Species delimitation in a range‐restricted group of cascudinhos (Loricariidae: Epactionotus) supports morphological and genetic differentiation across coastal rivers of southern Brazil

Abstract

Epactionotus species are known for inhabiting the rocky-bottom stretches of fastflowing rivers in a limited geographic area along the Atlantic coast of southern Brazil. These species are endemic to single coastal river drainages (two neighbouring drainages for Epactionotus bilineatus) isolated from each other by the coastal lacustrine environments or the Atlantic Ocean. E. bilineatus is from the Maquiné and Três Forquilhas River basins, both tributaries of the Tramandaí River system, whereas E. itaimbezinho is endemic to the Mampituba River drainage and Epactionotus gracilis to the Araranguá River drainage. Recent fieldwork in the Atlantic coastal drainages of southern Brazil revealed new populations in the Urussanga, Tubarão, d'Una and Biguaçu River drainages. Iterative species delimitation using molecular data (cytochrome c oxidase subunit I) and morphology (morphometrics and meristics) was applied to evaluate species recognition of isolated populations. With regard to new data, the genus was re-diagnosed, the status of Epactionotus species/populations was re-evaluated, formerly described species were supported and population structure was recognized. As for the newly discovered populations, both morphological and molecular data strongly support the population from the Biguaçu River drainage, in Santa Catarina State, as a new species. Molecular data revealed strong per-basin population structure, which may be related to species habitat specificity and low or no dispersal among drainages.

A new species of Sturisoma Swainson, 1838 (Loricariidae: Loricariinae), from the Madeira River basin, with a discussion of historical biogeography of western Amazonas and Paraguay River basins

“…According to several authors (e.g., Delapieve et al, 2020;Reis et al, 2021), for Loricariidae and Loricariinae, this value is within the accepted threshold to warrant and support divergence between two lineages.…”

“…lyra from the Juruá River basin (type locality of the species), is between 4.3% and 4.4% (Table 3). According to several authors ( e.g ., Delapieve et al ., 2020; Reis et al ., 2021), for Loricariidae and Loricariinae, this value is within the accepted threshold to warrant and support divergence between two lineages.…”

Ficha de Epactionotus itaimbezinho

“…Dentes acessórios localizados mais internamente e ligados ao osso dérmico formando posteriormente (em pré-maxila) e anterior (no dentário) margens de dentes, que encerram a principal série de dentes bífidos emergentes e pré-emergentes. Dentes acessórios alongados, nitidamente apontados, dirigidos em posição ventral posterior (no pré-maxila) e ventral anterior (no dentário) (Reis & Schaefer, 1998 (Reis & Schaefer, 1998;Abrahão et al, 2015;Delapieve et al, 2020).…”

Ficha de Epactionotus advenus

“…Estados Santa Catarina Biomas Mata Atlântica Bacias Hidrográficas Sub-bacia Litoral SP PR SC Epactionotus advenus é endêmica do Brasil e conhecida apenas do material-tipo coletado no rio Rachadel e um pequeno tributário, drenagem do rio Biguaçu, no estado de Santa Catarina (Delapieve et al, 2020).…”