Urban Spider Assemblages in a Neotropical City: Diversity, Functional Composition, and Introduced Species in Public Parks of Chetumal, Mexico

Urban parks in rapidly expanding tropical cities function as novel ecosystems where habitat filtering, human-mediated dispersal, and management practices can shape arthropod assemblages. Spiders are useful indicators of these processes because they combine high taxonomic diversity, functional heterogeneity, and sensitivity to microhabitat structure. Here, we evaluated whether public urban parks in Chetumal, Mexico, sustain diverse spider assemblages while also showing signals of urban biotic mixing, functional filtering, and detectability biases in citizen-science records. We sampled 20 parks using two daytime techniques, look-up and look-down searching, and compared the results with citizen science observations. In total, we collected 4870 spiders belonging to 27 families, 100 genera, and 167 species. The richest families were Salticidae, Araneidae, and Theridiidae, whereas abundance was mainly driven by Tetragnathidae, Lycosidae, and Oecobiidae, indicating a highly uneven community structure. Inventory completeness was high according to rarefaction and coverage analyses. Nine introduced species were detected, representing about 18% of all individuals, which suggests urban mixing. Only one medically important species, Loxosceles yucatana, was recorded, and it was rare. Spider communities included all major hunting guild strategies, especially orb-web weavers and ground hunters, highlighting the ecological value of urban parks as biodiversity reservoirs in a rapidly urbanizing Neotropical region.