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| Tritonia callogorgiae Chimienti, Furfaro & Taviani in Chimienti, Angeletti, Furfaro, Canese & Taviani, 2020. |
Highlights
• A forest of the Primnoidae Callogorgia verticillata was found in the Adriatic Sea.
• The forest develops between 420 and 426 m depth, with a mean density of 1.34 colonies m−2.
• The nudibranch Tritonia callogorgiae sp. nov. is described strictly associated with the corals.
• Our study describes the first deep-sea tritoniid in the Mediterranean Sea.
• Stomach content analysis showed that Tritonia callogorgiae sp. nov. feeds on C. verticillata.
Abstract
The continuing exploration of the Mediterranean deep sea reveals that a complete census of the biodiversity of one of the most studied marine areas in the world is yet to be fully accomplished. A tritoniid nudibranch new to science is described upon material recovered off the Montenegro margin, Adriatic Sea, associated with the alcyonacean Primnoidae Callogorgia verticillata (Pallas, 1766). Here, a coral forest dominated by C. verticillata, together with other alcyonaceans, antipatharians and scleractinians, represents the habitat of the new species. As documented by Remotely Operated Vehicle (ROV) observations, the coral forest covers an area of 600 m2 at 420–426 m depth, with dense growth of C. verticillata colonies (1.34 ± 0.08 colonies m−2). As many as 66 nudibranch specimens have been observed on C. verticillata. Tritonia callogorgiae sp. nov. (Gastropoda, Nudibranchia, Tritoniidae) is up to 12 cm long, yellow to orange/reddish in colour with white papillae all over the body. It has a velum with six appendages (three per side), and 4–5 pairs of dichotomous gills. Internally, the species is distinguished from other tritoniids for the absence of stomach plates and a distinctive radula with formula 50 × 110.1.1.1.108. It represents the first case of Tritonia species living in the deep Mediterranean Sea and the only one associated to C. verticillata. Stomach content documents that Tritonia callogorgiae sp. nov. feeds on C. verticillata. Further visual ROV records from other sectors of the Mediterranean Sea indicate that the distribution of this new described species is almost basin-wide. The discovery of another undescribed member of the benthic megafauna related to deep-sea coral grounds further highlights the need for conservation of such habitats.
Keywords: Coral forest, Alcyonacea, Primnoidae, Mollusca, Nudibranchia, Mediterranean sea
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| Tritonia callogorgiae sp. nov. (paratype A_31_1; MUZAC-6555). in vivo. |
Order Nudibranchia Cuvier, 1817
Family Tritoniidae Lamarck, 1809.
Genus Tritonia Cuvier, 1798
Tritonia callogorgiae Chimienti, Furfaro & Taviani, sp. nov.
Etymology: The name identifies the consistent association of the news species with the Primnoidae sea fan Callogorgia verticillata.
Conclusions:
The presence of rare or uncommon taxa represents a robust argument for the consideration of their host habitats as meritorious for proper conservation measures. In this respect, forests of C. verticillata represent a unique habitat for several associated species, including the newly discovered Tritonia callogorgiae sp. nov. This study provides the elements to identify this noticeable species even based solely on images and without the need of complex sampling operations. It is expected that further records of T. callogorgiae sp. nov. will be added in the future, as part of new deep-sea explorations and monitoring programs all over the Mediterranean Sea. Colorful and extravagant invertebrates like nudibranchs are often noted for their vibrant colour palettes and widely appreciated from an aesthetic point of view. They could thus act as ‘flag species’ to push general public and decision makers towards the importance to protect the vulnerable habitats where they live.
Giovanni Chimienti, Lorenzo Angeletti, Giulia Furfaro, Simonepietro Canese and Marco Taviani. 2020. Habitat, Morphology and Trophism of Tritonia callogorgiae sp. nov., A Large Nudibranch Inhabiting Callogorgia verticillata Forests in the Mediterranean Sea. Deep Sea Research Part I: Oceanographic Research Papers. 165: 103364. DOI: 10.1016/j.dsr.2020.103364