margaritinae (including Margarites, mainly from high latitudes of 

 the northern hemisphere) and Gibbulini of the Trochinae (including 

 Margarella from southern high latitudes). However, they pointed out 

 that both radular types can be found among the southern species, and 

 that a revision is required. Using a different radular character, 

 Deambrosi ( 1 969) segregated two groups among the southern species, 

 for which the names Margarella and Margarites were used, although 

 the relationship with northern forms was not addressed. Later, Dell 

 ( 1 990) noted that the type species of Margarella in fact belonged to the 

 'Margarites' group, and therefore used the next available generic 

 name, Promargarita, for the former. Until these relationships are 

 resolved, we have retained the familiar generic name Margarella. 



Family TURBINIDAE 



Homalopoma cunninghami (Smith, 1881) 



(Figure 7F) 



Collonia cunninghami E.A. Smith, 1881: 33, pi. 4, figs 10, 10a. 

 Homalopoma cunninghami - Dell, 1971: 193-194 (synonymy). 

 Castellanos & Landoni, 1989: 31, pi. 2, fig. 2, pi. 4, fig. 7. 



Description. Shell to 3.9 by 4.6 mm; globular; surface with fine 

 spiral grooves, small umbilicus in young shells, becoming closed in 

 adults; colour dark pink to magenta; interior nacreous; operculum 

 calcified externally. 



HABITAT. Dredged from 10-15 m depth, on substrates of cobbles 

 with encrusting calcareous red algae, and on pebbles with shell 

 gravel. Recorded from 66 m depth by Powell ( 195 1 ). 



RECORDS. Stations 7, 14. Elsewhere I. Chiloe to Magellan Strait 

 (Dell, 1 971) and Tierra del Fuego (Powell, 1951). Range: 43-55°S. 



REMARKS. Superficially this speciesresemblesMargarellaviolacea, 

 with which it is found, but is distinguished by its pink (not violet) 

 coloration, spirally striated surface and calcified operculum. The 

 thickness of calcification on the operculum is apparently variable, 

 being thick only at the margin and thinner centrally in the present 

 specimens, although thick overthe whole surface in the types (NHM). 



Family LITTORINIDAE 



Nodilittorina araucana (d'Orbigny, 1840) 



(Figure 7C) 



Littorina araucana d'Orbigny, 1840: 393, pi. 53, figs 8-10. 

 Littorina (Austrolittorina) araucana - Marincovich, 1973: 25, figs 



48, 49 (synonymy). 

 Nodilittorina (Nodilittorina) araucana - Reid, 1989: 99. 



Description. Shell to 12 by 7 mm; tall conical, solid; smooth or 

 with fine spiral lines, but spire whorls usually eroded; colour purple 

 black to purple brown; aperture black with basal white stripe. 



Habitat. Locally abundant, among uppermost barnacles and the 

 crustose red alga Hildenbrandia in upper eulittoral on moderately 



exposed shores. Sometimes on algal rocks, shell midden material 

 and among Mytilus, in upper and mid eulittoral on sheltered shores. 

 In central and northern Chile this species is also typical of the upper 

 eulittoral barnacle zone on exposed coasts (Ruiz & Giampaoli, 

 1981; Santelices, 1991), although Marincovich (1973) observed 

 that, while generally common, it was absent from strongly exposed 

 shores at Iquique. Dell (1971) and Brattstrom (1990) recorded this 

 species from throughout the littoral zone. 



RECORDS. Stations 1, 10, 12, 14. Elsewhere Salaverry (Peru) to I. 

 Chiloe (D.G. Reid, unpublished), Canal Moraleda (45°S; Brattstrom 

 & Johanssen, 1983), extended southwards by the present records. 

 Range: 8-46°S. 



Remarks. Although very abundant on some shores, this species 

 had an unpredictable occurrence in the Estero Elefantes. The pelagic 

 egg capsules and planktotrophic reproduction of this species were 

 described by Jordan & Ramorino (1975). 



Family CALYPTRAEIDAE 



Crepidula dilatata Lamarck, 1 822 [sensu lato] 



(Figure 3F, G) 



Crepidula dilatata Lamarck, 1822: part 2: 25. 



Crepipatella dilatata - Marincovich, 1973: 32, fig. 66 (synonymy). 



Castellanos, 1990: 13, pi. 2, fig. 18 a-c. 

 Crepidula dilatata - Gallardo, 1977: 241-251 (development). 



Gallardo, 1979: 215-226, fig. 1 (synonymy). 

 Crepidula dilatata - Hoagland, 1977: 372 (synonymy). 

 Crepidula fecunda Gallardo, 1979: 215-226, fig. 2. 



Description. Shell to 72 mm; irregularly oval tocircular; marginal 

 apex, twisted to right side; smooth; colour often entirely white; 

 otherwise pinkish and marked externally with numerous fine radiat- 

 ing lines of purple brown and one central white stripe, interior 

 variously marked with pinkish purple, septum white; animal greyish 

 white, sides of foot, neck, head and mantle margin dark grey to black. 



HABITAT. Common in pools and under rocks on rocky shores of 

 moderate exposure; under stones on sand in lower eulittoral of 

 sheltered bay; dredged on shell fragments to 15 m depth (to 18 m, 

 Dell, 1971); on pebbles in shallow tidal channels. Found in maxi- 

 mum abundance densely packed on subtidal rocks at depths of up to 

 2 m, in entrance of lagoon with strong tidal currents (station 1 1). At 

 Isla Chiloe Brattstrom (1990) recorded it commonly in the lower 

 eulittoral zone. This species is a common epibiont on Aulacomya 

 atra and large barnacles (Marincovich, 1973; Gallardo, 1979). 



Records. Stations 1, 11, 12, 14, 15, 20. Elsewhere I. Lorenzo 

 (Peru) to Punta Arenas (Marincovich, 1973), possibly as far north as 

 Mazatlan (Mexico) (23°N) (Hoagland, 1977). Range: 12-53°S. 



REMARKS . Gallardo ( 1 979) has shown that two sibling species can 

 be recognized within this taxon, C. dilatata s.s. and C. fecunda, on 

 the basis of their larval development. In C. dilatata s.s. the veliger 

 larvae develop within the egg capsule, feeding on nurse eggs, and 

 hatch as juveniles, whereas in C. fecunda planktonic veligers hatch 

 from the capsule (Gallardo, 1977). Morphologically, the shells and 

 animals of these two species are too similar for reliable identifica- 

 tion, although C. dilatata is often white with a grey animal, whereas 

 C. fecunda has a pink shell of larger size and a more darkly 

 pigmented animal (Gallardo, 1979). No egg capsules were collected 

 during the present survey and the available material displays aspects 

 of both species. The large size attained (72 mm) and the generally 



