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Epitoniidae Berry, 1910 (1812)

Epitonium tenuicostatum

(G. B. Sowerby II, 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.


Distribution:

Off the Pacific Coast from Sagami Bay to Kyushu, Japan; Philippines [Nakayama, 2003:51]; Korean Peninsular [NIBR, 2019:328]; Gulf of Thailand [Wells et al., 2021:128]; East Nusa Tenggara, Indonesia [Schepman, 1909: 224]; Brazier [1875] also 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.


SpeciesImage

Reeve, L. A. (1873). Plate v. Fig. 31.

Distribution

as listed in source literature

Type Material:

This species has two names in the literature.
Sowerby [1844: 87] 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 [1913d: 82] 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.

The following list brings together type material and other cited specimens as reported in the sources examined, grouped under the names and designations used in each source. The same specimen may appear in multiple entries drawn from different sources. Some entries concern other species included by authors for comparison; inclusion in this list does not imply synonymy.
Epitonium (Hirtoscala) tenuicostatum (Sowerby, 1844)TypeLuzon Island, Philippines. [Nakayama, 2003: 51].
Scalaria tenuicostata G. B. Sowerby II, 1844Type not locatedLuzon, Philippines. [Brown & Neville, 2015: 147].
Spiniscala tenuicostata (Sowerby II, 1844 in 1842-87)Type designation not provided in text/ source documentLuzon, Philippines. [Higo et al., 1999: G1912].


Sowerby, G. B. II. (1844).
Shown in text as Scalaria tenuicostata G. B. Sowerby II, 1844
Species Image
pp: 87.
Original description
Species Image
Plate xxxiv. Fig. 76.
Sowerby, G. B. II. (1873).
Shown in text as Scalaria tenuicostata G. B. Sowerby II, 1844
Species Image
Plate v. Fig. 31.
Species Image
Species Image
Tryon, G.W. (1887).
Shown in text as Scalaria tenuicostata Sowerby
Species Image
Plate 11. Fig. 44.
Species Image
pp: 56.
Clessin, S. (1897).
Species Image
Plate 3. Fig. 8.
Species Image
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.
Boury, E. de (1913d).
Shown in text as Scala extenuicostata de Boury, 1913
Species Image
pp: 82.
We propose the replacement name Scalaria extenuicosta for Scalaria tenuicosta Sowerby, which is not Scalaria tenuicosta Michaud.
Nakayama, T. (2003).
Shown in text as Epitonium (Hirtoscala) tenuicostatum (Sowerby, 1844)
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)
Brown, L. G. (2010b).
Species Image
pp: 28. Fig. 6.
East China Sea

Synonymy:

Epitonium (Hirtoscala) tenuicostatum (G. B.Sowerby, 1844) [Wells et al., 2021: 128; Gemert, 2003: 105]
Epitonium (Hirtoscala) tenuicostatum (Sowerby, 1844) [Nakayama, 2003: 51; Weil et al., 1999: 96]
Epitonium extenuicostum (de Boury, 1913) [Brown, 2010b: 7]
Scala extenuicostata de Boury, 1913 [Boury, 1913d: 82]
Scala tenuicostata Sowerby [Schepman, 1909: 224]
Scalaria tenuicostata G. B. Sowerby II, 1844 [Sowerby, 1844: 87; Brown & Neville, 2015: 147; Reeve, 1873: pl. 5, fig. 31; Clessin, 1897: 10; Brazier, 1875: 250]
Scalaria tenuicostata Sowerby [Tryon, 1887: 56]
Spiniscala tenuicostata (Sowerby II, 1844 in 1842-87) [Higo et al., 1999: G1912]


Source Literature:

Boury, E. de (1913d). Observations sur quelques espèces ou sous-genres de Scalidae. Journal de Conchyliologie. 61(1). http://biodiversitylibrary.org/page/16294279 [Accessed 4 December 2025]
Brazier, J. (1875). Shells collected during the Chevert Expedition, with Descriptions of the New Species. Proceedings of the Linnean Society of New South Wales. 1(3). Linnean Society of New South Wales.. https://www.biodiversitylibrary.org/item/22887 [Accessed 3 September 2025]
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]
Brown, L. G. (2010b). Report on the Epitoniidae of the East China Sea - Part 2. American Conchologist: quarterly bulletin of the Conchologists of America, Inc. 38 (3). Lipps-National Pres. https://www.biodiversitylibrary.org/item/262812 [Accessed 23 July 2025]
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]
Gemert L van (2003). Marine schelpen verzamelen op Ko Samui (Golf van Thailand). De Kreukel. 39
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
NIBR National Institute of Biological Resources, (2019). National Species List of Korea II. Vertebrates · Invertebrates · Protozoa. National Institute of Biological Resources.
Reeve, L. A. (1873). Monograph of the genus Scalaria. Conchologia iconica, or illustrations of the shells of molluscous animal. 19. London. https://www.biodiversitylibrary.org/page/8217819 [Accessed 24 August 2023]
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]
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
Wells, E., Sanpanich, K., Tan, S. K, & Duangdee, T. (2021). The Marine and Estuarine Molluscs of Thailand. Lee Kong Chian natural History Museum
WoRMS Editorial Board (2025). World Register of Marine Species. https://www.marinespecies.org at VLIZ. [Accessed 8 November 2025]

WoRMS direct page link: Open WoRMS record