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| Fissidentalium aurae Linse & Neuhaus, 2024 |
Abstract
The benthic biodiversity of the abyssal Labrador Sea was investigated using Agassiz trawl and in situ imagery. A megafaunal scaphopod associated with an epizoic anemone was recovered from soft sediments. Morphological and molecular investigations revealed the scaphopod to be an undescribed species in the dentaliid genus Fissidentalium P. Fischer, 1885. The new scaphopod species is characterised by a large size for the genus, is moderately curved, with numerous narrow, longitudinal ribs (60 ribs at 11 mm diameter ventral aperture), a dentaliid radula, and is described herein as Fissidentalium aurae sp. nov. The new species shows a close genetic relationship to congeners of Fissidentalium and separates from the sister genera Dentalium Linnaeus, 1758 and Antalis H. Adams & A. Adams, 1854. Genetic COI barcoding of the epizoic anemone suggests the species is a member of the family Actinostolidae Carlgren, 1932. The discovered association of a burrowing scaphopod with an epifaunal anemone at abyssal depth is a new record for the region and is indicative of how little is known about symbioses in the deep sea.
Keywords: Species-pair-associations, Ocean seafloor observation system, Abyssal plain, Taxonomy, Lebensspuren
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| In situ and life images of scaphopod-actinostolid symbiosis; a Scaphopod (black arrow) hosting anemone with retracted tentacles and its Lebenspur (grey arrows).; b Anemone with extended tentacles (white arrow) and scaphoid created Lebensspur (grey arrow); c Scaphopod (Paratype 1 SMF 366429) with an epizoic actinostolid anemone |
Class Scaphopoda Bronn, 1862
Order Dentaliida Starobogatov, 1974
Family Dentaliidae Children, 1834
Genus Fissidentalium P. Fischer, 1885
Type species: Dentalium ergasticum P. Fischer, 1883: 275–277;
accepted as Fissidentalium capillosum (Jeffreys, 1877) type by monotypy.
Fissidentalium aurae sp. nov.
Diagnosis: A large-sized, over 60 mm in length and 10 mm in ventral aperture width, Fissidentalium with numerous regular, fine longitudinal ribs. The white shells are robust and no posterior slit on the dorsal aperture was observed in the examined specimens. Most live specimens with shell lengths of 32–63 mm have a sea anemone attached to the concave, anterior surface of the shell. The ventral and dorsal apertures are slightly wider than high. Preserved, unrelaxed soft body dividable into a ventral buccal, a middle gut and a dorsal gonad region (following Shimek and Moreno 1996) and is about 2/3 of total shell lengths. Buccal and gonadal regions are of similar size and each about 3 times longer than the gut region.
Etymology: “aura” means breeze in Latin and used in genitive case. This name refers to the windy conditions during SO286 as well as to the shipping company Briese Research operating RV Sonne.
Katrin Linse and Jenny Neuhaus. 2024. A New Species of Fissidentalium (Scaphopoda: Dentaliidae) in association with an actinostolid Anemone from the abyssal Labrador Sea. Marine Biodiversity. 54, 88. DOI: doi.org/10.1007/s12526-024-01481-1
