Thecacera pennigera

Thecacera pennigera (Montagu, 1815)

• Doris pennigera Montagu, 1815 (original)
• Thecacera lamellata Barnard, 1933
• Thecacera maculata Eliot, 1905

Description
This species can reach up to 30 mm in length. The body color is translucent white and it is completely covered with small irregular patches of orange and yellow, sprayed with black dots of varying density. The black dots are smaller but appear in greater numbers. Atlantic individuals differ from Pacific ones in color, density and size of the spots. Individuals occasionally appear with orange spots larger than normal. The anterior side of the body is wider than the rear side, converging into a thin and long foot with a keel on each side. The head is short, blunt and wide, without digitations or oral tentacles on its anterior edge. The rhinophores are lamellate and have the same colour pattern as the rest of the body; they are surrounded by a flared sheath that does not cover them completely. The gill consists of 3-5 bipinnate or tripinnate leaves, not retractile, and laid in a horseshoe shape around the anal papilla. Gill is located in the middle of the dorsum, right ahead of two elongated protuberances, coloured similar to the rest of the body, that Picton & Morrow (1994) considered glandular and of defensive mission. The foot has two propodial tentacles of sensory character, used for locating and orienting at short distances.

Biology
This nudibranch is very cryptic on the substrate, and has nocturnal habits. It can live from the intertidal down to 36 m (Swennen 1961; Willan & Coleman, 1984). It is a highly specialized carnivorous species that feeds exclusively on certain species of colonial bryozoans such as Crisularia (=Bugula) plumularia, C. turrita, Bugula neritina, Bugulina (=Bugula) flabellata, B. turrita and B. stolinifera (McDonald & Nybakken, 2009). It appears closely associated with these populations of bryozoans. Their narrow, white, ribbon-like spawn are laid on the bryozoans, and they are often the best indicator of its presence (Willan & Coleman 1984, Dekker 1986). Usually they are found in low densities among the bryozoans, until favorable environmental conditions trigger massive recruitment episodes with lots of new individuals.

Etymology

• Thecacera. From Greek “theke” (θήκη), a receptacle, a scabbard or sheath + “kērós” (κηρός), horn, for the shielded rhinophores.
• Pennigera. From Latin “penna”, feather +‎ “gerere”, bearing. Overall meaning is “feathered” or “winged”.

Distribution
The distribution of this species, that prefers temperate climate but has a wide thermal tolerance, is cosmopolitan (Thompson, 1976). It can be found from the south and west of the British Isles, Ireland’s west coast, the west coast of Europe, the Mediterranean Sea, the macaronesic region (Wirtz, 1999), West Africa, South Africa, Brazil coasts, the eastern United States (from Massachusetts to Florida, possibly discontinuous), Pakistan, Japan, Korea, eastern and southern Australia and New Zealand (Willan 1976; Gosliner 1987; Picton and Morrow 1994; Valles et al, 2000). Willan (1976) suggested that the species has spread beyond its original range of distribution due to transport marine. One reason to assert this claim could be the fact that it feeds on colonial bryozoans, and these species are often part of the “fouling”, the epibiont fauna that can grow on the hull of ships. Several specimens of various world populations have been studied, and there have been found no significant morphological differences between samples from the different countries but the size and number of spots on the mantle (Jung et al., 2013). In the Iberian Peninsula it has been observed in the Cantabrian coast, in Portugal and in the Andalusian Atlantic coast. First observations in the Catalan coast are from Sant Feliu de Guixols.

Known georeferenced records of the species: Thecacera pennigera

Sources:
OBIS GROC 2010-2011 Enric Madrenas João Pedro Silva Bernard Picton GBIF	OPK VIMAR Manuel Ballesteros M@re Nostrum Altres fonts Marine Regions

More pictures

Thecacera pennigera

Thecacera pennigera Feeding on Bugula plumosa, Sark, Channel Isles, June 2010. – Photograph ©Bernard Picton

Thecacera pennigera Observed at Mar Piccolo, Taranto, Puglia, Italia (23/04/2014 – 05/08/2014) by Cataldo Licchelli

Thecacera pennigera @ Islas Canarias by Aketza Herrero

Thecacera pennigera @ Islas Canarias by Aketza Herrero

Thecacera pennigera @ Islas Canarias by Aketza Herrero

Thecacera pennigera @ Netherlands 1-09-2017 by Stefan Verheyen

Thecacera pennigera @ Netherlands 1-09-2017 by Stefan Verheyen

Thecacera pennigera @ Netherlands 1-09-2017 by Stefan Verheyen

Thecacera pennigera @ Netherlands 6-03-2017 by Stefan Verheyen

Thecacera pennigera @ Netherlands 6-03-2017 by Stefan Verheyen

Thecacera pennigera @ Netherlands 6-03-2017 by Stefan Verheyen

Thecacera pennigera @ Netherlands 7-10-2017 by Stefan Verheyen

Thecacera pennigera feeding on Bugula plumosa @ Netherlands 22-08-2017 by Stefan Verheyen

Thecacera pennigera @ Netherlands by Stefan Verheyen

Thecacera pennigera by Fabio Vitale

Thecacera pennigera by Cataldo Licchelli

Bibliography

1246567 Thecacera pennigera 1 eunomia-revista-en-cultura-de-la-legalidad 50 creator asc 1 10724 https://opistobranquis.info/wp-content/plugins/zotpress/
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

Cite this article as: