Doto millbayana

Doto millbayana (Lemche, 1976)

Doto millbayana @ “Depuradora” (L’Escala, Girona), 21/04/2012 by Enric Madrenas

Taxonomic note: Doto dunnei Lemche, 1976 has long been regarded as a distinct species within the Doto coronata complex, but recent molecular studies (Shipman & Gosliner, 2015; Martinsson et al., 2021) have revealed no significant genetic divergence from Doto millbayana Lemche, 1976, with minor morphological differences in radula, pseudobranchs, pigmentation, and feeding preferences now attributed to intraspecific variation. The most recent systematic revision (Vázquez-Alcaide et al., 2025) confirms that both represent the same species, proposing D. dunnei as a junior subjective synonym of D. millbayana (syn. nov.), since the latter was described first in the same paper by Lemche (1976) and holds nomenclatural priority under the International Code of Zoological Nomenclature. This change is also adopted in taxonomic databases such as WoRMS.

Synonyms

• Doto dunnei Lemche, 1976

Description
Small nudibranch of the coronata group, elongated narrow translucent white or cream body. Adults with 4–6 (up to 7–8 in some populations) pairs of dorsolateral cerata. Ceratal tubercles bear terminal round reddish-brown or purple-black, with extra irregular spots between them; in some morphs, dense patches/streaks of reddish-brown or purple-black pigment on back and sides. Body with variable mottling of reddish-brown or purple-black pigment. Rhinophore sheaths show conspicuous white rims, dilated and forward-extended (Lemche, 1976; Picton & Morrow, 2023; Vázquez-Alcaide et al., 2026).

Biology
Generalist predator of thecate and athecate hydrozoans; sucks coenosarc fluid by cutting perisarc on stalks without harming polyps. Prey includes Plumularia setacea, Kirchenpaueria pinnata, K. halecioides, Nemertesia ramosa, Tridentata perpusilla, Obelia sp., and Aglaophenia sp. Lays white egg masses in meandering cord or circular shape (up to 6 folds), on rocks or the same hydrozoans it feeds on. Adults present from October to May (Atlantic) or January to June (Mediterranean). Active during the day, always associated with rocky substrates or Posidonia oceanica meadows with hydrozoans (Lemche, 1976; Thompson & Brown, 1984; Picton & Morrow, 2023; Vázquez-Alcaide et al., 2026; Martinsson et al., 2021).

Etymology

• Doto. Name of a Nereid, a Sea Nymph in Greek Mythology.
• Millbayana. After Mill Bay, Isle of Cumbrae, Scotland.

Distribution
Species of the northeastern Atlantic, distributed from the western coasts of the British Isles (including Shetland, Ireland, Scotland, Wales and England) southwards to Galicia (Spain), Portugal and the Strait of Gibraltar. Following synonymy with D. dunnei, it also extends into the northwestern Mediterranean (Catalonia, Balearic Islands and Iberian Mediterranean coasts). Not  a very common species; records occur mainly on subtidal rocky substrates (5–40 m) and in Posidonia oceanica meadows (Lemche, 1976; Picton & Morrow, 2023; Vázquez-Alcaide et al., 2026; Martinsson et al., 2021; Wikipedia & NBN Atlas).

More 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

• AsturNatura
• Biodiversity Heritage Library
• Encyclopedia of Marine Life of Britain and Ireland
• Estran 22 - Faune et flore de la zone de balancement des marées en Côtes d'Armor
• Flickr pictures
• Interim Register of Marine and Nonmarine Genera
• NCBI GenBank
• OBIS - Search by Taxon
• World Register of Marine Species

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