Rostanga rosi (Ortea, 1979)
Discodoris rosi @ Costa Brava 2-05-2015 by Enric MadrenasTaxonomy
Class: Gastropoda Cuvier, 1797
Subclass: Heterobranchia J.E. Gray, 1840
Clade: Euthyneura Spengel, 1881
Clade: Nudipleura Wägele & Willan, 2000
Order: Nudibranchia Cuvier, 1817
Suborder: Euctenidiacea Tardy, 1970
Infraorder: Doridacea Thiele, 1931
Superfamily: Doridoidea Rafinesque, 1815
Family: Discodorididae Bergh, 1891
Genus: Discodoris Bergh, 1877
Species: Discodoris rosi (Ortea, 1979)
Taxonomic note (from Ortea, Moro, Bacallado & Caballer, 2014): Foale & Willan (1987) and Valdes & Gosliner (2001) suggest that all dorids with caryophyllic tubercles are a monophyletic group, something already intuited by Labbé (1933) to address the usefulness of such tubercles for classification. Discodoris Bergh, 1877 (type species Discodoris boholensis) is a genus without caryophyllic and labial armor, so Discodoris rosi, with caryophyllic and a smooth labial cuticle is not a Discodoris and needs to be included in a genus within the line of the dorids with caryophyllic, a genus that does not exist for all the characters of this species, so some authors choose to keep it within Discodoris pending further studies (Sánchez-Tocino., 2003; Cervera et al, 2004) while others (Dayrat & Gosliner, 2005) include it either in Discodoris or Rostanga Bergh, 1879 despite the differences between the caryophyllic and radula of both genus, or labial cuticle, smooth on D. rosi and armed with sticks in Rostanga and Discodoris.
Moreover, we must bear in mind that in some species belonging to genus without caryophyllic such as Thordisa diuda, these structures are present in juvenile specimens and disappear as they grow and in other species spicules of tubercles are reabsorbed as the animal grows (Discodoris confusa), or do it from the body center to the margins, keeping the caryophyllic tubercles only at the edges of the mantle in adults, as in Gargamella perezi. These anatomical facts raise serious questions about a monophyletic line for dorids with caryophyllic for an elementary reason: juveniles can not have a different lineage than adults. Therefore we choose not to increase controversy and maintain the species in the genus in which it was originally described, waiting for molecular systematic studies to clarify their position.
- Rostanga rosi Ortea, 1979
The specimens of this species usually measure between 20 and 25 mm in length and have an oval body contour. Its color is uniform orange or red-orange and it may also have some small white colored spots. Besides color, the most characteristic trait of this species are the thin white lines marking circular, oval or elongated areas. In some specimens these white lines are very visible. The entire back is covered with small caryophyllic tubercles, well spaced and with slightly protruding spicules. Some of these tubercles have white pigment in its base and its union is what causes white spots on the back. The rhinophores have a translucent yellow base without lamellae and a red-orange end with about 15 lamellae. At the base without lamellae there could be seen spicules by transparency. The rhinophoric sheath is rather high and has small tubercles on its upper edge. The gill consists of 6 or 7 red or orange gill leaves that are kept erect when the animal is at rest or wandering. In the gill leaves spicules can be seen by transparency. The spine of the gill leaves is wider at the base. The upper margin of the branchial sheath has the same tubercles of the rhinophoric sheath. The foot is of the same color of the body, is furrowed and cleft on the front side and rounded on the rear side. The mouth has a pair of oral palps.
This species is usually located under stones or among algae from the intertidal or subtidal to about 15 m deep. It has been cited that, in the coasts of Portugal, feeds on the sponge Clathria gradalis. The spawn consists of a narrow transparent ribbon with orange eggs enclosed within a semitransparent capsule.
- Discodoris. From Latin “discus”, disc + “Doris”, according to Greek mythology, daughter of Tethys and Ocean, married Nereus and were the parents of the Nereids.
- Rosi. Dedicated to Dr. Joandomènec Ros, professor of the Ecology Department of the Universitat de Barcelona, who restarted the studi of Iberian opisthobranchs from 1973.
This recently described species is distributed throughout the Atlantic coasts of eastern Europe and the western Mediterranean. In the Iberian Peninsula it has been cited on the Cantabrian coast, in Galicia, in Portugal, in the Andalusian coast and in Catalonia. In the Catalan coast it has been located in Tossa de Mar and Begur, among other locations.
|: OBIS||: OPK|
|: GROC 2010-2011||: VIMAR|
|: Enric Madrenas||: Manuel Ballesteros.|
|: João Pedro Silva||: M@re Nostrum|
|: Bernard Picton||: Other sources|
|: GBIF.ORG||: Marine Regions|
References for the species: Discodoris rosi
Cantabria: Ortea (1979a), Ávila Escartín (1993). Galicia: Ortea (1979a), Ortea and Urgorri (1979c), Urgorri and Besteiro (1983), Rolán (1983). Portugal: García-Gómez et al. (1991), Malaquias and Morenito (2000), Calado et al. (1999, 2003). Gibraltar: García-Gómez (1983), García-Gómez et al. (1989). Andalucía (Med.): Luque (1986), Sánchez Tocino, Ocaña and García (2000a), Ocaña et al. (2000). Catalunya: Cervera et al. (1988), Ballesteros (datos no publicados) [Cap Falcó, L’Almadrava de Roses, Tossa de Mar], M@re Nostrum [Reserva Marina de Ses Negres (Begur) 5/2006, Els Ullastres (Llafranc) 8/2007] como Discodoris rosi.
Sources: Cervera et al., 2004, Ballesteros, 2007, McDonald, 2006 and other sources.
This chart displays the observation probability for Discodoris rosi
based on our own records.
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.