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Asthenotoma

Asthenotoma is a genus of sea snails, marine gastropod mollusks in the family Borsoniidae.

Description

This genus, almost entirely represented by extinct species, is of slender form and elevated, evenly and gradually acuminate spire, conspicuous development of the spiral lyrae and short aperture. It should evidently be considered especially with Trypanotoma and allies, but it is somewhat of an annectant form, as the American species at least have true ribbing on the nepionic whorls which becomes completely lost on the larger volutions of the shell. It is therefore one of those puzzling exceptions which render an arrangement of the genera in a dichotomous table so difficult and unsatisfactory. The embryo in the type, Pleurotoma basteroti Desm., of the European Miocene, is said by Cossmann to be paucispiral, but the drawing shows a multispiral protoconch. This is, however, a matter of minor importance. The anal sinus is broad, sometimes very feeble and always median in position on the spire whorls though not identified with any particular one or more of the subequal and rather coarse flat spirals. The beak has no external oblique tumidity. There can be but little doubt, in view of geographical variations and wide distribution of this genus, that Endiatoma, of Cossmann, should be regarded as a synonym or as constituting a slightly differentiated section of Asthenotoma.

Species

Species within the genus Asthenotoma include:

Taxon inquirendum:
  • Oligotoma sirpata <small>Jousseaume, 1891</small>
Synonyms:
  • Subgenus Asthenotoma (Drilliola) <small>Locard, 1897</small>: synonym of Drilliola <small>Locard, 1897</small>
  • Asthenotoma (Drilliola) emendata <small>(Monterosato, 1872)</small>: synonym of Drilliola emendata <small>(Monterosato, 1872)</small>
  • Asthenotoma cicatrigula <small>Hedley, 1922</small>: synonym of Tomopleura cicatrigula <small>(Hedley, 1922)</small>
  • Asthenotoma eva <small>(Thiele, 1925)</small>: synonym of Maoritomella eva <small>(Thiele, 1925)</small>
  • †Asthenotoma exbasteroti <small>Peyrot, 1931</small>: synonym of † Drilliola basteroti <small>(Des Moulins, 1842)</small>
  • Asthenotoma komakimonos <small>Otuka, 1935</small>: synonym of Pulsarella komakimonos <small>(Otuka, 1935)</small>
  • † Asthenotoma obesa <small>Peyrot, 1931</small>: synonym of † Drilliola obesa <small>(Peyrot, 1931)</small>(original combination)
  • Asthenotoma spiralis <small>(E. A. Smith, 1872)</small>: synonym of Tomopleura spiralissima <small>Gofas & Rolán, 2009</small>
  • Asthenotoma subtilinea <small>Hedley, 1918</small>: synonym of Tomopleura subtilinea <small>(Hedley, 1918)</small>
  • † Asthenotoma tricarinata <small>Peyrot, 1931</small>: synonym of † Boettgeriola tricarinata <small>(Peyrot, 1931)</small> (original combination)
  • Asthenotoma vertebrata <small>(E. A. Smith, 1875)</small>: synonym of Tomopleura vertebrata <small>(E. A. Smith, 1875)</small>

References

External links