Epitonium gracile
(G. B. Sowerby II, 1844)
Description:
Dimensions range from 6.6 mm - 18 mm high and 3.2 mm - 5 mm wide.
Width to height ratio: 0.48:1 ~ 0.28:1
Shell: narrow, elongate conical, slender; sturdy; minute to small. Exterior colour white, fulvous, costae white. About 12 whorls, separated by a deeply fenestrate suture, contiguous; protoconch conical with ~3 whorls convex whorls, 1st one somewhat mamilliform; basal diameter 0,4 mm; termination at first axial lamella; teleoconch with ~9 whorls strongly rounded, convex. Spire greatly elevated. Suture deeply fenestrate. Umbilicate: slightly fenestrated or almost closed. Approximately 6 - 10 costae on the body whorl. Costae are prosocline, thick. Costae continuous; emarginated and aculeated near the suture, blunt coronation below the suture [Kilburn, 1985: 325], however Nakayama [2003: 54] states that it is not coronated at shoulder; somewhat recurved. Intercostal spaces with cancellate, granulate microstriae. Base thick, moderately expanded anteriorly. Fasciole narrow. Aperture roundly ovate; peristome thick, moderately expanded anteriorly.
Nakayama [2003: 54] distinguished this species from E. angustum primarily by the shape of the axial costae and the cancellated intercostal sculpture
Distribution:
Philippines [Sowerby, 1844:86]; Pacific coast from Boso Peninsula to Kyushu, southern coast of Sea of Japan, the Inland Sea, Japan [Nakayama, 2003:54]; Korean Peninsular [NIBR, 2019:328]; New Caledonia [Héros et al., 2007:218]; Gulf of Thailand [Wells et al., 2021:128];Red Sea to Natal, South Africa [Kilburn, 1985:325].
Habitat:
intertidal [Nakayama, 2003: 54].
Etymology:
[latin] from gracilis = slender, slim, fine or graceful, a reference to the elegance or narrowness of the shell's shape.
Sowerby, G. B. II. (1844). Plate xxxii. Fig. 33-34.
Distribution
as listed in source literature
Type Material:
Kilburn [1985: 325] considered the status of Graciliscala rostrata uncertain, noting that whether it represented a valid species, subspecies or genetic morph remained unresolved.
Jousseaume [1912: 205] considered Epitonium subauriculatum (Souverbie, 1866) a junior synonym of Epitonium gracile (G.B. Sowerby II, 1844b), however WoRMS [WoRMS Editorial Board, 2025] considers them to be two distinct species.
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 gracile (G. B. Sowerby II, 1844)SyntypeBMNH 98143. [Kaicher, 1981: EP2-3053].
Epitonium (Laeviscala) gracile (Sowerby, 1844)TypeMNHN4258. [Bonfitto, 2018: 127].Type designation not provided in text/ source documentDumaguete, Negros, Philippines. [Nakayama, 2003: 54].
Graciliscala rostrata Jousseaume, 1912HolotypeMNHN-IM-2000-4392. Red Sea, Djibouti. [Muséum national d'Histoire naturelle, 2026: MNHN-IM-2000-4392].MNHN 4392. Djibouti. [Brown & Neville, 2015: 133].
Sowerby, G. B. II. (1844).
Shown in text as Scalaria gracilis G. B. Sowerby II, 1844
Plate xxxii. Fig. 33-34.
pp: 86.
original description
Sowerby, G. B. II. (1873).
Shown in text as Scalaria gracilis G. B. Sowerby II, 1844
Plate viiI. Fig. 53.
Species 53. (Mus. Brit.)
SCALARIA GRACILIS.
Tryon, G.W. (1887).
Shown in text as Scalaria gracilis G. B. Sowerby II, 1844
Plate 14. Fig. 28-29.
pp: 67.
Clessin, S. (1897).
Plate 16. Fig. 4.
pp: 60.
pp: 74.
Clessin, S. (1897).
Plate 5. Fig. 6.
pp: 20.
Shell small, tapered, yellowish between the varices; spire very elevated; whorls numerous, contiguous; varices white, successive, notched and spined near the suture.
Jousseaume, F. (1912).
Shown in text as Graciliscala gracilis Jousseaume, 1912
pp: 205.
Graciliscala gracilis
Pl. VI, figs. 1-8.
Scalaria subauriculata Sowerby. Journal de Conchyliologie, 1866, p. 147, 260, pl. VI, fig. 2.
Of this species I found a fairly large number of specimens. Some are much larger than those which served as the types of the species established by Sowerby, while others are more slender and narrower. I compared the latter with the species labelled Sc. gracilis in the galleries of the British Museum. I had no doubt whatsoever as to their identity; but here the matter becomes more complicated.
Is the Sc. gracilis in the British Museum really identical with the species described and figured under that name by Sowerby in the Thesaurus Conchyliorum, p. 86, pl. XXIV, figs. 33-34?
This is what the author says of the species:
Shell very similar to aculeata, but more slender.
Yet, neither in gracilis nor in aculeata does the author mention spiral striae, whereas on the Sc. gracilis specimens in the British Museum these striae are clearly visible and well developed. This fact, together with many others of a similar nature, clearly indicates that the type specimens of species should be housed in public collections, and reminds us of the care and caution with which they ought to be preserved.
Here we have two species: Sc. subauriculata Sowerby, whose description is adequate but whose illustration is fanciful; and Sc. gracilis Sowerby, whose illustration is fairly accurate but whose description is almost entirely lacking.
How, with such documentation, can one hope to determine with certainty similar species that may be before one's eyes?
pp: 206.
If I were asked what I think of these two wentletraps, I would say that one is merely a variety of the other because, apart from the more tapering form of one and the somewhat stouter form of the other, I can see no specific character separating them.
Habitat. Suez, Jeddah, Aden, Djibouti.
The number of specimens collected in the Red Sea and the Gulf of Aden has enabled me to study the variability of this species. The form and size of some specimens differ greatly from those of others and, when arranged in series, it becomes apparent that every intermediate form exists, with no break in continuity.
This variability in form, size, and ornamentation is so great that I have wondered - and still wonder - whether the following species might not simply be constant varieties or races of Sc. gracilis Sowerby (= subauriculata Sowerby).
If that were the case, the spiral striae and the shape of the ribs would be characters of little importance; we already know that neither the number of ribs nor the size attained by individuals can be relied upon.
The study of the Scalariidae is beset with difficulties that cannot be appreciated by authors who describe a species from one or two shells that happen to come into their hands.
The majority of wentletraps are colourless, and those that are coloured display colours of such variable and unstable intensity that they often disappear shortly after the death of the animal. One must possess the courage and perseverance of Mr. de Boury to devote oneself to the study of this numerous and interesting family. I know well enough the difficulties presented by this field of study to offer him my congratulations and to say:
"Remain deaf to criticism and press onward."
Plate VI. Fig. 1-2.
Dall, W. H. (1917).
Shown in text as Scalaria gracilis G. B. Sowerby II, 1844
pp: 487.
Kaicher, S.D. (1981).
Card #: EP2-3053.
Shell sturdy; dull white; with 7 somewhat recurved costae;
under magni-fication, spirals and growth lines give cancel-late appear-ance; to approx. 15 mm. Offshore.
BMNH type coll. 198143 - syntype)
Card #: EP2-3053
Kilburn, R.N (1985).
148. NM B309, Durban Bay. 6.8 v 3.1mm. 1
Nakayama, T. (2003).
pp: 127. Plate 12. Fig. 35.
Epitonium(Laeviscala) gracile (Sowerby, 1844)
height 13.9 mm; breadth 5.0 m
Kushimoto, Kii Peninsula, Japan, at beach
Muséum national d'Histoire naturelle (2026).
Shown in text as Graciliscala rostrata Jousseaume, 1912
