Epitoniidae Berry, 1910 (1812)

Cirsotrema amplsum

T. 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); Paratype (WMNH-Mo-28) [as Cirsotrema (Elegantiscala) amplsum Nakayama, 2000] - Type Locality: Off Kushimoto, Kii Peninsula, Japan, at about 420 m deep. [Nakayama, 2003: 26]
Holotype: NSMT-M0 71410 for Cirsotrema amplsum T. Nakayama, 2000 - Type Locality: Off Kushimoto, Kii Peninsula, Wakayama Prefecture, Japan. 420m. [National Museum of Nature and Science, 2026: NSMT-M0 71410]

SpeciesImage

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

Distribution

as listed in source literature

Nakayama, T. (2000).

Shown in text as Cirsotrema (Elegantiscala) amplsum Nakayama, 2000

Species Image

pp: 280. Fig. 7-8.

Cirsotrema (Elegantiscala) amplsumn.sp.

Species Image

pp: 279.

Brown, L. (2009).

Species Image

pp: 23. Fig. 10.

Synonymy:

Cirsotrema (Elegantiscala) amplsum Nakayama, 2000 [Nakayama, 2000: 279; Nakayama, 2003: 26; Brown & Neville, 2015: 37]

Source Literature:

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
National Museum of Nature and Science (2026). Collection database of specimens and materials: Mollusca. National Museum of Nature and Science Mollusca database. https://db.kahaku.go.jp/webmuseum_en/search?cls=col_a2_19 [Accessed 9 August 2026]
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