Integrative taxonomy reveals presence a new species West African mane jelly (Cyanea altafissura)

NEWS - A new species of Cyanea is described from samples collected in the Gulf of Guinea during 2017-2019. The species is a member of the nozakii group that has discontinuous radial septa and is characterized by, among other things, deeper rhopalial than velar marginal clefts, uniform papillose exumbrella, up to 200 tentacles per cluster and a dense network of anastomosing canals in a broad quadrate fold.

West African mane jelly (Cyanea altafissura) can be genetically distinguished from relatives in the ITS1 and COI regions as confirmed by several phylogenies and other analyses. This is the first record of a member of the nozakii group in the Atlantic Ocean and the first description of a genus Cyanea from the west coast of Africa and the tropical Atlantic Ocean.

Cyanea Péron & Lesueur (1810) currently includes 17 species and is the second largest number of valid and recognized species in the Semaeostomeae of Agassiz (1862), after Aurelia Lamarck (1816). Both genera are rarely reported from the South and East Atlantic, although they are widespread in coastal waters of the Northern Hemisphere and in the Indo-Pacific.

Both genera have been the subject of taxonomic confusion with their respective type species, Cyanea capillata (Linnaeus, 1758) and Aurelia aurita (Linnaeus, 1758). It is practically impossible to draw distinctions between the various forms of Cyanea in the North Atlantic. Intergradational forms are common and many races are separated only geographically or by differences in coloration that are not entirely distinct and stable.

The only Cyanea species formally described from coastal waters of West Africa is Cyanea annasethe (Haeckel 1880) which was originally described as Desmonema annasethe Haeckel (1880) from specimens collected off the west coast of South Africa by Wilhelm Bleek in 1877.

Yusra Samsodien, Michael Brown and Mark Gibbons from the University of the Western Cape in Bellville collected specimens of the new species in this study at depths of 20-118 metres. The name altafissura refers to the relatively deep depth of the rhopalial fissure.

Analysis of the COI data revealed three monophyletic lineages supporting the separation of all known Cyanea species and C. altafissura. This divergence is consistent with the species divergence of many other Scyphozoa. The analysis places the West African species as the sister group to C. nozakii.

In contrast, analysis of the ITS1 data revealed two monophyletic lineages placing C. altafissura in its own lineage with C. capillata, C. rosea, C. tzetlinii and C. nozakii forming a monophyletic clade. In particular, the mitochondrial DNA sequence data showed less variation between the West African species and C. nozakii with both forming a monophyletic clade.

However, the nuclear DNA sequence data showed greater variation between C. altafissura and C. nozakii with C. altafissura as its own monophyletic group, sister to all other Cyanea species. This is partly because the pairwise genetic distance between West African Cyanea and other Cyanea species is higher for nuDNA (ITS1) than for mtDNA (COI).

Original research

Yusra Samsodien, Michael K. Brown and Mark J. Gibbons (2024). Integrative taxonomy reveals the presence of a new species of Cyanea (Scyphozoa: Discomedusae: Semaeostomeae: Cyaneidae) from the West coast of Africa. Zootaxa 5507 (3): 401-426, DOI:10.11646/zootaxa.5507.3.1

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