Abyssal Pacific Seafloor Megafauna Atlas (APSMA) version 1 [402 taxa in 13 Phyla]The APSMA code-based abyssal megafauna (invertebrates > 1 cm) catalogue was developed by morphological and taxonomical alignment of over 50K specimens encountered in seabed imagery collected in 28 seabed locations across the Clarion Clipperton Fracture Zone, in the NE Pacific basin (see Simon-Lledó et al. 2023, for further details, below). This work was conducted during a range of scientific workshops held between 2016 and 2021, in collaboration with taxonomic experts (see acknowledgements section) and by reference to existing literature (e.g. where available, links to studies describing collected specimens are provided in taxon descriptions). The catalogue follows the Horton et al. 2021 open nomenclature (e.g. 10.3389/fmars.2021.620702) to report the taxonomic resolution reached in the identification of each classified metazoan morphotype. Each morphotype was assigned a unique 7 character identification code (i.e. “XXX_nnn”). All taxa identified were deemed as sufficiently different morphologically by taxonomic experts to be confidently considered separate species. Note the catalogue is periodically revised, as new photographed and collected specimens get examined, and hence some taxonomic identifications may vary in subsequent versions of this guide. The latest version of the APSMA catalogue is available as label tree for image/video annotation on BIIGLE (biigle.de; please contact the authors for more detail). This field guide was used to develop (please cite as): Simon-Lledó, et al. (2023). Carbonate compensation depth drives abyssal biogeography in the northeast Pacific. Nature Ecology & Evolution; doi:10.1038/s41559-023-02122-9. See paper for more methodological details