Nacella magellanica

NACELLA MAGELLANICA (GMELIN, 1791)

(FIG. 4)

Patella magellanica Gmelin, 1791: 3703; Reeve, 1854: pl. 10, figs 19A, B; Carcelles, 1950: 52, pl. 1, fig. 12. Patella atramentosa Reeve, 1854: pl. 17, fig. 41A, B. Patella venosa Reeve, 1854: pl. 10, fig. 18A–C.

Patella chiloensis Reeve, 1855: pl. 33, fig. 98A, B. Patella meridionales Rochebrune & Mabille, 1885: 109. Patella metallica Rochebrune & Mabille, 1885: 109. Patella pupillata Rochebrune & Mabille, 1885: 110. Patella tincta Rochebrune & Mabille, 1885: 110. Patinella aenea var. magellanica – Pilsbry, 1891: 119, pl. 44, figs 9, 12, 15, 16; pl. 43, figs 1, 6.

Patinella magellanica atramentosa – Strebel, 1907: 146, pl. 6, figs 86, 88; pl. 7, figs 91, 92, 94, 95. Patinella aenea var. minor Strebel, 1907: 137, pl. 5, fig. 67a–d.

Patinella chiloensis – Strebel, 1907: 151, pl. 7, figs 89, 90.

Patinella venosa – Strebel, 1907: 150, pl. 7, fig. 93.

Patinigera magellanica – Powell, 1951: 81; Dell, 1964: 273; Castellanos & Landoni, 1988: 22, pl. IV, figs 1, 2.

Patinigera chiloensis – Dell, 1964: 273.

Patinigera magellanica venosa – Dell, 1964: 273.

Nacella (Patinigera) magellanica magellanica – Powell, 1973: 198, pl. 73, figs 14, 15; pl. 178, figs 1, 2; Ramírez, 1981: 54; Linse, 1999: 400; Aguirre, 2003: 14; Aguirre, Richiano & Sirch, 2006: 252; Aguirre et al., 2009: 423.

Nacella (Patinigera) magellanica venosa – Powell, 1973: 198, pl. 180, figs 3, 4; Ramírez, 1981, 54; Linse, 1999: 400.

Nacella magellanica – Guzmán, 1978: 205; Ríos & Gerdes, 1997: 49; Adami & Gordillo, 1999: 186; Ríos & Mutscke, 1999: 196; Bazterrica et al., 2007: 22; Yoon et al., 2007: 64; González-Wevar et al., 2010: 116; 2011a: 1937; 2012a: 448; 2012b: 139; 2017: 863; Aldea & Rosenfeld, 2011: 117; de Aranzamendi, Bastidas & Gardenal, 2011: 2405; 2014: 53; Rosenfeld, Marambio & Aldea, 2013: 11, 2016: 77; Rosenfeld et al., 2015: 62; 2018: 1; Andrade & Brey, 2014: 65; Andrade et al., 2016: 2286.

Nacella (Patinigera) magellanica chiloensis – Ramírez, 1981: 55.

Nacella (Patinigera) magellanica – Guzman & Rios, 1987: 159; Mutshke et al., 1998: 8; Reid & Osorio, 2000: 118; fig. 2L–O; Malanga et al., 2005:551; Valdovinos & Rüth, 2005: 509 (in part), fig. 6A; de Aranzamendi et al., 2009: 1, fig. 2A–O; Thatje & Rios, 2010: 97.

Nacella (Patinigera) chiloensis – Valdovinos & Rüth, 2005: 497.

Nacella (Patinigera) venosa – Valdovinos & Rüth, 2005: 510.

Nacella venosa – González-Wevar et al., 2011a: 1937.

Nacella chiloensis – González-Wevar et al., 2011a: 1937. Nacella magallanica [sic.] – Ojeda et al., 2014: 504.

Material studied: Puerto Montt; Reloncaví Fjord (41°28’32.78’’ S, 72°55’15.04’’ W) N = 30; Metri, Reloncaví Fjord (41°35’37.30’’ S, 72°42’42.80’’ W) N = 25; Ancud, Chiloé Island (41°53’00.69’’ S, 73°49’52.29’’ W) N = 25; Concoto Island, Pacific Patagonia (44°14’41.60’’ S, 73°37’05.68’’ W) N = 35; Puerto Aguirre, Pacific Patagonia (45°09’57.09’’ S, 73°32’27.07’’ W) N = 25; Costa Channel, Pacific Patagonia (45°48’05.79’’ S, 74°44’28.52’’ W) N = 40; Serrano Channel, Pacific Patagonia (46°26’45.22’’ S, 73°47’44.12’’ W) N = 30; Wager Island, Pacific Patagonia (47°48’’33.22’’ S, 75°00’45.33’’ W) N = 30; Madre de Dios Island, Pacific Patagonia (50°07’09.82’’ S, 75°15’24.79’’ W) N = 20; London Island, Pacific Patagonia (54°40’00.30’’ S, 72°03’58.67’’ W) N = 30; Carlos III Island, Strait of Magellan (53°38’55.41’’ S, 72°15’31.04’’ W) N = 30; Port Famine, Strait of Magellan (53°36’34.07’’ S, 70°55’53.40’’ W) N = 50; Otway Sound, Strait of Magellan (52°56’13.10’’ S, 71°11’39.07’’ W) N = 30; Chabunco, Strait of Magellan (52°59’14.66’’ S, 70°48’44.43’’ W) N = 30; Laredo Bay, Strait of Magellan (52°56’59.14’’ S, 70°48’03.96’’ W) N = 30; Possession Bay, Strait of Magellan (52°13’55.50’’ S, 69°17’50.71’’W) N = 30; Santa María Bay, Tierra del Fuego (53°19’29.86’’ S, 70°22’34.30’’ W) N = 60; Caleta River, Tierra del Fuego (53°51’45.32’’ S, 70°19’54.11’’ W) N = 60; Pía Fjord, Beagle Channel (54°49’36.81’’ S, 69°39’11.31’’ W) N = 40; Garibaldi Fjord, Beagle Channel (54°43’20.63’’ S, 69°57’48.27’’ W) N = 50; Wulaia Bay (54°59’20.30’’ S, 68°09’02.97’’ W) N = 25; Tekenika Bay (55°03’24.66’’ S, 68°07’52.22’’ W) N = 30; Orange Bay (55°27’21.44’’ S, 68°04’02.33’’ W) N = 30; Virginia Bay, Beagle Channel (54°54’16.95’’ S, 67°56’05.35’’ W) N = 30; Puerto Williams, Beagle Channel (54°56’04.95’’ S, 67°36’48.33’’ W) N = 26; Lapataia Bay, Beagle Channel (54°50’58.94’’ S, 68°28’41.95’’ W) N = 30; Hornos Island, Cape Horn (55°58’38.36’’ S, 67°16’36.39’’ W) N = 30; Diego Ramírez Island, Cape Horn (56°30’08.86’’ S, 68°43’38.85’’ W) N = 25; Puerto Deseado, Atlantic Patagonia (47°45’16.17’’ S, 65°52’17.58’’ W) N = 25; Comodoro Rivadavia, Atlantic Patagonia (45°51’52.17’’ S, 67°28’25.50’’ W) N = 26; Hookers Point, Falkland / Malvinas Islands (51°42’09.60’’ S, 57°46’07.49’’ W) N = 50.

Shell: The shell shape and sculpture are very variable in this species (de Aranzamendi et al., 2009; González- Wevar et al., 2011a) (Fig. 4A–C). The species exhibits a conical morphology, dorsally raised with a very thick and non-translucent shell (Fig. 4A–F). The anterior part of the animal is laterally compressed (Fig 4D–F). The shell is large (maximum length 140 mm), with a high profile. The apex is situated at the anterior 40–50% of the shell’s length (Fig. 4A–F). All the slopes of the shell are convex (Fig. 4A–C). The aperture of the shell is oval. The surface of the shell is sculptured with raised angular primary radial ribs, weaker secondary ones and concentric growth lines across the interspaces. The margin of the shell is highly crenulated. The external coloration of the shell is very variable in the species across its distribution (pale reddish brown, white with dark lines, grey, green and brown). The primary and secondary ribs are brown ash-coloured to dark brown, with clearer interspaces. The internal part of the shell has soft metallic brown coloration with dark lines corresponding to external colour patterns, bordered by a white/brown halo.

External anatomy: The ventral area of the foot is light grey and the epipodial fringe is recognizable. The mantle fold is thick and dun-brown coloured. The mantle tentacles are in alternate series of three white shorter and a white longer one and are absent of pigmentation (Fig. 4G). The cephalic tentacles are dorsally pigmented with a black line (Fig. 4G).

Radula: See Valdovinos & Rüth (2005) (Fig. 4H).

Distribution: Magellanic province. Pacific Patagonia from Chiloé Island to Cape Horn. Atlantic Patagonia from Tierra del Fuego to the Río Negro Province. Falkland/ Malvinas Islands (Fig. 4I).

Habitat: High and medium intertidal rocky ecosystem between 0 and 25 m depths.

Comments: The species is highly abundant, with a continuous distribution along Pacific Patagonia from Chiloé Island to Cape Horn, including fjords and channels, the Strait of Magellan and Tierra del Fuego, Cape Horn, Hornos Islands and Diego Ramírez Islands (Guzman, 1978; Rios & Gerdes, 1997; Linse, 1999; Reid & Osorio, 2000; Aldea & Rosenfeld, 2011; Gonzalez- Wevar et al., 2012a; Ojeda et al., 2014; Rosenfeld et al., 2015). In the Atlantic, N. magellanica is also highly abundant up north to the Río Negro Province. However, along the Atlantic coast the distribution and abundance of N. magellanica depends on the availability of suitable rocky habitats (Bazterrica et al., 2007; de Aranzamendi et al., 2009, 2011, 2014). Similarly, N. magellanica is highly abundant in the Falkland/ Malvinas Islands. Nacella magellanica comprises a single genetic unit throughout Pacific (González-Wevar et al., 2012a) and Atlantic (de Aranzamendi et al. 2009, 2011) Patagonia, with Falkland/ Malvinas Islands populations detectably different (González-Wevar et al., 2012a). Molecular and geometric morphometric comparisons showed that N. chiloensis and N. venosa are synonyms of N. magellanica (González-Wevar et al., 2011a).