Knoutsodonta pictoni

Knoutsodonta pictoni  Furfaro & Trainito, 2017

Knoutsodonta pictoni by Enric Madrenas

Taxonomy
 

Superdomain

Biota  

 

Kingdom

Animalia  

 

Phylum

Mollusca  

 

Class

Gastropoda  

 

Subclass

Heterobranchia  

 

Infraclass

Euthyneura  

 

Subterclass

Ringipleura  

 

Superorder

Nudipleura  

 

Order

Nudibranchia  

 

Suborder

Doridina  

 

Infraorder

Doridoidei  

 

Superfamily

Onchidoridoidea  

 

Family

Onchidorididae  

 

Genus

Knoutsodonta  

 

Species

Knoutsodonta pictoni  Furfaro & Trainito, 2017

 
 Classification according to Bouchet et al. (2017)
Taxonomic source: World Register of Marine Species (AphiaID: 1039653).
Taxonomic Note: This recently described species has been identified repeatedly as Onchidoris pusilla (Alder & Hancock, 1845) because of its similar morphology: dark brown body due to scores of the same color and completely white rhinophores. However, the gill leaves in K. pictoni are of the same color as the body, in contrast to the white gill of the original description and the other reports of true O. pusilla. Hallas & Gosliner (2015) in their study on the phylogeny of the Onchidoridae establish the new genus Knoutsodonta Hallas & Gosliner, 2015 where they include several Onchidoris species (brasiliensis, depressa, jannae and oblonga) lacking a medial tooth in their radula. In the article describing K. pictoni, Furfaro & Trainito (2017) extend to 16 the number of known species of the genus Knoutsodonta, of which 6 are species living in the Mediterranean (K. pictoni, K. albonigra, K. bouvieri , K. depressa, K. neapolitana and K. sparsa).

Description
Animals of this species may reach up to 13 mm in length, but they do not usually exceed a size of 9-10 mm. The body shape is almost circular and it has a very dark brown color, formed by almost continuous spots of the same color. There are whitish spots near the edge of the mantle. Under the mantle the typical spiculation of the genus Onchidoris can be seen by transparency. The dorsum has slightly conical elevated and well spaced tubercles. The tubercles at the edge of the mantle are smaller. The tubercles have whitish the base and brown the apex. The rhinophores are completely white and retractile; have rudimentary lamellae, up to 10 in the largest specimens. The rhinophoral sheath is not high and has two large tubercles, one antero-internal and one lateral. The gill is formed by up to 9-10 bipinnate leaves in the largest specimens; the gill leaves are arranged in a circle around the anus, they are not retractile, they are semitransparent but they have numerous brown spots that give them a dark color. The intrabranchial circle has three tubercles, two anterior and one posterior, which closes the circle of gill leaves. The foot is whitish but has tiny brownish-red spots, visible with a binocular microscope, and a reddish-brown stain corresponding to the internal viscera. There are also brown spots on the flanks of the body and on the back of the foot. The mouth is located at the center of a sort of oral veil that extends laterally.

Biology
Specimens of this species were known in different points of the Catalan Costa Brava (Spain) since 1992 but were erroneously assigned to the species Onchidoris pusilla. It lives under rocks and almost always on colonies of encrusting bryozoans such as Reptadeonella violacea (see Furfaro & Trainito, 2017) on which it is usually unnoticed due to its color similarity. The predated areas of the bryozoan colony appear whitish, making it easier to tell if the nudibranch is around or not. The spawn, which is usually laid on top of the bryozoan briozoo, is formed by a semitransparent cord wrapped in a tight circular spiral of up to 7 turns, with numerous white eggs. It has been reported how two animals can lay a complex pattern in which one egg spiral is completely enclosed within another. Eggs are usually laid from April to May.

Etymology

  • Knoutsodonta, from the Greek meaning “lame tooth”, to represent
    nudibranch species that lack a rachidian or middle tooth.
  • Pictoni. After Bernard Picton, eminent British specialist in opistobranchs of the North Atlantic.

Distribution
K. pictoni has an Atlantic-Mediterranean distribution and has only been found so far on the Scottish and Irish coasts and in the central and western Mediterranean (see Furfaro & Trainito, 2017). In the Iberian Peninsula there are only reliable reports from the Costa Brava (Port Lligat to Lloret de Mar), and from the Maresme, where it has been reported in Llavaneres (Ballesteros et al., 2016), in all cases cited as O. pusilla or Knoutsodonta sp.

Known georeferenced records of the species: Knoutsodonta pictoni
Sources:
: OBIS
: GROC 2010-2011
: Enric Madrenas
: João Pedro Silva
: Bernard Picton
: GBIF.ORG
: OPK
: VIMAR
: Manuel Ballesteros.
: M@re Nostrum
: Altres fonts
: Marine Regions

Abundance

    Western Mediterranean:
    Eastern Mediterranean:
    Atlantic Ocean:

More pictures

Bibliography

Further reading

Cite this article as:

Ballesteros, Manuel, Enric Madrenas, Miquel Pontes (2012-2018) "Knoutsodonta pictoni" in OPK-Opistobranquis, Published: 15/09/2015, Accessed: 18/10/2018 at (https://opistobranquis.info/en/Zv9eN)

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