Halgerda wasinensis (Eliott, 1904)

Halgerda wasinensis Eliot, 1904

This species has been observed on Reunion, Mayotte, Madagascar and Seychelles Islands

Order : Nudibranchia
Suborder : Euctenidiacea
Superfamily : Doridoidea
Family : Discodorididae
Distribution : Indian Ocean
Maximal size : 50 mm
Abundance :

Species characteristics :

Mantle covered with a reticulate pattern of thin yellow ridges and often with a strong background colour of black caused by the dark internal visceral envelope showing through the translucent body wall.

Usually there is a rounded black spot in each 'valley' between the yellow ridges, and around the mantle edge there are many black spots. In some animals black spots are completely absent from the mantle.

The upper two-thirds of the rhinophore club is black, the lower third white, and there are black spots, sometimes forming a continuous line along the posterior side of the white rhinophore stalk

The translucent white gills have scattered black spots and markings.

Showing species characteristics...

Photo Sully Bachel
Madagascar, nosy Bé, 12-14 m, 21 Jully 2010, size : 20-25 mm

Remarks :

Type 4 :

Type 5 :

Identification confirmed by Angel Valdès , and Nathalie Yonow
    In our region we can found five patterns for this species. I preferred this hypothesis to that of making 5 species including 4 not described ...
    According Gary Cobb Type 4 is an undescribed species.

Type 1 :

Type 2 :

Type 3 :

    Synonymous : (according Worms)
          - No other name

Bibliographic data :

We normally think of H. wasinensis as having a black mantle and a network of yellow ridges, but it is more complex than that. The black is made of two components. The first component is a large black spot in each 'valley' between the yellow ridges. The second component is a tough fibrous layer which encloses the visceral mass internally. In many species of Halgerda this visceral envelope is black. It is visible through the translucent body wall and gives this species its usually very dark background colour. In some animals the black spot on the skin would appear to enlarge to fill the whole space between the yellow ridges while in other animals the black internal envelope covering the viscera lacks black pigmentation or else the body wall is sufficiently thick to prevent the colour showing through the body wall. In these instances the animal appears white with scattered black spots.
    The translucent white gills have scattered black spots and markings. The black sometimes appears as a continuous line but in smaller individuals it is present as a black tip.
    There are blackish brown spots in the white band round the mantle edge (not observed in ours specimens).
    The underside of the mantle and the foot are white with large rounded dark purplish brown or black spots (not visible in ours specimens).
    According Rudman :" Specimens I have examined from Kenya and Tanzania have relatively sharply angled mantle ridges and narrow yellow lines. However photo from South African suggests that specimens from there have more rounded ridges and subsequently wider yellow lines."

References :

Bill Rudman Seaslug site : Sea Slug Forum : Halgerda wasinensis
Nudipixel Halgerda wasinensis

Publications :

Eliot, C. N. E. 1904. On some nudibranchs from east Africa and Zanzibar. Part III. Dorididae Cryptobranchiatae, I. Proceedings of the Zoological Society of London 2:354-385, pls. 22-24.
Rudman, W.B. (1978) The dorid opisthobranch genera Halgerda and Sclerodoris from the Indo-West Pacific. Zoological Journal of the Linnean Society, 62 : 59-88.

Other photos of Halgerda wasinensis :