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Phylum Arthropoda
Subphylum Crustacea
Class Eumalacostraca
Order Thermosbaenacea
Family Tulumellidae

Tulumella unidens Bowman & Iliffe, 1988

Taxonomic Characterization:
Unpigmented, blind thermosbaenacean with small but non-functional eyestalks. Telson separate from pleoite 6. Seven pairs of perepods present. Exopod of pereopod 6 1- or 2- segmented. Antenna 2 with scale. Maxilliped of female with or without endopod. Right or both mandibles without lacinia mobilis; molar slender, cylindrical; chewing surface divided into a few slender spiniform teeth (Bowman & Iliffe, 1988).

Ecological Classification: Stygobitic

Size: Length to 3 mm

Number of Species in Genus: Three, all stygobitic

Genus Range:

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Tulumella: genus range

Species Range: Known only from Cenote Najaron, Cenote Temple of Doom, and Cenote Carwash, Tulum, Quintana Roo, Mexico.

Closest Related Species: Both T. unidens and T. grandis from the Bahamas share a long and multi-segmented first antennae, although the latter species is considerably larger.

Habitat: Anchialine limestone caves

Ecology: Three specimens were collected from near the halocline at -10 to -18 m depth. Salinities above and below the halocline at -14 m were 1.5 and 35 ppt, respectively.

Life History: Not known. The 29 specimens of the two Bahamian species reported by Yager (1987) are all females.

Evolutionary Origins: The distribution of thermosbaenaceans with hypogean species in the West Indies, Yucatan, Texas, the Canary Islands, the Mediterranean region, Somalia and Cambodia is taken to indicate a Tethyan origin associated with the breakup of Pangea in post-Jurassic time (Schram, 1986; Cals & Monod, 1988).

Conservation Status: Known from three caves, all within the vicinity of Tulum, Quintana Roo, Mexico.


  • Cals, P. and T. Monod. 1988. Évolution et biogéographie des Crustace´s Thermosbénace´s. Comptes Rendus Hebdomadaires des Seances de l’Academie des Sciences, series 3, 307:341–348.
  • Schram, F. R., 1986: Crustacea. New York, Oxford: Oxford University Press.
  • Bowman, T.E. and T.M. Iliffe. 1988. Tulumella unidens, a new genus and species of thermosbaenacean crustacean from the Yucatan Peninsula, Mexico. Proceedings of the Biological Society of Washington, 101(1): 221-226, 2 figures.
  • Stock, J. H. 1986. Thermosbaenacea. In: Stygofauna Mundi: A Faunistic, Distributional, and Ecological Synthesis of the World Fauna inhabiting Subterranean Waters (including the marine interstitial). L. Botosaneanu (ed.) Leiden, The Netherlands - E.J. Brill / Dr. W. Backhuys.
  • Wagner, H.P. 1994. A monographic review of the Thermosbaenacea (Crustacea: Peracarida): A study on their morphology, taxonomy, phylogeny and biogeography. Zoologische Verhandelingen (Leiden). 291:3-338.


Contributor: Giuseppe L. Pesce, University of L'Aquila, Italy

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