Integrative taxonomy of troglobitic palpigrades: what molecular and morphological evidence can tell us about diversity and endemism of Eukoenenia (Eukoeneniidae: Palpigradi) from south-eastern Brazil

Palpigrades are found across tropical and temperate regions, with several cave-adapted species. In Brazil’s Iron Quadrangle, the troglobitic species Eukoenenia navi, E. eywa, and E. neytiri have been identified. Due to morphological similarities, molecular studies have been recommended to clarify their taxonomic classification. This study describes two new troglobitic palpigrades from the Iron Quadrangle: Eukoenenia renatae Souza and Ferreira sp. nov. and E. piloi Souza and Ferreira sp. nov. Moreover, we investigate the patterns of endemism, genetic diversity, and structuring within the species sampled in the region, incorporating lineage delimitation analyses based on complete mitochondrial genome (mitogenome) and nuclear 45S rDNA sequencing data. The results from the lineage delimitation and phylogenetic analyses based on molecular data identified six short-range troglobitic lineages within a 3,500 km2 area: E. navi, E. neytiri, E. eywa, the two newly described species, and an undescribed taxon. In contrast, genetic evidence showed the presence of a single, highly polymorphic edaphic lineage, E. cf. ferratilis, which has a broader distribution. These findings establish the Iron Quadrangle as a significant hotspot for Eukoenenia diversity. However, ongoing human activities pose threats to these species, underscoring the need to balance conservation with economic development.