Polycerella emertoni A.E. Verrill, 1880

Salvador, Xavier, Fernández-Vilert, Robert & Moles, Juan, 2022, Sea slug night fever: 39 new records of elusive heterobranchs in the western Mediterranean (Mollusca: Gastropoda), Journal of Natural History 56 (5 - 8), pp. 265-310 : 276-277

Polycerella emertoni A.E. Verrill, 1880

( Figure 3 (c))

Material examined

Cala Maset caves, Sant Feliu de Guíxols ( Spain), 41°47 ʹ 10”N, 3°2 ʹ 44”E, 23 August 2017, 1 m depth, 11 spcs, juveniles, adults and egg masses, L = 2–5 mm; Alfacs mussel farms, Sant Carles de la Ràpita, Montsià ( Spain), 40°37 ʹ 20.1”N, 0°39 ʹ 48.5”E, 12 September 2018, 0.7 m depth,>20 spcs, adults and egg masses, L = 4–5 mm; le Ponton, Étang de Thau, Sète ( France), 43°25 ʹ 28.5”N, 3°42 ʹ E, 1 November 2018, 1.2 m depth, 7 spc., adults and egg masses, L = 5–7 mm.

External morphology

Body short, narrow, background colour white with irregular black and white-yellow punctuation. Gills composed of three leaves, with short, smooth papillae found on dorsum and body laterals. Rhinophores smooth.

Ecology

All specimens at each locality were found on the bryozoan Amathia verticillata (Delle Chiaje, 1822) where they laid egg masses.

Distribution

Species originally from the east coast of North America (GBIF.org 2021); Pacific coast of North America ( Terrence 1988); now found in Morocco, Portugal and the south of Spain ( Cervera et al. 2004); Italy ( Servello et al. 2019); Greece ( Crocetta et al. 2017); France (this study) and Catalonia ( Camps and Prado 2018; this study).

Remarks

Originally described from the North American Atlantic coast ( Verrill 1881), this species has been reported from the American Atlantic and Pacific coasts, and the Mediterranean Spanish, Italian, Greek and African coasts . Its bryozoan prey is commonly found attached to boat hulls. In the case of the specimens found in Catalonia, it was found in ports, bays and eutrophic locations.

Genus Thecacera J. Fleming, 1828

Figures

Figure 3. Photographs of live Nudibranchia species: (a) Palio nothus and its egg mass. (b) The alien Polycera hedgpethi. (c) Polycerella emertoni and egg mass on Amathia verticillata. (d) Thecacera pennigera on top of the bryozoan Bugula sp. (e) Two specimens of Anteaeolidiella lurana and their egg masses. (f) Doto cervicenigra. (g) Doto fragilis (photo credit: Oriol Planas). (h) Doto pygmaea.