Berthella aurantiaca

Berthella aurantiaca (Risso, 1818)

Berthella aurantiaca by Enric Madrenas

Taxonomy
Class: Gastropoda Cuvier, 1797
Subclass: Heterobranchia J.E. Gray, 1840
Clade: Euthyneura Spengel, 1881
Clade: Nudipleura Wägele & Willan, 2000
Subclade: Pleurobranchomorpha Schmekel, 1985 (formerly NOTASPIDEA)
Superfamily: Pleurobranchoidea J.E. Gray, 1827
Family: Pleurobranchidae J.E. Gray, 1827
Genus: Berthella de Blainville, 1824
Species: Berthella aurantiaca (Risso, 1818) [Pleurobranchus]

Taxonomic note: This species has been traditionally confused with Berthellina edwardsii because its external morphology is very similar, so much so that it is virtually impossible to distinguish them “de visu”. To differentiate these species is mandatory an study of the mandibular structure and the radular teeth. The radula of B. edwardsii has numerous denticulate teeth (more than 150) in each semi-row and an elongated jaws and with smooth mandibular parts while the teeth of the radula of B. aurantiaca are much less numerous (from 50 to 80 per semi-row) ) the mandibles are shorter and with the mandibular parts with denticles on the sides. Adult specimens can also be differentiated by the size of the inner shell, which in B.edwardsii never exceeds 5.5mm (in specimens up to 60mm) since it stops growing when the animals reach circa 15mm in length (Jakov Prkić, com.pers.), whereas in Berthella aurantiaca the shell is proportionally larger (Vayssière reported a 15mm shell in a 30mm specimen), as it protects the entire visceral mass.

Synonyms

  • Pleurobranchus aurantiacus Risso, 1818 (original)
  • Pleurobranchus elongatus Cantraine, 1835

Description
The specimens of this species usually measure around 20mm with a maximum reported length of 30mm. The body color is orange or red. The body is convex and the dorsal mantle is relatively small and does not completely cover the foot. In the living animal the dorsal integument is hyaline and inside there are stellate spicules, with 3-5 extensions, which have a tissue support mission. The oral veil is highly developed when the animal is moving and has a trapezoidal shape. The rhinophores are tubular and open at the distal end, in the interior zone there are transverse folds corresponding to the rhinophore olfactive areas. The gill is located under the right edge of the mantle, it is bipinnate and has between 15 and 18 lamellae on both sides of the rachis. Gill color is slightly lighter than the rest of the body. The inner shell is ear-shaped and it is fairly developed, taking approximately half of the total length of the animal; the dorsal surface of the shell has more or less marked growth grooves. The foot is very wide, protruding from all the edges of the notum: front, sides and back. Lacaze-Duthiers (1859) describes the anatomy and physiology of this species.

Biology
Berthella aurantiaca has been cited living under rocks at shallow depth (Vayssière, 1898), in Posidonia oceanica meadows (Cattaneo-Vietti, 1986) or on sandy or muddy bottoms where commercial fishing trawlers work (Ros, 1975). Until recently, it has been repeatedly cited and confused as Berthellina edwardsii because of the similar coloration and morphology of both species. A summary of the discussion on identifying aurantiaca / edwardsii can be found in Sea Slug Forum. Only by studying the internal anatomy and analyzing the mandibular teeth and radular structure, among other details, it can be told one species or another. VIMAR group has studied the anatomy of the specimens of  aurantiaca / edwardsii morphology that can be observed in the northern Costa Brava (N.E. of Spain), under stones, from low tide zone down to 15-20 m deep and, so far, all specimens belong to B. edwardsii .

Etymology

  • Berthella. Probably dedicated to Sabin Berthelot (1794-1880), a French naturalyst who enrolled the Navy and participated in the Napoleonic wars. He lived part of his life at the Canary islands, in his post as French consul in Tenerife. He wrote the “Historia Natural de Canarias” and directed the Botanical Garden of Puerto de la Cruz.
  • Aurantiaca. From Latin “aurantiacus” which means “gold coloured”.

Distribution
Due to the morphological and coloring similarity between Berthella aurantiaca and B. edwardsii , reports of both species should be confirmed by anatomical studies. Many European reports of B. aurantiaca are, in fact, B. edwardsii (Cervera et al. 2004). These authors indicate, however, that B. aurantiaca is found along most of the Iberian coast (Bay of Biscay, Strait of Gibraltar area and the entire Mediterranean coast), the Balearic Islands and the Azores. B. aurantiaca does not occur in the Adriatic, while B. edwardsii is very common (Jakov Prkić, pers.com.). VIMAR group has studied the anatomy and morphology of specimens aurantiaca / edwardsii found in the Costa Brava (N.E. Spain), under stones, from the lower tide area down to 15-20 m deep and, so far, they are all B. edwardsii . However, in the Catalan coast, B. aurantiaca has been properly cited at Es Caials (Cadaqués), the coastline of the Medes Islands and Blanes.

Known georeferenced records of the species: Berthella aurantiaca
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:
This chart displays the observation probability for Berthella aurantiaca based on our own records.

More pictures

Bibliography

Further reading

Cite this article as:

Ballesteros, Manuel, Enric Madrenas, Miquel Pontes et al. (2012-2017) "Berthella aurantiaca" in OPK-Opistobranquis, Published: 15/05/2012, Accessed: 18/12/2017 at (https://opistobranquis.info/en/KqRSQ)

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