Integrative systematics unveils the controversial identity of Engraulidae fishing stocks in a Neotropical estuary, northeast Brazil

Redescription of Anchoviella cayennensis (Puyo, 1945) (Clupeiformes: Engraulidae), with the synonymization of Anchoviella sanfranciscana Barbosa, Gomes da Silva, da Rocha Araújo & Carvalho, 2017 and remarks on Anchoviella perfasciata (Poey, 1860)

Anchoviella cayennensis (Puyo, 1945) is a relatively small-sized, coastal and estuarine western Atlantic species of anchovy distributed from Suriname to southeastern Brazil. The species is morphologically similar to Anchoviella perfasciata (Poey, 1860) from the Central and western North Atlantic, and it has been suggested in the literature that both are actually synonyms. The recently described Anchoviella sanfranciscana (Barbosa et al., 2017) was reported as endemic to the estuary of the São Francisco River, northeastern Brazil. Most characters proposed as diagnostic for A. sanfranciscana in the description are, however, similar to the ones reported for A. cayennensis and A. perfasciata. To determine the complex taxonomic scenario involving the three species, 24 morphometric and 13 meristic characters of 171 specimens tentatively identified as A. perfasciata (including the holotype) and A. cayennensis from the Central and South Atlantic in addition to the holotype and 19 paratypes of A. sanfranciscana (total: 191 specimens) were analysed. The PCAs of morphometric characters indicate the existence of two groups, which are recognized as A. perfasciata and A. cayennensis, with A. sanfranciscana proposed as a junior synonym of the later. Further evidence from gill arch dentition also indicates that A. perfasciata and A. cayennensis are distinct valid species. A redescription of A. cayennensis is presented, with a neotype proposed for the species. Confirmation of the identity of specimens attributed to A. cayennensis indicates that its southern limit of distribution is in the Rio de Janeiro State, southeastern Brazil. An updated taxonomic key for the estuarine and coastal Atlantic species of Anchoviella is also presented.