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.


Etymology:

[latin] from nebula = mist or cloud, and [greek] derma = skin. May be interpretted as having a clouded surface; however, this derivation has not been confirmed by the author or any source examined.


SpeciesImage

Masahito (Prince) & Habe T. (1976). pp: 171. Fig. 7.

Fragilopalia bitaeniata Masahito & T. Habe, 1976
Holotype

Distribution

as listed in source literature

Type Material:

The NSMT online database does not specify the type status of this specimen [National Museum of Nature and Science, 2026: NSMT-Mo 52448].

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.
Amaea (Acrilla) bitaeniata (Masahito & Habe, 1976)HolotypeNSMT-Mo 52448. Off Esuzaki, Susami, Kii Peninsula, Japan. about 150m. [Nakayama, 2003: 119].
Amaea (Acrilla) nebulodermata (Azuma, 1972)Type designation not provided in text/ source documentOff South West of, Taiwan. about 130m. [Nakayama, 2003: 17].
Fragilopalia nebulodermata Azuma, 1972HolotypeAzuma collection 15771. southwest Off coast, Taiwan. 146m [80 fthms]. [Brown & Neville, 2015: 111].Mr. Masao Azuma, Takarazuka, Hygo prefecture, Japan Private collection. off southwestern, Taiwan. [± 80 fthms]. [Higo et al., 2001: GI855].Azuma collection 15771. South China Sea, Southwest of Taiwan, 144m. [DuShane, 1988h: 7].ParatypeMr. Masao Azuma, Takarazuka, Hygo prefecture, Japan Private collection. off southwestern, Taiwan. [± 80 fthms]. [Higo et al., 1999: G1855].Azuma collection 15771A. South China Sea, Southwest of Taiwan, 144m. [DuShane, 1988h: 7].
Frogilopalia bitaeniata Masahito & Habe, 1976HolotypeNSMT-Mo 52448. off Esuzaki (cape), Wakayama prefecture (Kii peninsula, central Honshu), Japan. 15m. [Higo et al., 1999: G1856].NSMT-Mo 52448. Off Esuzaki, Wakayama Pref, Honshu, Japan. about 150m. [Masahito & Habe, 1976: 173].NSMT Mo- 52448. off Esuzaki, Wakayama Prefecture, Honshu, Japan. about 150m. [Brown & Neville, 2015: 45].NSMT-Mo 52448. [Higo et al., 2001: 54].TypeNSMT-Mo 52448. Off Esuzaki, Susami-cho, Nishimuro-gun, Wakayama-ken, Japan. [National Museum of Nature and Science, 2026: NSMT-Mo 52448].


Masahito (Prince) & Habe T. (1976).
Shown in text as Frogilopalia bitaeniata Masahito & Habe, 1976
Species Image
pp: 171. Fig. 7.
Fragilopalia bitaeniata Masahito & T. Habe, 1976
Holotype
DuShane, H. (1988h).
Shown in text as Fragilopalia nebulodermata Azuma, 1972
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 nebulodermata Azuma, 1972
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
Higo, S., Callomon, P. & Goto, Y. (2001).
Shown in text as Frogilopalia bitaeniata Masahito & Habe, 1976
Species Image
pp: 54. Fig. G1856.
Fragilopalia bitaeniata
MASAHITO & HABE, 1976
Holotype: NSMT-Mo 52448
G1856
27.9mm

Synonymy:

Amaea (Acrilla) bitaeniata (Masahito & Habe, 1976) [Nakayama, 2003: 119]
Amaea (Acrilla) nebulodermata (Azuma, 1972) [Nakayama, 2003: 17]
Amaea (Fragilopalia) nebulodermata (Azuma, 1972) [Weil et al., 1999: 84]
Fragilopalia nebulodermata Azuma [Kaicher, 1983: EP3-3583]
Fragilopalia nebulodermata Azuma, 1972 [DuShane, 1988h: 7; Brown & Neville, 2015: 111; Brown, 2010b: 29; Higo et al., 1999: G1855; Higo et al., 2001: GI855; DuShane, 1990: 6]
Frogilopalia bitaeniata Masahito & Habe, 1976 [Brown & Neville, 2015: 45; Higo et al., 2001: 54; Higo et al., 1999: G1856; Masahito & Habe, 1976: 173; National Museum of Nature and Science, 2026: NSMT-Mo 52448]


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. & 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]
Brown, L. G. (2010b). 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]
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
Huang, C. W. & Lee, Y.C. (2016). Checklist of the family Epitoniidae (Mollusca: Gastropoda) in Taiwan with description of a new species and some new records. Biodiversity Data Journal. 4. doi: 10.3897/ BDJ.4.e5653 [Accessed 25 August 2023]
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]
Masahito (Prince) & Habe T. (1976). Systematic study of Japanese Epitoniidae (III). Bulletin of the National Science Museum, Series A (Zoology). 2(3). https://www.kahaku.go.jp/english/kenkyu/gakujutsu/zoology/v02.html [Accessed 7 August 2026]
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]
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