Doomed before they are described? The need for conservation assessments of cryptic species complexes using an amblyopsid cavefish (Amblyopsidae: Typhlichthys) as a case study

The delimitation of cryptic species and lineages is a common finding of phylogenetic studies. Species previously considered to be of low conservation priority might actually be comprised of multiple lineages with substantially smaller geographic ranges and smaller populations that are of much greater conservation concern and that require different conservation strategies. Cryptic biodiversity is an especially common finding in phylogenetic studies of subterranean fauna; however, most cryptic lineages remain undescribed and have not been subjected to conservation assessments. As many subterranean species are of high conservation concern, the conservation assessment of cryptic lineages is important for developing effective conservation and management strategies. In particular, some lineages might be in need of immediate conservation action even before formal taxonomic description. Here we explore this issue by conducting IUCN Red List and NatureServe conservation assessments on recently discovered cryptic lineages of the southern cavefish (Typhlichthys subterraneus) species complex. We ascertained threats associated with extinction risk, identified priority lineages and populations for immediate conservation efforts, and identified knowledge gaps to expedite the development of conservation and management strategies before formal taxonomic description. Most cryptic lineages are at an elevated risk of extinction, including one lineage classified as “Critically Endangered.” We identified ten threats impacting cavefish lineages that vary in both scope and severity, including groundwater pollution, hydrological changes from impoundments, and over-collection. Our threat assessments and recommendations can be used by stakeholders to prioritize effective and appropriate management initiatives aiding in the conservation of these lineages even before they are formally recognized.