Hypselodoris maculosa
(Pease, 1871)

Order: NUDIBRANCHIA
Suborder: DORIDINA
Family: Chromodorididae

DISTRIBUTION

Found throughout the tropical western Pacific and Indian Oceans.

PHOTO

Upper: Heron Is, Great Barrier Reef, Queensland, May 1981. Lower: Mbudya Is, Dar es Salaam, Tanzania, November 20 1976, 18mm long alive. Photos: Bill Rudman.

RELATED TOPIC

See also Hypselodoris cf. maculosa

The colour pattern is complicated and very variable. One of the simplest patterns is illustrated by the Tanzanian specimen [lower right photo]. The background colour of the mantle is a pale milky orange-brown. Around the anterior of the mantle is a broad translucent pinkish-purple margin with scattered white and darker pinkish-purple spots. At the posterior end the margin is similarly coloured but the band is not as broad. From the level of the rhinophores back to the gill pocket, there is a broad orange band at the edge. On the inside edge of the orange band, at the junction with the milky orange-brown central region, there is a series of reddish-purple streaks running back from the rhinophore pocket to the gill pocket on each side. In the gaps between the reddish-purple streaks are a pair of white streaks, one inside and one outside the red. The orange band appears wider adjacent to the red streaks because the outer white line of the alternating pair of white lines narrows the orange band on each side. Running down the central part of the mantle are four narrow white lines. There are five small dark pinkish-purple spots down the midline between the gills and rhinophores. The rhinophore stalks are translucent white and the clubs are white with a broad orange band at the base and another just below the tip. The simple gills are translucent white with a deep orange line down the outer edge and an orange tip. The bottom half of each gill is translucent orange. The sides of the body and the foot are a translucent pinkish-purple with a colourless band at the edge. On the sides of the body there are white lines and streaks running parallel to the edge of the foot and some pinkish-purple spots. On the posterior part of the foot extending beyond the end of the mantle there are scattered white spots and around the inside edge of the colourless translucent margin are a row of elongate pinkish-purple streaks.

Many variations are illustrated in other messages on this page. For example, the white lines on the back can be broken into a series of short streaks and there can be many pinkish-purple spots on the mantle and also the posterior part of the foot. Also the orange mantle border can be very pale, it can be reduced to a thin line, and it can be accompanied by a series of reddish spots. There can also be one, two or three orange bands on the rhinophore club. Many colour variants are described in an earlier publication (Rudman, 1986).
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The mantle is elongately oval, widening at the anterior end to give a spatulate appearance. The mantle overlap is very reduced, especially along the sides, and the foot extends some distance behind the posterior limit of the mantle. The animal is relatively high and narrow and the simple gills are arranged in a circle, open posteriorly, around the anus. There is a large aggregation of mantle glands opening at the edge, around the posterior end of the mantle. A few small mantle glands are found on each side adjacent to the rhinophores but they are absent elsewhere.

Originally described from Tahiti, this species has wide Indo-West Pacific distribution. Other names which have been used for this species include Chromodoris decorata (Risbec, 1928) and Glossodoris xishaensis Guang-Yu, 1975).

References:
• Guang-Yu, L, 1975. Opistobranchia from the intertidal zone of Xisha Island, Guangdong Province, China. Studia Marina Sinica, 10: 141-154, pls 1, 2.
• Pease, W.H. (1871). Descriptions of new species of nudibranchiate Mollusca inhabiting Polynesia. No. 2. American Journal of Conchology, 7(1): 11-19, Pls 3-9.
• Risbec, J., 1928. Contribution à l'etude des nudibranches Néo-Calédoniens. Faune des Colonies Françaises, 2(1): 328, pls 1-12.
• Rudman, W.B., 1984. The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: a review of the genera. Zoological Journal of the Linnean Society, 81: 115-273.
• Rudman,W.B., 1986. The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: Noumea purpurea and Chromodoris decora colour groups. Zoological Journal of the Linnean Society, 86(4): 309-353.

Authorship details
Rudman, W.B., 2003 (October 4) Hypselodoris maculosa (Pease, 1871). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/hypmacu

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