Tuluweckelia cernua Holsinger, 1990
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
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.
Contributor: John Holsinger, Old Dominion University, Norfolk, VA
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