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After nearly a decade of taxonomic detective work, scientists from the University of Cape Town (UCT), the Sea Change Project, the University of Tokyo and Stellenbosch University have confirmed the discovery of a parasitic sea snail that represents not just a new species, but an entirely new genus.
The findings, published in the Journal of Molluscan Studies, describe a snail whose biology is unprecedented in molluscan science: it lives as an internal parasite of brittle stars.
The organism was first observed in 2015 by Sea Change Project marine scientist Dr Jannes Landschoff and Rebecca MacKinnon, then an honours student at UCT, while studying the equitailed brittle star Amphiura capensis. Brittle stars are echinoderms related to starfish, but unlike starfish that glide using tube feet, brittle stars move by whipping their flexible, serpent-like arms across the seafloor.
Landschoff, who has conducted extensive research on brittle stars—particularly species that brood their young inside small chambers—began a project on A. capensis early in his research career with UCT Emeritus Professor Charles L Griffiths. That work later became MacKinnon’s honours thesis, setting the stage for an unexpected discovery.
“This is an exciting discovery, though, as it is the first time one of these parasitic molluscs has been found in a brittlestar, although many species are known from related groups such as starfish and sea urchins,” Griffiths said.
He added: “Finding new species in marine environments in South Africa is fairly routine, and both Jannes and I regularly discover new species in the course of our work. I have been involved in over 100 such discoveries over my 50-year career at UCT.”
Several months into the study, MacKinnon and Landschoff noticed white, round globules—about a millimetre in size—inside the brittle star’s brood chambers. Further investigation revealed they were parasitic snails from the family Eulimidae, a highly specialised group unfamiliar to the researchers. After struggling to find specialists, the team was referred to Associate Professor Yasunori Kano and his student, Dr Tsuyoshi Takano, at the University of Tokyo. Specimens were sent to Japan, where a meticulous, long-term taxonomic analysis began.
Nearly 10 years later, the results have confirmed the star-snail—named Introphiuricola rebeccae n. gen. n. sp., in honour of MacKinnon—as both a new species and a new genus. Its internal parasitic lifestyle within brittle stars is entirely new to science.
The discovery underscores how much remains unknown in the biodiverse Great African Seaforest and contributes to the ongoing 1001 Seaforest Species project—a collaboration between the Sea Change Project and the Save Our Seas Foundation—which aims to scientifically document and tell the stories of the kelp forest’s distinctive species.
Cape Argus
