Loricifera inhabiting spherical agglutinated structures in the abyssal eastern equatorial Pacific nodule fields
Loriciferans are known to survive in extreme environments, most notably in the case of a recently described Spinoloricus species from a hypersaline anoxic Mediterranean basin. Our new discovery of members of the genus Rugiloricus inside spherical agglutinated structures from sediment samples collected in the manganese nodules fields of the eastern Clarion-Clipperton Zone (CCZ, abyssal equatorial Pacific) demonstrates that these tiny animals are able to spring fresh surprises. Nearly all developmental stages of an undescribed Rugiloricus species were found inside the spheres, from the first instar larva and large free larva to the two stages of the postlarva inside the larval exuvium. Only the adults were missing. The spheres themselves were almost certainly not created by the loriciferans. Their origin is unclear, although similar agglutinated structures from the same study area contain cells that resemble monothalamous foraminifera, suggesting that they are possibly made by foraminifera. One of our CCZ samples also yielded a single free specimen of the loriciferan genus Pliciloricus that was not hidden inside an agglutinated structure. This specimen is particularly interesting because, like nested Russian dolls, it has all stages inside the larval exuvium: first the larval exuvium itself with the two toes, then a very thin postlarval exuvium and finally the adult male with two testes filled with mature spermatozoa.
KeywordsMetazoan meiofauna Loriciferans Rugiloricus Pliciloricus Monothalamous foraminifera Polymetallic nodules
We thank Craig Smith for his inviting two of us to participate in the ABYSSLINE project and for his management of both the project and the two cruises during which the samples were collected. We also thank Ivan Voltski and Alexandra Weber who supported our work at sea. Laura Pavesi (NHMD) is acknowledged for the registration of the slides. We thank four anonymous Reviewers for their detailed comments that helped to improve the manuscript.
RMK received funding from the Carlsberg Foundation grant CF-16-0236. The wider ABYSSLINE project, including the salary of AG, part of the salary of AJG, and costs associated with the two cruises, was funded by UK Seabed Resources Ltd. under contract number SRD100300.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with animals performed by any of the authors.
Sampling and field studies
The sampling was conducted in international waters within areas covered by contracts for seabed exploration issued by the International Seabed Authority.
All data generated or analysed during this study are included in this published article.
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