Through a narrow lens: exploring the molecular biodiversity of <i>Paramecium sexaurelia</i> ‐ tropical freshwater ciliate populations from the Palm House of the Jagiellonian University Botanical Garden, Kraków

The biodiversity of protists, which are key players in many ecosystems, remains understudied, particularly in tropical regions. The ciliate Paramecium sexaurelia , a cryptic species within the Paramecium aurelia complex, is typically restricted to warm climates. In this study, we examine the genetic variability of P . sexaurelia populations collected over three years (2016‐2018) from water bodies in the palm houses of the Jagiellonian University Botanical Garden in Kraków. These artificial palm-house environments, which contain tropical plants, may serve as reservoirs for microbial eukaryotes native to warm climates, thereby providing a unique opportunity to study protist diversity outside their native regions. Our molecular analysis revealed a considerable amount of genetic diversity within these populations, as we detected 13 distinct COI haplotypes (Pa6COI ‐ 02, 07, 14‐24). While two haplotypes (Pa6COI_02 and 07) matched previously known sequences, the remaining eleven haplotypes (Pa6COI ‐ 14‐24) were novel to this study, demonstrating the unexplored genetic richness of P . sexaurelia , even in artificial habitats. Given the high genetic diversity and widespread distribution of the species, these results provide valuable insights into its population structure in controlled environments. The presence of P . sexaurelia in a temperate-climate palm house suggests possible plant-mediated introductions, raising intriguing questions about the dispersal and persistence of tropical protists beyond their native ranges. These findings highlight the often-overlooked role of botanical gardens in preserving microbial and eukaryotic diversity, while underscoring the value of such artificial habitats as natural laboratories for studying the biodiversity of tropical protists in non-native settings.