Hawaii nudibranchs and opisthobranch molluscs mollusks

hawaiisfishes.com

Some interesting nudibranchs not in Hawaii's Sea Creatures
Some of these are in the Revised Edition released March 2006.

Some recent Hawai`i nudibranch sightings by Keoki Stender posted on Dr. Bill Rudman's Sea Slug Forum
Phyllidiopsis loricata Glossodoris atromarginata Phyllidia scottjohnsoni Elysia obtusa
Hoplodoris bifurcata Elysia tomentosa

Keoki's website has lots more Hawai`i opisthobranch shots.
Hawaiian Nudibranchs and Flatworms - new photo gallery by Laura and Ed Blackshaw

NEW!! SEA SLUGS OF HAWAII WEBSITE
by Cory Pittman and Pauline Fiene
This site blows all the others, including this one, out of the water.
Cory and Pauline have found and photographed literally hundreds of Hawaiian nudibranchs.
Many are new discoveries and most are not in any of the books. Check it out!

http://seaslugsofhawaii.com

Photo: Robert Whitton
Ardeadoris scottjohnsoni Bertsch & Gosliner, 1989
family Chromodorididae
Rare in most years, populations of this beautiful slug seems to have bloomed in 2008. Rob Whitton videoed this one at about 50 ft. along the wall at the Haleiwa Trench, Oahu, and sent me this frame. The species was named after Scott Johnson, co-author of the pioneering 1981 book Hawaiian Nudibranchs (in which it appears as Chromodoris sibogae). It is known primarily from the Hawaiian Islands, but has also been found in Okinawa. You can read more about it here: http://slugsite.us/bow2007/nudwk582.htm

Photo: Bruce Mundy
Hoplodoris grandiflora (Pease, 1860)
family Dorididae
Bruce Mundy sent me this photo, stating: "I found the animal at night on June 11 in the shallow lagoon of Hanauma Bay a few yards off the beach. It was crawling in about two feet of water on the top of a foot high rock on the edge of the sand. The animal was about the size of quarter." I forwarded Bruce's message to Cory Pittman, who identified the slug. It has a flat, oval body covered with round tubercles. Color is brown.

VIOLET-GILLED HYPSELODORIS
Hypselodoris violabranchia Gosliner & Johnson 1999
family Chromodorididae
I found this slug while diving at Molokini at the end of August 2005. Depth was about 40 ft. It has a whitish body marked with fine white lines and diffuse pale spots. The rhinophores and gills are violet, and there are violet marginal bands around the head and tail (which is not visible in this photo. I had never seen this species before, but I dive mostly on O`ahu; perhaps it is more common on Maui. Species of Hypselodoris often have many fine white lines running lengthwise along the body. This is one of three in Hawaiian waters with such lines. H. peasei (listed as H. andersoni in the original ed. my book) and H. insulana are the other two. The latter is known only from the Northwest Hawaiian Islands and is not in my book. Mike Miller's Slugsite has a good photo of it.

Chromodoris sp.
family Chromodorididae
photo: Midway Atoll
This beautiful nudibranch occurs at Midway Atoll. It is probably undescribed and seems related to a group of similar nudibranchs marked with red reticulations. More information is available on Mike Miller's Slugsite.

INDIAN NUDIBRANCH
Caloria indica (Bergh 1896)
family Facelinidae
This is the photo that should appear at the bottom of p. 177 of Hawaii's Sea Creatures. Although labeled Caloria indica, the image in the book is actually a picture of the somewhat similar Flabellina exoptata. More details are posted on Mike Miller's Slugsite. See also the PDF updates page for the book. Photo: Käne`ohe Bay, O`ahu, 2 ft,

Fryeria sp.
family Phyllidiidae
This is one of the exciting new nudibranchs to be featured in a website on Hawaiian opisthobranchs in preparation by Terry Gosliner, Cory Pittman and Pauline Fiene. In many years of diving I have seen this slug only five times, once on mixed sand and hard substrate at about 40 ft. off the Sheraton at Ka`anapali, Maui, and the rest on hard substrate off O`ahu and the Big Island between 40-80 ft.
The resemblance to the much more common Phyllidia varicosa is striking--undoubtedly some sort of mimicry is involved. One way to tell the two apart is to look at the underside. P. varicosa always has a dark line running the length of the foot; this species does not. Keep tuned!
photo: Ka`anapali, Maui. 40 ft.

Phyllidia sp.
Family Phyllidiidae
Here is another apparent mimic of the common Phyllidia varicosa. Tina Owens writes:
" I was looking through a bunch of boxes of slides I haven't put away yet and found these two again. They are of the same critter, and I took them because it didn't look quite like a normal phyllidia. The markings are much more sparse that the average P. varicosa and they're not quite symmetrical. Also there is a distinct yellow band around the mantle margin. I turned it over but the photo of that didn't turn out well enough, but the underside was a yellowish-gray, no stripe and had that yellow margin on the underside as well (as best I remember it). It was average size (a little more than an inch long) so it wasn't a juvenile. Found south of Au Au, Big Island of Hawaii, 25 ft. of water."

FISSURED NUDIBRANCH
Phyllidiopsis fissuratus Brunckhorst, 1993
family Phyllidiidae
While diving at Püpüukea on the north shore of O`ahu during the summer of 2000, I saw what I took to be several abnormally large Phyllidiella pustulosa. At about 2 inches, they were twice as large as usual for this species in Hawai`i. Although I had plenty of shots of this common slug, I finally photographed one of these big guys just for the record. Still not suspecting that it might be something else, I emailed Pauline Fiene and Cory Pittman to see if they had observed any extra large 2-inch pustulosa on Maui. They had not, but Cory remembered a slide taken years ago by Scott Johnson during his Hawai`i days. Scott had been going through his old slides, thought this one might be Phyllidiopsis fissuratus (which had not been described when Scott took the photo and which would be a new record for Hawaii), and had emailed a scan to Cory. Cory recognized my scan as similar to Scott's. Scott was right--the animals most closely resemble Phyllidiopsis fissuratus, which has a black ground color with high pink tubercles instead of the lower, rounded tubercles typical of P. pustulosa. Also, the back and top of the rhinophores is black, the lower front pink, and the margin of the head is banded pink and black. (Brunckhorst records the rhinophores as pink with a black tip and a black line down the posterior edge, so the Hawaii species might be slightly different.) Brunckhorst records the species from the central Great Barrier Reef, Fiji and Lord Howe Island. Scott has also seen what he believes to be this species in the Marshall Islands. The Sea Slug Forum also records it from the Philippines and Vanuatu.

YELLOW NOUMEA
Noumea flava (Eliot, 1904)
Heidi Miller sent me this photo of a pair of nudibranchs laying eggs. She found them on the YO 257 off Waikiki at about 70-80 ft. I sent the photo to Cory Pittman who wrote: "I think these are large Noumea flava. They get pretty "frilly" when scrunched up on their host sponge" This species is apparently seen more often around Maui than O`ahu. Other photos of these slugs on the web do not show such a frilly edge.

Noumea varians (Pease, 1871)
family Chromodorididae
This tiny slug was less than 1/2 in. long. I photographed it in the boat channel at Magic Island, O`ahu, at about 30 ft. It belongs to the Noumea purpurea color group. Read more about these slugs on Bill Rudman's Sea Slug Forum.

Plocamopherus maculatus (Pease, 1860)
Family Polyceridae
This pale, translucent slug exhibits little color except for some irregular patches of orange and yellow. It is nocturnal and, according to Bertsch and Johnson, the patches sometimes emit a bioluminescent glow when the animal is disturbed. Described from the Hawaiian Islands, the species has also been found in Sodwana Bay, South Africa. Debelius records it from Shark Bay, Western Australia. It probably feeds on bryozoans. This specimen was photographed in a cave at night at South Point, Hawai`i, the southernmost point in the United States. Depth was about 20 ft. (6 m.).

Phyllidiopsis cardinalis (Bergh, 1875)
family Phyllidiidae
Unlike most slugs of the genera Phyllidia and Phyllidiopsis, this species is inconspicuous and even well-camouflaged on certain substrates. However, it has the typical leathery body and firm tubercles as others in its family. The entire underside is yellow.

Platydoris formosa (Alder & Hancok, 1866) juvenile
Family Platydoridae
Here's another unusual nudibranch photographed in Kona by Tina Owens. Tina sent the photo to me but I didn't know what it was. I passed it on to Cory Pittman, who quickly identified it as a juvenile Speckled Platydoris Platydora formosa. There is a photo of the adult in my book. It's not as pretty as the juvenile.

Dendrodoris albopurpura Burn, 1957
Family Dendrodorididae
Tina Owens found this beautiful 3-inch slug off Kona in December 2003 and sent the photo to Dr. Bill Rudman. He identified it and said that it's definitely a new record for the Hawaiian Islands. See the Sea Slug Forum

Dendrodoris carbunculosa (Kelaart, 1858)
Family Dendrodorididae
This large nudibranch has recently been reported from Hawaii by several divers. It is easily confused with Dendrodoris tuberculosa. The easiest way to tell them apart is to examine the underside: This species is plain brown or gray underneath, whereas tuberculosa has large white oval spots. Clean your hands well if you handle this animal and don't touch your face afterward--there are reports that its mucus can cause painful burning sensations. In other parts of the Indo-Pacific these animals can attain a huge size--up to about 15 inches. Champion slug hunter Tina Owens took the photo off Kona in September 2003. See her posting on Dr. Rudman's website the Sea Slug Forum and also Jerry Kane's photo of a juvenile D. carbunculosa on Mike Miller's Slugsite. (I misidentified it as tuberculosa when I posted to the Slugsite some years ago, and it's probably still mis-labeled.)

Siphopteron quadrispinosum Gosliner, 1989
Family Gastropteridae
These colorful slugs are bright yellow with red rhinophores and a red "flagellum." They live on sand bottoms and are sometimes superabundant. Most divers never see them, though, because they are only a few millimeters long. (Notice the size of the sand grains compared to the slug!) The species is known to date from Hawaii, New Guinea, New Caledonia, Australia, and Japan. Teri Stewart took this photo at 55 ft. in the sand channel near Reef's End, at Molokini, Maui. She also finds them at about 30 ft. at Ulua Beach, Maui. The similar Siphopteron flavum (yellow with black markings) also occurs in Hawai`i.

Berthella sp.
Family Pleurobranchidae
This slug, with its characteristic dark central dark spot, was on the sponge-covered roof of a cave at the Halona Blowhole, O`ahu. Depth was about 15 ft. More information available on Dr. Bill Rudman's Sea Slug Forum

Chelidonura sp.
Family Aglajidae
This small headshield slug resembles the Blue Swallowtail Slug Chelidonura hirundinina but has blue spots instead of blue lines. Both can be found along the margins of the boat channel at Magic Island, O`ahu, in several feet of water.

Notarchus indicus Schweiger, 1820
family Aplysiidae
This sea hare is orange-yellow with scattered small black spots and a short tail visible only when the slug stretches out. It has scattered papillae with whitish tips. The parapodia are fused and thus not obvious. In its normal resting position it appears round except for the head. It has the habit of squirting water from the orifice on its back as if trying to propel itself down and backwards. Darrell Takaoka collected it in 2 feet of water on seaweed covered rock at Ala Moana Beach Park, Honolulu. Read more about it here.

Polybranchia orientalis (Kelaart, 1858)
family Caliphyllidae
This unusual sacoglossan (member of the order Sacoglossa, popularly known as sap sucking slugs) is usually found under slabs but occasionally ventures into the open. It's many leaflike cerata detach easily and are very sticky, no doubt a defensive mechanism. Read more about it on Dr. Rudman's Sea Slug Forum.