Tenellia adspersa (Nordmann, 1845)

(Figure 4 (g))

Material examined

Port de Blanes (Spain), 41°40 ʹ 25.5”N, 2°47 ʹ 48.6”E, 21 January 2019, 0.1 m depth, 1 spc ., adults, L = 7 mm.

External morphology

Body elongate, narrow, background colour black. Rhinophores smooth; oral veil very well developed and without oral tentacles. Cerata lateral, elongated; tip swollen.

Ecology

A single specimen was found in a mass of hydrozoans in a floating dock with other sea slugs.

Distribution

North-east Atlantic (OBIS 2021); Pacific North American coast (iNaturalist.org 2021; OBIS 2021); Portugal (Encarnação et al. 2020); Spain: Canary Islands, Atlantic Andalusian coast, Galicia, Levantine coast (Cervera et al. 2004), Catalonia (this study).

Remarks

This species has a widespread and cosmopolitan distribution (Roginskaya 1970), being found in oceanic and brackish waters (Thompson and Brown 1984). Tenellia adspersa can be differentiated from conspecifics by having an oral veil connecting the oral tentacles and the cerata are clustered (Evertsen et al. 2004). Typically, the colour of the body and cerata varies from black to creamy with their diet (authors pers. obs.). Encarnação et al. (2020) found this species associated with the invasive hydrozoan Cordylophora caspia (Pallas, 1771) on artificial structures.

Genus Trinchesia Er. Ihering, 1879