Marionia pambanensis   O'Donoghue,  1932 (Sea Slug)
Organism information awaits expert curation
Taxonomy
Kingdom:Animalia
Phylum:Mollusca
Class: Gastropoda
Order:Nudibranchia
Family:Tritoniidae

Description
Size: 22 mm long by 12 mm wide and 7 mm high

Color: Dark, dirty, greenish grey all over, with no signs of markings.

The body is limaciform but almost rectangular in transverse section, except at the posterior end, where it tapers off to a somewhat pointed and flattened tail. The dorsum is flat and covered with a number of small rounded tubercles. It has a slight pallial flange around its edges, which bears a line of branchial appendages on each side. At its front end it passes forwards into a free, shallowly bilobed, cephalic veil, which bears six digitiform processes on each side of the middle line. The two mesial processes on each side are small and simple, but the lateral ones are larger and bifid for their last quarter. The lateral margin of the veil is thickened, but there is no distinct grooved tentacle.
The head is sub-globose, moderately distinct, but completely overhung by the cephalic veil of whose ventral surface it forms part. The mouth is a longitudinal slit in the middle of the head. The foot is well developed and muscular; it is of the same length and width as the dorsum and marked off from the sides of the body by a wide flange. Its anterior end is rounded, thickened, and bilabiate for a noticeable distance postero-laterally, and its hinder end is pointed. The rhinophores are contractile within erect, cylindrical sheaths, slightly wider above than below. The clavus consists of a crown of nine simply pinnate phimes: the anterior pair is small and the others increase in size so that the posterior, unpaired plume is largest and it is continued on as a short, blunt ended, cylindrical projection. The branchise are a series of twelve pairs of dendritic tufts borne on the pallial flange. They vary in size, the largest lying just behind the middle of the body; the first pair is small and the last pair very small. On the body wall beneath the third branchial tuft on the right side lies the reproductive aperture, and in a similar position between the fourth and fifth tufts lies the anus. The buccal mass is large and it measures 4.5 mm long by 3 mm in diameter. The lips are covered with a thin, dark brown layer of chitin, which is reflected inside the mouth tube. Dorsally and ventrally it is continued into thicker pointed extensions, which give it a characteristic appearance in side view. The jaws are stout and oval in outline, and the crista connective is long. The cutting edge of the mandible bears a series of pointed, papilliform, chitinous projections arranged in five or six rows. Near the crista these projections are minute and again at the end of the processus masticatorius, but they are considerably larger over the intervening regions and reach their maximum just before the origin of the processus. The radula is well developed and, flattened.
It contains 40 rows of teeth; the formula for the first row is 0.1.1, for the second 1.1.1, for the third 3.1.1.1.3, for the sixth 11.1.1.1.7, and for the complete rows half-way back 43-41.1.1.1. 41-43. The median tooth has a roughly rectangular base, slightly wider than long; its posterior corners are rounded; its anterior corners are pointed, and it bears a median rounded indentation in the posterior side. The greater part of the base plate is thickened, so that its anterior corners stand up as sharp cutting blades and from the middle of the anterior side arises a forwardly directed sharp denticle between which and the lateral blades lie deep, curved indentations on the upper surface. The first lateral tooth has an oblique rhomboidal plate, with its anterior and lateral borders raised into a strong ridge, which forms a sharp vertical cutting edge at the antero-median corner of the tooth. The remaining pleural teeth are of the common recurved spine shape and reach their maximum about half-way out. The last three or four decrease rapidly in size. The stomach is provided with a considerable number of chitinous plates. They vary in size from .6 mm to 1.1 mm in long diameter, and the large ones have a thickened recurved edge.


Synonym (s)

Common Name (s)
Economic Importance and Threats

Ecology

Biogeography


• Tamil Nadu, Pamban INDIA
• Tamil Nadu, Gulf of Mannar INDIA

Literature Source(s)
  • O'Donoghue, CH (1932) Notes on Nudibranchiata from southern India Journal of Molluscan Studies The Malacological Society of London 20(3) 141-166 Available at - http://mollus.oxfordjournals.org/content/20/3/141.full.pdf+html
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at - http://www.marinespecies.org

Page last updated on:2010-11-26

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