Mauidrillia secta

Mauidrillia secta Temporal range: late Eocene 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. secta
Binomial name
†Mauidrillia secta A. W. B. Powell, 1944
Synonyms [1]
Mauidrillia secta sectaA. W. B. Powell, 1944

Mauidrillia secta is an extinct species of sea snail, a marine gastropod mollusc in the family Horaiclavidae. ^[1] Fossils of the species date to the late Eocene strata of the St Vincent Basin of South Australia, and the Otway Basin of South Australia and Victoria.

Description

Reverse view of holotype

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

Differing from all other species in the deeply incised lines which cut the surface into broad, rounded, spiral folds. Two or three linear grooves below periphery on spire-whorls, nine on body-whorl and base, plus five linear-spaced weaker cords on the anterior end. Subsutural fold moderate. Shoulder without spiral sculpture. Axials very oblique, planed off above, 13 per whorl, strongest at periphery, where they are sharply tubercular, but becoming obsolete before reaching lower suture. ^[2]

The holotype of the species measures 12 mm (0.47 in) in height and 4.5 mm (0.18 in) in diameter. ^[2] The shell has a rounded protoconch of 1.5 whorls, with a slightly flattened and deviated tip. ^[3]

Taxonomy

The species was first described by A.W.B. Powell in 1944. ^[2] The holotype was collected from the Blanche Point Formation in Aldinga, South Australia at an unknown date prior to 1945, and is held by the Auckland War Memorial Museum. ^{[4] [5]} In 1981, D. C. Long described a subspecies, M. secta otwayensis, ^[3] which has since been raised to species level. ^[6]

Distribution

This extinct marine species occurs in late Eocene strata of the St Vincent Basin and Otway Basin, including the Blanche Point Formation and Browns Creek Formation of South Australia and Victoria. ^{[4] [6]}

References

1. Mauidrillia secta A. W. B. Powell, 1944 † . 4 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. 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.
4. 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.
5. "Mauidrillia secta". Collections Online. Auckland War Memorial Museum . Retrieved 4 December 2025.
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.