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Description

Yoldia (Aequiyoldia) eightsi (Couthouy, 1839) (pl. II, 11).

 

 

Nucula eightsii Couthouy (in Jay), 1839, p. 113, pl. 1, figs. 12, 13.

 

Yoldia sp.n. Woodward, 1854, p. 270, fig. 182 (animal).

 

Leda ( Yoldia) eightsii Hanley, 1860a, p. 142, fig. 164.

 

L. (Yoldia) woodwardi Hanley, 1860a, p. 140, figs. 17, 22.

 

Yoldia woodwardi Hanley, 1860b, p. 370.

 

Y. eightsii Sowerby (in Reeve), 1871, pl. 5, fig. 26.

 

Y. woodwardi Sowerby (in Reeve), 1871, pl. 1, fig. 2.

 

Y. eightsii Smith, 1902, p. 211.

 

Y. woodwardi Pelseneer, 1903, p. 10.

 

Y. woodwardi Lamy, 1906a, p. 52.

 

Y. woodwardi Lamy, 1906b, p. 19.

 

Y. woodwardi Lamy, 1906c, p. 125.

 

Y. woodwardi Lamy, 1910b, p. 393.

 

Y. eightsii Hedley, 1911a, p. 3.
Y. woodwardi Lamy, 1911a, p. 29.

 

Y. woodwardi Melvill & Standen, 1914, p. 127.

 

Y. eightsii Melvill & Standen, 1914, p. 127.

 

Y. woodwardi Carcelles, 1950, p. 74.

 

Y. woodwardi Carcelles & Williamson, 1951, p. 325.

 

Y. eightsii Carcelles & Williamson, 1951, p. 325.

 

Y. (Aequiyoldia) eightsii Soot-Ryen, 1951, p. 6.

 

Y. (Aequiyoldia) woodwardi Soot-Ryen, 1951, p. 7, pl. 1, figs. 1-6.

 

Y. (Aequiyoldia) woodwardi Carcelles, 1953, p. 208.

 

Y. (Aequiyoldia) eightsii Carcelles, 1953, p. 208.

 

Y. (Aequiyoldia) woodwardi Powell, 1960, p. 171.

 

 

OCCURRENCE: St. 146, South Georgia, 728 m; St. 156, South Georgia, 200-236 m; St. 162, South Orkneys, 320 m; St. 164, South Orkneys, 24-36 m; St. 167, South Orkneys, 244-344 m; St. 1961, South Orkneys, 340 m; WS 210, Falkland Islands, 161 m; WS 219, Falkland Islands, 116-114 m; WS 825, Falkland Islands, 135-144 m.

 

 

DISTRIBUTION: Falkland Islands; South Georgia; South Orkneys; South Shetlands; Palmer Archipelago; Bellinghausen Sea; Ross Sea; probably circum-Antarctic.

 

 

Two Antarctic species, eightsi Couthouy and woodwardi Hanley, usually classified as Yoldia but recently placed in a new subgenus Aequiyoldia by Soot-Ryen (1951, p. 6), have always been difficult to determine, and treatment by subsequent authors has been varied. Soot-Ryen (1951, pp. 6-8) has summarized the situation. Unfortunately, he was not able to consult the original descriptions and figures, and was forced to rely upon figures given by subsequent authors. Both the original descriptions and the later figures were rather obscure. Nucula eightsi was attributed to Couthouy in an appendix to the third edition of Jay's Catalogue, there being no description, but reasonable figures of the interior and exterior of a valve were given and the locality was stated as ‘New South Shetland'. Yoldia woodwardi Hanley was published first without a figure, but it was stated ‘that the species was figured under the name Yoldia sp.n. by Woodward (1851-6) in the Manual of Mollusca p. 270'.

 

The type-localities are near the Falkland Islands (woodwardi) and the South Shetland Islands (eightsi).

 

The original figure of eightsi shows a deeply excavated posterior dorsal slope and it is difficult to match this with any of the Antarctic shells examined. On the other hand it does not seem possible to divide the Antarctic series into two species. Shells subsequently obtained from the South Shetlands do not show the excavated posterior dorsal slope. This character should be treated therefore as an individual variant or an artist's error. When dried shells of this type are forcibly opened, instead of snapping across the ligament the shell often breaks, removing a crescent from the posterior dorsal slope, the resulting shape being very like Jay's figure. Some such accident may have produced this aberrant figure. From all the material available it is obvious that only one species is present, which should bear the earlier name, eightsi. This name will therefore cover all the forms previously identified as woodwardi. The shells identified as eightsi by Smith (1902) from the Ross Sea cannot be distinguished from specimens identified as woodwardi by other writers.”

 

 

(Dell, 1964: 146-147)

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© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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