Corresponding author: Jozef Grego (
Academic editor: Oana Moldovan
The biospeleological investigations of several cenotes in the eastern region of Yucatán state, Mexico, during January 2018 yielded, among other invertebrates, two new truncatelloid gastropod species described herein as
Grego J, Angyal D, Beltrán LAL (2019) First record of subterranean freshwater gastropods (Mollusca, Gastropoda, Cochliopidae) from the cenotes of Yucatán state. Subterranean Biology 29: 79–88.
The North American stygobiont or phreatic
The studied material was collected during a SCUBA-dive biospeleological field trip during 2–6 January 2018 (Figs
Map of the cenote distribution in the Yucatán state, Mexico with studied localities. The type locality of
Images of cenote Xoch, the type locality of
The scarce shell material obtained by sampling at a depth of 46 m in cenote Xoch near the municipality of Cenotillo contained two subterranean species not resembling hitherto known stygobiont species from Coahuila and San Luis de Potosí and described herein as new to the science.
The diagnostic features of the genus are the same as those of the type species
Named after the country of origin and cenotes, the specific vertical sinkhole karstic formations of Yucatán´s plateau, whose phreatic waters and aquifers host the new genus.
The shell shape of the new species closely resembles subterranean species belonging to family
Mexico, Yucatán state, Cenotillo Municipality, Cenote Xoch, at 46m deep by SCUBA dive, inside cave sediments,
Holotype, Type locality: leg. Angyal and Liévano, 5 Jan. 2017. (
Holotype: H 1.84 mm; W 1.05 mm;
Derived from the type locality in Cenote Xoch, Cenotillo municipality, Yucatán state, Mexico.
The snow-white elongate-conical shell with five rounded slightly convex whorls with a weak suture and a blunt apex. The surface smooth and shiny with very faint, almost invisible, transverse growth lines. Aperture elongate oval, ear-shaped, adapically, separated from the body whorl by a weak furrow. The peristome margin expanded, and its reflexed outline bordered by a slightly corrugated, thin and fragile collar. The columellar lip very slightly wavy in its lateral plane, the outer lip straight. Umbilicus closed and obscured.
The cenote Xoch is a deep vertical cavern (Fig.
Only known from the type locality. Within the type locality the new species was found together with the
Due to absence of molecular and anatomical data, the proposed positioning of the new genus in the family
Compared to the most closely related
Holotype, Type locality: leg. Angyal and Liévano, 5 Jan. 2017. (
Holotype: H 1.58 mm; W 1.56 mm;
Named after renowned malacologist and good friend Fred Thompson from University of Florida, Gainesville, who contributed much to the knowledge of
The milky whitish, translucent conical shell with 3 inflated convex whorls with a deep suture, blunt apex, and flat protoconch. The first teleoconch whorls rapidly expanding, forming a characteristic depressed, sometimes umbilicated appearance. The surface finely lirated, crossed by very fine axial ribs. The spiral lirated sculpture gradually coarsened towards the upper suture of the body whorl, on which the prominent carina-like spiral rib with fine regular conical spines. In some specimens only nodules or only faint knobs present (paratype 1). The body whorl broadened near the aperture. The aperture axially elongated and oval; the columellar peristome reflexed and characteristically sinuated. Umbilicus broad and open.
See
Only known from the type locality. Within the type locality the new species was found together with the
The empty shells of both new taxa were found in organic sediments in the vertical cavern at a depth of 46 m below the water surface. The almost stagnant freshwater at the sampling point would exclude longer transportation of empty shells and accumulation in thanatocoenosis. As the total volume of the phreatic caves under cenote Xoch is huge, additionally the phreatic cave walls surface with bottom floor comprise complicated forms of cave morphology increasing the surface of possible habitats, it is very hard to estimate the exact spot of the true habitat of both minute species within the spread of the cave system. Most likely the new species inhabits the rocky cave surfaces of the cave, feeding on the chemolithotrophic bacterial mats, likely on the blotches with rusty brown, orange or black incrusts layers of oxidation residuals after chemolithotrophic process or on any cave sediments covered by similar layers. We cannot exclude, that the main food could be also exogenous organic plant debris originating on the surface. Nevertheless, to find the site with live specimens of both new species will be rather challenging and more likely depending on luck than knowledge of the habitat.
The first findings of subterranean freshwater gastropod species in the cenote Xoch also indicates the possible larger distribution and diversity of stygobiont gastropods within the remarkable cavernous karstic aquifer of Yucatán. The several hundred kilometers-long cave systems inside the Yucatán carbonate plateau suggest the potential for existence of a very high, so far unexplored, molluscan biodiversity. Due to large cave systems accessible only by SCUBA diving, frequently with complicated logistic of material transport over very long distances, the research of minute cave animals has thus far been nearly impossible. We hope this study will motivate future researches to focus on the study of tiny cave invertebrates inhabiting the freshwater saturated cave labyrinths of the Yucatán Peninsula.
We would like to thank to Anita Eschner and Nesrine Akkari from