Mauidrillia inaequalis

Mauidrillia inaequalis Temporal range: late Oligocene–early Miocene PreꞒ Ꞓ O S D C P T J K Pg N
Holotype from Auckland War Memorial Museum
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Caenogastropoda
Order:	Neogastropoda
Family:	Horaiclavidae
Genus:	Mauidrillia
Species:	†M. inaequalis
Binomial name
†Mauidrillia inaequalis A. W. B. Powell, 1942

Mauidrillia inaequalis is an extinct species of sea snail, a marine gastropod mollusc in the family Horaiclavidae. ^[1] Fossils of the species date to the late Oligocene and early Miocene, and are found in South Canterbury and Otago, New Zealand.

Description

Reverse view of holotype

The species has a moderately sized shell, with 7.5 whorls and a protoconch of 1.5 inflated whorls. The whorls are strongly angulate just above the middle, and the shells are deeply concave at the shoulder. The shells have broad axials and are crossed by fine, close spaced spirals. The holotype of the species measures 10 mm (0.39 in) in height and 4 mm (0.16 in) in diameter. ^[2]

Taxonomy

The species was first described by A.W.B. Powell in 1942. ^[2] The holotype was collected from Otiake, Waitaki Valley, Otago at an unknown date prior to 1943, and is held by the Auckland War Memorial Museum. ^{[3] [4]}

Distribution

This extinct marine species occurs in late Oligocene and early Miocene strata of Blue Cliffs and the Pareora River of South Canterbury, and the Waitaki Valley of Otago, New Zealand. ^{[3] [2] [5]}

References

1. Mauidrillia inaequalis A. W. B. Powell, 1942 † . 8 December 2025. Retrieved through: World Register of Marine Species .
2. Powell, A. W. B. (1942). "The New Zealand recent and fossil Mollusca of the family Turridae, with general notes on Turrid nomenclature and systematics". Bulletin of the Auckland Institute and Museum . 2: 86. ISSN   0067-0456. OCLC   1826451. Wikidata   Q115110377.
3. 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.
4. "Mauidrillia inaequalis". Collections Online. Auckland War Memorial Museum . Retrieved 8 December 2025.
5. Maxwell, P. A. (15 July 1969). "Middle Tertiary Mollusca from North Otago and South Canterbury, New Zealand". Transactions of the Royal Society of New Zealand : Geology. 6 (13): 155–185 – via Papers Past.

Further reading

• P. A. Maxwell. 1988. Late Miocene Deep-Water Mollusca from the Stillwater Mudstone at Greymouth, Westland, New Zealand: Paleoecology and Systematics. New Zealand Geological Survey Paleontological Bulletin 55
• Maxwell, P.A. (2009). Cenozoic Mollusca. pp. 232–254 in Gordon, D.P. (ed.) New Zealand inventory of biodiversity. Volume one. Kingdom Animalia: Radiata, Lophotrochozoa, Deuterostomia. Canterbury University Press, Christchurch