Sept nouvelles espèces montrent que le groupe marin de 250 millions d'années est toujours en évolution

A team of researchers has uncovered seven previously unknown species of hornerid bryozoans in the waters off southern Aotearoa New Zealand, revealing that this marine group, which dates back over 250 million years, continues to evolve and diversify. The findings, published in the Zoological Journal of the Linnean Society, challenge previous assumptions about the evolutionary status of these ancient organisms, suggesting they are not remnants of a bygone era but active participants in modern ecological dynamics. The study, led by Emeritus Professor Abby Smith of the University of Otago’s Ōtākou Whakaihu Waka Department of Marine Science, along with colleagues including Dr. Helen Jenkins, Dr. Paul Taylor, and Dr. Andrea Waeschenbach of the Natural History Museum in London, identified 11 new species within the Horneridae family. Of these, seven are entirely new to science, while four were previously known but reclassified under newly established taxonomic criteria. The research highlights the ongoing evolution of hornerid bryozoans, which are characterized by their intricate, lace-like skeletal structures and their role as key contributors to deep-sea habitat formation. Bryozoans, a phylum of aquatic invertebrates, have inhabited Earth’s oceans for over 250 million years. While many ancient bryozoan groups have gone extinct, hornerids have persisted, adapting to specific ecological niches. This latest discovery suggests that the group is far more dynamic than previously understood. The researchers found that hornerid bryozoans continue to develop novel survival strategies and occupy diverse habitats in southern Aotearoa, indicating a robust capacity for adaptation and speciation. To identify the new species, the team employed both molecular genetic analysis and detailed morphological examination of specimens collected from the seafloor near Cook Strait and the subantarctic islands. Their work resulted in the description and naming of 11 species, spanning three genera, one of which is newly defined, and one of which was reinstated after being overlooked in earlier studies. Three of the newly named species were given special honors: Hornera polaris pays tribute to the research vessel RV Polaris II, while Hornera girvanae and Hornera currieae commemorate the contributions of scientists Elizabeth Girvan and Kim Currie to marine biodiversity research. Professor Smith expressed surprise at the sheer number and diversity of the newly discovered species. “We never thought there would be this many species and that they would turn out to be this diverse,” she remarked. The findings underscore the importance of continued exploration and classification efforts, particularly in understudied regions such as the deep waters surrounding Aotearoa. Understanding these species is critical for effective conservation and management practices, as many remain undocumented and poorly studied. The study also challenges long-held views about the evolutionary trajectory of hornerid bryozoans. Previously considered a relic lineage from the Paleozoic Era, the group was thought to represent a surviving fragment of an older biological lineage. However, the new data suggest that hornerids are actively evolving, demonstrating remarkable adaptability and resilience in the face of environmental change. Looking ahead, the researchers plan to examine additional specimens from northern New Zealand, which may yield further discoveries. As the team notes, the potential for uncovering more species in this genus remains high, emphasizing the need for sustained scientific inquiry into the rich and complex ecosystems of the Southern Hemisphere.