Taxonomic Characterization: Body translucent to white, lacking any
pigment. Eyes reduced and without pigment. Rostrum triangular, unarmend, extending anteriorly reaching distal margin of
eyes. Carapace smooth, lacking spines. Abdomen smooth. An updated
key to the 17 species in the genus is presented in Alvarez, Iliffe and
Disposition of Specimens: Colección Nacional de
Crustáceas, Instituto de Biología, Universidad Nacional
Autónoma de México, catalog numbers CNCR 21795, CNCR
21796 and CNCR 21797.
Ecological Classification: Stygobitic
Size: To 24 mm in total length. Carapace length of males to 7.0 mm; of females to 8.2 mm (Alvarez, Iliffe and Villalobos, 2005).
Number of Species in Genus: Seventeen, all stygobitic
Species Range: Collected from three caves: Cenote Cervera, Cenote Dzilamway
and Cenote Buya Uno, near Dzilam de Bravo, Yucatan on the northern Gulf
of Mexico coast of the Yucatan Peninsula.
Closest Related Species: Typhlatya dzilamensis is the fourth species to be described from the Yucatan Peninsula in Mexico. While the ranges of T. mitchelli and T. pearsei overlap considerably over the north central portion of the peninsula, T. dzilamensis appears to be in an area where no other Typhlatya species are present. T. dzilamensis is more similar to T. mitchelli than to the other two Mexican species. However, the two species can be easily distinguished because in T. mitchelli the rostrum is directed upwards, is short, and is acuminate in dorsal view, whereas in T. dzilamensis it is directed frontwards, it reaches the distal margin of the eyes, and is triangular in dorsal view; in T. mitchelli the carpi of pereiopods 1–2 are longer and thinner; and in T. dzilamensis there are three pairs of spines and two pairs of setae on the distal margin of the telson versus two pairs of spines and two pairs of spiniform setae in T. mitchelli (Alvarez, Iliffe and Villalobos, 2005).
Habitat: Fully marine cave waters.
Ecology: Found below the halocline at depths ranging from 10 to 27 m. Collected from bottom sediments and several depressions containing milky, sulfurous waters. Other specimens collected were cirolanid isopods (Creaseriella anops), mysids and thermosbaenaceans (Alvarez, Iliffe and Villalobos, 2005).
Life History: Of the 6 specimens collected 4 were females and 2 males (Alvarez, Iliffe and Villalobos, 2005).
Evolutionary Origins: Of the 17 species in the genus, six (from the Galapagos Islands, Bahamas, Bermuda, Ascension Island, Yucatan and the Caicos Islands) inhabit brackish or marine waters, while the remainder are found in freshwater habitats. According to Iliffe (1986:7), "species within the genus appear to have evolved from an open water marine ancestor in the Atlantic which spread westward through the Caribbean into the Pacific with prevailing currents before the closure of the Panama land bridge." Iliffe et al. (1983) suggested an origin of the genus on submerged and emergent seamounts associated with the Mid-Atlantic Ridge during the separation of the American and African continental masses.
Sanz and Platvoet (1995) believe that the occurrence of the genus in Europe links the origin of the genus Typhlatya to the Tethys Sea. The ancestor was probably a marine, coastal shrimp inhabiting low latitude seas. Maximal development of the ancestral range probably occurred in the Late Cretaceous (about 90 MYA). The full opening of the Atlantic and the end of global Tethyan currents divided its range into three populations: European, Mid-Atlantic Ridge and Central American. Central American populations were further subdivided by plate tectonics into Yucatan, Antilles and Galapagos populations. For unknown reasons, the ancestral marine populations disappeared, leaving only those species that had earlier entered the cave environment. Absence of clear morphological patterns within the recent species may be due to the early timing of isolation between and within lineages.
Conservation Status: Found in only three cenotes on the north central coastline of the Yucatan Peninsula.
Contributor: Fernando Alvarez, Universidad Nacional Autónoma de México
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