Edmundsella pedata

Edmundsella pedata (Montagu, 1816)

Taxonomic note: The classification of the Flabellinidae had remained fairly stable until in 2017 a series of works appeared (Furfaro et al., 2017; Korshunova et al., 2017) that intended to clarify the status of the Flabellinidae family. The main objective of the paper by Furfaro et al. was to molecularly characterize the Mediterranean species while the paper by Korshunova et al. wanted to delve into the phylogenetic relationships between various members of the Flabellinidae family and the other families of aeolidaceans.
Both works were based on the combination of molecular and morphological techniques and, in fact, do not offer very different results, but differ on the size and origin of the studied samples and, mainly, on the interpretation of the results. After the appearance of the paper by Furfaro et al., many Mediterranean species of the genera Calmella, Flabellina and Piseinotecus were grouped under the common genusFlabellina, but had certain problems with some species that did not fit well with the proposed classification (e.g,Flabellina babai) , discovered that the Mediterranean and Atlantic populations ofFlabellina ischitana correspond to two different cryptic species, and noted the problems of the cryptic group formed by Calmella cavolini / Flabellina confusa / Piseinotecus gaditanus, indicating the need for further studies to clarify their status.
Curiously, these studies were being carried out practically in parallel by the group of Korshunova et al. but on a much wider sample of species that included specimens from the Arctic, North Atlantic, Pacific and Indian Oceans. This second paper confirms the polyphily of the family Flabellinidae, but the interpretation of these results becomes a real revolution for the taxonomy of the aeolidaceans, especially for the family Flabellinidae.
Both papers show that there are two well differentiated clades (groups) in the Flabellinidae: species like Coryphella pedata and similars, with cerata that come directly from the back, and species like Flabellina affinis and similars, with cerata of each group coming from a stalk or pod. Although Furfaro et al. consider the species of both clades belonging to the genusFlabellina within the family Flabellinidae, Korshunova et al. distinguishes two families: Coryphellidae and Flabellinidae sensu stricto, also creating many different genera in these families to include the species they study. Its taxonomic proposal, curiously, solves the problems found by Furfaro et al.
In a way, both papers complement to each other, although in the paper by Korshunova et al. it is evident the lack of studies on tropical flabellinid species and those from southern America and Africa, so the subject has not been settled. The proposal to create new genera to collect small groups of species, instead of multispecific genera, seems to be the trend in some of the phylogenetic works of recent years. A detailed discussion of this exciting controversy can be found at (https://opistobranquis.info/en/flabellinidae/).

• Coryphella pedata (Montagu, 1816)
• Doris pedata Montagu, 1816
• Eolis landsburgi Alder & Hancock, 1846
• Coryphella landsburgii (Alder & Hancock, 1846)
• Flabellina pedata (Montagu, 1816)

Description
This aeolidacean typically measures 10-15 mm in length although there have been reports of 40 mm specimens. The body is quite transparent and has a pink-purplish overall color, also in the head, the rhinophores, oral and propodials palps. The rhinophores are simple, without lamellae and have an iridescent white tip. Eyes are located on the base of the rhinophores. Oral palps are of the same length than the rhinophores and also have an iridescent white tip. The cerata are grouped in 6-7 groups on each side of the dorsum and grow directly from the body of the animal forming groups of 2 or 3 cerata each. The digestive gland in the cerata is coloured light brown, dark brown, orange or red depending on the specimens. The genital opening is located below the first group of cerata on the right or the body. The foot is transparent.

Biology
This aeolidacean lives on hydrarians in dark shallow vertical walls. It has been cited on several genus of hydroids and that it presumably eats like the sertularid Abietinaria, the plumularid Aglaophenia or the athecate Eudendrium, over which it usually lays the spawn.

Etymology

• Edmunsella, in honor to Malcolm Edmunds, distinguished English taxonomist specialized in opistobranchs, sadly deceased on January 2017.
• Pedata, refers to the cerata, that are joined at their base, hand-like.

Distribution
This is one of the most common nudibranchs in European waters. This species of aeolidacean is distributed along the European Atlantic continental coasts from Norway to the Iberian Peninsula, including the British Isles, the Azores and the Canary Islands. Also widespread in the Mediterranean, where it can be found both in the Eastern and Western basins. In the Iberian Peninsula it has been reported in all the shores, including the Catalan coast.

Known georeferenced records of the species: Edmundsella pedata

Sources:
OBIS GROC 2010-2011 Enric Madrenas João Pedro Silva Bernard Picton GBIF	OPK VIMAR Manuel Ballesteros M@re Nostrum Altres fonts Marine Regions

Similar species
Flabellina affinis and Paraflabellina ischitana have ringed rhinophores and cerata grow from dorsal stalks or pods. Piseinotecus soussi, nearly identical, but with white spots on cerata.

Videos

More pictures

Edmundsella pedata by Enric Madrenas

Edmundsella pedata by Enric Madrenas

Edmundsella pedata by Enric Madrenas

Edmundsella pedata by Enric Madrenas

Edmundsella pedata by Enric Madrenas

Edmundsella pedata by Enric Madrenas

Edmundsella pedata by Enric Madrenas

Flabellina pedata @ Taliarte, Gran Canaria in 3 m 2-09-2016 by Jose Juan Calderín Peñate

Edmundsella pedata @ La Herradura, Granada, Spain 3-04-2017 by Stefan Verheyen

Edmundsella pedata by Miquel Pontes

Edmundsella pedata by Miquel Pontes

Edmundsella pedata by Miquel Pontes

Edmundsella pedata by Nani Díez

Edmundsella pedata @ L’Escala, Spain by Eli Franco Valero

Edmundsella pedata @ France by Pascal Girard

Edmundsella pedata @ Costa Brava, Spain by Miquel Pontes

Bibliography

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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

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