Okenia elegans

Okenia elegans (Leuckart, 1828)

Okenia elegans 28mm @ Kašuni, Split (First cite for Croatia) 4-03-2016 7m by Jakov Prkić
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: Goniodorididae  H. Adams & A. Adams, 1854
Genus: Okenia  Menke, 1830
Species: Okenia elegans (Leuckart, 1828) [Idalia]

Synonyms

  • Euplocamus laciniosus Philippi, 1841
  • Idalia cirrigera Philippi, 1844
  • Idalia dautzenbergi Vayssière, 1919
  • Idalia elegans Leuckart, 1828 (original)

Description
The specimens of this species can reach a maximum size of 80 mm. The body is tall and its general color varies from pure white to white, sprayed with pink or orange-red dots. In all these cases the edge of the foot has a more or less marked yellow band. The most characteristic trait of this species are the digitiform papillae that surround the whole body from the front of the head, the sides of the dorsum and surround the gill leaves. The two most anterior papillae on the head are the longest. There are also papillae in the dorsum middle line. The color of these papillae is like the body at their base, whitish or reddish, but soon they turn yellow but on the apex that is usually whitish. The rhinophores are thick and in the white specimens are semitransparent in their base, white opaque in their middle third and red in their tip while in the most pigmented ones they are orange-red. There are up to twenty fine lamellae in each rhinophore. The gill is made up of 12-14 bipinnate gill leaves that form a complete circle surrounding the anal papilla; The gill leaves are white but their tips are pigmented from yellow to orange, depending on the color of the specimen. The anal papilla is not prominent, it is white with its upper border coloured in yellow or orange. The foot is very wide, slightly bilobed in the front side and pointed in the rear side. It is white coloured but it is finely dotted of pink or red in the most pigmented animals, as are the flanks of these specimens.

Biology
This species is usually found wandering in rocky bottoms where the individual or colonial ascidians of which it feeds on live. The following tunicated have been cited as prey for O.elegans: Ascidia sp., Ciona sp., Molgula sp., Microcosmus sp, Phallusia sp., Polycarpa rustica, P. scuba, Botryllus sp. and Dendrodoa grosularia (Picton & Morrow, 1994; McDonald & Nybakken, 1999). Frequently the specimens of O. elegans are almost completely buried in the body of the ascidian, from which only the gill leaves protrude.

Etymology

  • Okenia. In honor of Prof. Dr. Ludwig Gilbert Lorenz Oken, (1779-1851), German natural philosopher, editor of the magazine “Isis” and publisher of the book “Lehrbuch der Naturgeschichte”.
  • Elegans. From Latin “elegans”, delicious, reloaded, prodigious.

Distribution
This species has been reported from Norway, the British Isles (Picton & Morrow, 2016), the Bay of Biscay, the Iberian Peninsula (Strait of Gibraltar and Catalonia, Cervera et al. 2004) and the Mediterranean Sea (both in the Adriatic and Greek coasts). In the Catalan coasts it has only been observed in Cala Aiguablava (Begur) and in Blanes (both at Punta de Santa Anna and in the trawling location known as La Planassa).

Known georeferenced records of the species: Okenia elegans (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

References for the species: Okenia elegans

    Gibraltar: Sánchez-Santos (unpubl. data). Catalunya: Domènech et al. (2006), Ballesteros (datos no publicados) [Blanes].

    General: Alder & Hancock, 1854:103; 1855:fam. 1, pl. 27[P]; Bergh, 1881c:146; Hoffmann, 1926:15; ICZN, 1974:13; Jeffreys, 1869:78; Lemche, 1972:196; Vayssiere, 1901a:78; 1913a:354; 1919:78 as Idalia elegans; Barletta, 1981:48[P]; Brown & Picton, 1979:9; Hayward, Wigham, & Yonow, 1990:715; Hunnam & Brown, 1975:150; McMillan, 1968:69; Nordsieck, 1972:52; Picton & Morrow, 1994:56[P]; Pruvot-Fol, 1954b:308; Riedl, 1983:333; Schmekel & Portmann, 1982:125; Thompson, 1976:[P]; 1976a:[P]; 1988:162[P]; Thompson & Brown, 1976:82[P]; 1984:43[P]; Vicente, 1967:154 as Okenia elegans

    Sources: Cervera et al., 2004, Ballesteros, 2007, McDonald, 2006 and other sources.

Abundance

        Western Mediterranean:1 Stars
        Eastern Mediterranean:1 Stars
        Atlantic Ocean:2 Stars
This chart displays the observation probability for Okenia elegans
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) "Okenia elegans" in OPK-Opistobranquis, Published: 11/09/2014, Accessed: 18/10/2017 at (http://opistobranquis.info/en/0w1tC)

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