Anton M. Tikhomirov

Aim: To reconstruct the phylogeny of the genus Pasiphaea across the benthopelagic interface, a unique evolutionary frontier involving migrations between the seafloor and the water column, and to analyse the environmental variables associated with clade separation. Location: Global deep‐sea ecosystems, encompassing both horizontal geographic distributions (latitudinal gradients) and vertical marine dimensions (pelagic water column and seafloor topography). Time Period: Contemporary global distribution data. Major Taxa Studied: Global fauna of the Glass shrimps Pasiphaea (Decapoda: Pasiphaeidae). Methods: Reconstruction of a robust molecular phylogenetic dataset comprising 121 sequences from three genes, integrating available reliable data on the geographical and bathymetric distribution and phylogeny of Pasiphaea , followed by the evaluation of environmental variables associated with clade separation using various statistical models. Results: Primary deep‐scale phylogenetic divergence was linked to pelagic environmental filtering, specifically latitude (as a proxy for temperature and productivity) and pelagic depth (nighttime habitat), which separated a high‐latitude, deep‐mesopelagic lineage (Clade A) from a lower‐latitude, shallower‐dwelling radiation (Clade B). In contrast, secondary diversification into terminal clades was associated with benthic factors, including seafloor geography (vicariance) and bottom depth (daytime habitat). Main Conclusions: We propose a “dual‐link” hierarchical framework for benthopelagic evolution, showing that while pelagic factors explain the broad evolutionary trajectory and deep‐scale divergence of benthopelagic taxa, the seafloor provides the geographic anchors necessary for further terminal speciation. This underscores the critical importance of integrating both vertical and horizontal environmental dimensions to understand the complex mosaic of deep‐sea benthopelagic diversification.

The present correction concerns the catalogue numbers of the examined material in the paper

The genus Pasiphaea Savigny, 1816, comprises a diverse assemblage of meso- to bathypelagic shrimps, currently including 69 valid species. Taxonomic investigations have long been hampered by numerous synonymies and by species known only from their original, overly brief descriptions. Here, we address these deficiencies by examining Pasiphaea specimens collected in the Western and Central Pacific during multiple research cruises using mid-water trawls. Integrating traditional morphological characters (carapace carination, pleonal relief, telson end morphology, and pereopodal dentition) with a novel morphometric framework, we standardized terminology and defined a suite of quantitative measurements across the carapace, pleon, telson, and chelae. In order to corroborate species boundaries, we sequenced three mitochondrial gene markers (COI, 16S rDNA, and 12S rDNA) and calculated genetic distances under the Kimura two-parameter model. This combined approach extended or confirmed the geographic ranges of five described taxa, facilitated the formal description of eight new species, and demonstrated the synonymy of P. gracilis Hayashi, 1999, and P. fragilis Hayashi, 1999. Phylogenetic reconstructions further highlighted cases of pseudocryptic speciation in neighboring bathyal habitats. Our results expose substantial lacunae in the Southwest Pacific Pasiphaea fauna and substantiate the necessity for a comprehensive, genus-level revision. This study thereby contributes to both refining species diagnoses and advancing our understanding of deep-sea crustacean biodiversity.