Be or Not to Be: Aegla schmitti Hobbs III, 1979 - Historical DNA from the Type Series Reveals Cryptic Diversity

Historically, Aegla schmitti has been considered one of the most widely distributed aeglid species in Brazil and classified as “Least Concern” according to the IUCN criteria. Given that recent studies have shown that many aeglids possess restricted distributions, some limited to their type localities, we investigated the taxonomic status of A. schmitti using historical DNA (hDNA) extracted from paratypes. We compared these sequences with historical sequences deposited in GenBank derived from distinct river basins (Ribeira do Iguape and Iguaçu), which have been systematically used as the standard molecular reference for the species by various authors. Phylogenetic via Bayesian inference revealed that the paratypes represent a distinct, monophyletic lineage (Aegla schmitti sensu stricto), whereas sequences historically deposited in GenBank under this name belong to distantly related clades because of taxonomic misidentification. Crucially, the sequences previously attributed to this species represent three distinct, undescribed candidate cryptic species. These results highlight the need for caution when working with groups that potentially form species complexes and when using sequences deposited in GenBank. Furthermore, the conservation status of A. schmitti requires re-evaluation, as the present existence of the topotypic population remains a testable hypothesis requiring urgent field surveys; moreover, the populations currently attributed to A. schmitti, and now recognized as newly discovered cryptic lineages, might be restricted to smaller drainage areas, highlighting the need for extensive field surveys to assess their actual distribution and potential vulnerability to local anthropogenic pressures.