Phyllidia polkadotsa

Phyllidia polkadotsa Brunckhorst, 1993
Family Phyllidiidae

Enough of Latin and Greek--here's a species name that's clear to everyone.. Conspicuous but rare, the animal is bright yellow with about 10 round black dots. Several ridges run down its back. Like others in its genus, it is tough-bodied and leathery. This slug occurs along walls and ledges to depths of at least 75 ft. I was thrilled to find my first 2 specimens on a remote sea stack off the north shore of Molokai several years ago. Hoping to photograph sharks, I of course had the wrong lens on my camera. I collected a specimen to photograph later but it died overnight and I donated it to the California Academy of Sciences. Nudibranchs such as this require lots of oxygen--they cannot be left in a bucket without aeration for any length of time. Despite intense searching I did not see the species again until I visited Midway Atoll in June, 1998. It attains perhaps 1 in. (2.5 cm.) and is known from Hawaii, the Banda Islands of Indonesia and Taiwan. Photo: Midway Atoll, 40 ft.

A similar and perhaps rarer Hawaiian species Phyllidia scottjohnsoni, , is white with black spots. My wife Marcia spotted this pair within several yards of the polkadotsa pictured above. They were the first P. scottjohnsoni I'd ever seen. The species was discovered off O`ahu by Scott Johnson, who with Hans Bertsch pioneered the use of scuba in the study of Hawaiian opisthobranchs the late 1970's. David Brunckhorst named it in his honor in 1993.

P. polkadotsa was another Bertsch and Johnson discovery. The two planned at one time to describe it under the name Phyllidia nokaoi (which in Hawaiian means "the best") but never got around to it.

Webmaster's Note: It would appear that P. polkadotsa doesn't have exclusive rights to the polkadot design. If you haven't already, please visit Wolfgang Seifarth's excellent Marine Flatworm Page Site and a Pseudoceros sp. that mimics P. polkadotsa.

Photos and Text courtesy of John Hoover

Author/photographer John P. Hoover lives in Honolulu. He has published two books on marine life of the Hawaiian Islands. His third, a field guide to the marine invertebrates of the Hawaii, will be available approximately February 1999. With over 600 photographs, it will cover 500 species, including 66 of Hawaii's most colorful and interesting opisthobranchs.

Hawaii's Fishes, a Guide for Snorkelers, Divers and Aquarists Mutual Publishing, 1993

Hawaii's Underwater Paradise, Mutual Publishing, 1997

Hawaii's Sea Creatures, a guide to Hawaii's Marine Invertebrates. Mutual Publishing, 1999.

John's books are available through Sea Challengers !

Send John E-Mail at

© The Slug Site, Michael D. Miller 1998. All Rights Reserved.