Aplysia dactylomela

Aplysia dactylomela (Rang, 1828)

Aplysia dactylomela @ Es Caials 18-08-2016 by Àlex Bartolí
Taxonomy
Class: Gastropoda Cuvier, 1797
Subclass: Heterobranchia J.E. Gray, 1840
Clade: Euthyneura Spengel, 1881
Clade: Euopisthobranchia Jörger et al., 2010
Clade: Aplysiomorpha Pelseneer, 1906
Superfamily: Aplysioidea Lamarck, 1809
Family: Aplysiidae Lamarck, 1809
Genus: Aplysia Linnaeus, 1767
Species: Aplysia dactylomela Rang, 1828

Taxonomic note: according to the work by Jennifer Alexander and Ángel Valdés: The ring doesn’t mean a thing: Molecular data suggest a new taxonomy for two Pacific species of sea hares (Mollusca: Opisthobranchia, Aplysiidae), published in Pacific Science in 2013, A. dactylomela is an Atlantic species, while Aplysia argus  (Rüppell & Leuckart, 1828), is the oldest valid name for the Indo-Pacific specimens. The question was to determine the species for Mediterranean specimens. Again, according to the paper by Valdés et al. 2013 – The origin and dispersal pathway of the spotted sea hare Aplysia dactylomela (Mollusca, Opisthobranchia) in the Mediterranean Sea, all Mediterranean specimens studied so far are of Atlantic origin, hence they are true Aplysia dactylomela.

Synonyms

  • Aplysia aequorea Heilprin, 1888
  • Aplysia angasi G.B. Sowerby II, 1869
  • Aplysia annulifera Thiele, 1930
  • Aplysia benedicti Eliot, 1899
  • Aplysia bourailli Risbec, 1951
  • Aplysia fimbriata Adams & Reeve, 1850
  • Aplysia megaptera Verrill, 1900
  • Aplysia ocellata d’Orbigny, 1839
  • Aplysia odorata Risbec, 1928
  • Aplysia operta Burne, 1906
  • Aplysia protea Rang, 1828
  • Aplysia radiata Ehrenberg, 1831
  • Aplysia schrammi Deshayes, 1857
  • Aplysia scutellata Ehrenberg, 1831
  • Aplysia tigrina Rang, 1828
  • Aplysia velifer Bergh, 1905

Description
This spectacular species of sea hare can reach a size of 40 cm in length. The body of this species is thick, with well developed parapodia that are free at the rear end and can completely cover the dorsum of the animal. The background color of the body varies from light to dark brown to yellowish or olive green on which appear numerous black rings of different sizes that make this species unmistakable. There are also thin or thick sometimes dashed black lines that starting from the rings may converge among them, those lines can be very abundant in the outer edge of the parapodia. The inner face of the parapodia has usually very wide, dark, almost black, spots radiating from the visceral mass to the edge of the parapodia. The oral tentacles are very well developed, enlarged and leaf-like. The dorsal zone of the mantle also usually has large dark spots like those inside the parapodia. The anal siphon is highly developed. The rhinophores, as in other species of sea hares, are auriculate. The spermatic groove is very visible and stands out as a dark line from the right anterior edge of the mantle to somewhere ahead the rhinophore of the same side. The shell is completely covered by the dorsal mantle and there is no dorsal foramen. The foot is wide and slightly darker than the body color.

Biology
Aplysia dactylomela lives in rocky or sandy shallow waters and in intertidal pools with an abundance of algae. It has also been observed in more depth, up to 40 m. Like all sea hares they are herbivorous and has a voracious appetite, feeding on a wide range of red algae of the genera Corallina, Laurencia, Acanthophora, Centroceras and Gracilaria or green algae like Ulva and Cladophora. Due to the structure of the parapodia, unfused on the rear end, it is capable of swimming movements. When specimens are abruptly disturbed they are able to segregate a reddish defensive fluid from some glands in the mantle. Like all sea hares, this species is a simultaneous hermaphrodite and when mating several individuals can copulate in chain. The spawn is like a scrambled cord with lots of eggs that can be yellow, pink or purple.

Etymology

  • Aplysia. From greek word for “dirty”, “unwashed”.
  • Dactylomela. Composed word of Greek origin, “Dactylo” from the word for “ring” and “Mela” from the word for “black”: “Black rings”.

Distribution
Although it was thought that this species had a very wide circumtropical distribution, having been reported in almost all warm waters and tropical seas of the world, according to the work (Alexander & Valdés, 2013) findings from the Pacific and Indian Oceans of A.dactylomela are actually A.argus. Thus, the distribution of A.dactylomela covers from the Cape Verde archipelago (which are the type specimens of the species), the Caribbean and around the Gulf of Mexico, off the coast of Florida, Bermuda, Bahamas, Belize, Brazil, Senegal and the Canary islands. It has recently been found in the Mediterranean Sea, with reports from Israel, the island of Malta, Sicily, the Greek islands and in Croatia, where it has proven it can reproduce. It has recently been found in the Balearic Islands (Cap d’en Font, Menorca, 05/25/2016 by Joop Werson [GROC]) and Catalonia (Cala Secains, Sant Feliu de Guixols, 06/20/2016 by Xavier Salvador [GROC] and Es Caials, Cadaqués, Girona, Spain 18/08/2016 by Àlex Bartolí) in what are the first reports for Spain and Catalonia.

Known georeferenced records of the species: Aplysia dactylomela (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:1 Stars
        Eastern Mediterranean:2 Stars
        Atlantic Ocean:3 Stars
This chart displays the observation probability for Aplysia dactylomela
based on our own records.

Video
The following video has been recorded in waters of Sicilia (Italy): 

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) "Aplysia dactylomela" in OPK-Opistobranquis, Published: 15/05/2012, Accessed: 23/04/2017 at (http://opistobranquis.info/en/R2dRy)

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