Phylum Arthropoda Typhlatya kakuki:
after Alvarez et al., 2005
Subphylum Crustacea
Class Eumalacostraca
Order Decapoda
Family Atyidae
Typhlatya kakuki
Alvarez, Iliffe and Villalobos, 2005
Taxonomic Characterization: Rostrum unarmed, oriented frontwards, not reaching distal margin of eyes, acuminate in dorsal view. Carapace smooth, devoid of spines; in lateral view, dorsal margin arched, ventral margin almost straight; orbit deeply excavated; anterior margin, from antennal angle to pterygostomian angle, straight; antennal angle slightly produced, pterygostomian angle simple; posterior margin broadly rounded laterally, overlapping first abdominal somite. Depth of carapace similar to that of abdomen. Eyes reduced, with 2 clusters of pigmented granules each. Abdomen smooth. An updated key to the 17 species in the genus is presented in Alvarez, Iliffe and Villalobos (2005).
Disposition of Specimens: Colección Nacional de
Crustáceas, Instituto de Biología, Universidad Nacional
Autónoma de México, catalog numbers CNCR 21791 - 21794.
Ecological Classification: Stygobitic
Size: To 19 mm in total length. Carapace length of males to 6.4 mm; of females to
6.2 mm (Alvarez, Iliffe and Villalobos, 2005).
Number of Species in Genus: Seventeen, all stygobitic
Genus Range:
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Species Range: Collected from two caves: Shrimp Hole and Liza Bay Cave near the southern end of Acklins Island, Bahamas.
Closest Related Species: Typhlatya kakuki is
the first species of the genus to be described from the Bahamas proper, although
T. garciai has been reported from the Caicos Islands, a geographical and
geological continuation of the Bahamian archipelago. Geographically, T.
kakuki could be related to the five known Cuban species, because the island
of Cuba is the closest large land mass to Acklins Island that possesses species of Typhlatya. However,
morphologically, the new species cannot be clearly related to any of them.
Typhlatya consobrina, T. elenae, and T. taina have unpigmented
eyes, and the ischium and merus of pereiopods 3–5 are not fused. Typhlatya
garciai has pigmented eyes and an articulated ischium and merus of
pereiopods 3–5. Typhlatya garciadebrasi has very long carpi of pereiopods 1–2 and a long sixth
abdominal segment (Alvarez, Iliffe
and Villalobos, 2005).
Habitat: Brackish to fully marine cave waters.
Ecology: Liza Bay Cave is a large cave, inhabited by
bats, which contains a series of interconnected rooms and shallow, high-salinity
(34‰) pools. The cave is the type locality for the stygobitic laomediid shrimp
Naushonia manningi. Specimens of
Typhlatya, along with copepods and amphipods, were collected with a plankton
net from a 5 m deep pool in one corner of the cave. The copepods include the
stygobitic epacteriscid
Cryptonectes brachyceratus. Shrimp Hole, located 1 km northeast of Liza
Bay Cave, consists of a 5 m long by 3 m wide and 2 m deep anchialine pool in a
shallow karstic depression completely open to the surface. A cave appeared to
extend off from the main pool as a low crack about a silt bottom. Surface
salinity was 10.5‰, but below a well-defined halocline at 15 cm depth, it
increased to 35‰ at 2 m. Shrimp were very abundant in the water column and on
rock walls and bottom sediments (Alvarez, Iliffe and Villalobos, 2005).
Life History: Of the 11 specimens collected, 7 were females and 4 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 two caves near the southern end of
Acklins Island, Bahamas.
References:
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Contributor: Fernando Alvarez, Universidad Nacional Autónoma de México
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