107 — Cheeseman's trophon, Paratrophon cheesemani

Paratrophon cheesemani, Maori Bay,
west coast of Auckland, March 2011.

Paratrophon cheesemani, between green-lipped
mussels, Maori Bay, west coast of Auckland,
March 2011.

Cheeseman's trophon, Paratrophon cheesemani (Hutton, 1882), is a small gastropod (~14mm) named after Thomas Frederic Cheeseman (1845–1923), an ex-curator at Auckland Museum. It's endemic to the northwest coast of North Island, where it lives in the lower intertidal zone of exposed coasts. There is a transition zone around Port Waikato where this form is replaced by the predominantly southern P. cheesemani exsculptus Powell, 1933.
Once these two forms are genetically analysed* they may turn out to be separate species.

Very little appears to be known regarding their ecology. However, Cheeseman's trophon is a muricid whelk and these whelks feed by boring through the shells of other animals (typically other gastropods, bivalves, and barnacles). My observations suggest that this species possibly fulfils a similar role to that of the oyster borer (Haustrum scobina (Quoy & Gaimard, 1833)), but lower on the shore, especially since vertical distributions of these two species don't appear to overlap. I suspect that this small gastropod is easily overlooked and the exposed nature of its habitat makes working on it difficult in situ.

*Barco et al. (2015) looked at P. cheesemani exsculptus but not P. cheesemani cheesemani, so no comparison was made between the two forms.



More info:

Barco A, Marshall B, Houart R, Olivero M. 2015. Molecular phylogenetics of Haustrinae and Pagodulinae (Neogastropoda: Muricidae) with a focus on New Zealand species. Journal of Molluscan Studies, 81(4): 476–488.

Paratrophon cheesemani http://www.mollusca.co.nz/speciesdetail.php?speciesid=1000&species=Paratrophon%20cheesemani

Paratrophon cheesemani exsculptus http://www.mollusca.co.nz/speciesdetail.php?speciesid=1001&species=Paratrophon%20cheesemani%20exsculptus