This study presents a description of Bispira riccardi sp. nov., a new habitat-forming sabellid polychaete from the mesophotic NW Mediterranean Sea. Individuals, up to 20 cm long, show a peculiar morphology of radioles, thoracic uncini, companion chaetae and ventral shield of the collar. The phylogenetic position of this new taxon in the genus Bispira has been validated using nuclear (18S rRNA) and mitochondrial (COI) markers. Aggregations of B. riccardi sp. nov. were found by ROV on horizontal muddy bottoms between 56 and 85 m, in areas subjected to high trophic inputs. Patches are fragmented and dense (up to 943 individuals m−2) probably accounting for various hectares. A 5-days continuous monitoring, carried out using an autonomous lander, revealed that the contraction of the branchial crown was positively affected by temperature and current, rapidly responding to meteorological events. The filtering activity and high density of these fields suggest a considerable impact on the pelagic-benthic coupling and the amount of organic matter in the sediments. Indeed, meiofaunal abundance and diversity within the aggregations resulted significantly higher than in outer stations. These findings highlight the undisclosed potential of the deep Mediterranean Sea for sabellid diversity and their importance as habitat-forming species on mesophotic soft bottoms.

Depth range
30- 220 m

Mesophotic “mentions”
12 x (total of 9995 words)

Classification
* Presents original data
* Reports new species
* Focused on 'temperate mesophotic ecosystem'

Fields
Biodiversity
Ecology
Taxonomy
Molecular ecology

Focusgroups
Fishes
Other invertebrates
Overall benthic (groups)

Locations
France - Mediterranean Sea
Italy - Ligurian-Tyrrhenian

Platforms
Autonomous Underwater Vehicle (AUV)
Remotely Operated Vehicle (ROV)
SCUBA (open-circuit or unspecified)