Chromodoris hamiltoni     Rudman, 1977

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This species has been observed on Madagascar Island


Order : Nudibranchia
Suborder : Euctenidiacea
Superfamily : Doridoidea
Family : Chromodorididae
Distribution : Western Indian Ocean
Maximal size : 60 mm
Abundance :


Species characteristics :

Mantle blue with a broad pale orange to pink salmon mantle margin surrounded by a thin white border and three longitudinal deep blue to black line. Sometimes presence of a distinctive orange patch in the centre of the dorsum,

The gills and rhinophores are orange, and the gill and rhinophores pockets are edged with orange

The foot has a wide orange border

 

 

chromodoris hamiltoni
Showing species characteristics...
Photo Alain Barrére
Madagascar, Andavadoaka, 2005

See more about : Sightening and mating periods
   See more about : Chromodoris hamiltoni variability in Southwest Indian ocean

Remarks :

Identification confirmed by Nathalie Yonow
    We observed in our area two classical pattern for this species : pattern 1 with orange markings on the dorsum
    See also Chromodoris quadricolor group
    Synonymous : No other name

Bibliographic data :

This is a very variable species, many variations are observed :
          - The blue background colour but this can be very pale in some specimens becoming white border along the margin
          - There are usually three thin dark blue black lines down the mantle but sometimes there can be extra lines and sometimes the inner lines can be replaced by broader diffuse brown or orange lines
          - In the center of the dorsum of some specimen there is an oval patch in which the background colour is very pale and the dark blue lines are a dirty orange colour.
          - In some specimen, the medium dark line on the dorsum is completely obliterated. It runs from just in front of the rhinophores to just behind them. From there back to the gills is a large elongate orange patch which widens just anterior to the gills.
          - In some specimen, just behind the rhinophores the median dark blue line become dirty orange and the pale blue almost white line that runs along side of it is replaced by orange
   There are three deep blue to black lines running down the mantle
          - A central one runs from the white inner border back between the rhinophores to the gills pocket
          - The other two, one on each side, run alongside the white inner border, finishing behind the gills.
   There are 11 to 15 gills and they form an incomplete circle open posteriorly
   The sides of the foot are pale blue with three dark blue lines running from the head to the tail. The central line of each side joins the other in the posterior midline
   The foot has a wide orange border and the genital pore is ringed with orange
   The head and oral tentacle are orange
   Pika & Faulkner (1995) reporting the presence of  chemicals in the skin, and spicules in the stomach, typical of the bright red sponge Latrunculia (which is now considered to be a species of Negombata). Several messages on Rudman Forum suggest that C. hamiltoni possibly feeds on a thorectid similar to Phyllospongia and two messages associate C. hamiltoni with both the red Negombata and a dark grey thorectid, possibly Petrosaspongia or Semitaspongia
   It is similar only to Chromodoris quadricolor, but usually lacks the distinctive white line between the black outermost line and the orange margin, the orange margin is paler and slightly more pink, and usually it has additional patches of orange and/or black dorsally. It is a much more variable species than C. quadricolor
   It looks like Chromodoris elisabethina but there is a white band between the orange mantle margin and the outer black line while in C. hamiltoni there is usually not.

References :

Bill Rudman Seaslug site : Sea Slug Forum : Chromodoris hamiltoni
   Nudipixel Chromodoris hamiltoni

Publications :

Rudman, W.B. (1977) Chromodorid opisthobranch Mollusca from East Africa and the tropical West Pacific. Zoological Journal of the Linnean Society 61 : 351-397
   Pika, J. & Faulkner, D. J. (1995) Unusual chlorinated Homo-Diterpenes from the South African nudibranch Chromodoris hamiltoni . Tetrahedron , 51, 81898198.

Other photos of Chromodoris hamiltoni :


Pattern 1 : with orange markings on the dorsum

Alain Barrère

Madagascar, Andavadoaka, 2005

There are usually three thin dark blue black lines down the mantle but sometimes there can be extra lines( a) and sometimes the inner lines can be replaced by broader diffuse brown or orange lines (a and b)

 


Alain Barrère

Madagascar, Andavadoaka, 2005

Pattern 1 : with orange markings on the dorsum

With an intense orange coloration


Sully Bachel

Madagascar, Ile aux Nattes, sec de lakana, 28 m, 20 October 2008, size : 20 mm

Pattern 1 : with orange markings on the dorsum

But with a large white inner band between the orange margin and the black longitudinal line.

 


 More photos from Indian Ocean
See more about : Chromodoris hamiltoni variability in Southwest Indian ocean