Molecular phylogeny reveals a new species of ghost electric knifefish <i>Porotergus</i> Ellis 1912 (Gymnotiformes: Apteronotidae), from the Amazon basin

A new species of ghost electric knifefish, Porotergus sambaibensis sp. nov., is described from the Javaés River, a tributary of the Araguaia River in Brazil. The new species was assigned to the genus Porotergus as the closest relative to Porotergus gimbeli through maximum likelihood reconstruction of a concatenated multilocus dataset. Additionally, the origin of adductor mandibulae, pars stegalis in P. sambaibensis sp. nov. provided further evidence to support the molecular hypothesis. External and internal anatomical characters diagnosed the new species. DNA barcode data were used to test species monophyly and its genetic divergence from other species in the clade. Porotergus sambaibensis sp. nov. is distinguished from its closely related species by the colour pattern of the trunk, dark brown; the lower count of total anal-fin rays, 146-160; the higher number of teeth rows on the dentary, two; the presence of premaxilla teeth; two prominent foramina on dorsal portion of hyomandibula and its distribution pattern; and the second basibranchial, unossified. The genetic divergence between the new species and its relatives ranged from 3.7% in P. gimbeli to 10.3% in Porotergus duende. The species was categorised as deficient data (DD) based on the International Union for Conservation of Nature (IUCN) criteria.