Circumglobal Distribution of the Benthic Ctenophore Vallicula multiformis (Rankin 1956), Documented Through Diverse Observation Types

This is the authors' abstract. We don't add key points for this paper.

Aim To improve our understanding of the distribution of Vallicula multiformis , we integrate a series of diverse observation types, including citizen science records, published literature, metagenomic datasets, published sequences, and newly acquired material, to evaluate whether geographically isolated records reflect a single broadly distributed species or unresolved cryptic diversity. Location Circumtropical and subtropical marine environments. Taxon Vallicula multiformis (Phylum: Ctenophora, Order: Platyctenida, Family: Benthoplanidae). Methods In this study, we use a broad range of observations, as listed previously, to (a) elucidate the geographic range of V. multiformis through morphological and phylogenetic analysis, (b) assess the possibility of cryptic speciation, and (c) investigate population genetic structure across major ocean regions. Results After reviewing the published literature, confirming more than 100 photo‐based observations in iNaturalist, and analysing 67 mitochondrial COX1 sequences using three species delimitation models, we can confirm 107 iNaturalist citizen science observations, 20 literature sources, 43 published sequences from specimens and environmental samples, and 11 newly sequenced specimens. Additionally, we find that the holotype of Coeloplana reichelti from the Great Barrier Reef, Australia, is a misidentified V. multiformis . Main Conclusions We conclude that all observations of V. multiformis belong to a single species that inhabits shallow tropical and subtropical waters worldwide. Population genetic analyses using COX1 suggest that this broad distribution is an ancient phenomenon, likely achieved through long‐distance natural dispersal. We also detect a signal consistent with anthropogenic introductions. Future work is needed to test these hypotheses and more rigorously assess population histories and hypothetical migration pathways.