Onchidoris sparsa

Onchidoris sparsa (Alder & Hancock, 1846)

Onchidoris sparsa by Manuel Ballesteros
Taxonomy
Class: Gastropoda  Cuvier, 1797
Subclass: Heterobranchia  J.E. Gray, 1840
Clade: Euthyneura  Spengel, 1881
Clade: Nudipleura  Wägele & Willan, 2000
Order: Nudibranchia  Cuvier, 1817
Suborder: Euctenidiacea  Tardy, 1970
Infraorder: Doridacea  Thiele, 1931
Superfamily: Onchidoridoidea  J.E. Gray, 1827
Family: Onchidorididae  J.E. Gray, 1827
Genus: Onchidoris  de Blainville, 1816
Species: Onchidoris sparsa (Alder & Hancock, 1846)

Synonyms

  • Doris sparsa Alder & Hancock, 1846

Description
This is a small species of Onchidoris that does not usually exceed 6 mm in length. The body is very flat and with an oval contour. The coloration is generally yellow, with the center of the dorsum slightly reddish because of the viscera. The mantle margin has small orange-brown spots that contrast with somewhat paler color of the rest of the mantle. When the specimens are observed under binocular microscope a thin black dotting on the mantle becomes apparent, something most clearly visible on the edge of the mantle in ventral view. By transparency the typica spiculation of the dorsum is visible: Transverse spicules in the middle, obliquely laterally and radially arranged around the mantle margin. The dorsum has conical tubercles but with a rounded apex, semitransparent but with an orange-brown tip and a smaller size the closer they are to the mantle margin. The rhinophores are very small, whitish, with few lamellae and some brown spot; there is no rhinophoric sheath but the white gill opening has 2-3 small tubercles like the ones on the dorsum, brown pigmented on the tip. Gill is formed by 5-9 gill leaves depending on the size of the specimen; the unipinnate gill leaves are very small, whitish, forming an incomplete arc around the anus. The foot is white, the reddish-brown digestive gland clearly visible in the center of the foot by transparency. The mouth does not have labial palps.

Biology
This small nudibranch, like others of the same genus, is associated with several species of bryozoans they food on, among which may be mentioned, among others, Cellepora pumicosa, Porella concinna, Celleporina caliciformis (=hassalli) or Schizomavella linearis. Because of its small size, its flattened form, and its peculiar coloration, this is a very cryptic species on the bryozoan colonies on which it is found so it passes almost unnoticed. Little else is known about its biology and reproduction.

Etymology

  • Onchidoris, tuberculate Doris.
  • Doris, a sea nymph in Greek mythology.
  • Sparsa, sparse.

Distribution
There are very few citations of this species, mainly found in the British Isles, Ireland and also in the Iberian Peninsula, where it has been cited in the Cantabrian and Galician coast. First observations in the Mediterranean are credited to Ballesteros (1984) among specimens collected in Tossa de Mar; later on it has also been collected in waters of the Levantine coast.

Known georeferenced records of the species: Onchidoris sparsa (z-200).
Sources:
: OBIS : OPK
: GROC 2010-2011 : VIMAR
: Enric Madrenas : Manuel Ballesteros.
: João Pedro Silva : M@re Nostrum
: Bernard Picton : Other sources
: GBIF.ORG : Marine Regions

Abundance

        Western Mediterranean:0 Stars
        Eastern Mediterranean:0.0 Stars
        Atlantic Ocean:0.0 Stars
This chart displays the observation probability for Onchidoris sparsa
based on our own records.

More pictures


Bibliography

Bibliography based on the works by Steve Long, 2006. Bibliography of Opisthobranchia 1554-2000 and Gary McDonald, 2009. Bibliographia Nudibranchia, with later updates from other resources.

Further reading

Cite this article as:

Ballesteros, Manuel, Enric Madrenas, Miquel Pontes et al. (2012-2017) "Onchidoris sparsa" in OPK-Opistobranquis, Published: 29/08/2012, Accessed: 22/09/2017 at (http://opistobranquis.info/en/N0Mwa)

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