Paradoris indecora

Paradoris indecora (Bergh, 1881)

Paradoris indecora by Enric Madrenas

Taxonomic note: Fernández-Vilert et al (2024) performed genetic analysis on a wide sample of seaslugs from the family Discodorididae and, among many other novel and interesting results, concluded that Paradoris indecora was the only valid species in the amphi-Atlantic and Mediterranean regions within Paradoris genus and it constitutes a species complex. The authors found three different morphotypes assigned to Paradoris indecora due to colour variability. One has a translucent white body and several small, black spots on the dorsum (true Paradoris indecora), another has a translucent white body without the presence of black spots (Paradoris sp. 1), and the last one with an opaque brownish/greyish body (Paradoris sp. 2). The two latter are pending morphological study to determine whether they are undescribed species or belong to an already described species. Paradoris aviles Ortea and Moro, 2022 and Paradoris rafaherreroi Ortea and Moro, 2021, both described from Cape Verde, are externally similar to Paradoris sp. 1 and sp. 2, respectively. Alternatively, these could represent the currently synonymized species Paradoris porri (Vérany, 1846), Paradoris granulata Bergh, 1884, or Paradoris cavernae (Starmülhner, 1955) studied in Trainito and Doneddu (2014), which should, therefore, be resurrected. We keep the different “forms” of Paradoris indecora in the present species record until their status is clarified.

Synonyms

• Discodoris indecora Bergh, 1881 (original)
• Discodoris cavernae (Starmühlner, 1955)
• Discodoris porri (Vérany, 1846)
• Doris porri Vérany, 1846
• Paradoris cavernae Starmülhner, 1955
• Paradoris granulata Bergh, 1884

Description
Specimens measure from 20 to 30 mm but literature shows that this species can reach up to 40 mm in length. The body is flattened and oval contoured. The general body color is translucent white or gray, more or less dark, sometimes with violet tones.  There are small clear and black spots scattered around the dorsum, sometimes grouped together forming patches of these colors that match glandular openings. Rounded tubercles of different sizes but well spaced are scattered on the notum; large tubercles may have a cream coloured apex due to concentration of light spots. The binocular microscope shows tiny spikes protruding from the apex of the tubercles. The rhinophores are semitransparent at their base and the laminar portion has 10-16 brown spotted yellowish lamellae. The rhinophores terminal mucro is slightly developed. The rhinophoric orifice has a slightly elevated sheath that is slightly lobed (8-10 lobes) on the top edge; the rhinophoric sheath also has a few small tubercles. Gill consists of 6-8 tripinnate grayish or brown gill leaves, of the same colour of the body, with a semitransparent central shaft and with the end of the gill ramifications coloured cream or yellowish. Gill sheath, as the rhinophores’ sheath, is also high and lobed at its upper edge. As a characteristic feature, the gill leaves head backwards when extended. The anal papilla is located in the center of the gill leaves. The head has two short brown spotted oral tentacles that are cleft in their lower side. The foot and the underside of the mantle are coloured whitish with scattered reddish brown spots. The flanks of the foot also have the same colour spots. The mantle is very spiculous and radial arranged spiculae and crossing spiculae can be seen in the underside. The foot has a cleft and furrowed leading edge, while viscera can be seen as a blackish stain in the midsection.

Biology
This doridacean usually lives in shallow water, on the underside of rocks and near sponges like Ircinia fasciculata or Dysidea fragilis, on which it apparently feeds (Ortea, 1995). The animals of this species move very slowly and when disturbed they are capable of secreting a defensive whitish substance that forms a diffuse cloud around the animal. The spawn is a semitransparent strip about 5 mm high laid in a spiral of 4-5 turns; The eggs are white and measure about 165 microns on average (Ortea, 1995).

Etymology

• Indecora. From Latin “indecore”, improperly, inglorious, shameful, ugly, unbecoming, unseemly.

Distribution
This species is distributed throughout the Mediterranean, from Israel to the Strait of Gibraltar. It has also been cited in all the Iberian Peninsula but Cantabria and Galicia, in the archipelago of Cape Verde, the Canary islands and the Balearic islands. In the Catalan coast it has been reported on the Costa Brava in locations like Cala Fredosa, Cala Sant Antoni, Es Caials (Cadaqués), L’Escala, Cala Aigua-Xelida, Cala Aiguafreda, Llafranc, Cala Margarida, Caleta de Palamos, Sant Feliu de Guixols and Tossa de Mar.

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Bibliography

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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

• Biodiversity Heritage Library
• BiologiaMarina.org
• CIB - Club Immersio Biologia
• El Litoral de Granada
• Flickr pictures
• GROC
• Interim Register of Marine and Nonmarine Genera
• NCBI GenBank
• OBIS - Search by Taxon
• Sea Slug Forum
• World Register of Marine Species

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