Underexplored Microbiota of Testate Amoeba in Southeast Asian Ecosystems: A Systematic Review and Meta-Analysis

Single-celled protists, such as testate amoebae, have garnered significant attention as potential bioindicators which translate into their recognition of being ecologically sensitive. They are known for their use in ecological and paleoecological studies, yet their diversity and distribution remain poorly documented in blind spot regions of the Paleotropics. This study systematically consolidates all published species records of testate amoebae, evaluates spatial research bias, and assesses regional richness from Southeast Asian countries. A comprehensive literature search was conducted across digital databases and web-based repositories. In total, there are 497 testate amoebae belonging to 70 genera, including infra-specific species from the 46 studies scoped in this review. Species richness curves revealed steep trajectories in under sampled countries, indicating untapped diversity. Despite geographical proximity, the seeming overlap of species per country was limited, pointing toward predominance of species turnover than nested clustering of richness. This disjunct pattern in species composition suggests the influence of potential ecological specialization or, perhaps, a mere result of uneven research effort in the unexplored regions. The research for testate amoebae has been in a progressive state, yet strong emphasis needs addressing species exploration in response to intensified climate change and degradation of habitats as these would mean potential biodiversity loss.