Dunga ocellata
(Alder & Hancock, 1864)

Order: NUDIBRANCHIA
Suborder: AEOLIDINA
Family: Eubranchidae

DISTRIBUTION

Indo-west Pacific

PHOTO

North Reef (sewer pipe), entrance to Dar es Salaam Harbour, Tanzania. DSM26, 16 August 1973. Photos: Bill Rudman

Relatively small aeolids with up to 5 rows of cerata on each side, 2 in front of the heart, 3 behind. There are up to 5 cerata in each row. The inner cerata in the anterior rows are enormous, some almost half the size of the whole body. The cerata can change shape considerably, and at their largest are greatly inflated, the basal two-thirds being cylindrical and the upper third tapering to a point. A ring of 7 - 8 tubercles form a ring around the ceras at about a third the way from the tip. The ceratal wall is transparent with a scattering of small brown and opaque white specks, the density of which varies in different animals. Also present are some small red rings each filled with an orange-yellow colour. These rings are usually very small, almost indistinguishable from the red spots, but in some animals they are much larger. Within an individual the rings can become larger when the cerata become inflated. The tip of each ceras is reddish pink, below which can be a white ring and a yellowish band. The digestive gland duct in each ceras is a thin tube, usually brown in colour.

The animal is transparent colourless with the yellowish viscera showing through the body wall. There are scattered brown spots all over the body, rhinophores and oral tentacles, often aggregated into bands and patches.

Alder & Hancock (1864) described this species as Eolis ocellata, from Waltair on the Bay of Bengal coast of what is now Andrha Pradesh State in northeastern India [see message #13245 ]. It is distinguished from species of Eubranchus by its tentacular anterior foot corners. It has been well described by Edmunds (1969) from Tanzania, where it is a relatively common species. The tentacular foot corners, swollen nodulose cerata, and red rings are also features of  Dunga nodulosa Eliot, 1902, from Tanzania and I consider them to be the same species.  I have followed Edmunds in leaving this species in the genus Dunga, although a further review of the family may consider it to be a synonym of Eubranchus.

Apart from Alder & Hancock's and Eliot's records of this species, it has also been reported from Tanzania (Edmunds, 1969), and in the Forum from the Red Sea [Oren Lederman message #13214], Tanzania [Bill Rudman message #13249], and New Caledonia [Bill Rudman message #13239], suggesting it has a wide Indo-West Pacific distribution 

• Alder, J. & Hancock, A. (1864) Notice of a collection of nudibranchiate mollusca made in India by Walter Elliot Esq., with descriptions of several new genera and species. Transactions of the Zoological Society of London, 5: 113-147.
• Eliot, C.N.E. (1902) On some nudibranchs from Zanzibar. Proceedings of the Zoological Society of London, 1902(2): 62-72. (Pls.5-6)
• Edmunds, M. (1969) Opisthobranchiate Mollusca from Tanzania I. Eolidacea (Eubranchidae and Aeolidiidae). Proceedings of the Malacological Society of London, 38: 451-469.

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