At the international workshop on Opisthobranchs held in Menfi, Italy in June 2001, Rebecca Johnson and Terry Gosliner introduced two new species of Thorunna , one from Hawai'i and the second from Papua New Guinea and the Philippines. Thorunna halourga is a small but colorful chromodorid. The name is derived from the Greek word, "halourgus", which means sea-purple, to draw attention to the animal deep purple body color. Because Thorunna lacks several of the classical internal features used to differentiate members of chromodorid genera, Rebecca and Terry introduced the use of several novel characteristics to distinguish this genus, such as presence or absence of very tiny dorsal mantle glands, buccal bulb glands and two structures found in the male portion of the reproductive system. I will not go into these in detail here but this has to do with the size of the receptaculum seminis and its connection to the bursa copulatrix. -- What did he just say?
Thorunna halourga is a member of Bill Rudman's Noumea purpurea color group, but most of these have some form of mid doral clor of stripe. The most similar to Thorunna halourga is Thorunna punicea which has purple tipped rhinophores and gills, and Durvilledoris albofimbriata , which externally has a much thinner white marginal band. Another photo of this species taken in Batangas, Philippines by Jeff Rosenfeld is found on the Sea Slug Forum. Some specimens even look similar to one of the color variations found in the Hypselodoris bullocki color group .
This species is now known from throughout the tropical western Pacific - southern Japan, Philippines, Marshall Ids, Papua New Guinea and eastern Australia.
The other species described in this paper was aptly named the big "kahuna" or the islands medicine man or healer. I hope we can share this critter with you soon.
Johnson, R.F. & Gosliner, T.M. 2001. Two new species of Thorunna Bergh 1878
(Mollusca: Nudibranchia: Chromodorididae) from the Indo-Pacific. Bollettino Malacologico , 37(5-8): 143-150.
David W. Behrens
Pacific Coast Nudibranchs
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