Prosthiostomum trilineatum Yeri & Kaburaki 1920

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This species has been observed on Mayotte Island

Order : Polycladida
Suborder : Cotylea
Superfamily : Euryleptoidea
Family : Prosthiostomidae
Distribution : Indo West Pacific
Maximal size : 60 mm
Abundance :

Species characteristics :

Body extremely elongate and narrow, rounded anteriorly, tapering posteriorly, semi-transparent, flesh coloured with distinct orange median line bordered by black stripes that join posteriorly

Anterior transverse white and black stripes across the cerebral eyes

prosthiostomum trilineatum
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Photo Philibert Bidgrain
Mayotte, Mtsanga M'titi Sada, on the reef flat zone, less 1 m, 30 July 2010, size : 25 mm

Remarks :

Our specimen has only a black stripe across the cerebral eyes, no white stripe as in the species description...
   This specimen looks like specimens of P. trilineatum in Newman, 2003 (except the absence of the anterior white stipe). But in Discover life and Marine flatworms of the world, specimens use to illustrated this species are in fact specimen of P. cf trilineatum....

Bibliographic data :

Colour pattern distinct, although the intensity of the colour may vary
   They have eyes in two cerebral clusters or fan-like clusters over the head region
   No head tentacles or marginal pseudotentacles.
   Habitat : Found on the reef crest under rocks and rubble
   Ethymology : tri = three, lineatum = line, refers to the three median stripes
   This species is similar to Prosthiostomum cf trilineatum but there are some differences :


P. trilineatum

P. cf trilineatum

Median lines

Orange median line bordered by black stripes that join posteriorly

White median line bordered by orange stripes that join posteriorly

Anterior transverse stripes

White and black or only black in our specimen


References :

Publications :

Faubel, (1984) : The Polycladida, Turbellaria. Proposal and establishment of a new system. Part II. The Cotylea . Mitteilungen des hamburgischen zoologischen Museums und Instituts 80. 189259
    Newman, L.J. & Cannon, L.R.G. (2003). Marine Flatworms: the world of Polyclads. CSIRO Publishing : Melbourne 112 p
    Yeri, M. & Kaburaki, T. (1920). Notes on two species of Japanese polyclad Turbellia. Annotationes Zoologicae Japonenses 9: 591598

Other photos of Prosthiostomum trilineatum :

 More photos from Indian Ocean