Centres of species richness, neoendemism, and paleoendemism for marine fishes occur in different regions of Aotearoa New Zealand

Biogeography has traditionally relied on species-based measures of biodiversity, partially reflecting the processes shaping spatial patterns. Incorporating the evolutionary relationships among taxa can provide a greater understanding of how distinct processes define different regional patterns over time. Here, we describe the biogeography of marine ray-finned fishes (Actinopterygii) in Aotearoa New Zealand and adjacent areas of the Southwest Pacific using phylogenetic measures of richness and endemism. Defining a geographic area of 30° latitude by 20° longitude that encompasses New Zealand’s main and offshore islands, we compiled distributional maps for 313 taxa occurring in 0–500 m waters using AquaMaps, a web-based tool that generates occurrence probability maps based on environmental and occurrence data. We describe spatial patterns of biodiversity with species and phylogenetic metrics of richness and endemism, including phylogenetic diversity and phylogenetic endemism, using a comprehensive molecular phylogeny of New Zealand’s marine fishes. To identify endemism centres, we employ the “categorical analysis of neo- and paleoendemism” (CANAPE) method which distinguishes locations with an over-representation of spatially rare short phylogenetic branches (neoendemism) and spatially rare long phylogenetic branches (paleoendemism). Latitudinal patterns of richness and endemism differ, with richness peaking at 35°S along the North Island, while endemism reaches maximum values in the northernmost oceanic islands where neoendemism dominates. Significant paleoendemism clusters around two coastal areas of mainland New Zealand. Our study shows that richness and endemism hotspots are geographically distinct for New Zealand’s marine fishes, likely the result of distinct acting processes. The richness maximum appears to be the result of a range overlap between distantly related tropical taxa shifting towards high latitudes and a lower number of older temperate taxa. Neoendemism is likely driven by the isolation of young volcanic islands, and coastal paleoendemism might be the legacy of locally stable environmental conditions that served as a refuge for relict lineages over time. We identify areas where evolutionary processes have left a signal unnoticed by species richness alone. Northern subtropical marine fish assemblages are composed of a heterogeneous mixture of distantly related taxa. Southern temperate and subantarctic areas are characterized by the presence of a low number of old lineages as well as the absence of extremely young and old taxa. We generate a phylogenetic landscape from which future biogeographic research can test hypotheses to unveil underlying evolutionary and ecological processes.