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Epitoniidae Berry, 1910 (1812)

Epitonium tenuicostatum

(G. B. Sowerby, 1844)

Description:

Dimensions range from 11.9 mm - 20 mm high and 7.3 mm wide.
Width to height ratio: 0.61:1 ~ 0.37:1

Shell: conical, subventricose; thin; small. Exterior colour white. About 9 whorls, rather oval; protoconch smooth. Suture deep. Imperforate: umbilicus closed. Approximately 13 costae on the body whorl. Costae are blade-like, thin, laminated. Costae angled at the shoulder. Intercostal spaces smooth glossy. Columella margin thick and curved. Aperture circular, rather ovate, circular to rather ovate; outer lip outer lip expanded into an elevated angle.

This species has two names in the literature., Sowerby (1844) originally described it as Scalaria tenuicostata, but that name is a junior primary homonym of Scalaria tenuicostata Michaud (1829). To resolve the homonymy, de Boury (1913) introduced the replacement name Scala extenuicostata, now placed in Epitonium as E. extenuicostum., Both names refer to the same species., Epitonium tenuicostatum is the senior name and has priority, while Epitonium extenuicostum is the valid replacement name created solely to avoid using the homonym. Both names are therefore retained in catalogues for clarity and citation, but only one biological species is involved.


Distribution:

Off the Pacific Coast from Sagami Bay to Kyushu, Japan; Philippines. Brazier [1875] aslo reported specimens from Torres Strait


Habitat:

recorded from 20-91m. Fine grey sand [Brazier, 1875:250 and Schepmann, 1909:224]


Etymology:

[latin] from tenuis = thin, slender or delicate and costatum = ribbed. This may be in reference to the thin costae of the shell


Type Material:

Type not located [as Scalaria tenuicostata G.B. Sowerby II, 1844: ~ Scala extenuicosta de Boury, 1913c.] - Locality: Luzon, Philippines. [Brown, L. & Neville, B.D., 2015]
Type not indicated in text for Epitonium tenuicostatum (G. B. Sowerby, 1844) - Locality: Luzon, Philippines.. [Higo, S., Callomon, P. & Goto, Y., 1999]


SpeciesImage

Sowerby, G. B. II. (1873-1874). Plate v. Fig. 31.

Distribution

as listed in source literature

Sowerby, G. B. II. (1844).
Species Image
pp: 87.
Original description
Species Image
Plate xxxiv. Fig. 76.
Sowerby, G. B. II. (1873-1874).
Shown in text as Scalaria tenuicostata G. B. Sowerby II, 1844
Species Image
Plate v. Fig. 31.
Species Image
Species Image
Tryon, G.W. (1879).
Shown in text as Scalaria tenuicostata G. B. Sowerby II, 1844
Species Image
Plate 11. Fig. 44.
Species Image
pp: 56.
Clessin, S. (1897).
Species Image
Plate 3. Fig. 8.
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pp: 10-11.
Shell white, somewhat swollen, thin, imperforate; whorls few, somewhat ovate; varices lamellar, thin, projecting, angularly raised at the suture; aperture somewhat ovate, outer lip expanded upward into an angle.
Nakayama, T. (2003).
Species Image
pp: 127. Plate 12. Fig. 16-17.
figs 16-17: Epitonium (Hirtoscala) tenuicostatum (Sowerby, 1844)
h 11.9 mm; w 7.3 mm (NSMT-MoR 14935)

Synonymy:

Scalaria tenuicostata G. B. Sowerby II, 1844 [in Sowerby, G. B. II., 1873-1874].
Scalaria tenuicostata G. B. Sowerby II, 1844 [in Tryon, G.W., 1887].
Scalaria tenuicostata G.B. Sowerby II, 1844: ~ Scala extenuicosta de Boury, 1913c. [in Brown, L. & Neville, B.D., 2015].


Source Literature:

Brown, L. & Neville, B.D. (2015). Catalog of the recent taxa of the families Epitoniidae and Nystiellidae (Mollusca: Gastropoda) with a bibliography of the descriptive and systematic literature. Zootaxa. 3907(1). Magnolia Press Auckland, New Zealand. http://dx.doi.org/10.11646/zootaxa.3907.1.1 [Accessed 22 October 2023]
Clessin, S. (1897). Die Familie der Scalariidae. In W. Kobelt (Ed.), Systematisches Conchylien-Cabinet von Martini und Chemnitz. Neu herausgegeben und vervollständigt. 2(13). Bauer & Raspe, NürnbergBauer & Raspe, Nürnberg. https://www.biodiversitylibrary.org/page/34259905 [Accessed 21 June 2025]
Higo, S., Callomon, P. & Goto, Y. (1999). Catalogue and Bibliography of the Marine Shell-Bearing Mollusca of Japan.. https://www.researchgate.net/publication/266375656_Catalogue_and_Bibliography_of_the_Marine_Shell-Bearing_Mollusca_of_Japan [Accessed 25 July 2025]
Nakayama, T. (2003). A Review of Northwest Pacific Epitoniids. Monographs of Marine Mollusca. 6. Backhuys Publishers
Schepman, M.M. (1909). The Prosobranchia of the Siboga Expedition. Part 2. Taenioglossa and Ptenoglossa. E.J. Brill,Leyden. https://www.biodiversitylibrary.org/page/34314807 [Accessed 27 July 2025]
Sowerby, G. B. II. (1844). Monograph of the genus Scalaria.. Thesaurus conchyliorum, or monographs of genera of shells.. 1 (4). London, privately published.. http://biodiversitylibrary.org/page/11076419 [Accessed 22 June 2023]
Sowerby, G. B. II. (1873-1874). Monograph of the genus Scalaria. Conchologia iconica, or illustrations of the shells of molluscous animals, vol. 19, pls 1-16 and unpaginated text.. 19. London. https://www.biodiversitylibrary.org/page/8217819 [Accessed 24 August 2023]
Tryon, G.W. (1887). Manual of conchology, structural and systematic with illustrations of the species. IX. Academy of Natural Sciences. https://www.biodiversitylibrary.org/page/11026889 [Accessed 20 September 2025]
Weil, A., Brown, L. & Neville, B. (1999). The Wentletrap Book. Evolver
WoRMS Editorial Board (2025). World Register of Marine Species. https://www.marinespecies.org [Accessed 8 November 2025]

WoRMS direct page link: Open WoRMS record