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Phylum Arthropoda
Subphylum Crustacea
Class Malacostraca
Order Amphipoda
Family Hadziidae

Tuluweckelia cernua Holsinger, 1990

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Tuluweckelia cernua: after Holsinger, 1990

Taxonomic Characterization: Amphipod without eyes and pigment. Readily distinguished from all other hadziid amphipods by the anterior region of the body, which is bent downward at a sharp angle. Gnathopods are not sexually dimorphic. Lacks basofacial spines on uropod 1 (Holsinger, 1990).

Disposition of Specimen: National Museum of Natural History, Smithsonian Institution, catalog numbers USNM 2553530-1; and Zoölogisch Museum, Amsterdam collection number ZMA Amphipod 108.691.

Ecological Classification: Stygobitic

Size: Adult males are up to 5.0 mm in length, while largest adult females are 8.0 mm

Number of Species in Genus: One

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Tuluweckelia cernua

Species Range: This species is known only from six caves, all anchialine, in the vicinity of Tulum just inland from the northeastern coast of Quintana Roo. The six caves are as follows: Cenote Temple of Doom, Cueva de la Calavera, Cenote Carwash, Cenote Maya Blue, Cenote Mojara and Cenote Najaron.

Closest Related Species: Tuluweckelia belongs to the weckeliid group of Hadziidae that consists of marine relict species inhabiting subterranean freshwaters of south-central Texas, northern Mexico, Yucatan, Cuba, Puerto Rico, and Haiti (Holsinger, 1990). In addition, specimens closely resemble a sister genus Mayaweckelia Holsinger.

Habitat: Anchialine limestone caves

Ecology: Found in fresh to weakly brackish waters of anchialine caves, at depths of 13-26 m, near the northeastern coast of Quintana Roo. Associated fauna include Mayaweckelia cenoticola, cirolanid isopods Bahalana mayana and Creaseriella anops, mysid Antromysis cenotensis, decapod shrimps Typhlatya sp. and Creaseria sp., remipede Speleonectes tulumensis and thermosbaenacean Tulumella unidens (Holsinger, 1990).

Life History: Highly disproportionate sex ratio favoring females. Of the 56 specimens reported by Holsinger (1990), 40 were female, 4 were male and 12 were juveniles. Some larger females had setose brood plates but none was ovigerous (Holsinger, 1990).

Evolutionary Origins: The geographic distribution and ecology of Tuluweckelia suggest that its origin from putative marine ancestors is more recent than that of Mayaweckelia. The colonization of Yucatan Peninsula caves by marine ancestors of Tuluweckelia may be related to the recession of a high sea stand during the Pleistocene (Holsinger, 1990).

Conservation Status: Restricted to anchialine caves in Quintana Roo, Mexico.


  • Holsinger, J.R. 1990. Tuluweckelia cernua, a new genus and species of stygobiont amphipod crustacean (Hadziidae) from anchialine caves on the Yucatan Peninsula in Mexico. Beaufortia, 41(14):97-107, 5 figures.
  • Iliffe, T.M. 1992. An annotated list of the troglobitic anchialine and freshwater cave fauna of Quintana Roo. Pp. 197-215 in: Diversidad Biológica en la Reserva de la Biosfera de Sian Ka'an, Quintana Roo, México, Vol. II, D. Navarro and E. Suárez-Morales, eds., Centro de Investigaciones de Quintana Roo, Chetumal, Q.R., Mexico, 382 pp.


Contributor: John Holsinger, Old Dominion University, Norfolk, VA

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