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Bathytoma

Bathytoma is a genus of deep-water sea snails, marine gastropod mollusks in the family Borsoniidae.

Fossil records

This genus is known in the fossil records from the Paleocene to the Quaternary (age range: 55.8 to 0.781 million years ago). Fossils are found in the marine strata throughout the world.

Distribution

This marine species occurs in the Eastern Indian Ocean (Madagascar, Mozambique, South Africa); off Indonesia, New Caledonia, Panglao Island, Sulu Sea, Vanuatu, Wallis and Futuna, Bohol, Kerala, New Zealand, Philippines, Sea of Japan; off Australia (New South Wales, Queensland, Victoria, Western Australia). They are all known from deep waters from 100 m to about 1500 m, but usually at 200–700 m.

Description

The lines of specific distinction appear to be drawn narrowly in this genus and to depend chiefly upon sculpture. The novelty appears intimately related to Bathytoma engonia (Watson, 1881) differing by the sharper keel, more elevated tubercles and generally coarser sculpture.

The biconical or fusiform shell is medium-sized to rather large. Its periphery is smooth or nodose, angulate or keeled. The peripheral anal sinus is deep. The columella is somewhat swollen, sometimes showing a pleat. The paucispiral protoconch consists of 1 to 3 conical or globose whorls, smooth or with faint spiral striae. The operculum is broadly oblanceolate to ovate shape, with an eccentric to terminal nucleus. The ground color of the shell is white to yellowish-brown.

Their protoconch morphology seems to infer a non-planktotrophic larval development.

Species

Species within the genus Bathytoma include:

Species brought into synonymy:
  • Bathytoma biconica <small>Hedley, 1903</small>: synonym of Benthofascis biconica <small>(Hedley, 1903)</small>
  • Bathytoma colorata <small>Sysoev & Bouchet, 2001</small>: synonym of Gemmuloborsonia colorata <small>(Sysoev & Bouchet, 2001)</small>
  • † Bathytoma condonana <small>F.M. Anderson & B. Martin, 1914</small>: synonym of Megasurcula condonana <small>(F.M. Anderson & B. Martin, 1914)</small>
  • † Bathytoma excavata <small>Suter, 1917</small>: synonym of † Austrotoma excavata <small>(Suter, 1917)</small>
  • Bathytoma sulcata excavata <small>Suter, 1917</small> synonym of † Austrotoma excavata <small>(Suter, 1917)</small>
  • Bathytoma gratiosa <small>Suter, 1908</small>: synonym of Fenestrosyrinx gratiosa <small>(Suter, 1908)</small>, synonym of Taranis gratiosa <small>(Suter, 1908)</small>
  • Bathytoma sarcinula <small>Hedley, 1905</small>: synonym of Benthofascis sarcinula <small>(Hedley, 1905)</small>
  • Bathytoma tremperiana <small>(Dall, 1911)</small>: synonym of Megasurcula tremperiana <small>(Dall, 1911)</small>
  • Bathytoma tremperiana <small>Dall, 1911</small>: synonym of Megasurcula carpenteriana <small>(Gabb, 1865)</small>
  • Subgenus Bathytoma (Parabathytoma) <small>Shuto, 1961</small> represented as Bathytoma <small>Harris & Burrows, 1891</small>
  • Bathytoma (Parabathytoma) helenae <small>Kilburn, 1974</small> represented as Bathytoma helenae <small>Kilburn, 1974</small>
  • Bathytoma (Parabathytoma) visagei <small>Kilburn, 1973</small> represented as Bathytoma visagei <small>Kilburn, 1973</small>

References

  • Harris G. F. & Burrows H. W. (1891). The Eocene and Oligocene beds of the Paris basin. Geologists' Association, London 129 pp.: page(s): 113
  • Wilson, B. 1994. Australian Marine Shells. Prosobranch Gastropods. Kallaroo, WA : Odyssey Publishing Vol. 2 370 pp.

External links