Sleeper gobies (Eleotridae) are found predominantly in the tropical Indo-Pacific. About 180 species are known and many pass through a planktonic stage in the sea. Some spend their entire lives in the sea but the majority of the adults live in freshwater streams and brackish waters. A few species are troglobitic which means they live in caves all their life.
Our new species, the Oaxaca Cave Sleeper, is one of them and well adapted to the cave environment. It does not have eyes or pigment, but it has a shovel-shaped head and well-developed sensory papillae, which contain its taste buds. It has not been collected or seen in more than 20 years and lives in a cave system threatened by damming.
The species was named after Thomas L. Morris, the discoverer and collector of this new fish. He is a renowned cave diver and speleobiologist, and respected conservationist devoted to the protection of karst habitats.
For the experts: Caecieleotris morrisi, new genus and species of sleeper (family Eleotridae), is described from a submerged freshwater cave in a karst region of the northern portion of the State of Oaxaca, Mexico, Río Papaloapan drainage, Gulf of Mexico basin. The new species represents the first cave-adapted sleeper known from the Western Hemisphere and is one of only 13 stygobitic gobiiforms known worldwide, with all others limited in distribution to the Indo-Pacific region. The new taxon represents a third independent evolution of a hypogean lifestyle in sleepers, the others being two species of Oxyeleotris (O. caeca and O. colasi) from New Guinea and a single species, Bostrychus microphthalmus, from Sulawesi. Caecieleotris morrisi, new species, is distinguished from epigean eleotrids of the Western Atlantic in lacking functional eyes and body pigmentation, as well as having other troglomorphic features. It shares convergent aspects of morphology with cave-dwelling species of Oxyeleotris and B. microphthalmus but differs from those taxa in lacking cephalic pores and head squamation, among other characters. Description of C. morrisi, new species, brings the total number of eleotrid species known from Mexico to 12. Seven of these, including the new species, occur on the Atlantic Slope.