Epitonium tenellum
(F. W. Hutton, 1885)
Description:
Dimensions range from 9.86 mm - 22 mm high and 4.87 mm - 9 mm wide.
Width to height ratio: 0.49:1 ~ 0.41:1
Shell: avergae width, moderately tall, elongate broadly oval; rather thin; small to moderately small. Exterior colour fawn or light brown, sometimes with a brown peripheral stripe around the base, costae white. About 8 whorls, rounded, connected; rounded; protoconch Apex missing. Suture deep. Umbilicate: very small, almost concealed by inner lip of aperture. Approximately 15 - 26 costae on the body whorl. Costae are low, thin, rounded, flattened on the last whorl. Costae not continuous from whorl to whorl; not peaked. Intercostal spaces smooth and shining. Base without basal chord. Aperture ovate; peristome almost complete, slightly flaring anteriorly; outer lip with normal rib externally. Operculum corneous.
Distribution:
Port Douglas, Queensland, NSW [Beechey, 2008] south to Western Port, Victoria [Macpherson & Gabriel, 1962:115] and north coast of Tasmania [Tate & May, 1901:379]; New Zealand [Hutton, 1885:943].
Habitat:
intertidal and shallow water to 27m, also in beach drift [Beechey, 2008].
Etymology:
[latin] from tenellus = diminutive form of tener, meaning tender or delicate.
Type Material:
Brown & Neville [2015: 113] considered Scalaria novoseelandiae Clessin, 1897 to be conspecific with Epitonium tenellum (Hutton, 1885).
Iredale [1936:299] considered the Australian shells referred to as Epitonium tenellum (F. W. Hutton, 1885) to differ from Hutton's species in being smaller, narrower, and having fewer ribs, and consequently proposed Limiscala helicornua.
After comparing approximately 100 eastern Australian shells with a series from New Zealand, Kerslake [1969:18] concluded that these differences did not exist. Limiscala helicornua is currently regarded as a junior synonym of E. tenellum [WoRMS Editorial Board, 2025].
Brown & Neville [2015:146] cited NMNZ M.000173 as a possible syntype of Epitonium tenellum (Hutton, 1885). However, the specimen is not identified as a syntype in the Museum of New Zealand Te Papa Tongarewa online catalogue [Museum of New Zealand Te Papa Tongarewa, 2026: M.000173].
Type possibly lost: Stuttgart Museum; not listed in the Museum's on-line type catalog. [as Scalaria novoseelandiae Clessin, 1897] - Type Locality: Neuseeland, i.e., New Zealand.. [Brown & Neville, 2015: 113]
Syntype [possible]: NMNZ M.000173 [as Scalaria tenella Hutton, 1885] - Type Locality: Stewart's Island, Auckland, New Zealand.. [Brown & Neville, 2015: 146]
Holotype: Australian Museum: C.60649 [as Limiscala helicornua Iredale, 1936] - Type Locality: Australia, New South Wales, Sydney Harbour (33° 51' 00' S, 151° 14' 00' E) 1928 - 1929, Comtesse, Captain D L(Collector), Dredged.. [Australian Museum, 2026: C.60649]
Paratype: Australian Museum: C.346137 [as Limiscala helicornua Iredale, 1936] - Type Locality: Australia, New South Wales, Sydney Harbour (33° 51' 00' S, 151° 14' 00' E) 1928 - 1929, Comtesse, Captain D L(Collector), Dredged.. [Australian Museum, 2026: C.346137]

Museum of New Zealand (2025c).
Museum of New Zealand Te Papa Tongarewa
Registration number
M.000173
Distribution
as listed in source literature
Clessin, S. (1897).
Shown in text as Epitonium novoseelandiae (Clessin, 1897)
Iredale, T. (1936).
Shown in text as Limiscala helicornua, sp. novo
Kerslake, J. (1969).
Australian Museum (2026).
Shown in text as Limiscala helicornua Iredale, 1936







