Vertical gradients in species richness and community composition across the twilight zone in the North Pacific Subtropical Gyre.

Although metazoan animals in the mesopelagic zone play critical roles in deep pelagic food webs and in the attenuation of carbon in midwaters, the diversity of these assemblages is not fully known. A metabarcoding survey of mesozooplankton diversity across the epipelagic, mesopelagic and upper bathypelagic zones (0-1500 m) in the North Pacific Subtropical Gyre revealed far higher estimates of species richness than expected given prior morphology-based studies in the region (4,024 OTUs, 10-fold increase), despite conservative bioinformatic processing. Operational taxonomic unit (OTU) richness of the full assemblage peaked at lower epipelagic-upper mesopelagic depths (100-300 m), with slight shoaling of maximal richness at night due to diel vertical migration, in contrast to expectations of a deep mesopelagic diversity maximum as reported for several plankton groups in early systematic and zoogeographic studies.

Corrigenda: Cepeda GD, Sabatini ME, Scioscia CL, Ramírez FC, Viñas MD (2016) On the uncertainty beneath the name Oithona similis Claus, 1866 (Copepoda, Cyclopoida). ZooKeys 552: 1-15. doi: 10.3897/zookeys.552.6083.

[This corrects the article DOI: 10.3897/zookeys.552.

On the uncertainty beneath the name Oithona similis Claus, 1866 (Copepoda, Cyclopoida).

The marine cyclopoid Oithona similis sensu lato Claus, 1866, is considered to be one of the most abundant and ubiquitous copepods in the world. However, its minimal original diagnosis and the unclear connection with its (subjective) senior synonym Oithona helgolandica Claus, 1863, may have caused frequent misidentification of the species. Consequently, it seems possible that several closely related but distinct forms are being named Oithona similis or Oithona helgolandica without explicit and accurate discrimination.

Molecular systematic of three species of Oithona (Copepoda, Cyclopoida) from the Atlantic Ocean: comparative analysis using 28S rDNA.

Species of Oithona (Copepoda, Cyclopoida) are highly abundant, ecologically important, and widely distributed throughout the world oceans. Although there are valid and detailed descriptions of the species, routine species identifications remain challenging due to their small size, subtle morphological diagnostic traits, and the description of geographic forms or varieties. This study examined three species of Oithona (O.