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. Fossils are found in the marine strata throughout the world.

Distribution

This marine species occurs in the Eastern Indian Ocean ; off Indonesia, New Caledonia, Panglao Island, Sulu Sea, Vanuatu, Wallis and Futuna, Bohol, Kerala, New Zealand, Philippines, Sea of Japan; off 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 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:Bathytoma agnata Hedley & Petterd, 1906Bathytoma arbucklei Kilburn, 1986Bathytoma atractoides Bathytoma badifasciata Puillandre, Sysoev, Olivera, Couloux & Bouchet, 2010
;Species brought into synonymy:Bathytoma biconica Hedley, 1903: synonym of Benthofascis biconica Bathytoma colorata Sysoev & Bouchet, 2001: synonym of Gemmuloborsonia colorata