Mauidrillia trispiralis

Mauidrillia trispiralis Temporal range: middle 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. trispiralis
Binomial name
†Mauidrillia trispiralis A. W. B. Powell, 1944

Mauidrillia trispiralis is an extinct species of sea snail, a marine gastropod mollusc in the family Horaiclavidae. ^[1] Fossils of the species date to the middle Miocene strata of the Otway Basin of Victoria, Australia.

Description

Reverse view of holotype

In the original description, Powell described the species as follows:

Shell very slender, sculptured with relatively few strong spirals which are rendered nodulose at the axial intersections. Subsutural fold strong, 2 to 3 threads on shoulder ; peripheral carina and two cords below it, all equally strong. About 19 cords on body-whorl from periphery to the anterior end. The holotype exhibits abnormal sculpture on the front of the body-whorl, due to a shell injury and its subsequent repair. Axials 13 per whorl, producing nodulation where they cross the three main spirals. Body-whorl crossed by numerous axial riblets which render the spirals weakly crenulate. The absence of strong axial nodulation on the body-whorl may be due to the shell injury already mentioned. ^[2]

The holotype of the species measures 9.9 mm (0.39 in) in height and 3.5 mm (0.14 in) in diameter. ^[2]

Taxonomy

The species was first described by A.W.B. Powell in 1944. ^[2] The holotype was collected from the Gellibrand River in Victoria, Australia at an unknown date prior to 1945, and is held by the Auckland War Memorial Museum. ^{[3] [4]} In 1981, D. C. Long theorised that the late Eocene species M. aldingensis was ancestral to M. torquayensis. ^[5]

Distribution

This extinct marine species occurs in middle Miocene strata of the Otway Basin of Victoria, including the Gellibrand Formation. ^{[3] [6]}

References

1. Mauidrillia trispiralis A. W. B. Powell, 1944 † . 8 December 2025. Retrieved through: World Register of Marine Species .
2. Powell, A. W. B. (1944). "The Australian Tertiary Mollusca of the Family Turridae". Records of the Auckland Institute and Museum . 3: 3–68. ISSN   0067-0464. JSTOR   42905993. Wikidata   Q58676624.
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 trispiralis". Collections Online. Auckland War Memorial Museum . Retrieved 8 December 2025.
5. Long, D. C. (1981). "Late Eocene and Early Oligocene Turridae (Gastropoda: Prosobranchiata) of the Brown's Creek and Glen Aire Clays, Victoria, Australia" (PDF). Memoirs of the National Museum of Victoria. 42 (1): 15–55. doi:10.24199/J.MMV.1981.42.03. ISSN   0083-5986. Wikidata   Q56195002.
6. Darragh, Thomas A. (August 2024). "A checklist of Australian marine Cenozoic Mollusca". Memoirs of Museum Victoria . 83: 37–206. doi:10.24199/J.MMV.2024.83.02. ISSN   1447-2546. Wikidata   Q136396722.