The current study adds 23 new records to the previously described monogonot rotifers of Cozumel, increasing the number of reported species to 40; these species are grouped into two orders, 11 families and 18 genera. Littoral and limnetic samples from 17 aquatic systems were examined, including wet dolines, coastal lagoons, temporary pools and artificial systems (reservoirs). Of the 36 species found, the following organisms represent new findings for Cozumel: Anuraeopsisfissa, Brachionusangularis, B.rubens, B.plicatilis sensu lato, Beuchampiellaeudactylota, Euchlanisdilatata, Mytilinabisulcata, Colurellaadriatica, Lepadellaovalis, L.rhomboides, Squatinellamutica, Lecaneaculeata, L.climacois, L.crepida, L.cornuta, L.grandis, L.obtusa, L.pyriformis, Cephalodellaforficula, Scaridiumbostjani, Trichocercapusilla, Polyarthracf.dolichoptera, P.vulgaris, Dicranophorusepicharis and Testudinellapatina. Additional information is reported for these species.

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The spatial distribution of rotifers in the aquatic ecosystems of the Yucatán peninsula is unclear. The peninsula is a karstic platform with heavy anthropogenic activity that presently puts pressure on and increases the fragmentation of aquatic systems. As the distribution of rotifers is unknown in this region, this study was performed to model spatial distribution of rotifers. Based on the analysis of their absence and presence in aquatic systems, using data from specimens collected in the field and bibliographic information from 1997 to 2018, our goal was to provide protection agencies as well as local and regional users with information on the distribution of microorganisms in the aquatic systems. With this material, an 877-record database with was produced. The bioregion outlined is an area in which 45 genera and 140 species of been observed; the study area contains 47.85% of all the rotifer species reported in Mexico. The essential genera in this bioregion are Brachionus with nine species, Keratella with three and Lecane with 44. In these three genera, we observed two morphotypes of rotifers: a small type in the southern zone and a large type in the northern zone.

The genus Lecane is highly diverse, there are 209 species, most of which inhabits tropical aquatic systems. In Quintana Roo 42 species have been reported, one of these is Lecane bulla described at the widest distribution throughout the Yucatan peninsula however; their morphotypes and demographic features are unknown. Therefore, the objective of this work was identify the presence of morphotypes L. bulla and their life history traits. We evaluated life history and morphometric data of females and asexual and sexual eggs from the populations were established from clonal strains, which remained in laboratory conditions for 6 months. They were kept in a bioclimatic chamber with photoperiod of 12 hours of light and 12 hours darkness, at a 25 ± 2 °C, and were feeding with the green algae Nannochloropsis oculata at 1 × 106 cell/ml. Thirty-four clonal strains from six locations were analyzed. Statistical analysis determined significant differences between morphometric measurements (p < 0.001) in the six localities as well as showed statistically significant differences in all demographic parameters. In conclusion, this study indicates the possible coexistence in the same geographical area of two different morphotypes of L. bulla, one is a small-sized distributed in the northwest of Quintana Roo and another large-sized in the southwest.