MOLLUSCA OF SOUTHERN CHILE 



137 



Remarks. This species is extremely similar in external appear- 

 ance to Carditella tegulata, which occurs in the same habitat. 

 Carditopsis flabellum flabellum is recognized by the absence of an 

 external ligament which, although small, is clearly visible behind 

 the beaks of Carditella tegulata. A subspecies, Carditopsis flabel- 

 lum malvinae (d'Orbigny, 1846), occurs in the Falkland Islands 

 (Dell, 1964). 



Family MACTRIDAE 



Mulinia edulis (King & Broderip, 1832) 



(Figure 4L) 



Mactra edulis King & Broderip, 1832: 335. 



Mulinia edulis -Soot-Ryen, 1959: 66. Osorio& Bahamonde, 1970: 



205. Bernard, 1983: 40 (synonymy). 

 Mulinia byronensis (Gray, 1838) - Soot-Ryen, 1959: 65-66. 

 Mulinia sp. Osorio, Atria & Mann, 1979: 33-34, fig. 40. 



DESCRIPTION. Shell to 77 mm; large, solid, rounded-trigonal, 

 moderately inflated; sculpture smooth with strong concentric growth 

 lines; hinge with large internal ligament in deep chondrophoral pit, 

 cardinal teeth fused to form inverted V below beak; colour white, 

 texture chalky, with yellow brown periostracum (usually eroded 

 except near margin). 



Habitat. Living specimens partly buried in soft mud near low 

 water level, on sheltered shores in brackish conditions (salinities 

 15-20 %c), sometimes near freshwater stream outflows. This species 

 is found at low tide in the Magellan Strait (Urban & Tesch, 1 996) and 

 on intertidal and subtidal sandbars, in sediments with a high silt and 

 clay content, in the estuaries of southern Chile (Jaramillo, Mulson & 

 Navarro, 1985; Gonzalez & Jaramillo, 1991). 



RECORDS. Stations 20, 22, 25. Elsewhere Callao (Peru) to Magellan 

 Strait (Soot-Ryen, 1959). Range: 12-54°S. 



Remarks. The taxonomy of this genus in southern South America 

 is confused, as a result of variability in shell outline, and a revision 

 is required (Soot-Ryen, 1959; Herm, 1969; Osorio era/., 1979). The 

 present specimens are most similar in shape to M. byronensis which 

 is, however, probably only a form of the widespread M. edulis. 

 Shells were present in the extensive shell middens of Isla Traiguen. 



Family PHARIDAE 



Ensis macha (Molina, 1782) 

 (Figure 5M) 



Solen macha Molina, 1782: 203-204. 



Ensis macha - Carcelles, 1950: 81, pi. 5, fig. 92. Soot-Ryen, 1959: 

 67. Osorio & Bahamonde, 1970: 206. Osorio, Atria & Mann, 

 1979: 34-35, fig. 41. Bernard, 1983: 41 (synonymy), von Cosel, 

 1990:301. 



DESCRIPTION. Shell estimated 130 mm (to 21 1 mm, NHM); thin- 

 shelled, very elongate, slightly concave dorsally, margins parallel, 

 ends truncated and gaping, beaks at extreme anterior end; sculpture 

 smooth, with concentric growth lines; ligament external, hinge with 

 1 cardinal in right valve, 2 in left, 1 posterior lateral in each valve; 

 colour white with strong yellow brown periostracum, eroded away 

 at umbos, internally white. 



Habitat. Single broken dead shell dredged from 5-15 m on 



bottom of cobbles, mud and shell. This is a common deep-burrowing 

 species found in fine sediments in shallow water in southern Chile, 

 and has been reported at 2-10 m depth in sand and silt (Urban, 1994, 

 1996) and living in coarse sand at 13 m (to Soot-Ryen, 1959). 

 Ramorino (1968) found juveniles in sand at 26 m in the Bahia de 

 Valparaiso. 



RECORDS. Station 1 . Elsewhere Caldera to Magellan Strait (Soot- 

 Ryen, 1959; Osorio & Bahamonde, 1970). Range: 27-54°S. 



Remarks. This is a commercially important edible species; the 

 1997 catch was 5361 tonnes (SERNAP, 1998). The family was more 

 familiar by the name Cultellidae, but Pharidae has priority (von 

 Cosel, 1990). 



Family SEMELIDAE 



Cumingia mutica Sowerby, 1833 



(Figure 5G) 



Cumingia mutica Sowerby, 1833b: 34. Soot-Ryen, 1959: 65. Olsson, 

 1961: 372, pi. 66, fig. 4. Osorio & Bahamonde, 1970: 205. Keen, 

 1971: 257, fig. 658. Dell, 1971: 176-177. Bernard, 1983: 46 

 (synonymy). 



DESCRIPTION. Shell to 25 mm (to 30 mm, NHM); outline rounded 

 anteriorly and produced posteriorly; sculpture of closely-spaced 

 concentric growth lines with microscopic radial striae between; 

 hinge with internal part of ligament attached to large cup-shaped 

 chondrophore, cardinal teeth weak, strong lateral teeth in right valve 

 only; colour white, with brown periostracum (worn away except 

 near margin). 



Habitat. Dead valves dredged from 5-15 m on bottoms of cob- 

 bles, gravel and coarse sand; uncommon. Other authors have recorded 

 this species intertidally on sandy mud (Sowerby, 1 833b; Soot-Ryen, 

 1 959) and to a depth of 1 8 m (Dell, 1 97 1 ). 



Records. Stations 1,7, 14. Elsewhere Guayaquil (Ecuador) to I. 

 Wellington (Soot-Ryen, 1959; Dell, 1971). Range: 2^9°S. 



Family PSAMMOBIIDAE 



Tagelus (Tagelus) dombeii (Lamarck, 1818) 



(Figure 5K) 



Solen dombeii Lamarck, 1818: 454. 



Tagelus dombeii - Soot-Ryen, 1959: 61-62. Osorio & Bahamonde, 



1970: 204. Osorio, Atria & Mann, 1979: 32, fig. 37. Bernard, 



1983: 48 (synonymy). 

 Tagelus (Tagelus) dombeii - Olsson, 1961: 351, pi. 62, figs 1, la, 5 



(synonymy). 



Description. Shell to 82 mm (to 90 mm, Olsson, 1961); narrowly 

 elongate, dorsal and ventral margins almost parallel, ends rounded, 

 valves gaping at either end, beaks central; sculpture smooth with 

 fine concentric growth lines; hinge weak, 2 cardinal teeth in right 

 valve, 1 in left; colour purple to brown with paler rays radiating from 

 umbo, chalky white when eroded, covered by strong brown perio- 

 stracum, often eroded at umbos, interior white to purple. 



Habitat. Dead shells common on sheltered beaches of silty sand. 

 This is a deep-burrowing bivalve found in sand and silt (Urban, 

 1994, 1996). Its distribution is mainly intertidal, with records down 

 to depths of 16 m (Soot-Ryen, 1959) and 37 m (Ramorino, 1968). 





