Ostrácodos no-marinos de lagos en el altiplano este-centro de México

Abstract

The ostracode fauna of the neartic-neotropical transitional zone has remained poorly known until this study. Ten ostracode species inhabit ten highland lakes (five maar lakes (phreatic/phreato-magmatic explosion origin), one volcanic-tectonic lake, three natural dams and one man-made dam) in East-central Mexico. Surface sediments from the deepest part and the littoral zone from all studied lakes were collected. Environmental variables (pH, temperature, dissolved oxygen, conductivity, TDS) were measured <em>in situ</em> and parallel water samples for chemical analysis were collected for habitat description. Widely distributed species in the study area (≥5 lakes) include <em>Cypridopsis vidua</em>, <em>Darwinula stevensoni </em>and<em> </em><em>Eucandona </em>cf.<em> patzcuaro. Limnocytherina axalapasco</em> is an endemic species and was collected in three maar lakes and in one man-made dam. Rare species included: <em>Chlamydotheca</em> <em>arcuata</em>?,<em> Fabaeformiscandona acuminata</em>?<em>, Ilyocypris</em> <em>gibba</em>?,<em> Limnocythere friabilis</em>?, <em>Potamocypris smaragdina</em>?<em> </em>and<em> Potamocypris unicaudata</em>?. Highest species richness (6 spp.) was found in the large and shallow Lake Metztitlán (2.6km², 5.5m deep), with the lake water type HCO₃^-&gt;&gt;SO₄^2-&gt;Cl^- -- Ca²⁺&gt;Na⁺&gt;Mg²⁺. The rest of studied lakes (&lt;63m, &lt;27km²) had not more than three species. For instance, only two ostracode species were collected in Lake Alchichica, which is the largest, deepest and most saline studied maar lake.