Tritonia challengeriana

Photo courtesy of Peter Brueggeman
Library Director at Scripps Institution of Oceanography at the University of California San Diego

Tritonia challengeriana Bergh, 1884, and Boat-Named Nudibranchs

            Reaching lengths of 6.5 cm, this tritoniid has been found around the Antarctica, at the high southern latitude South Shetland, South Georgia, Malvinas (=Falklands), and Bouvet Islands, and along the coasts of southern Chile and Argentina. It has been reported from 1-481 m depth, with a high density at 7 m.

            The two type specimens were dredged from a depth of 175 fathoms, off the west coast of Patagonia, on 5 January 1876. Bergh wrote, “ I dissected both.”

            The combined radular formula of these specimens is 34-43 x 35- “The median plates (fig. 18a) are of the usual shape,” wrote Bergh, “as also the clumsy first lateral plate (fig. 18, b,b); the rest of the teeth are somewhat low and curved towards the point (Pl. XII, figs. 2–5), most ones are more slender in form.”

            “The color of Tritonia challengeriana , is milky white to transparent, sometimes yellowish to brownish, with yellowish or rose colored viscera shining through the body wall. White pigment is present on the gills, notal margin, rhinophore tips and sheath margins, velar tentacles, and papillae of the oral veil. Small white stripes radiate across the notum from the bases of gills” (Peter Brueggeman, Antarctica Field Guide:

            The Challenger Expedition inaugurated modern oceanographic research. Captains George S. Nares and Frank Towle Thomson led a crew of 243; six scientists were under the leadership of British naturalist John Murray and the Scot Charles Wyville Thompson. The 200' boat (a former British Navy corvette, converted into an oceanographic ship) left Portsmouth, England, on 7 December 1872. Although equipped with a 1200-HP engine, it was basically a sailing ship. During their 68,890 mile round-the-world voyage, they made 492 depth soundings, 133 dredges, and brought back over 4,500 new species of plants and animals. Publication of Report of the Scientific Results of the Voyage of H.M.S. Challenger during the Years 1873–1876, spanned 15 years, and dozens of volumes and collaborators. All are available on the web (copyright Dr. David C. Bossard of Dartmouth College, New Hampshire) at: . One can read the descriptions of human crania collected by the Expedition (Zool. 29), Cetacean bones (Zool. 4), or the complete Report on the Nudibranchiata (Zool. 26), by Dr. Rudolph Bergh, Physician to the General Hospital of Copenhagen. A marvelous essay on the Challenger Expedition can be found at: .

            Some weeks ago, Mike Miller posted the BOW Cuthona destinyae, commenting “It is a rare honor indeed to have one of our beloved sea slugs named after a boat! The only other instance that I know of this happening was the naming of Chromodoris marislae by Hans Bertsch back in 1973.” In later discussions, we became aware of other Boat-Named Nudibranchs. Tritonia challengeriana is of course, one of them. In addition to these three, there are a number of nudibranchs named in honor of Danish, Dutch and Russian research vessels.

            The Danish Ingolf was a 3-masted schooner, 64 m long, with a 996 ton displacement. Torben Wolff describes the voyages

made from May to August in 1895 and 1896. With our global warming crisis today, it is noteworthy that on the first expedition, “in the Denmark Strait the ice limit was found to lie much further south than usual” (Wolff). The Reports were published by the Zoological Museum (Copenhagen) over a 55-year period, from 1898 to 1953. Bergh's description of the nudibranchs were published in vol. 2, part 3 (1899 in Danish, 1900 in English). The “Boat-Named Species” are all very poorly known, some from only one or two specimens each!

            Doridoxa ingolfiana Bergh, 1899, is the only one of the four to have ever been seen alive: “semitransparent white with brown entrails showing through” (color drawings by Henning Lemche in Just & Edmunds, 1985). Schrödl, Wägele & Willan (2001) give an excellent description of the holotype and other known specimens of Doridoxa ingolfiana, including generic comparisons between Doridoxa and Heterodoris.

            The 93-mm long holotype (and only known specimen) of Bathydoris infolgiana Bergh, 1899, has been re-examined by Valdés (2002).

            Heterodoris ingolfiana (Bergh, 1899) was originally named as the type species of the genus Atthila. The holotype was re-examined by Odhner (1926), and Willan (1981) discussed the genus Heterodoris.

             Tritonia ingolfiana (Bergh, 1899) was originally named in the genus Candiella. The radula had 67 rows of teeth. “The number of tooth-plates in a series rose in the back part of the radula to 85. The median teeth were of the broad and short form common in the Tritoniae, with a clumsy median tooth, and a still more clumsy denticle on each side of this. The clumsy and rather low first lateral tooth was very finely denticulated along one edge of the hook; the hook of the second lateral tooth was a little longer, but, as all the others, without any trace of denticulation.” His use of “clumsy” may have been translated not be in the “inept” sense, but in the unwieldy sense of “bulky.”

            The Dutch Siboga was another converted navy gunboat; it had originally been destined for military purposes in the Dutch East Indies. The guns were replaced with two huge steam-driven winch sounding machines. The 170' long vessel left Surabaya on 7 March 1899, under the command of Captain Gustaaf Frederik Tydeman. The total crew consisted of 63 people (10 Dutch Navy officers, 6 scientists, 45 mostly Javanese sailors, and 2 private servants). Most notable was the presence of a lady on a marine expedition, algae expert Mrs. Anna Weber, wife of the chief scientist Max Wilhelm Carl Weber. On the web site: is a fine description of the expedition, with archival photos.

            In Die Opisthobranchiata der Siboga-Expedition Bergh (1905) named 5 species in honor of the boat.

            Two species are synonyms of earlier named animals. Phestilla sibogae Bergh, 1905 = Phestilla lugubris (Bergh, 1870), and Discodoris sibogae Bergh, 1905 = Platydoris scabra (Cuvier, 1804).

            To my knowledge, Anisodoris sibogae Bergh, 1905, has not been observed nor discussed since the original description, which included a color drawing of the living animal and several 350x drawings of the radular teeth. It needs rediscovery!

             Cuthona sibogae (Bergh, 1905) was originally placed in the genus Hervia; photos and descriptions are available on Bill Rudman's site: The cerata of this beautiful pale lilac animal have a golden yellow tip with a subterminal deep reddish purple band. Widely distributed throughout the Indo-Pacific from South Africa to New Guinea, Indonesia and the Philippines (Gosliner, Behrens & Williams, 1996), the living animal can extend to 35 mm in length. It feeds on the hydroid Sertularella quadridens.

            Glossodoris sibogae (Bergh, 1905) (originally Chromodoris sibogae) has a dirty looking yellow brown body, with a bright white margin, at the very edge of which it has a ribbon of black (Rudman, 1986). Additional information is available at Dr. Rudman's site: The species has been reported from Indonesia, Fiji and French Polynesia.

            In 1910, the 38-meter Norwegian steamship Michael Sars spent 4 months cruising the North Atlantic, “to pick up the threads after the Challenger expedition.” This expedition was jointly headed by Norwegian scientist John Hjort and British oceanographer John Murray (the latter edited the Challenger Reports); See:

Among “new” species encountered was Dactylopus michaelsarsi Bonnevie, 1921. It would have been appropriate to have a Boat-Named pelagic nudibranch, but this species is a junior synonym of Cephalopyge trematoides (Chun, 1889).

            The Russian research vessel Vitiaz was never a warship, but its history was intimately involved in World War II:          First named MARS, it was built in Bremerhaven, Germany, in 1939 for the Neptune Company to carry fruit from southern countries to Germany. During February–April 1946 she carried refugees from the ports of Danzig and Pillau. The British took it as “spoils of war,” renaming it Empire, Forth! Then it was transferred to Russia, renamed, overhauled and outfitted for research, and did some 65 scientific expeditions between the late 1940s to 1979. Today it is moored at the Museum of the World Ocean, in Kaliningrad (Russia's Baltic sea port), where it is open for viewing.

            Valdés (2002) wrote that Bathydoris vitjazi Minichev, 1969, “is most likely a synonym of Bathydoris hodgsoni, but it is provisionally regarded as nomen dubium until more material becomes available.”

            The last species with a ship's name may arguably be said to be named after a slug named after a ship! Japanese specimens previously identified as Chromodoris sibogae (by Eliot, 1913, Baba, 1949, et al.) were named Glossodoris misakinosibogae Baba, 1988. This 40-50 mm long animal is a colorful white-on-white, with black-tipped rhinophores and gills. It appears to be a cooler-water allopatric form to its “namesake sister,” occurring in Japan, China and Korea (Koh, 2006). Again, many references are on Bill's site:

            To summarize, currently valid Boat-Named Nudibranch taxa are:

Tritonia challengeriana Bergh, 1884

Doridoxa ingolfiana Bergh, 1899

Bathydoris ingolfiana Bergh, 1899

Heterodoris ingolfiana (Bergh, 1899)

Tritonia ingolfiana (Bergh, 1899)

Anisodoris sibogae Bergh, 1905 (of unknown status)

Glossodoris sibogae (Bergh, 1905)

Cuthona sibogae (Bergh, 1905)

Bathydoris vitjazi Minichev, 1969 (of uncertain status)

Chromodoris marislae Bertsch, 1973

Glossodoris misakinosibogae Baba, 1988

Cuthona destinyae Hermosillo & Valdés, 2007

            Long may they sail!


            Special thanks are given to Gary McDonald and Peter Brueggeman for useful comments, and as always, to Webmaster Mike Miller.



Baba, Kikutaro. 1949. Opisthobranchia of Sagami Bay collected by His Majesty the Emperor of Japan. Iwanami Shoten, Tokyo. 194 pp. + 7 pp.

Baba, Kikutaro. 1988. Comparative studies on two species of Glossodoris from Japan (Nudibranchia: Chromodorididae). The Venus (Japanese Journal of Malacology) 47 (3): 158-166.

Bergh, R. 1870. Malacologische Untersuchungen. In: C. Semper, Reisen im Archipel der Philippinen. C. W. Kreidel, Wiesbaden. Sect. 2, I (1): 1-30.

Bergh, R. 1884. Report on the Nudibranchiata collected by H.M.S. Challenger, during the Years 1837-1876. In: Report on the Scientific Results of the Voyage of H.M.S. Challenger during the Years 1873-76 under the Command of Captain George S. Nares, R.N., F.R.S, and Captain Frank Tourle Thomson, R.N. Stationery Office, London. 10 (26): 1-154.

Bergh, R. 1899. Nudibranchiate Gasteropoder. In: Den Danske Ingolf-Expedition. Hagerup, Copenhagen. 2 (3): 1-46.

Bergh, R. 1900. Nudibranchiate Gasteropoda. In: The Danish Ingolf-Expedition. Hagerup, Copenhagen. 2 (3): 1-49.

Bergh, R. 1905. Die Opisthobranchiata der Siboga-Expedition. Résultats des Explorations...Siboga. Brill, Leiden. 50: 1-248.

Bertsch, Hans, Antonio J. Ferreira, Wesley M. Farmer & Thomas L. Hayes. 1973. The genera Chromodoris and Felimida (Nudibranchia: Chromodorididae) in Tropical West America: Distributional data, description of a new species, and scanning electron microscopic studies of radulae. The Veliger 15 (4): 287-294.

Bonnevie, Kristine Elisabeth Heuch. 1921. Dactylopus michaelsarsi nov. gen. et sp. Vertreter einer neuen Familie pelagischer Nudibranchia. Zoologischer Anzeiger 53: 145-152.

Chun, Carl. 1889. Bericht über eine nach den Canarichen inseln im Winter 1887, 1888 ausgeführte Reise. Mathematische und Naturwissenschaftliche Mittheilungen aus den Sitzungsberichten der Königlichen Preussischen Akademie der Wissenschaften zu Berlin, pt. 6, pp. 329-363 [519-553].

Cuvier, Georges. 1804. Memoire sur le genre Doris. Ann. Mus. Nation. Hist. Nat. Paris 4: 447-473.

Eliot, C. N. 1913. Japanese Nudibranchs. Journal of the College of Science, Imperial University of Tokyo 35: 1-47.

Gosliner, Terrence M., David W. Behrens & Gary C. Williams. 1996. Coral Reef Animals of the Indo-Pacific: Animal Life from Africa to Hawaii Exclusive of the Vertebrates. Sea Challengers, Monterey, CA. vi + 314 pp.

Hermosillo, Alicia & Ángel Valdés. 2007. Five new species of aeolid nudibranchs (Mollusca, Opisthobranchia) from the Tropical Eastern Pacific. American Malacological Bulletin 22: 119-137.

Just, Hanne & Malcolm Edmunds. 1985. North Atlantic Nudibranchs (Mollusca) seen by Henning Lemche. Ophelia, International Journal of Marine Biology, Supplementum 2: 1-170.

Koh, Dong Bum. 2006. Sea Slugs of Korea. Pungdeung Publ., Korea. 248 pp.

Minichev, Y. S. 1969. The organization of Bathydoris vitjazi sp.n., and the problem about the origin of nudibranch molluscs (Opisthobranchia Nudibranchia). [In Russian.] Vestn. Leningr. Gos. Univ. 21: 51-58.

Ohhner, Nils H. 1926. Nudibranchs and Lamellariids from the Trondhjem Fjord. Det Kongelige Norske Videnskabers Selskabs Skrifter, 1926, N.R. 2. Meddelelse fra Trondhjems Biologiste Stasjon N.R. 24: 36 pp.

Rudman, W. B. 1986. The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: The genus Glossodoris Ehrenberg (=Casella, H. & A. Adams). Zoological Journal of the Linnean Society 86 (2): 101-184.

Schrödl, Michael, Heike Wägele & Richard C. Willan. 2001. Taxonomic redescription of the Doridoxidae (Gastropoda: Opisthobranchia), an enigmatic family of deep water nudibranchs, with discussion of basal nudibranch phylogeny. Zoologischer Anzeiger 240: 83-97.

Valdés, Ángel. 2002. Phylogenetic systematics of “Bathydoris” s.l. Bergh, 1884 (Mollusca, Nudibranchia), with the description of a new species from New Caledonian deep waters. Canadian Journal of Zoology 80: 1084-1099.

Willan, Richard C. 2001. A new abyssal arminacean nudibranch from New Zealand. New Zealand Journal of Zoology 8: 325-330.

Hans Bertsch

Imperial Beach, California, and Tijuana, Mexico

October 2007

Hans Bertsch and Rosa Campay

            Hans Bertsch and Rosa Campay are seen inside the German U-boat Wilhelm Bauer, which they just visited this July in Bremerhaven. This submarine was originally the U-2540, one of the Type XXI of Nazi Germany, the most advanced submarines in the world at the time. However the design was conceived when the defeat of Germany had already become inevitable. The sub was scuttled at the end of the war, having never gone on patrol. Raised in 1957, it was fixed up as a research vessel, and then in 1983 it was restored to its original WWII configuration to serve as a permanently moored exhibit at the German Maritime Museum (Deutsches Schiffahrtsmuseum). A virtual tour can be taken:

            Two tales need be told. Rosa was wearing her Bahía de los Ángeles cap; a young man approached, they spoke Spanish. He was from La Paz, and knows Orso Angulo! Rosa spent more time at the periscope than in the galley! Girls Rule!, eh what?

            Hans is the author of Sea of Cortez Marine Invertebrates where you can discover the Boat-Named Anemone, Isoaulactinia hespervolita, the Western Flyer, Steinbeck & Ricketts' boat in their 1940 Sea of Cortez expedition.