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Epitoniidae Berry, 1910 (1812)

Opalia apostolorum

(Iredale, 1936)

Description:

Dimensions range from 7 mm - 9 mm high and 2 mm wide.
Width to height ratio: 0.29:1 ~ 0.22:1

Shell: tall, slender with blunt apex; minute to small. Exterior colour fawn, whitish. About 7 whorls, weakly rounded; protoconch with ~1 whorls ; teleoconch with ~6 whorls. Imperforate: umbilicus closed. Approximately 10 - 12 costae on the body whorl. Costae aligned from whorl to whorl. Intritacalx present. Base strong basal keel present, bicarinate, [with 2 ridges]. Aperture elongate oval.


Distribution:

Known only from holotype and paratype, both dredged between Balls Head and Goat Island, Port Jackson, NSW [Beechey, 2008].


Habitat:

offshore species.


Etymology:

[latin] apostolorum = of the apostles. Iredale did not give his reasons for the naming of the species.


Type Material:

Kaicher [1981:EP2-3132] and Brown & Neville [2015:39] both cited the holotype as Australian Museum C.7863. The Australian Museum's current collection records, however, identify the holotype as C.7868 and the paratype as C.334096 [Australian Museum, 2026: C.7868; Australian Museum, 2026: C.334096].

Holotype: Australian Museum, C.7868 [as Nodiscala apostolorum Iredale, 1936] - Type Locality: Australia, New South Wales, Sydney, Port Jackson, between Balls Head & Goat Is (33° 51' 06' S, 151° 11' 48' E) 1864 - 1864, Brazier, John(Collector), Dredged. [Australian Museum, 2026]
Paratype: Australian Museum, C.334096 [as Nodiscala apostolorum Iredale, 1936] - Type Locality: Australia, New South Wales, Sydney, Port Jackson, between Balls Head & Goat Is (33° 51' 06' S, 151° 11' 48' E) 1864 - 1864, Brazier, John(Collector), Dredged. [Australian Museum, 2026]


SpeciesImage

Iredale, T. (1936). Plate xxii. Fig. 27.

Distribution

as listed in source literature

Iredale, T. (1936).
Species Image
Plate xxii. Fig. 27.
Species Image
pp: 304.
original description
Beechey, D. (2008).
Species Image
pp: Opalia apostolorum. Fig. 1.
Holotype: dredged between Balls Head and Goat Island, Port Jackson, NSW (C.007868)
Australian Museum (2026).
Shown in text as Nodiscala apostolorum Iredale, 1936
Species Image
Fig. C.7868.
Nodiscala apostolorum Iredale, 1936
Holotype: C.7868
Australia, New South Wales, Sydney, Port Jackson, between Balls Head & Goat Is (33° 51' 06" S, 151° 11' 48" E) 1864 - 1864, Brazier, John(Collector), Dredged
Australian Museum. Photograph: M. Allen.
Copyright Australian Museum. Released under Creative Commons Licence CC BY-NC 4.0.

Synonymy:

Nodiscala apostolorum Iredale, 1936 [in Australian Museum, 2026].
Nodiscala apostolorum Iredale, 1936: [in Brown, L. & Neville, B.D., 2015].


Source Literature:

Australian Museum (2026). Australian Museum provider for OZCAM. Occurrence dataset. Atlas of Living Australia. https://doi.org/10.15468/e7susi accessed via GBIF.org [Accessed 18 July 2026]
Beechey, D. (2008ad). Opalia_apostolorum. Seashells of NSW. https://seashellsofnsw.org.au/Epitoniidae/Pages/Opalia_apostolorum.htm [Accessed 10 May 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]
Hutchings, P. & Ahyong, S. & Ashcroft, M. & Mcgrouther, Mark & Reid, A. (2013). Sydney Harbour: its diverse biodiversity. Australian Zoologist. 36. http://dx.doi.org/10.7882/AZ.2012.031 [Accessed 28 February 2026]
Iredale, T. (1936). Australian molluscan notes. No. 2.. Records of the Australian Museum. 19(5). Australian Museum, Sydney. doi:10.3853/j.0067-1975.19.1936.704 [Accessed 14 September 2023]
Kaicher, S.D. (1981). Epitoniidae II [Pack 30]. S. D. Kaicher, St. Petersburg, Florida. http://www.femorale.com/kaicher/species.asp?f=Epitoniidae&c=125 [Accessed 8 May 2023]
Weil, A., Brown, L. & Neville, B. (1999). The Wentletrap Book. Evolver
Wilson, B.R. (1993). Australian Marine Shells. Australian Marine Shells. Vol.1. Odessey Publications
WoRMS Editorial Board, (2025). World Register of Marine Species. https://www.marinespecies.org [Accessed 8 November 2025]

WoRMS direct page link: Open WoRMS record