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Epitoniidae Berry, 1910 (1812)

Cirsotrema amplsum

Nakayama, 2000

Description:

Dimensions range from 2.9 mm - 43.2 mm high and 14.3 mm - 20.1 mm wide.
Width to height ratio: 04.93:1 ~ 0.47:1

Shell: wide; thick; microscopic to medium. Exterior colour dull white. About 8 whorls; protoconch usually defected. Spire elevated. Suture deep. Imperforate: umbilicus closed. Approximately 18 - 25 costae on the body whorl. Costae are thick, stout, overlapping like roof tiles. Costae sharply coronated on shoulder; slightly reflexed, with margin piled over previous whorl. Intercostal spaces weakly striated with spiral threads. Interstices with approximately 18 spiral striae per whorl. Base surrounded by low and weak peripheral keel forming a basal disc. Fasciole stout. Aperture circular; peristome complete; outer lip very strongly varicose, dilated below on the base of the columella.


Distribution:

off Kii Peninsula to Tosa Bay, Japan (Nakayama 2003: 27); East China Sea (L. Brown 2009: 22, fig. 10).


Habitat:

at about 420 m deep [Nakayama, 2000]


Etymology:

In the original description, Nakayama [2000] states "The name amplsum means wide for this rather wide shell". However it appears that aplsum is a misspelling of the latin word amplus meaning wide or broad.


Type Material:

Holotype: (NSMT Mo-71410), height 43.2 mm; breadth 20.1 mm (Figs. 7, 8). for Cirsotrema amplsum Nakayama, 2000 - Type Locality: Off Kushimoto, Kii Peninsula, at about 420 m deep.. [Nakayama, T., 2000]
Holotype: (NSMT-Mo 71410); Paratype (WMNH-Mo-28) for Cirsotrema amplsum Nakayama, 2000 - Type Locality: Off Kushimoto, Kii Peninsula, Japan, at about 420 m deep. [Nakayama, T., 2003]
Holotype: HSMT Mo- 71410 [as Cirsotrema (Elegantiscala) amplsum Nakayama, 2000:] - Type Locality: off Kushimoto, Kii Peninsula, Japan, 420 m.. [Brown, L. & Neville, B.D., 2015]


SpeciesImage

Brown, L. (2009). pp: 23. Fig. 10.

Distribution

as listed in source literature

Nakayama, T. (2000).
Species Image
pp: 280. Fig. 7-8.
Cirsotrema (Elegantiscala) amplsumn.sp.
Species Image
pp: 279.
Nakayama, T. (2003).
Species Image
pp: 111. Plate 4. Fig. 9-11.
Cirsotrema (Elegantiscala) amplsum Nakayama, 2000
height 43.2 mm; breadth 20.1 mm
(holotype: NSMT-Mo 71410); fig. 11, base
Species Image
pp: 111. Plate 8. Fig. 9-11.
Cirsotrema (Elegantiscala) amplsum Nakayama, 2000
height 43.2 mm; breadth 20.1 mm
(holotype: NSMT-Mo 71410); fig. 11, base
Brown, L. (2009).
Species Image
pp: 23. Fig. 10.
arsint.com (2023).
Species Image
Cirsotrema Dannevigena amplsum
arsint.com (2023).
Species Image
Cirsotrema Dannevigena amplsum

Synonymy:

Cirsotrema (Elegantiscala) amplsum Nakayama, 2000: [in Brown, L. & Neville, B.D., 2015].


Source Literature:

arsint.com (2023). Shells for Sale:Epitonidae. arsint.com. http://www.arsint.com/seashells_epitoniidae_opalia.html [Accessed 21 October 2023]
Brown, L. (2009). Report on the Epitoniidae of the East China Sea. American Conchologist: quarterly bulletin of the Conchologists of America, Inc. 37(2). Lipps-National Press. https://www.biodiversitylibrary.org/item/321313 [Accessed 23 July 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]
Nakayama, T. (2000). Descriptions of a New Subgenus,Fourteen New Species,and Thee Substituted Names of Epitoniids from Japan. VENUS. 59(4). Malacological Society of Japan. https://www.jstage.jst.go.jp/article/venusjjm/59/4/59_KJ00004345136/_pdf [Accessed 24 August 2023]
Nakayama, T. (2003). A Review of Northwest Pacific Epitoniids. Monographs of Marine Mollusca. 6. Backhuys Publishers
WoRMS Editorial Board (2025). World Register of Marine Species. https://www.marinespecies.org [Accessed 8 November 2025]

WoRMS direct page link: Open WoRMS record