Alcithoe wilsonae

Alcithoe wilsonae
Holotype from the Auckland War Memorial Museum
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Caenogastropoda
Order:	Neogastropoda
Family:	Volutidae
Genus:	Alcithoe
Species:	A. wilsonae
Binomial name
Alcithoe wilsonae (A. W. B. Powell, 1933)
Synonyms [1]
Alcithoe chathamensis(Dell, 1956) Alcithoe knoxi(Dell, 1956) Alcithoe wilsonae acuminataBail & Limpus, 2005 Alcithoe wilsonae wilsonae(Powell, 1933) Leporemax chathamensisDell, 1956 Pachymelon grahamiPowell, 1965 Pachymelon smithiPowell, 1950 Pachymelon wilsonaePowell, 1933 Pachymelon (Palomelon) grahamiPowell, 1965 Pachymelon (Palomelon) smithiPowell, 1950 Pachymelon (Palomelon) wilsonaePowell, 1933 (original combination) Palomelon grahamiPowell, 1965 Palomelon smithiPowell, 1950 Palomelon wilsonaePowell, 1933 Teremelon knoxiDell, 1956

Alcithoe wilsonae is a species of sea snail, a marine gastropod mollusc in the family Volutidae, the volutes. ^[1] A highly morphologically varied species, it endemic to New Zealand, found on the Chatham Rise, off the coast of the eastern South Island, and on a section of the Campbell Plateau between the South Island and the Auckland Islands.

Description

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

Shell large, solid, fusiform. Spire half height of aperture. Nucleus damaged. Post-embryonic whorls 5, spire whorls sub-angled at the middle, body-whorl moderately inflated, contracting gradually to a feeble fasciole. Sculpture consisting of narrow axial ribs, extending from suture to suture on the spire whorls, and to just below the periphery on the body-whorl. These axials are thickened slightly in the middle, where they cross the subangle. On the last half-whorl they become sub-obsolete. There are 14 axials on the penultimate whorl and 12 on the ante-penultimate. Aperture elongate, with a moderately wide but very shallow basal notch. Columella straight, with four strong oblique plaits, upper-most strongest, lower three becoming weaker in descending order. Inner-lip spread as a thin glaze in one wide sweep over the body-whorl. Colour pinkish-buff, maculated with three zones of irregular zigzag markings of dark reddish-brown. Upper band below suture, middle band at periphery, and lower one bordering the fasciole. ^[2]

The holotype of the species measures 109 mm (4.3 in) in height (112 mm (4.4 in) estimated undamaged height) and 47 mm (1.9 in) in diameter. ^[2] The species has four strong pillar plaits. ^[3] It is a highly morphologically variable species. ^[4]

Taxonomy

A. wilsonae was first described by A.W.B. Powell in 1933, using the name Pachymelon (Palomelon) wilsonae. ^[2] The holotype was collected from Owenga Beach in the Chatham Islands by Miss B. M. Wilson in 1933. ^{[5] [6]} In 1978, Richard Dell synonymised Pachymelon with the genus Alcithoe, recombining the species as Alcithoe wilsonae. In the same paper, Dell synonymised Pachymelon (Palomelon) grahami and Pachymelon (Palomelon) smithi with Alcithoe wilsonae. ^[7] In 2011, A. knoxi was synonymised with A. wilsonae. ^[8]

The species likely diverged from other members of Alcithoe between 4.6 and 13.1 million years ago. ^[8]

Distribution and habitat

The species is endemic to New Zealand, found in the waters of the Chatham Rise, the eastern South Island and a section of the Campbell Plateau between the South Island and the Auckland Islands. ^[9] The fossil record extends back to the Tongaporutuan stage of the Cenozoic Era (between 10,920,000 and 6,500,000 years ago). ^[4]

Gallery

• 
  Reverse view of holotype
• 
  Type specimen (holotype of Alcithoe wilsonae acuminata)
• 
  Type specimen (holotype of Pachymelon (Palomelon) grahami)
• 
  Type specimen (holotype of Pachymelon (Palomelon) smithi)
• 
  Shell found near the Auckland Islands
• 
  Shell found off the coast of eastern Otago

References

1. Alcithoe wilsonae (A. W. B. Powell, 1933) . 4 December 2025. Retrieved through: World Register of Marine Species .
2. Powell, A. W. B. (1933). "The Marine Mollusca of the Chatham Islands". Records of the Auckland Institute and Museum . 1: 181–208. ISSN   0067-0464. JSTOR   42905950. Wikidata   Q58676558.
3. Powell, A.W.B. (1979). New Zealand Mollusca: Marine, Land and Freshwater Shells. Auckland: Collins. pp. 209–210. ISBN   0002169061.
4. Hills, Simon Francis Kahu (2010), Evolution in a marine gastropod : rocks, clocks, DNA and diversity, Massey Research Online, hdl:10179/1628, Wikidata   Q112158836
5. 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.
6. "Alcithoe wilsonae". Collections Online. Auckland War Memorial Museum . Retrieved 4 December 2025.
7. Dell, R.K. (1978). "Additions to the New Zealand Recent molluscan fauna with notes on Pachymelon (Palomelon)". National Museum of New Zealand Records. 1 (11).
8. Hills, Simon F. K.; Trewick, Steven A.; Morgan-Richards, Mary (6 October 2011). "Phylogenetic information of genes, illustrated with mitochondrial data from a genus of gastropod molluscs". Biological Journal of the Linnean Society . 104 (4): 770–785. doi:10.1111/J.1095-8312.2011.01756.X. ISSN   0024-4066. Wikidata   Q60902816.
9. "Alcithoe wilsonae (Powell, 1933)". New Zealand Mollusca. Retrieved 4 December 2025.

Further reading

• Bail, P.; Limpus, A. (2005). "The Recent Volutes of New Zealand, with a revision of the genus Alcithoe H. & A. Adams, 1853". A Conchological Iconography 11. Hackenheim, Germany: ConchBooks.