Author: Ekimova, Deart,  Antokhina, Mikhlina & Schepetov, 2022

Order: Nudibranchia  Family: Flabellinidae

Maximum Size: 6 mm

Sightings: Sunshine Coast

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Coryphellina pannae Ekimova, Deart,  Antokhina, Mikhlina & Schepetov, 2022

Coryphellina O’Donoghue, 1929, was re-erected (from synonymy, first with Coryphella and latterly Flabellina) by Korshunova et al, 2017 thus making Coryphellina rubrolineata O’Donoghue, 1929 the Type Species. Phylogenetic and morphological investigations of a number of specimens collected in Vietnam waters (Ekimoiva et al, 2022) found several cryptic species previously all lumped into Coryphellina rubrolineata. Additionally the findings have confirmed that Coryphellina rubrolineata rather than being a widespread tropical species is actually confined to its type locality and adjacent waters – Red Sea and Arabian Sea but also introduced into the Mediterranean Sea.

Form:
A small (~6 mm) but typical aeolid form with slender body and foot. Anterior foot corners well-developed – tentacular. Oral tentacles 1.5 to 2 times rhinophore length and with tapered tips. Rhinophores are highly papillate on the posterior face and bear pointed tips. There are 5 ceratal groups on each side (in those so far examined) – first group largest, second and subsequent located posterior to the inter-hepatic space. Cerata on elevations (pedunculate), cylindrical, elongated and pointed. Tail short, quickly tapering following posterior-most ceratal group.

Colouration:
– Background (body and notum): Translucent white to very light translucent magenta.
– Oral tentacles: Translucent magenta gradually becoming more intense towards the tip, but the tip is white.
– Rhinophores: Light pink to very pale orange with magenta sub-apical band and white tips.
– Cerata: Translucent milky white, magenta to red subapical band varying in intensity with white or pastel orange tip. Digestive diverticulum visible, creamy colouration.
– Mid-dorsal line: Continuous prominent – pink to magenta in colour.
– Lateral lines: Continuous prominent – pink to magenta in colour.

It can be seen that there is variability in colour and also in the intensity of colours.

Care should be exercised in making comparisons as only two specimens were examined and illustrated for the description.

Formerly listed on this site as Flabellina sp. 08.

Note on Coryphellina:
As mentioned above, Coryphellina O’Donoghue, 1929, was re-erected by Korshunova et al, 2017. Since then its use has become frequent despite reservations from some taxonomists who cite that: some taxa were omitted, paraphyly was simply transferred and sampling was insufficient. Ekimova et al, 2022 conducted further molecular testing and subsequently identified and described four new closely related cryptic species and two putative species of Coryphellina. In order to stay in step with most common usage we are now using Coryphellina. There is no doubt that there is a clade involved. There is also no doubt there were issues of paraphyly in Flabellina previously and the splitting into additional genera such as Samla and Coryphellina may not entirely solve that issue, however, given the current usage (>4 years), it may be more confusing not to make the change at this point. Once larger sampling across more geolocations is undertaken a clearer picture may be resolved.

David A. Mullins – May 2022

References:
– Gosliner, T. M. & Willan, R. C. (1991). Review of the Flabellinidae (Nudibranchia: Aeolidacea) from the tropical Indo–Pacific, with descriptions of five new species. Veliger, 34, 97–133.

– Schulze, A. & Wägele, H. (1998). Morphology, anatomy and histology of Flabellina affinis (Gmelin, 1791) (Nudibranchia, Aeolidoidea, Flabellinidae) and its relation to other Mediterranean Flabellina species. Journal of Molluscan Studies 64: 195–214.

– Yonow, N. (2008). Sea Slugs of the Red Sea. Pensoft Publishers.

– Furfaro, G., Salvi, D., Mancini, E. & Mariottini, P. (2017 Online). A multilocus view on Mediterranean aeolid nudibranchs (Mollusca): Systematics and cryptic diversity of Flabellinidae and Piseinotecidae. Molecular Phylogenetics & Evolution, 118, 13–22.

– Korshunova, T., Martynov, A., Bakken, T., Evertsen, J., Fletcher, K., Mudianta, I. W., Saito, H., Lundin, K., Schroedl, M. & Picton, B. (2017). Polyphyly of the traditional family Flabellinidae affects a major group of Nudibranchia: Aeolidacean taxonomic reassessment with descriptions of several new families, genera, and species (Mollusca, Gastropoda). ZooKeys 2017, 717, 1.

– Gosliner, T. M., Valde ́s, A ́. & Behrens, D. W. (2018). Nudibranch & Sea Slug Identification – Indo-Pacific, 2nd Edition. New World Publications, Jacksonville, Florida, USA.

– Ekimova, I., Deart, Y.,  Antokhina, T., Mikhlina, A. & Schepetov, D. (2022). Stripes Matter: Integrative Systematics of Coryphellina rubrolineata Species Complex (Gastropoda: Nudibranchia) from Vietnam. Diversity,14,294.