Thecacera pennigera (Montagu, 1813)

(Figure 3 (d))

Material examined

Cala Maset caves, Sant Feliu de Guíxols (Spain), 41°47 ʹ 10”N, 3°2 ʹ 44”E, 14 February 2018, 1.5 m depth, 1 spc ., adult, L = 20 mm.

External morphology

Body short, thick, background colour white with numerous black and yellow dots. Rhinophores lamellar, protected by two papillae, the posterior one longer than those anterior. Gill leaves discoid in shape, protected by long posterior papillae.

Ecology

The singleton specimen was found on an unidentified bryozoan species of the genus Bugula . The species is nocturnal; during the day slugs are found ‘resting’ at the base of bryozoans.

Distribution

Originally described from the North Sea (England; Montagu 1813); New South Wales, Australia (Burn 1978); south-west coast of India (Mohamed Hatha 2017); north-east American coast, Portugal and Italy (Gerovasileiou et al. 2017; Bariche et al. 2020); Spain: the Canary Islands, Cantabric Sea (Cervera et al. 2004), Catalonia (this study).

Remarks

This species has a broad distribution and is usually found in temperate waters (Dekker 1986). In the western Atlantic, T. pennigera has peaks of abundance during which, over the course of a few days, large numbers of specimens appear (Willan and Coleman 1984).

Suborder CLADOBRANCHIA

Family AEOLIDIIDAE Gray, 1827

Genus Anteaeolidiella M.C. Miller, 2001