Thordisa azmanii

Thordisa azmanii Cervera & García-Gómez, 1989

Thordisa azmanii @ Bajo O Champiñon, Ria de Arousa, Galicia, Spain 10-06-2011 in 22m by Jacinto Pérez Dieste

Taxonomy
 

Superdomain

Biota  

 

Kingdom

Animalia  

 

Phylum

Mollusca  

 

Class

Gastropoda  

 

Subclass

Heterobranchia  

 

Infraclass

Euthyneura  

 

Subterclass

Ringipleura  

 

Superorder

Nudipleura  

 

Order

Nudibranchia  

 

Suborder

Doridina  

 

Infraorder

Doridoidei  

 

Superfamily

Doridoidea  

 

Family

Discodorididae  

 

Genus

Thordisa  

 

Species

Thordisa azmanii  Cervera & García-Gómez, 1989

 
 Classification according to Bouchet et al. (2017)
Taxonomic source: World Register of Marine Species (AphiaID: 139590).
Nota taxonómica: Ortea & Martínez (1991) consider that this species is the same as Thordisa diuda Marcus, 1955 but this proposal has been rebutted by Cervera et al (2004) and by Alvim & Dias-Pimenta (2013).

Description
The oval shaped body can reach a maximum size of about 15mm. It is coloured from orange to dark brown, with a convex notum and a spiculous texture. The mantle, whose edges have small white dots, is covered with spiculated conical shaped tubercles of different sizes, the largest ones are stained in white at the tips, and the smaller ones appear aligned at the edges of the mantle and rhinophoric and gill sheaths, giving them an irregular appearance. The lower part of the mantle shows the radial arrangement of the spicules in the tissue, as well as branched spiculous groups. The foot, coloured light yellow, has two lobes and is spiculous, and occasionally extends behind the mantle when the animal is in movement. The rear edge of the foot has tiny white spots. The oral tentacles are short and have a cylindrical shape. The dark brown rhinophores have between 9 and 11 lamellae, the tips of the 3 or 4 more distal are stained white. The branchial plume has 5 to 7 bipinnate leaves, coloured dark brown in its basal part and white in the distal part, surrounding the anal papilla.

Biology
The specimens found in Galicia (Almón et al., 2011) lived on sponges of the Raspailia genus: specifically Raspailia hispida (Montagu, 1818), Raspailia (Raspailia) ramosa (Montagu, 1818) and Raspailia (Raspailia) cf. viminalis (Schmidt, 1862) and they are supposed to feed on them, but this point has not been proven. The spawn consists of a light yellow ribbon, fixed by one of its sides to the substrate -generally on the sponge-, wound in a spiral of between one and two turns, with eggs of about 100 microns in diameter, arranged transversely in rows of about 25 in two overlapping layers (Ortea et Martínez, 1990). Observed at a certain distance, the general appearance of this nudibranch is similar to that of the bryozoan Cellepora pumicosa, which could be understood as a form of camouflage in which the animal adopts the appearance of a species unattractive for predators. The spiculous notum facilitates the retention of marine debris in the same way Raspailia sponges do, so they can pass unadverted to predators.

Etymology

  • Thordisa. Woman name of Old Norse origin, cited in the Sagas. A fair woman to look on, high-minded, and rather hard of heart.
  • Azmanii, in honor of Dr. J. Azmani (M.D.), “who eliminated a chronic ailment of one of us” (Cervera et García-Gómez, 1989).

Distribution
This species has been cited on the Atlantic coasts of the Iberian Peninsula: in Cádiz (Cervera and García Gómez, 1989), in Portugal (García Gómez, 1991;), in the Ría de Arousa, Galicia (Almón et al., 2011) and in Cudillero, Asturias (Ortea et Martínez, 1990 as T.diuda). The specimens of Asturias and Cádiz were collected in the intertidal, while those of Galicia were collected by diving down to 20 meters, so that their bathymetric distribution is not clear. It has also been found on the shores of St.Agnes, Cornwall, Great Britain (Picton, 1978 [in] Medslugs). There is a report from Cape Verde (Ortea et Cabrera, 1999) as T.diuda that probably corresponds to T.azmanii, since the authors assimilate it to the findings from the North of Spain, although (Alvim et Pimenta, 2013) only indicate that it is not T.diuda. There is a single report for this species in the Mediterranean: Federico Betti found a 10mm specimen in Numana, Italy in 2010.

Known georeferenced records of the species: Thordisa azmanii
Sources:
: OBIS
: GROC 2010-2011
: Enric Madrenas
: João Pedro Silva
: Bernard Picton
: GBIF.ORG
: OPK
: VIMAR
: Manuel Ballesteros.
: M@re Nostrum
: Altres fonts
: Marine Regions

Abundance

    Western Mediterranean:
    Eastern Mediterranean:
    Atlantic Ocean:

More pictures

Bibliography

Further reading

Cite this article as:

Ballesteros, Manuel, Enric Madrenas, Miquel Pontes (2012-2018) "Thordisa azmanii" in OPK-Opistobranquis, Published: 04/02/2018, Accessed: 19/08/2018 at (https://opistobranquis.info/en/fX8n4)

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