Seven species in one: new discovery in the Southern Ocean reveals the “hidden side” of a small sea snail

Through molecular and morphological studies, including more than 750 mollusks, Chilean scientists recognized the true diversity hidden by the intertidal mollusk Laevilitorina caliginosa throughout its distribution in the Southern Ocean, which surrounds the Antarctic continent.

Valdivia, July 6, 2022.-The nominal species L. caliginosa, which has a wide distribution in different areas of the Southern Ocean, actually includes a total of seven species. Six of the recognized species are restricted to the southern coast of South America and four of them are completely new to science.

The research, led by a team from the Austral University, the BASE Millennium Institute and the IDEAL Center, was published in the prestigious magazine Journal of Biogeography and includes the participation of international researchers from the United Kingdom, France, Australia and New Zealand.

The diversity hidden by the small sea snail Laevilitorin caliginosa, in its distribution throughout the Southern Ocean, it required a major task: More than 750 specimens from 16 populations, along 8,000 kilometers, which included not only South America and the Antarctic Peninsula, but also sub-Antarctic islands of difficult access located in the Indian Ocean. However, it was not until a genetic analysis that the way to decipher and understand the evolutionary history of these snails came to light.

Thus, molecular data revealed that the species Laevilitorin caliginosa includes at least seven species, all supported by morphological data: “We examined the biogeographic structure of this marine gastropod, which is apparently an exception to this rule because it has a wide distribution in different provinces of the Southern Ocean,” says Dr. Claudio González- Wevar, associate professor at the Institute of Marine and Limnological Sciences (ICML), of the Faculty of Sciences of the Austral University of Chile.

Thus, says González-Wevar, also a researcher at the BASE Millennium Institute and the Fondap IDEAL Center, diversification in Laevilitorin it does not fit the cryptic speciation model, that is, a genetic differentiation without morphological changes, a common phenomenon in many invertebrates of the Southern Ocean, but rather a speciation process accompanied by morphological diversification.

The finding, based on phylogenetic reconstructions, which investigate the relationships between species and their genes, considered the incidence of the Antarctic Circumpolar Current (ACC) and the Antarctic Polar Front (FPA) as important barriers that separate the biota from the Southern Ocean : “This study represents the most detailed review of littorhinid gastropods from high latitudes,” says González-Wevar, Marine Biologist and Doctor of Science with a major in Ecology and Evolutionary Biology. A) Yes, Laevilitorin caliginosaone of the most widely distributed invertebrates in the Southern Ocean, is an excellent model for evolutionary and biogeographical studies.

The results obtained in Laevilitorin allowed the identification of new species and recognize the need to carry out integrative biogeographical studies to better understand the biodiversity that hides this important region of the planet.

A big family

The gender Laevilitorin includes a total of 21 species of small intertidal and subtidal gastropods distributed in high latitudes including southern Australia, Tasmania, New Zealand and throughout the Southern Ocean. Most species of Laevilitorin they have very restricted distributions and are endemic to provinces and/or particular islands of the Southern Ocean. The exception to the rule is the species L. caliginosa which is described in different provinces of the area surrounding the Antarctic continent.

The data collection and analysis work took three years, and the scientific research team was made up of Nicolás I. Segovia, Sebastián Rosenfeld, Claudia S. Maturana, Vanessa Jeldres, Ramona Pinochet, Thomas Saucède, Simon A. Morley, Paul Brickle , Nerida G. Wilson, Hamish G. Spencer, and Elie Poulin. All the collected biological material is available at the Antarctic and Sub-Antarctic Genomics and Molecular Ecology Laboratory (LAGEMAS), at the Institute of Marine and Limnological Sciences (ICML), Universidad Austral de Chile, Isla Teja Campus.