The genus Hypanus consists of ten known species distributed along coastal habitats worldwide. Until recently, only two species —known as the longtail stingray (Hypanus longus) and diamond stingray (Hypanus dipterurus) — were recognized in the Eastern Tropical Pacific (ETP), while the rest were found in the western Atlantic and off the west coast of Africa. Now, a newly described species, Hypanus rubioi, joins the list! And while one may believe this is a recent discovery, scientists have actually studied this ray for two decades, documenting its distinctive features and confirming its classification through both anatomical and molecular analyses.
For years, local fishers in the Pacific waters of Colombia had been catching rays that didn’t quite match the known local species, but without formal classification, these specimens remained unidentified. Between 2003 and 2023, researchers examined a total of 90 individuals — 47 females, 40 males, and three unsexed specimens — collected from artisanal fishing landings along the Colombian Pacific coast. Many of the captured rays had been eviscerated, or had their tails removed for sale, which complicated the ability for researchers to properly ID them. However, a dedicated research cruise in Uramba Bahía Málaga National Natural Park allowed scientists to collect intact specimens and tissue samples for genetic sequencing, ultimately leading to the confirmation of H. rubioi as a new species.
The longnose Pacific stingray (that’s H. rubioi’s “common name”) stands out from other rays in the area because of its unique body shape and impressive size. With a disc width of about 49 inches (125 cm) and a length-to-width ratio between 1.0 and 1.1, its spade-shaped form is unlike other species in the genus. Its blunt snout extends nearly 30% of its disc width, while its tail (which tapers smoothly) can grow to more than twice the size of its body! It also has three rows of enlarged denticles — tiny, tooth-like scales — running down its back, with the central row extending to its caudal sting. Genetic analysis also confirms that this stingray is not just a variation of an existing species but an entirely new addition to the Hypanus lineage. DNA comparisons using the COI gene — a standard genetic marker for species identification — revealed significant differences between the longnose Pacific stingray and its closest relatives. In particular, its genetic distance from the western Atlantic longnose stingray (Hypanus guttatus), its closest known relative, ranges from 2.27% to 2.94%, further solidifying its classification as a distinct species. The phylogenetic analysis places the longnose Pacific stingray as a sister species to H. guttatus, meaning they share a common ancestor but have since evolved separately.
Understanding where this new stingray lives and how it fits into its environment is just as important as identifying it. Like other Hypanus species, the longnose Pacific stingray is likely a bottom-dwelling ray that prefers sandy or muddy coastal habitats, including bays, estuaries, and seagrass beds. Preliminary ecological niche modeling suggests that its range could extend from central Mexico to northern Peru, influenced by factors such as salinity and light availability. These habitats are critical for the survival of many stingray species, but are increasingly threatened by human activities. Many are caught as bycatch in fisheries, while others are directly targeted for consumption. Habitat degradation, pollution, and climate change also pose risks to these predators. Of the ten recognized Hypanus species, several have been assessed as vulnerable or endangered by the International Union for the Conservation of Nature. For example, the IUCN lists sharpsnout stingray (H. geijskesi) and smalltooth stingray (H. rudis) as critically endangered, while the longtail stingray (one of the longnose Pacific stingray’s regional counterparts) is listed as vulnerable. Even species classified as near threatened, such as the western Atlantic longnose stingray, show declining population trends. Without proper monitoring and conservation efforts, the same risks could apply to the longnose Pacific stingray.
Stingrays are an essential part of ocean ecosystems, often serving as both predators and prey. Accurately identifying species allows scientists to better understand population sizes, habitat preferences, and threats, leading to more effective management strategies. In the case of the longnose Pacific stingray, the lack of clear classification had previously resulted in misidentified catches, making it difficult to assess its status. Now, with its formal recognition, conservationists can begin to properly evaluate its population health and potential vulnerabilities.
Continued exploration and research are crucial, not just for expanding our knowledge of marine life but for ensuring that newly discovered species receive the protection they need. The discovery of this new stingray also raises broader questions about biodiversity in the Eastern Tropical Pacific. If a large, distinct stingray species remained undocumented for so long… what else might be hiding in these waters?
