New fish species discovered in the Gulf of Mexico

Scientists from the Leibniz Center for Tropical Marine Research, along with colleagues from Central America, have identified a new fish species, Hypoplectrus espinosai, in the Alacranes Reef of the southern Gulf of Mexico. Part of the hamlet group, this species was distinguished using genetic analysis, geographical data, and photographs. Hamlets are predatory reef fish native to the Caribbean and tropical northwestern Atlantic, feeding on small fish and invertebrates. With this discovery, there are now 18 recognized hamlet species, seven of which have been described in the past 14 years. These fish are mainly identified by their genetically driven color patterns and grow up to 15 centimeters.

The newly discovered fish species Hypoplectrus espinosai, also called the Campeche Bank Hamlet, averages 11 centimeters in length and is distinguished by a prominent black saddle patch covering its caudal peduncle and sometimes the rear dorsal fin. It was first noticed by Mexican scientist Alfonso Aguilar-Perera during a dive at the Alacranes Reef. Although its coloration resembles that of the butter hamlet (Hypoplectrus unicolor) and the Veracruz hamlet (Hypoplectrus castroaguirrei), H. espinosai displays distinct markings that set it apart. The species was formally described by marine biologist Oscar Puebla and colleagues through careful comparison and analysis.

To confirm the identity of the newly discovered Hypoplectrus espinosai, Oscar Puebla and Alfonso Aguilar-Perera expanded their research team to include ichthyologists, a bioinformatics expert, and underwater photographers. Recognizing that visual similarities alone weren’t enough, they emphasized the need for genetic data and a wider geographic scope. Ichthyologists Omar Domínguez-Domínguez and Ross Robertson, bioinformatics expert Martin Helmkampf, and photographers Allison and Carlos Estapé all contributed critical data and images from the Campeche Bank, enabling a thorough scientific analysis of the new species.

Through a collaborative effort, researchers compiled genetic data, geographic records, and photographs to confirm the discovery of Hypoplectrus espinosai. Genomic comparisons with other species, including the butter hamlet and Veracruz hamlet, confirmed it as a distinct species. The new fish is set apart by its fully black saddle patch on the caudal peduncle—more extensive than that of the butter hamlet—and the absence of a black eye mask, which is a defining feature of the Veracruz hamlet. Specimens were collected and analyzed to formally describe the species.

Previously believed to be mere color variations of a single species, hamlets like Hypoplectrus espinosai are now recognized as distinct species. According to Oscar Puebla, the ongoing speciation within this group makes them ideal for studying the genetic mechanisms behind rapid diversification. This discovery highlights how natural evolutionary processes can help counter biodiversity loss. The new species was named in honor of Mexican ichthyologist Héctor Salvador Espinosa Pérez, recognizing his contributions to fish science. Its common name, Campeche Bank Hamlet, reflects its native habitat in the Campeche Bank, a biologically rich area in the southwestern Gulf of Mexico that merits conservation attention. Go to Andrea Daschner, Leibniz-Zentrum für Marine Tropenforschung (ZMT) article to learn more https://phys.org/news/2025-04-fish-species-gulf-mexico.html#google_vignette