Placida tardyi ( Trinchese, 1874 )

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 : 299-300

Placida tardyi ( Trinchese, 1874)

( Figure 6 (e))

Material examined

Fòrum pools, Barcelona ( Spain), 41°24 ʹ 34.5”N, 2°13 ʹ 36.8”E, 23 November 2017, 0.4 m depth, 12 spcs, juveniles, adults and egg masses, L = 3–20 mm; le Ponton, Étang de Thau , Sète ( France), 43°25 ʹ 28.5”N, 3°42 ʹ E, 21 May 2018, 0.5 m depth, 3 spcs, adults, L = 17–25 mm; Cala Maset caves, Sant Feliu de Guíxols ( Spain), 41°47 ʹ 10”N, 3°2 ʹ 44”E, 19 December 2018, 2 m depth, 2 spcs, adults and egg masses, L = 10–15 mm; 1 January 2019, 1.3 m depth, 3 spcs, adults, L = 13–15 mm; Cala Sa Tuna, Begur ( Spain), 41°57 ʹ 38”N, 3°13 ʹ 52”E, 31 January 2019, 0.5 m depth, 1 spc., juvenile, L = 3 mm; Tamariu Beach ( Spain), 41°55 ʹ 0.5”N, 3°12 ʹ 27.1”E, 10 September 2019, 1 m depth, 4 spcs, adults with egg masses, L = 10–20 mm; Punta de la Mona, Andalucía ( Spain), 36°43 ʹ 12.9”N, 3°43 ʹ 43.1”W, 19 September 2020, 2 m depth, 2 spcs, adults, L = 15–20 mm .

External morphology

Body elongate, narrow, background colour white and semi-transparent with a central white circle on dorsum. Lateral body parts and foot with dark brown or purple colour. Cerata long, smooth; background colour green, with white spots, tip dark garnet in colour. Rhinophores smooth, large, with white dots concentrated at apexes. Oral tentacles wide and short.

Ecology

Specimens found in masses of the green alga Bryopsis duplex , mating, and laying whitish and cylindrical egg masses at the base of the alga. This species can go completely unnoticed within the algal masses; moves actively at night.

Distribution

Originally described from Italy: Genoa ( Trinchese 1874), Gulf of Naples ( Gascoigne and Sordi 1980); also, Portugal ( Calado et al. 2003); Gibraltar ( Cervera et al. 1988); Spain: Andalusian coast (this study), Catalonia (this study); France (this study).

Remarks

This species can be misidentified as P. vidiris ( Trinchese, 1874) , but it is distinguishable by its brown or purple body margins and the tip of the cerata darkly coloured in garnet ( Pruvot-Fol 1954).

Figures

Figure 6. Photographs of live Sacoglossa species: (a) Hermaea bifida and close-up on its egg mass at the base of an alga. (b) Hermaea cantabra. (c) Hermaea paucicirra. (d) Limapontia capitata on Ulva lactuca. (e) Placida tardyi. (f) Placida viridis. (g) Elysia flava. Siphonariidae: (h) Williamia gussoni.