A New Reef Fish Found in Cuba
New species of coral reef fishes are still being discovered, even in relatively well-studied regions such as the Caribbean. One particularly interesting example is DeJong's Basslet (Gramma dejongi), a colorful reef fish closely related to the familiar Fairy Basslet (Gramma loreto).
The species was first discovered by aquarist Arie de Jong on reefs near Trinidad, Cuba, and was formally described in 2010 by Benjamin Victor and John Randall. At the time of its discovery, the fish was known only from a small area along the southern coast of Cuba, making it one of the most geographically restricted reef fishes in the Caribbean.
Gramma dejongi is typically found at depths of about 20 to 30 metres, overlapping with both of its close relatives. The Fairy Basslet (G. loreto) is generally more common in shallower reef habitats, while the Blackcap Basslet (Gramma melacara) is usually found at greater depths.
One of the most surprising findings of the original study was that the standard mitochondrial DNA barcode used for species identification showed little or no difference between G. dejongi and G. loreto. Despite their distinct color patterns and apparent reproductive isolation, the two species could not easily be distinguished using this commonly employed genetic marker. This illustrates an important limitation of DNA barcoding: recently evolved species may still share very similar genetic signatures despite being biologically distinct.
The photographs below show the two better-known Caribbean basslets, the Blackcap Basslet (Gramma melacara) and the Fairy Basslet (Gramma loreto). Unfortunately, Gramma dejongi does not appear in any of my photographs—yet. Finding and photographing this rare Cuban endemic remains a challenge for future dive trips to Cuba.
An interesting question is whether Gramma dejongi is truly restricted to the reefs around Trinidad or whether it occurs more widely in Cuba and has simply been overlooked because of its rarity and similarity to other basslets.
Further Reading
Victor, Benjamin C. & Randall, John E. (2010). "Gramma dejongi, a New Basslet (Perciformes: Grammatidae) from Cuba, a Sympatric Sibling Species of G. loreto"). Zoological Studies. 49 (6): 865–871. S2CID 32152520.