Header Image
Epitoniidae Berry, 1910 (1812)

Amaea nebulodermata

(Azuma, 1972)

Description:

Dimensions range from 7 mm - 39 mm high and 2.4 mm - 19 mm wide.
Width to height ratio: 0.34:1 ~ 0.49:1

Shell: elongated conical, highly turreted; thin-walled, fragile; minute to moderately small. Exterior colour glossy, dull white- brownish with 2 narrow brownish bands. About 18 whorls, moderately inflated; protoconch with ~3 whorls usually eroded, brownish, glassy; teleoconch with 7-15 whorls convex, clouded with brown on off-white background. Suture moderately deep to deep. Imperforate. Approximately 16 - 45 costae on the body whorl. Costae are distant, almost obsolete on body whorl, often coalescing. Intercostal spaces with weak axial and spiral striae forming indistinct reticulate pattern. Base distinct basal disc surrounded by a spiral cord, depressed with prominent basal keel. Columella thickened, rather straight. Aperture ovate; inner lip with indistinct callus. Operculum thin ovate, light yellow and paucispiral.

This species is very close to A. (Ac.) bitaeniata collected from off Kii Peninsula, Japan, but nebulodermata has a spiral rib near the suture, which bitaeniata does not have. [Nakayama, 2003].


Distribution:

East China Sea, south end of Japan to west of Taiwan; Kauai, Hawaii [Nakayama, 2003], Philippines [Dushane, 1990:6]


Habitat:

36 m [DuShane 1990: 6] to 200 m Higo et al. 1999: 177], sand


Type Material:

Holotype: Azuma coll. 15771 for Amaea nebulodermata (Azuma, 1972) - Type Locality: southwest off Taiwan, in 80 fms [= 146 m]. [Brown, L. & Neville, B.D., 2015]
Holotype: NSMT Mo- 52448 [as Fragilopalia bitaeniata Masahito & Habe, 1976] - Type Locality: off Esuzaki, Wakayama Prefecture, Honshu, at about 150 m.. [Brown, L. & Neville, B.D., 2015]
Paratype: Private collection of Mr. Masao Azuma, Takarazuka, Hygo prefecture, Japan. for Amaea nebulodermata (Azuma, 1972) - Type Locality: off southwestern Taiwan, ± 80 fms.. [Higo, S., Callomon, P. & Goto, Y., 1999]
Holotype: Private collection of Mr. Masao Azuma, Takarazuka, Hygo prefecture, Japan. for Amaea nebulodermata (Azuma, 1972) - Type Locality: off southwestern Taiwan, ± 80 fms. [Higo, S., Callomon, P. & Goto, Y., 2001]
Holotype: NSMT-Mo 52448 [as Fragilopalia bitaeniata Masahito & Habe, 1976] - Type Locality: off Esuzaki (cape), Wakayama prefecture (Kii peninsula, central Honsh


SpeciesImage

arsint.com (2023).

19.68 mm,
Taiwan. Trawled at 40-60 m. May, 2011

Distribution

as listed in source literature

Kaicher, S.D. (1983).
Species Image
Card #: EP3-3583.
DuShane, H. (1988h).
Species Image
pp: 7.
Fragilopalia nebulodermata Azuma, 1972.
Kauai, HI;
Length 17.5mm, width 4.5 mm.
McDowall Collection
Higo, S., Callomon, P. & Goto, Y. (2001).
Shown in text as Fragilopalia bitaeniata Masahito & Habe, 1976
Species Image
pp: 54. Fig. G1856.
Fragilopalia bitaeniata
MASAHITO & HABE, 1976
Holotype: NSMT-Mo 52448
G1856
27.9mm
Higo, S., Callomon, P. & Goto, Y. (2001).
Species Image
pp: 54. Fig. G1855.
Fragilopalia nebulodermata
AZUMA, 1972
Holotype: Private collection of Mr. Masao Azuma, Takarazuka, Hygo prefecture, Japan. Photo Y. Azuma

GI855
36.0mm
Nakayama, T. (2003).
Shown in text as Amaea bitaeniata (Masahito & Habe, 1976)
Species Image
pp: 119. Plate 8. Fig. 8-9.
Amaea (Acrilla) bitaeniata (Masahito & Habe, 1976)
figs 8-9:height 26.0 mm; breadth 8.5 mm (KC)
Species Image
pp: 119. Plate 8. Fig. 5-6.
Amaea (Acrilla) bitaeniata (Masahito & Habe, 1976)
height 28.3 mm; breadth 8.2 mm
holotype
Brown, L. (2010).
Species Image
pp: 29. Fig. 13.
East China Sea
Photo: Tom Eichorst
arsint.com (2023).
Species Image
19.68 mm,
Taiwan. Trawled at 40-60 m. May, 2011

Synonymy:

Amaea bitaeniata (Masahito & Habe, 1976) [in Nakayama, T., 2003].
Fragilopalia bitaeniata Masahito & Habe, 1976 [in Brown, L. & Neville, B.D., 2015].
Fragilopalia bitaeniata Masahito & Habe, 1976 [in Higo, S., Callomon, P. & Goto, Y., 1999].
Fragilopalia bitaeniata Masahito & Habe, 1976 [in Higo, S., Callomon, P. & Goto, Y., 2001].


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. (2010). 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]
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]
DuShane, H. (1988h). Hawaiian Epitoniidae pt.5. Hawaiian Shell News. 36(11). https://www.conchology.be/?t=5002&year=1988&volume=11&hsn=10345 [Accessed 16 September 2023]
DuShane, H. (1990). Hawaiian Epitoniidae. Hawaiian Shell News. 38(Sup.1). Hawaiian Malacological Society
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]
Higo, S., Callomon, P. & Goto, Y. (2001). Catalogue and Bibliography of the Marine Shell-Bearing Molluscs of Japan. Type Figures. Elle Scientific Publications
Kaicher, S.D. (1983). Epitoniidae III [Pack 35]. S. D. Kaicher, St. Petersburg, Florida. http://www.femorale.com/kaicher/species.asp?f=Epitoniidae&c=125 [Accessed 8 May 2023]
Nakayama, T. (2003). A Review of Northwest Pacific Epitoniids. Monographs of Marine Mollusca. 6. Backhuys Publishers
Weil, A., Brown, L. & Neville, B. (1999). The Wentletrap Book. Evolver
WoRMS Editorial Board (2025). World Register of Marine Species. https://www.marinespecies.org [Accessed 8 November 2025]

WoRMS direct page link: Open WoRMS record