Tayuva confusa

Tayuva confusa (Ballesteros, Llera & Ortea, 1985)

Tayuva confusa @ Gran Canaria by Mario Matute

Taxonomic note: Ortea, Pérez and Bacallado (1981) indicated that Discоdoris confusa was identified with the Indo-Pacific species D. fragilis (Alder & Hancock, 1864) because they have a very similar external morphology (colour, rhinophores, gills, mantle ornamentation, etc.) and also because they have similar anatomical details such as the labial armour, the radula and the structure of the genital apparatus. Dr. Edmunds sent to these authors some specimens of D. fragilis collected in Tanzania that allowed Ballesteros et al. (1985) to verify that there are some internal anatomical differences between the mentioned species. Later, the thorough revision of the Discodorididae by Dayrat (2010), based on morphological and internal anatomy characters, brought to light the existence of synonymous species from different seas around the world and reduced the number of valid species within the Discodorididae family. Such was the case of Discodoris maculosa, a well-known Mediterranean species that was included in the species Tayuva lilacina, a species with a very wide circumtropical distribution and in temperate seas such as the Mediterranean. However, new molecular phylogenetic studies revealed that Tayuva lilacina was a rather complex of different species masked with a very similar morphology. This point has been demonstrated by the recent work of Fernández-Vilert et al (2025) in which, after genetically analysing various specimens of Tayuva from different parts of the world, they discovered four different cryptic groups, proposing the transfer of the Mediterranean specimens, which correspond to Discodoris maculosa Bergh, 1884 to the new combination Tayuva maculosa, and the specimens from the north-eastern Atlantic, which correspond to Discodoris confusa Ballesteros, Llera and Ortea, 1985 are resurrected as the new combination Tayuva confusa. Fernández-Vilert et al (2025) also comment that the genus Peltodoris forms a clade very close to Tayuva, documenting several cases of previous synonymies of species initially classified as Peltodoris, for which reason they propose obtaining more genomic information to study these groups and their possible synonymy.

Synonyms

• Discodoris confusa Ballesteros, Llera & Ortea, 1985

Description
This species can reach up to 80 mm in length when fully extended. Its body is approximately twice as long as it is wide. It has a general light grey or greyish cream colour, with white, brown, grey or almost black spots of varying shapes and sizes, distributed irregularly across the back. In most specimens, three rows of darker spots stand out, located on both sides of the visceral mass and along the mid-dorsal line. In the ventral area, both the mantle and the foot have a pattern of spots similar to that of the back, although with a variable density depending on the individual. Some specimens are highly pigmented, with large dark spots on the flanks, while others have few spots. The head and lips on the anterior edge of the foot usually show a fine dark stippling. The mantle has small, elongated, conical or globose tubercles of unequal size and irregular distribution. Some of these tubercles, especially those located at the edge of the mantle or along the long axis of the body, have a white-pigmented apex. In living specimens measuring less than 40 mm, the tubercles are often accompanied by a bundle of spicules at the base, especially those closer to the edge of the mantle. Larger tubercles (“giant tubercles”) are often found, which are usually pigmented in brown and white tones. The edge of the mantle is slightly wavy. The rhinophoric sheath is raised and covered with numerous tubercles, some with a white apex. The rhinophores have a base with fine dark stippling, while their lamellae have dark and white spots. In larger specimens, the posterior part of the rachis is usually white. Seen from the side, the olfactory region of the rhinophore is triangular in shape, and the lower lamellae end at the same height as the peduncle. The gill is composed of six tripinnate or quadripinnate leaves, with a semitransparent, greyish rachis, sprinkled with brown and white spots. The pinnules have a similar colouring, which gives the whole a brownish appearance. In extension, the gill leaves lean slightly backwards and are grouped in two sets of three leaves, located on each side of the major axis of the body. The gill opening is slightly raised and is covered with tubercles similar to those of the rhinophoric sheaths, although smaller in size. When moving, the foot does not protrude from the back of the mantle.

Biology
It is found from the tidal zone to about 8 m depth, where it is believed to feed on sponges. Its spawn is a white ribbon coiled in a spiral of 2 to 3 turns and the eggs are aligned vertically and have a diameter of 190 microns (between 175 and 210 µm). When disturbed, it easily autotomizes the edge of the mantle, either partially or completely, while secreting large amounts of mucus.

Similar species

• Tayuva maculosa Bergh, 1884, is the species closest to T. confusa and with which it can be confused. However, T. maculosa has more uniform and tight mantle tubercles, does not present autotomy in the mantle, its copulatory sac is white and its labial armor elements are different.
• Taringa oleica and Peltodoris punctifera, species that also live in the Canary Islands, since they have the same coloration, six gill leaves, similar rhinophores and a head with oral tentacles, but they are very easily separated by their internal anatomy, since their radulae are very different.

Etymology

• Confusa. From the Latin “confundio”, to confuse, due to the confusion that has traditionally existed with the species Discodoris fragilis

Distribution
It is a fairly common species on the coast of the Canary Islands, it has also been found on the northern coast of the peninsula and in Madeira, usually cited as T. maculosa, although after the work of Fernández-Vilert et al (2025), in which they genetically analyzed the species of this cryptic group, all specimens of T. maculosa cited in the northeast Atlantic are considered T. confusa.

Other pictures

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

• Biodiversidad Virtual
• RedPROMAR
• World Register or Marine Species

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