Resolving species boundaries in the Atlanta brunnea species group (Gastropoda, Pterotracheoidea)

Abstract

Atlantid heteropods are a family of holoplanktonic marine gastropods that occur primarily in tropical and subtropical latitudes. Atlantids bear a delicate aragonitic shell (<14 mm) and live in the upper ocean, where ocean acidification and ocean warming have a pronounced effect. Therefore, atlantids are likely to be sensitive to these ocean changes. However, we lack sufficiently detailed information on atlantid taxonomy and biogeography, which is needed to gain a deeper understanding of the consequences of a changing ocean. To date, atlantid taxonomy has mainly relied on morphometrics and shell ornamentation, but recent molecular work has highlighted hidden diversity. This study uses an integrated approach in a global analysis of biogeography, variation in shell morphology and molecular phylogenies based on three genes (CO1, 28S and 18S) to resolve the species boundaries within the Atlanta brunnea group. Results identify a new species, Atlanta vanderspoeli, from the Equatorial and South Pacific Ocean, and suggest that individuals of A. brunnea living in the Atlantic Ocean are an incipient species. Our results provide an important advance in atlantid taxonomy and will enable identification of these species in future studies of living and fossil plankton.

Fossil-calibrated molecular phylogeny of atlantid heteropods (Gastropoda, Pterotracheoidea)

“…The majority of these putative species (11 of 17) show some degree of geographical separation, residing in different ocean basins, and seven of these putative species are also supported by the more slowly evolving, independently inherited nuclear markers, demonstrating that they are probably distinct species. However, further work in resolving the morphology and distributions of these new species would be necessary to describe and validate each one [ 32 ].…”

An integrative taxonomic approach to the Atlantic Hansarsia (formerly Nematoscelis) yields new krill taxa (Crustacea: Euphausiidae)

“…This approach may provide promising results for species delimitation (e.g. Stefani et al 2008; Wall-Palmer et al 2019; Smith et al 2022). Qualitative characters clearly associated with sexual dimorphism in adults were excluded from the PCA.…”

Multiple Introductions of the Pestiferous Land Snail Theba pisana (Müller, 1774) (Gastropoda: Helicidae) in Southern California

“…The K2P genetic distance between the CO1 barcode fragments of T. pisana from San Pedro and San Elijo is 13%, which, in many other taxa, would be enough to designate them as separate species [90][91][92]. However, in the stylommatophora (land snails and slugs), intraspecific CO1 genetic distance can be as high as 30% [93], while interspecific genetic distance may be 1-3% [94,95].…”