Thuridilla mazda

Thuridilla mazda  Ortea & Espinosa, 2000

Thuridilla mazda @ Punta del Vapor, Almuñécar, Granada by Miguel Vila




































Thuridilla mazda  Ortea & Espinosa, 2000

 Classification according to Bouchet et al. (2017)
Taxonomic source: World Register of Marine Species (AphiaID: 420576).
Relatively small body, with a maximum reported length of about 6 mm, black in color. The parapods, usually closed, protect the body. The edge of the parapods has a fine white or pale yellow line that, in the area near the head, forms a pattern similar to an inverted 3 that is continued by a streak of the same color that reaches the anterior end of the body . This line turns orange near the tail. The edges are also decorated on the outside with up to 7 semicircular colored areas alternated with black areas. From the edge and towards the body, each of these colored areas contains overlapping semicircles of yellow, orange, blue and orange. There are no color spots at the bottom of the parapods. The interior of the parapods is very dark green, almost black, uniform, with a grayish band along the inner edges and a striking blue line near the tail. There are some orange spots in the precardiac area. The edge of the parapods is slightly wavy so that the undulations of each parapod match its opposite. The color pattern of the parapods accentuates the ondulated look of the parapods. Smaller specimens appear to have a less elaborate color pattern than larger specimens. The rhinophores are short with a broad base, black on the anterior ventral half and white, with blue apical spots on the posterior dorsal half. A white “Y” shaped spot covers the dorsal surface of the head, neck and middorsal area of ​​the rhinophores, which may be pale yellow in its central area, ending in an iridescent blue spot before the orange precardiac crest. . Between the anterior margins of the rhinophores there is an orange spot. The front of the head is dark brown. The eyes are relatively small and inconspicuous, located at the base of the rhinophores, on the margins of the dorsal white spot, and have a small iridescent blue dot located in front of and below each eye. There is an orange band along the anterior part of the foot.

There are few reports of this species since its description, probably due to its small size, so little is known about its biology. All the specimens have been found on algae, on which it feeds. The egg-spawn is a flat ribbon wound in a spiral of about two turns with orange eggs (Ortea et al., 2015).


  • Thuridilla. Derived from Thurida (daughter of Thord of Höfdi), a character from the Icelandic saga of Viga-Glum.
  • Mazda. In memory of the car Mazda 626 GLX of the year 1987 used by the authors of the original description, who traveled 198,000 km on the roads of Cuba, with no spare parts, during their sampling campaigns.

Species described on specimens found on the coasts of Costa Rica and Cuba, it has also been cited in the Netherlands Antilles, on the island of Guadalupe, in Belize and Bahamas. Findings in 2011 also place this species in the eastern Atlantic, in the Azores and in the Canary Islands, thus confirming its ampiathlantic character. In 2021 a specimen was found off the coast of Granada (Spain), the first record for the Mediterranean Sea (Sánchez Tocino et al., 2021).

Known georeferenced records of the species: Thuridilla mazda
: GROC 2010-2011
: Enric Madrenas
: João Pedro Silva
: Bernard Picton
: Manuel Ballesteros.
: M@re Nostrum
: Altres fonts
: Marine Regions


    Western Mediterranean: ★☆☆☆☆
    Eastern Mediterranean: ☆☆☆☆☆
    Atlantic Ocean: ★☆☆☆☆

This chart displays the monthly observation probability for Thuridilla mazda based on our own records.



More pictures


    Ballesteros M, Madrenas E, Pontes M. 2024. OPK - Opistobranquis. Available from
    Carmona L, Malaquias MAE, Gosliner TM, et al. 2011. Amphi-atlantic distributions and cryptic species in sacoglossan sea slugs. Journal of Molluscan Studies 77: 401–412.
    Furfaro G, Modica MV, Oliverio M, et al. 2014. Phenotypic diversity of Thuridilla hopei (Vérany, 1853) (Gastropoda, Heterobranchia, Sacoglossa). A DNA-barcoding approach. Biodiversity Journal, 5 (2): 117–130.
    Malaquias MAE, Calado G, Da Cruz JF, et al. 2014. Opisthobranch molluscs of the Azores, results of the IV Internationa Workshop of Malacology and Marine Biology (4-13 July 2011) (Mosteiros, São Miguel, Azores). Açoreana, 2014, Supplement 10: 139-147.
    Malaquías MAE, Calado G, Filipe da Cruz J, et al. 2012. On the occurrence of the Caribbean sea slug Thuridilla mazda in the eastern Atlantic Ocean. Marine Biodiversity Records. 5(e50):1–4.
    Orfanidis S, Alvito A, Azzurro E, et al. 2021. New Alien Mediterranean Biodiversity Records (March 2021). Mediterranean Marine Science. 22(1):180–198.
    Ortea JA, Espinosa J. 2000. Nueva especie del género Thuridilla Bergh, 1872 (Mollusca: Sacoglossa) de Cuba y Costa Rica. New species of the genus Thuridilla Bergh, 1872 (Mollusca: Sacoglossa) from Cuba and Costa Rica. Avicennia 12/13:87-90; pl 1.
    Ortea J, Moro L, Bacallado JJ. 2015. Babosas Marinas Canarias. Turquesa Ediciones.
    Rudman W.B. et al. 1998 2010. Thuridilla mazda accessed through: Sea Slug Forum on 2014-12-14. Available from
    Sánchez-Tocino L, Chamorro M, Tierno de Figueroa JM. 2021. First record of the Caribbean Sea slug Thuridilla mazda Ortea & Espinosa, 2000 (Mollusca, Sacoglossa) in the Mediterranean Sea [in] Orfanidis et al. (2021) New Alien Mediterranean Biodiversity Records (March 2021). Mediterranean Marine Science. 22(1):185.
    WoRMS Editorial Board. 2023. World Register of Marine Species. WoRMS. Available from

    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:

Pontes, Miquel, Manuel Ballesteros, Enric Madrenas (2023) "Thuridilla mazda" in OPK-Opistobranquis. Published: 24/04/2021. Accessed: 14/04/2024. Available at (

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