Researchers have discovered a marine worm with markings resembling a jaguar's coat buried in the sand on Costa Rica's Pacific coast.
The new marine worm species, Sthenelais onca, was found at Playa Naranjo in Santa Rosa National Park in the Guanacaste Conservation Area, according to The Tico Times.
The formal description appeared in ZooKeys and was authored by Jeffrey A. Sibaja-Cordero and Waiomi Miranda-García.
Fieldwork in February 2016 yielded four specimens from moist sand, and a return visit in May 2024 collected additional specimens, enabling scientists to complete the formal species description.
Its name comes from its jaguar-like patterning. The worm's orange, gray, and cream coloration resembles Panthera onca, and researchers also noted its predatory role in the marine ecosystem.
The team confirmed it as a new species through anatomical analysis, scientific illustrations, COI DNA barcoding, and comparisons with related species. The results placed it in the genus Sthenelais, but as a separate group marked by traits including a notch in the scales at the front of the body.
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The species was found in a sandy intertidal habitat — a beach zone often overlooked in favor of coral reefs, mangroves, and rocky shores.
Better knowledge of coastal ecosystems can help scientists, park managers, and local communities make decisions about conservation, tourism, and the stewardship of beaches that support both nature and local economies.
The worm can reach roughly 11 centimeters, placing it among the larger worms recorded in this type of sandy coastal habitat. The find also expands Costa Rica's marine biodiversity record and reinforces the scientific importance of the Guanacaste Conservation Area, according to The Tico Times.
Protected areas also create opportunities for new research, training, and a deeper understanding of the natural systems people rely on.
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The discovery was confirmed through the BioMar-ACG project, a collaboration involving the University of Costa Rica's Center for Research in Marine Sciences and Limnology, the Guanacaste Conservation Area, and MINAE. The project has been documenting marine life in protected coastal zones since 2015.
BioMar-ACG also helps train university students and works with local parataxonomists, building community knowledge and expanding the country's scientific capacity.
The newly studied specimens were deposited in the Annelida collection of the University of Costa Rica Zoology Museum, and the genetic sequences were submitted to international reference databases. That means future researchers can build on the work rather than start from scratch.
According to The Tico Times, scientists said the study is "another reminder that protected areas continue to produce new scientific knowledge, even in places that have been studied for decades," and it shows "how much remains unknown about Costa Rica's Pacific coast, especially in sandy intertidal habitats."
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