In this review, we include rotifers, copepods, and cladocerans, including other groups not usually deemed as zooplankters: i.e., protists, acari, and large branchiopods. The objectives of this study were to integrate the dispersed literature on the taxonomy and diversity of these freshwater zooplankton groups and to explain (1) how these contributions can be arranged in distinct historical periods and (2) how this knowledge has allowed the detection of exotic and threatened species. We divided the freshwater zooplankton studies in Mexico into three historical periods: the first one comprised the 1840s to the 1940s when foreign researchers carried out most studies during several expeditions. Spanish researchers promoted surveys on different zooplankton taxa at the end of this first period. The second period, from the early 1950s to the end of the 1990s of the XX century, showed a remarkably increased research activity in its last ten years only (that is, during the 1990s to 2000), represented by contributions of a new generation of Mexican zooplanktologists. This period yielded more complete zooplankton listings and detailed morphological descriptions of rotifers, cladocerans, copepods, and large branchiopods. The third period started from the year 2000 to date. During this time, listings and online faunistic baselines based on integrative taxonomy have been the primary trend. An account of exotic zooplankters and conservation issues of several native species are discussed. The results of this review show that the knowledge of the freshwater zooplankton of this country has increased significantly over the last 40 years, with at least 408 first records of species for Mexico. Currently, the knowledge of Mexican freshwater zooplankton is among the most complete in the world. However, it is estimated that only a small fraction of the true diversity has been documented.

Bromeliads are a Neotropical family of monocots, colonized by several families of ciliates, with some species that inhabit only this type of microecosystems. Ecological factors such as the presence of water, plant volume, seasonality and predators, have been recognized as important factors, which play a role in the ciliate community structure in tank bromeliads. The objective of this study is to describe different communities of active ciliates from epiphytic and terrestrial bromeliads that inhabit the dry tropical forest, montane cloud forest, oak forest and semideciduous tropical forest in the Mexican Neotropics during the humid season of the year 2016. We found 22 species of active ciliates. A higher richness of ciliate species was found in the bromeliads of the montane cloud forest. Based on statistical tests, we determine that the pH and water temperature, plant diameter, its distance above the ground and altitude above sea level in relation to ciliate abundance explain <50% of the variation; however, the combination of plant diameter and its distance above the ground shows a positive effect in relation to ciliate abundance. We provide new evidence that bromeliads that inhabit mountains and lowland forests in a larger geographic area host ciliate communities with different species composition.

Species from almost all classes of ciliates are prone to be found inhabiting bromeliads in the Neotropics, from Mexico to Brazil, and the Antilles. Studies of ciliates recorded from bromeliads have been carried out from few bromeliad species, mainly in tropical forest. We compiled all available data of free living and sessile ciliates from bromeliads, including their geographic distribution and bromeliad identity. We provide a list of 170 ciliate species that have been recorded in 52 epiphytic and terrestrial bromeliad species, distributed in ten Neotropical countries . Most of the species belong to the Classes Oligohymenophorea, Colpodea and Spirotrichea. The largest number of ciliate species has been recorded in Brazil and Mexico. Bromeliothrix metopoides and Glaucomides bromelicola were the two species with the widest geographical distribution, 19 species have been recorded only in Mexico, 11 in the Antillean islands, and 89 only in Southamerica. Free living species prevailed over sessile species, and both represent 2% of the total ciliate species number. Sixteen ciliate species have been recorded only inhabiting in bromeliads. Although bromeliads show a high endemicity, their specificity is low in relation to ciliates.

Los manglares son ecosistemas en los que se han documentado comunidades de protistas heterótrofos en el medio acuático, así como sim-biontes de algunas especies de flora y fauna. Dentro de estos protistas se encuentran los ciliados (phylum Ciliophora, en el clado Alveolata). El conocimiento de la biodiversidad de ciliados que habitan en los sedimentos, en la columna de agua, así como simbiontes de algas, plantas y animales en los manglares mexicanos es parcial, si se considera su extensión en los litorales de México. El objetivo del presente trabajo fue compilar, analizar y validar la información taxonómica y de distribución de las especies de ciliados que habitan en los ecosistemas de manglar de México. A partir de una revisión bibliográfica de la literatura disponible hasta la fecha, se documentó un total de 293 especies de ciliados agrupados en 151 géneros desde el año 1967 hasta el año 2022. Las especies registradas se distribuyen en manglares de los estados de Cam-peche, Guerrero, Nayarit, Quintana Roo, Sinaloa, Veracruz y Yucatán. Veracruz con 200 especies, que equivale a 68% del total de especies registradas en el presente estudio, fue la entidad del país en donde se ha documentado la mayor riqueza específica de ciliados en manglares. En cuanto a su forma de vida, se catalogaron como especies de vida libre tanto bentónicas como planctónicas y simbiontes de invertebrados, algas y plantas acuáticas. Se concluye que el conocimiento de las comunidades de ciliados en los manglares mexicanos es aún incompleto.

Ciliophora is extremely diverse and probably the most studied group of heterotrophic protists, with cilia and a nuclear dimorphism (Simpson 2017). Records published in the 1920s identify 1026 species of ciliate protists (Alveolata: Ciliophora) in Mexico (Mayén-Estrada et al. 2020). Up to now, there has been no formal deposit of microscope slides in any collection in the country. The Protozoology Laboratory (at the Department of Comparative Biology in the Faculty of Sciences of the National Autonomous University of Mexico (UNAM) houses ciliate-mounted slides that are the result of research projects and theses since the 1990s. We aim to check the condition and quality of the slides to formalize an institutional collection. To date, we have found slides documenting around 90 ciliate genera, including both free-living species and symbionts, collected in 13 states of the Mexican Republic (Fig. 1). Slides contain representatives of the 11 classes proposed by Lynn (2008), with the genus Vorticella (Class Oligohymenophorea) distributed in 11 Mexican states, and the genus Bresslauides (Class Colpodea) only in one state. The slides were created with several stain and impregnation techniques (Figs 2, 3). Our goal is to inform and share the challenges faced to maintain this collection and achieve its recognition, all while exploring the possibilities of sharing it with the scientific community as part of Mexican natural history and protistological biodiversity.