Maurea granti
| Maurea granti Temporal range:
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Scientific classification 
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| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Subclass: | Vetigastropoda |
| Order: | Trochida |
| Family: | Calliostomatidae |
| Genus: | Maurea |
| Species: | M. granti
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| Binomial name | |
| Maurea granti A. W. B. Powell, 1931
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| Synonyms[1][2] | |
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Maurea granti, also known as Grant's top shell,[3] is a species of sea snail, a marine gastropod mollusc, in the family Calliostomatidae.[1] Endemic to New Zealand, the species is found offshore up to depths of 360 m (1,180 ft). It is a polymorphic species, with different shell thickness, colour and spiral cord numbers appearing in shallow water and deep water specimens.
Description
In the original description, Powell described the species as follows:
Shell acutely conical, moderately solid, inperforate and subangled at the periphery. Spire one and one-half times height of aperture. Outlines straight. Whorls 104, including typical protoconch. Sculpture fine, consisting of numerous closely spaced beaded spiral cords and interstitial threads, crossed by dense microscopic axial growth striae. Early post-nuclear whorls with three beaded cords, later whorls with six, each interspace having a fine spiral thread, which becomes beaded towards the close of the penultimate whorl. Base with twelve beaded cords, four closely spaced at periphery, the remainder more distant; each with a plain interstitial thread. Periphery angled, but not acutely. Columella oblique, arcuate, rather massive.[4]
The holotype of the species has a height of 34.25 mm (1.348 in), a diameter of 28.5 mm (1.12 in), and a thickness of 2.90 mm (0.114 in), and a spire angle of 62°.[4] The species has a maximum height of 45 mm (1.8 in) and diameter of 42 mm (1.7 in).[5]
The species is polymorphic,[2] differing in shell size, shape and number of spiral cords on the final two whorls. When found in shallow waters, the species tends to have thicker and more darkly pigmented shells with fewer spiral cords, while deep water specimens have thinner and lighter-coloured or white shells with more heavily nodular spiral cords. Transitional forms of shells exist where deep water and shallow water populations overlap or border.[6]
It can be differentiated from M. osbornei due to having a less acute spire, finer sculpture, and by M. osbornei having obsolescent interstitial threads.[4] It can be differentiated from M. punctulata due to having more robuse axial ribs.[6]
Taxonomy
The species was first described by A. W. B. Powell in 1931, using the name Maurea (Mucrinops) granti.[4] He named the species after Whanganui museum director and conchologist Maxwell James Grant Smart.[4] The holotype was collected in January 1931 by Powell near the mouth of the Waihi Stream near Hāwera, South Taranaki. It is held in the collections of Auckland War Memorial Museum.[7][8] When describing the species in 1931, Powell believed it was a fossil species ancestral to M. osbornei.[4]
In 2016, Maurea was raised to genus level,[9] leading to the species' accepted name in the World Register of Marine Species to become Maurea granti. The New Zealand Organisms Register lists the species' preferred name as Calliostoma granti,[10] and the New Zealand Inventory of Biodiversity (2009) lists the species' preferred name as Calliostoma (Maurea) granti.[11]
Ecology
M. granti primarily feeds on Cnidaria.[2] It is a known host for the slipper snail species Maoricrypta youngi.[12]
Distribution
The species is endemic to New Zealand, found offshore the North Island south of East Cape and Cape Egmont, South Island, Stewart Island, Auckland Islands, Campbell Islands and Chatham Islands at a depth ranging between 0–360 m (0–1,181 ft).[2][6][5] Fossils of the species date back to the Waipipian stage of the Pliocene (3.7 million years ago) in New Zealand.[11]
Gallery
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Holotype (front view) -
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Holotype (reverse view)
References
- ^ a b Maurea granti A. W. B. Powell, 1931. Retrieved through: World Register of Marine Species on 3 February 2026.
- ^ a b c d Marshall, Bruce A. (1995). "A revision of the Recent Calliostoma species of New Zealand (Mollusca: Gastropoda: Trochoidea)". The Nautilus. 108: 90–92 – via Biodiversity Heritage Library.
- ^ Wing, Stephen R.; Jack, Lucy (2010). Biological Monitoring of the Fiordland (Te Moana o Atawhenua) Marine Area and Fiordland's Marine Reserves (PDF) (Report). Department of Conservation.
- ^ a b c d e f Powell, A. W. B. (1931). "Waitotaran Faunules of the Wanganui System and Descriptions of New Species of Mollusca from the New Zealand Pliocene". Records of the Auckland Institute and Museum. 1: 85–112. ISSN 0067-0464. JSTOR 42905938. Wikidata Q58676540.
This article incorporates text from this source, which is under a CC BY 4.0 license.
- ^ a b "Maurea granti Powell, 1931". New Zealand Mollusca. Retrieved 3 February 2026.
- ^ a b c Callea, Antonio (November 2012). "Genere Calliostoma Swainson, 1840: il sottogenere Maurea Oliver, 1926 (Vetigastropoda: Calliostomatidae)". Notiziario della Società Italiana di Malacologia (in Italian). 30 (2): 17-29.
- ^ Blom, Wilma M. (2025). "Annotated Catalogue of Fossil and Extant Molluscan Types in the Auckland War Memorial Museum". Bulletin of the Auckland Museum. 22. doi:10.32912/BULLETIN/22. ISSN 1176-3213. OCLC 1550165130. Wikidata Q135397912.
- ^ "Maurea granti". Collections Online. Auckland War Memorial Museum. Retrieved 3 February 2026.
- ^ Marshall, Bruce A. (2 April 2016). "New species of Venustatrochus Powell, 1951 from New Zealand, and new species of Falsimargarita Powell, 1951 and a new genus of the Calliostomatidae from the southwest Pacific, with comments on some other calliostomatid genera (Mollusca: Gastropoda)". Molluscan Research. 36 (2): 119–141. doi:10.1080/13235818.2015.1128586. ISSN 1323-5818. Wikidata Q54669760.
- ^ "Calliostoma granti (Powell, 1931)". New Zealand Organisms Register. Retrieved 3 February 2026.
- ^ a b Maxwell, P.A. (2009). "Cenozoic Mollusca". In Gordon, D.P. (ed.). New Zealand Inventory of Biodiversity. Volume one. Kingdom Animalia: Radiata, Lophotrochozoa, Deuterostomia. Christchurch: Canterbury University Press. p. 240. ISBN 978-1-877257-72-8.
- ^ Beu, A. G. (September 2010). "Marine Mollusca of isotope stages of the last 2 million years in New Zealand. Part 3. Gastropoda (Vetigastropoda - Littorinimorpha)". Journal of the Royal Society of New Zealand. 40 (3–4): 59–180. doi:10.1080/03036758.2010.500717. ISSN 0303-6758. Wikidata Q29300120.