Onchidoris pusilla

Onchidoris pusilla (Alder & Hancock, 1845)

Onchidoris pusilla by Bernard Picton
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 pusilla (Alder & Hancock, 1845)

Synonyms

  • Doris pusilla Alder & Hancock, 1845

Description
This species of doridacean can reach a size of 9-10 mm in length. The body is oval shaped and very flattened, nearly circular when the animal is at rest. The body color is dark brown because of numerous densely packed colour patches covering it. Near the edge of the mantle there are usually whitish stains. All the dorsal mantle is covered with small conical brown tubercles, although frequently their base is whitish; tubercles located near the margin of the mantle are smaller. As in other species of Onchidoris, the mantle is very espiculous with elongated transversally laid spicules in the center, and diagonally laid near the edges, but this spiculation is not apparent due to the pigmentation of the body. The rhinophores are white, short, with up to nine lamellae and do not have a high rhinophoric sheath; the rhinophoric orifice has two tubercles in an anterior-internal position and in lateral-external position. The gill consists of up to nine small simply pinnate leaves arranged in a circle on the back of the dorsum, almost completely surrounding the anus; The gill crown is also tuberculate, with two tubers in anterior position and another one closing the gill circle. The gill leaves colour is white, like rhinophores, but Mediterranean specimens are pigmented dark brown with scores, like the mantle, although the spine is coloured cream. The cephalic region under the mantle does not differentiate oral palps; the cephalic veil border is usually pigmented brown. The foot is whitish with tiny brown spots; internal viscera can be glimpsed through the center of the foot as a reddish-brown stain.

Biology
The specimens of this species tend to live both in the intertidal and subtidal stratum, often under stones and on the bryozoan colonies from which they feed. There have been cited, as food or substrate,  the following species of bryozoans: Callopora spp., Escharella immersa, Microporella ciliata, Escharoides coccineus, Porella concinna and Schizomavella linearis (McDonald & Nybakken, 1999). The spawn consists of a semitransparent narrow cord with white eggs, wound in a tight flat spiral with up to 9 turns; sometimes there are two egg spirals surrounded by a unique exterior cord. The spawns have been observed in the month of May.

Etymology

  • Onchidoris, tuberculate Doris.
  • Doris, a sea nymph in Greek mythology.
  • Pusilla, from Latin “pusillus”, petty, trifling, insignificant, very small.

Distribution
There are few known references of this species. It has been observed in the Norwegian coast, in the British Isles, and in the Atlantic Iberian Peninsula shores. In the Iberian Coast it has been cited in the Cantabrian Sea and the Strait of Gibraltar.

Known georeferenced records of the species: Onchidoris pusilla (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 pusilla
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 pusilla" in OPK-Opistobranquis, Published: 17/05/2012, Accessed: 26/05/2017 at (http://opistobranquis.info/en/JuGvP)

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