Monothalamous soft-shelled foraminiferal image dataset from the Kveithola Trough (NW Barents Sea).

We present an image dataset of monothalamous soft-shelled Foraminifera (Monothalamea, [1]), an important component of benthic foraminiferal assemblage in sediment cores collected during two oceanographic expeditions that contributed to the MSM30-CORIBAR project (Ice dynamics and meltwater deposits: coring in the Kveithola trough, NW Barents Sea). 9 subsamples of sediment cores were collected during different years (2013-2016) in the Kveithola Trough, a glacially carved system in the NW Barents Sea. Cores were retrieved using a multi-corer (MUC) and a giant box-corer (GBC) and the subcores for foraminiferal analyses were obtained using Plexiglas tubes inserted manually into the cores. These subcores were sliced at 0.5 cm intervals down to 2 cm sediment depth and then every 1 cm down to 10 cm. Two staining methods, Cell Tracker Green (CTG) and Rose Bengal (RB), were used to distinguish between living and dead individuals. Then, the fixed sediment samples were sieved through 63 and 150 μm mesh screens and preserved in 10 % borax-buffered formalin. Six species and 37 undescribed morphotypes were recognized and included in this image dataset. Relatively few species of soft-shelled, monothalamous foraminifera have been described compared to a much larger number of undescribed morphotypes recognised from across the marine realm. Few researchers study with their taxonomy because of the time and difficulties that morphological identification involves. In addition, because "soft", delicate monothalamids rarely fossilize, they are generally overlooked by micropaleontologists. However, they are abundant and diverse and represent an important faunal component of marine as well as freshwater ecosystems. Further information about these frequently overlooked protists will help to address important knowledge gaps and enhance our ability to manage and conserve the planet's resources responsibly. In particular, our image dataset highlights the importance of monothalamous soft-shelled foraminifera in this peculiar Arctic environment and contributes to the first species/morphotype checklist for the area. We hope it will serve to fill gaps in knowledge regarding the ecology and biodiversity of benthic foraminifera, helping users to identify monothalamids species and morphotypes in Arctic waters and beyond. This data article is associated with the research papers: "Benthic foraminiferal assemblages and environmental drivers along the Kveithola Trough (NW Barents Sea)" by [2].