115 — Miller's nudibranch, Phidiana milleri

Phidiana milleri, from under Ngapipi Bridge,
Tamaki Drive, central Auckland 15/6/18.

Phidiana milleri, from under Ngapipi Bridge,
Tamaki Drive, central Auckland 15/6/18.

Phidiana milleri, crawling in between
green-lipped mussels, the Gap, Piha, 2015,
(~30mm).

Phidiana milleri, crawling on red algae,
Lion Rock, Piha, 2017, (~10mm).

Phidiana milleri, from under Ngapipi Bridge,
Tamaki Drive, central Auckland 15/6/18,
(~30–40mm).

Miller's nudibranch, Phidiana milleri * is a small (to 42mm) and attractive sea slug endemic to New Zealand. It's named after Prof. Michael Miller, an expert in this field. It's reported be found in exposed clean water situations north of Banks Peninsula.

They are thought to feed on hydroids, possibly mussel's beard, which is neither a mussel, nor a beard, but a type of thecate hydroid called Amphisbetia bispinosa (Gray, 1843).

Willan & Miller (1984) considered this to be a commonly seen nudibranch, but this has not been my experience (maybe I'm looking in the wrong places). I've seen it a handful of times and mostly at Piha, on Auckland's west coast: crawling between green-lipped mussels (Perna canaliculus) at the Gap (where there were also hydroids), and then in a rock pool on Lion Rock, where a tiny juvenile was crawling on red algae. I've also seen it under Ngapipi Bridge on Auckland's Tamaki Drive, from under a rock adjacent to the bridge supports—another hydroid-rich habitat.

* Rudman, 1980




































More info:

Sea slug forum: Phidiana milleri

Willan, R. C., Morton, J. E. 1984: Marine Molluscs Part 2: Opisthobranchia. University of Auckland, Leigh Marine Laboratory, Leigh, New Zealand. 106 pp.