Zygochlamys patagonica (King & Broderip, 1832)
KING, P. P. & W. J. BRODERIP. 1832. Description of the Cirrhipeda, Conchifera and Mollusca, in a collection formed by officers of H.M.S. Adventure and Beagle employed between the years 1826 and 1830 in surveying the southern coasts of South America, including the Straits of Magalhaens…. The Zoological Journal, 5: 332-349 (Dated 1831). [p. 337]
1832 Pecten patagonica King & Broderip, 1832
1845 Pecten australis Philippi, 1845
1850 Pecten lischkei Dunker, 1850
1853 Pecten rufiradiatus Reeve, 1853
1899 Pecten rosaceus Stempell, 1899
1918 Pecten (Chlamys) patriae Doello-Jurado, 1918
1935 Pecten (Chlamys) amandi Hertlein, 1935
1845 Pecten australis Philippi, 1845
1850 Pecten lischkei Dunker, 1850
1853 Pecten rufiradiatus Reeve, 1853
1899 Pecten rosaceus Stempell, 1899
1918 Pecten (Chlamys) patriae Doello-Jurado, 1918
1935 Pecten (Chlamys) amandi Hertlein, 1935
Pecten Lischkei Dkr; W. Dunker. 1858-1870. Novitates Conchologicae. Mollusca Marina, plate 6, figures 1-3.
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«P. testa sub-aequivalvi, brunnea, longitudinaliter creberrime elevato-radiata; intus albida, longitudinaliter sub-radiata; long. 2 4/8; lat. 2 4/8; poll.
OBS. auribus inaequalibus. Habitat in freto Magellanico passim. Mus. nost.» PHILLIP P. KING & W. J. BRODERIP, 1832
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«Remarks. Roth (1975: 85) referred to a holotype of Pecten australis Philippi, 1845 in the MNHS. However, a holotype does not exist because the description is not explicitly based on a single specimen. Roth (1975) did not select a lectotype by interference of the holotype (ICZN, Art. 74.6) and gave no measurements and depicted left and right valves of different sizes (textfig. 1, p. 85), which consequently stem from two different individuals. Because of the sparse information given by Roth (1975) on label or catalogue data associated with the MNHS data, we are not able to evaluate the status of the MNHS specimen at this point. As a consequence, we consider the respective valves as possible syntypes only.
In the ZMB collection, there is a second shell that closely matches the measurements given by Philippi. It originates from the Paetel collection and is accompanied by a label “Magellan Str”. On the outside of the right valve of the largest specimen is an old cross mark in ink, possibly indicating that this specimen is a type. However, because Paetel generally replaced all original labels with his own labels, the origin of the present specimen remains unclear. The name introduced by Philippi (1845) is preoccupied by Pecten australis Sowerby II, 1842 and therefore permanently invalid. Stempell (1899) introduced a nomen novum (replacement name), Pecten rosaceus, which is also preoccupied (Grau 1959: 83). A new replacement name was subsequently introduced by Hertlein (1935: 305): Pecten (Chlamys) amandi. The taxon is a junior synonym of Psychrochlamys patagonica (King & Broderip, 1832) according to Jonkers (2003: 43), placed in the family Pectinidae. The species occurs on the Patagonian shelf of southeastern South America, as far north as Uruguay, off the Falkland Islands, and in the Magellan Region to south of Tierra del Fuego (Jonkers 2003: 46).» DIJKSTRA, H. H. & F. KÖHLER. 2008. An annotated catalogue of Recent Pectinoidea (Mollusca, Pectinidae and Propeamussiidae) type material in the Museum of Natural History, Humboldt University, Berlin. Zoosystematics and Evolution, 84 (1): 31-44, figs. 1-4. [p. 32, 33] |
Pecten australis Philippi, 1845; H. H. Dijkstra & F. Köhler, 2008, An annotated catalogue of Recent Pectinoidea type material in the Museum of Natural History, figure 2b.
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«Stratigraphical age and distribution. Recent, Patagonian shelf off eastern South America, as far north as Punta del Este, Uruguay (c.35° S), off the Falkland Islands, and in the Magellan Region, from Puerto Montt (42° S) to south of Tierra del Fuego (56º S) (Fig. 20). In most parts of the Argentine shelf P. patagonica is the only pectinid present (\Waloβek, 1982), but in northern, shallow-water habitats it occurs together with Aequipecten tehuelchus (Orbigny, 1846) and Flexopecten felipponei (Dall,1922) (Waloszek, 1984; Orensanz et al., 1991); in the Magellan region it is sympatric with Austrochlamys natans (Philippi, 1845).
Remarks. Psychrochlamys patagonica is extremely variable throughout its distributional range. However, it occurs in a number of regionally recognizable populations, which has led to it being repeatedly redescribed under different names. Forms from its northernmost occurrence on the Patagonian shelf (e.g. Plate 8, figs. c, d) are relatively large and thin-shelled, and mostly of a pale yellowish-brown colour. Such forms have been named Pecten lischkei and P. patriae. Off the Falkland Islands shells may be heavy and radial sculpture may consist of strongly fasciculate, scaly ribs and riblets (Plate 9, figs. e, f). Such forms most closely resemble P. delicatula subantarctica (see below). Populations in the Magellan Region often consist of small but thick shells with simple costation, resembling shells referred to as Pecten rufiradiatus (Plate 8, figs. e, f). There are, however also areas where large and finely ribbed shells are found, e.g. Bahía Inútil (Tierra del Fuego). Populations in Golfo de Ancud and Seno Reloncaví, near Puerto Montt, Chile, again resemble the 'lischkei' morphotype from the Argentine shelf. However, whereas the free margin of the left valve anterior auricle is usually straight in the fugentine populations, this margin is mostly curved inward in the Chilean shells; hence this form possesses a true (albeit very shallow) byssal sinus (not present in the LV figured by Soot-Ryen,1959, pl. 1, fig. 8). Waloszek (1984, p. 250) compared material from the Argentine shelf and from the Magellan Region, and demonstrated a relatively longer outer ligament and a higher convexity in the latter area, which he ascribed to differences in ecology (e.g. stronger tidal currents). In our analysis such a difference is not evident, which may be due to a more representative sample from both areas, with shells collected from a wider variety of environments.» JONKERS, H. A. 2003. Late Cenozoic-Recent Pectinidae (Mollusca: Bivalvia) of the Southern Ocean and neighbouring regions. Monographs of Marine Mollusca, 5: i-viii + 1-125 pp, 17pls. Backhuys Publishers, Leiden. [p. 47]
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Psychrochlamys patagonica (King & Broderip); H. A. Jonkers, 2003, Late Cenozoic-Recent Pectinidae (Mollusca: Bivalvia) of the Southern Ocean and neighbouring regions, plate 8, figures c-f.
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«I have examined 27 locality lots of Chlamys patagonica patagonica in the National Museum of New Zealand, by courtesy of Dr R.K. Dell. Most come from 'William Scoresby', 'Discovery ll', 'Eltanin', 'Hero', and 'Vema' stations around southern Argentina, the Straits of Magellan, Tierra del Fuego, and the Falkland lslands, while other lots come from Uruguay to the Straits of Magellan. I have also examined one lot of four coarsely ribbed valves from southern Tierra del Fuego (WM7681, Puerto Williams, Navarino lsland, south shore of Beagle Channel; N.Z. Geological Survey). This material shows an extemely wide range of variation in the width and surface sculpture of the primary radial ribs and in the number of secondary and tertiary riblets; their range of variation is almost as great as that of all the named forms included below as subspecies of C. patagonica. Most South American authors (Doello-Jurado, 1918; Carcelles, 1944, 1950) and Fischer-Piette and Testud (1967) have interpreted the more narrowly ribbed, more finely scaly forms of this species as a separate species C. patriae (Doello-Jurado, 1918), which they thought occurred further northeastwards up the coast of northern Argentina, Uruguay, and southernmost Brazil
than the 'typical', more coarsely ribbed, smoother C. patagonica. Soot-Ryen (1959, pp. 29-30, pl. 1, figs 7, 8) went even further and recognised C. amandi (Hertlein, 1935) as a third South American species in this group, differing in its smaller size, finer ribs, and more oblique shape from C. patagonica and C. patriae; but his illustration shows an immature specimen of C. patagonica, not yet large enough to have begun the allometric shape changes that coincide with the adoption of the adult, free-living habit. Such small, oblique, finely sculptured shells are easily matched in a large number of New Zealand collections of C. patagonica delicatula. The range of material I have examined shows clearly that the more finely ribbed forms intergrade completely with the more coarsely ribbed forms. The more finely ribbed 'patriae' form is much the more common in dredgings from off-shore locations throughout the range of the species, and particularly in the material from southern Argentina, Tierra del Fuego and the Falkland lslands (Pl. 1, figs 1-4). Dell (1964, p. 179) noted that no type material is known for Pecten patagonicus King and Broderip, so it is not clear to which form this name should apply if the forms were recognised as distinct taxa; and he commented on the lack of characters distinguishing C. patriae from C. patagonica (Dell, 1964, p. 178; 1971, p. 169). There is little doubt that the differences used to distinguish these supposed 'species' are trivial features of the variation within the single subspecies C. patagonica patagonica. Features of the South American population that distinguish it from Chlamys patagonica delicatula are: (1) the primary ribs of the right valve have considerably wider surfaces lacking the scaly comarginal sculpture of C. patagonica delicatula in about 80% of specimens (but ribs of a few specimens in most large lots have narrow, finely scaly-surfaces similar to those of C. patagonica delicatula; Pl. 1, figs 3, 4); and (2) the darker colour —most specimens ot C patagonica patagonica have pale to medium brick-red left valves, with dark-red to purplish-red rib surfaces, and pink right valves, whereas most specimens of C. patagonica delicatula have pale pink to lemon-yellow left valves, with ribs only faintly darker than the rest of the shell, and white right valves with faintly tinged umbones. These differences are seen to be subtle when large suites are compared, and almost all features intergrade in the extreme forms, so a subspecies relationship seems the most likely genetic reality. The two subspecies were illustrated together in colour by Shikama (1964, pl. 32), although he figured an unusually dark Macquarie Island specimen of C. patagonica delicatula. Chlamys patagonica patagonica ranges from southern Chile and southernmost Brazil to Tierra del Fuego and the Falkland lslands (Dell, 1964, p. 178). Extreme northern limits are reported to be 'in southern Chile, at least as far as 49°S, and probably to Chiloe lsland' (Dell, 1971, p. 169) and to Puerto Montt, just north of Chiloe lsland (Carcelles, 1950, p. 77); and on the east coast, to 35°S (Carcelles, 1950, p. 76) and 'la côte du Rio Grande do Sul (Brésil)' (Fischer-Piette and Testud, 1967, p. 183).» BEU, A. G. 1985. Pleistocene Chlamys patagonica delicatula (Bivalvia: Pectinidae) off southeastern Tasmania, and history of its species group in the Southern Ocean. In: Lindsay, J. M. (ed. ), Stratigraphy, paleontology, malacology. Papers in honour of Dr Nell Ludbrook. Department of Mines and Energy, South Australia. Special Publication. 5: 1-11, pls. 1, 2. [p. 1, 2]
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Chlamys patagonica patagonica (King and Broderip); A. G. Beu, 1985, Pleistocene Chlamys patagonica delicatula off southeastern Tasmania, and history of its species group in the Southern Ocean, plate 1, figures 1-4.
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«Type material of Pecten australis Philippi (that is, Chlamys amandi) has never been illustrated. Its type locality, Chonos Archipelago, unboubtedly influenced Soot-Ryen's (1959) application of the name to a species common in the adjacent Golfo de Ancud. A photograph of the holotype has generously been supplied by Dr. Nibaldo Bahamonde N.; while not suitable for publication, it clearly shows the characters of the shell and substantiates Philippi's diagnosis, with the possible exception of his comparison to "P. ornatus". A drawing made from the photograph is reproduced here as Text Fig. 1. The holotype is moderately convex, substantial, nearly equilateral, with 34 straight, approximately equal-sized ribs which are narrower than their interspaces and strongly crenulate the shell margin. The ribs are borne singly. The auricles are unequal, but not as markedly so as in Chlamys ornata (Lamarck, 1819) (figured by Abbott, 1974: pl. 19, fig. 5140); they bear strong radiating ribs, 9 on the anterior and 7 on the posterior auricle of the left valve. The right valve is uniformly light coloured within; the exterior of the left valve has three darker concentric zones.
Several authors (von Martens, 1881; Smith, 1885; Grau, 1959) have suggested the synonymy of Chlamys patagonica (King, in King & Broderip, 1832) and C. amandi – none apparently having compared type material of both nominal species. Dall (1909) reported C. patagonica
to range, on the Pacific coast of Chile, from Chiloe Island and Puerto
Montt southward to the Magellanic region. The Lund University Expedition
did not collect it in the regions around Puerto Montt, and Soot-Ryen
(1959: 30, 72) considered records from north of about 52º south latitude to have been based on misidentifications. The holotype of C. amandi is clearly distinct from C. patagonica
as figured by Sowerby (1842) and Grau (1959), having a much narrower
umbonal angle and proportionally longer hinge line. In outline it more
nearly resembles Pecten rufiradiatus Reeve, 1853.
The latter species, with type locality "Strait of Magalhaens," has not
been positively identified since its original description, and various
authors have considered it synonymous with other Magellanic species.»
ROTH, B. 1975. Description of a new species of pectinid bivalve from the Juan Fernandez Islands, Chile. Journal of the Malacological Society of Australia, 3: 81-87, pl. 6, text-fig. 1. [p. 86]
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Chlamys phalara Roth, sp. nov.; B. Roth, 1975, Description of a new species of pectinid bivalve from the Juan Fernandez Islands, plate 6, figures 1-4.
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«Remarks [Chlamys amandi (Hertlein) 1935]: Following the description Philippi said, "This species has almost entirely the same outline, number of ribs, and formation of the ears, as P. ornatus, differing slightly, however, in the following characteristics; 1) the body of the shell is much more strongly arched, and describes more than a half-circle; 2) the ribs are all of equal size, not alternately smaller; 3) the latter are completely smooth, not scaled." (Translation from German.)
Stempell (loc. cit.) remarked of this species, "The largest, 60 millimetre examples of the Plate collection differ from the description of Philippi in that their ribs are not all the same size, and they evidence a scally sculpture toward the shell's edge, but nevertheless they may with certainty be classified with the species described by Philippi, particularly since a small example from out of the Philippi lot exhibits uneven ribbing and, at least at the edge, weak traces of scales. The number of ribs varies also in the specimens present, just as in those of the Philippi types, between 30 and 34." (Translation from German.) (...) Chlamys amandi and C. patagonica are almost certainly conspecific. However no figures of C. amandi were ever published and the author has not been able to locate any specimens identified as that species, so it does not seem advisable at present to place amandi in synonymy.» GRAU, G. 1959. Pectinidae of the eastern Pacific.
Allan Hancock Pacific Expeditions, 23: viii, 308 p., pls. 1-57.
University of Southern California Press. Los Angeles, California. [p.
84]
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Chlamys patagonica (King) 1831; G. Grau, 1959, Pectinidae of the eastern Pacific, plate 26.
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