Description of Halgerda toliara : Reunion island (Indian Ocean)

Halgerda toliara Fahey & Gosliner, 1999

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

Order : Nudibranchia
Suborder : Euctenidiacea
Superfamily : Doridoidea
Family : Discodorididae
Distribution : Described from Madagascar, and reported from South Africa.
Maximal size : 40 mm, usually less than 20 mm
Abundance : From time to time on the fore reef zone and on the rocky coast

Species characteristics :

Translucent white with pattern of reticulate yellow ridges.
   White gills tipped with black 'retracted in this photo)
   Black rhinophore clubs without a black band on the posterior side of the stalk.
   Fine pustules around the mantle edge and fine white line at the border

Showing species characteristics...

Photo Philibert Bidgrain
Reunion, Etang salé les bains, 25 October 2005, size : 8 mm

See more about : Sightening and mating periods

Remarks :

Identification confirmed by Bill Rudman and Nathalie Yonow
Synonymous : (according Worms)
- No other name

Bibliographic data :

Fahey, S. & Gosliner, T.M. (1999), describe small yellowish pustules near edge, but it seems that the pustules may be translucent and can appear white or yellowish.
    Some animals differ in having a single yellow ridge down the midline, this kind of specimen has been observed in Mayotte Island but not yet in Reunion Island , so if you find an animal with that particular pattern, please Contact us...
    A similarly coloured species is H. formosa which can be distinguished as follows:

H. formosa (Bergh, 1880)
- Some black spotting around mantle skirt
- The rhinophore club is black and the white stalk has a black line up the posterior midline
- The gills have a black line running along the inside upper edge
    H. toliara (Fahey & Gosliner, 1999).
- No black spots on mantle,
- There is no black line on the rhinophore stalk
- The distal half of each gill seems to be all black

References :

Bill Rudman Seaslug site : Sea Slug Forum : Halgerda toliara

Publications :

Fahey, S. & Gosliner, T.M. (1999) description of three new species of Halgerda from the western indian ocean, with a redescription of Halgerda formosa , Bergh, 1880. Proceedings of the California Academy of Sciences, 51(8) : 365-383.

Other photos of Halgerda toliara :

Some author considered that the specimen with a unique large yellow ridge is a different species (Halgerda sp. 9 in NSSI) but In our region we found intermediate pattern between this kind of specimen and the classical pattern of this species, so I considered that it's just variants of Halgerda toliara

Florence Trentin

Mohéli, Méa, 24 December 2004

Black rhinophore clubs without (b) a black band on the posterior side of the stalk..

A unique large yellow ridge (a)