First record of the genus Dermatobranchus van Hasselt, 1824, in the Mediterranean Sea (Nudibranchia: Arminidae)

Abstract

Three individuals of a nudibranch belonging to the genus Dermatobranchus (Arminidae) were found at a depth of 3 meters, in a bottom with sand and gravel, during night SCUBA diving activity in Porto Pirrone, Leporano, Taranto, Apulia, Italy. The external morphology and coloration of these Mediterranean individuals clearly resemble those of D. rubidus (Gould, 1852), a species known only from the central and western Pacific Ocean. This is the first record of the genus Dermatobranchus van Hasselt, 1824 for the Mediterranean Sea.

On the presence of the less known arminid nudibranch Dermatobranchus rubidus (Gould, 1852) in the Adriatic Sea

“…The habitats in which the specimens were found fit well with the mention of Colucci et al (2015) and Morley and Haywards (2015), who stated that the species lives on sand in semi-sheltered areas. The specimen from Croatia was buried in fine sediment mixed with small stones at a depth of 8 m. The specimen from Slovenia was sighted during a night dive in a depth range between 9 and 10 m, on bare muddy bottom.…”

“…On the other hand, Furuhashi et al (2006) described a species of Dermatobranchus with a long larval pelagic stage which could be transported for longer periods via ballast waters. Colucci et al (2015) support the idea that the species arrived in the Mediterranean with ballast waters or mariculture. However, due to the lack of knowledge on its biology and ecology, so far it is unclear whether it can endanger the native species.…”

“…The ecology of D. rubidus, which was described recently, is still poorly known. The behaviour of the specimen from Fiesa resembles those of the three specimens in Porto Pirrone reported by Colucci et al (2015). In both cases, sea slugs were spotted during night dive in October and began to bury themselves in the sediment immediately after being illuminated by a light torch.…”

“…This family is divided in six genera, of which only two are present (up to now) in the Mediterranean, namely the genus Armina (Rafinesque, 1814) with three species, and the genus Dermatobranchus van Hasselt, 1824, represented by only one species recently reported from the Mediterranean. In fact, the first Mediterranean finding of Dermatobranchus rubidus Gould, 1852 was published by Colucci et al (2015) who found three specimens at 3 m of depth in Porto Pirrone near Taranto (Italy, Ionian Sea). This paper aims to extend the knowledge on range of distribution of D. rubidus in the Adriatic Sea based on two findings from Northern and Middle Adriatic Sea.…”