Header Image
Epitoniidae Berry, 1910 (1812)

Gyroscala roberti

(Dall, 1917)

Description:

Dimensions range from 6 mm - 12 mm high and 3 mm - 6.5 mm wide.
Width to height ratio: 0.5:1 ~ 0.54:1

Shell: pyramidal, somewhat broad and squat; solid; minute to small. Exterior colour white. About 8 whorls; protoconch with ~2 whorls ; teleoconch with ~6 whorls. Imperforate. Approximately 13 costae on the body whorl. Costae are smooth, low, erect. Costae continuous over the suture; with a small spine present on the shoulder in earlier whorls, but this disappears on later whorls. Base rounded, marginated by a slender, inconspicuous cord [Dall, 1917: 485]; DuShane [1974: 22-23] found the basal cord variable, sometimes replaced by an incised line or occasionally doubled.. Aperture subovate, lip narrow.


Distribution:

Gulf of California [Dall, 1917:485], Baja Claifornia [DuShane, 1974:30], Mazatlan, Mexico, to Panama [Keen, 1958:274].


Habitat:

no information provided in available source documents, however [DuShane, 1974: 22] records specimens of Epitonium obtusum intertiadally to 11m under rocks and in sandy mud.


Etymology:

A stated by the author [Dall, 1917: 485], this species is 'named for Dr. Robert E.C. Stearns'.


Type Material:

DuShane [1974: 22-23] treated Epitonium roberti Dall, 1917 as a junior subjective synonym of Epitonium obtusum (G. B. Sowerby II, 1844), considering differences in sculpture to represent wear and intraspecific variation. She noted that the basal cord described by Dall [1917: 485] was variable among specimens of E. obtusum: some possessed a basal cord, others an incised basal line, and one had two cords, and therefore considered this character insufficient to distinguish E. roberti as a separate species. Weil et al. [1999: 158], however, questioned this placement, regarding the basal cord described by Dall as sufficient to exclude roberti from Epitonium as they defined it, and placed the species in Gyroscala.

Holotype: USNM 46251 for Gyroscala roberti (Dall, 1917) - Type Locality: Gulf of California. [Smithsonian National Museum of Natural History, 2026: USNM 46251]


SpeciesImage

Smithsonian National Museum of Natural History (2026). Fig. USNM 46251.

Epitonium roberti holotype, USNM 46251.
Photograph by Angelica Isgro
Smithsonian National Museum of Natural History.
CC0. EZID: ark:/65665/m36bfded4d-6639-42f5-92a9-cb8651fa5385.

Distribution

as listed in source literature

Dall, W. H. (1917).
Species Image
pp: 485.
Original description
DuShane, H. (1974).
Species Image
pp: 30. Fig. 49.
Epitonium (Nitidiscala) roberti Dall, 1917.
Holotype, USNM 46251
Length 12mm; width 6 mm X4.5
Species Image
pp: 30. Fig. 44.
Epitonium (Asperiscala) roberti Dall, 1917.
Bahía Concepción, Baja California, Mexico (DuShane Collection) Length 6mm; width 3 mm
X I
Smithsonian National Museum of Natural History (2026).
Species Image
Fig. USNM 46251.
Epitonium roberti holotype, USNM 46251.
Photograph by Angelica Isgro
Smithsonian National Museum of Natural History.
CC0. EZID: ark:/65665/m36bfded4d-6639-42f5-92a9-cb8651fa5385.

Synonymy:

Epitonium (Nitidoscala) roberti Dall, 1917 [Pilsbry & Lowe, 1932: 120]
Epitonium roberti Dall, 1917 [Smithsonian National Museum of Natural History, 2026: USNM 46251]


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]
Dall, W. H. (1917). Notes on the shells of the genus Epitonium and its allies of the Pacific coast of America.. Proceedings of the US National Museum. 53(2217). https://www.biodiversitylibrary.org/page/7553869 [Accessed 18 September 2023]
DuShane, H. (1974). The Panamic-Galapagan Epitoniidae. The Veliger. 16 (Sup. 14). https://www.biodiversitylibrary.org/page/42500298 [Accessed 25 September 2023]
Keen, A. M. (1958). Sea shells of tropical west America; marine mollusks from Lower California to Colombia. Stanford Univ. Press;
Pilsbry, H. A. & Lowe, H. N. (1932). West Mexican and Central American Mollusks Collected by H. N. Lowe, 1929-31. Proceedings of the Academy of Natural Sciences of Philadelphia. 84. http://www.jstor.org/stable/4064126 [Accessed 21 October 2025]
Smithsonian National Museum of Natural History (2026). Invertebrate Zoology collections [Specimen database]. Smithsonian Institution. https://collections.nmnh.si.edu/search/iz/ [Accessed 22 August 2026]
Weil, A., Brown, L. & Neville, B. (1999). The Wentletrap Book. Evolver
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