Phylogenetic Evidence for the Cyphocharax saladensis Clade with Description of a New Species of Cyphocharax Endemic to the Upper Rio Paraguai Basin (Teleostei: Curimatidae)
New genetic and morphological data support the recognition of a distinct monophyletic group, the Cyphocharax saladensis clade, which includes C. vanderi, C. saladensis, C. boiadeiro, and a new species. This four-species group can be recognized by modifications in the laterosensory system with instances of incomplete or interrupted poring, by the ontogenetic development of the lateral line with larger specimens having a more developed laterosensory system, and by the presence of a patch of dark pigmentation over the caudal peduncle. The new species is described from the upper Rio Correntes, an upland tributary of the upper Rio Paraguai in central Brazil and is diagnosed by the presence of a thin longitudinal black stripe, by the variable shapes of the dark blotches on the caudal peduncle, and by morphometric and meristic data. New mitochondrial data from paratypes provide clear evidence of genetic distinction between the new species and congeners, and additionally place it as the sister species to C. boiadeiro from the upper Rio Araguaia. Based on the updated molecular phylogeny and biogeographic information, we propose an evolutionary hypothesis with four events of river captures with subsequent allopatric speciation of the new species and C. boiadeiro in the Correntes and Araguaia systems. The new species is suggested to be categorized as Near Threatened, living in a strongly impacted region of the Brazilian Cerrado. Novos dados morfológicos e genéticos suportam o reconhecimento de um distinto grupo monofilético, o clado Cyphocharax saladensis, que inclui C. vanderi, C. saladensis, C. boiadeiro e uma nova espécie. Esse grupo de quatro espécies pode ser reconhecido pelas modificações no sistema látero-sensorial com séries incompletas ou interrompidas de poros, pelo desenvolvimento ontogenético da linha lateral com espécimes maiores tendo um sistema látero-sensorial mais desenvolvido, e pela presença de uma mácula escura no pedúnculo caudal. A nova espécie é descrita do alto Rio Correntes, um tributário do planalto no alto Rio Paraguai no Brasil central e é diagnosticada pela presença de uma faixa longitudinal fina e escura, pelos formatos variáveis das manchas escuras do pedúnculo caudal e por dados morfométricos e merísticos. Novos dados mitocondriais de parátipos mostram claras evidências de distinção genética entre a nova espécie e os congêneres, e adicionalmente aloca-a como irmã de C. boiadeiro do alto Rio Araguaia. Baseado na filogenia molecular atualizada e informações biogeográficas, nós propomos uma hipótese evolutiva com quatro eventos de capturas de rios com subsequente especiação alopátrica da nova espécie e C. boiadeiro nos sistemas dos rios Correntes e Araguaia. A nova espécie é sugerida como categoria Quase Ameaçada vivendo numa região fortemente impactada do Cerrado brasileiro.
Cyphocharax caboclo, MNRJ 52506, holotype, 59.1 mm SL, Brazil, Mato Grosso, Itiquira, Rio Correntes, upper Rio Paraguai basin.
Color pattern variation in the caudal peduncle of Cyphocharax caboclo, five uncatalogued topotypes ∼40–50 mm SL (A–E), and Cyphocharax boiadeiro, four paratypes ∼20–50 mm SL (F–I).
Topotypes of Cyphocharax caboclo photographed alive, showing color pattern variation in lateral view (A–E). Smaller black dots randomly scattered on the body apparently caused by unknown parasites. Uncatalogued specimens ∼40–50 mm SL. Photographs by L. F. C. Tencatt.
Map of central-southern South America showing the geographic distribution of species of the Cyphocharax saladensis clade. Red stars denote the type locality and additional records of the species in the Rio Correntes, upper Rio Paraguai. Remaining symbols represent museum records of C. boiadeiro in the upper Rio Araguaia (purple circles), C. saladensis in the lower Rio Paraná-Paraguai, Uruguay, and coastal rivers of southern Brazil (black diamonds), and C. vanderi in the upper Rio Paraná (white triangles). Each symbol may represent more than one locality.
Habitats of Cyphocharax caboclo in the Rio Correntes: (A–B) type locality, the Ribeirão Comprido; (C) córrego Ponte do Resolvido; (D) tributary of the córrego Lajeadão. Photographs by L. F. C. Tencatt (A–C) and H. Gimênes (D).
Maximum-likelihood tree of Curimatidae using the multilocus dataset (218 taxa, six loci, 5,358 bp) depicting the Cyphocharax saladensis clade (black dot) and the position of C. caboclo as sister to C. boiadeiro. Numbers at left of nodes represent bootstrap support. See Data Accessibility for tree file.
Pruned maximum-likelihood tree showing internal relationships of the Cyphocharax saladensis clade. Numbers at left of nodes represent bootstrap support. Codes at right of tip names represent museum catalog numbers and voucher specimens. Photographs: C. vanderi, LBP 8116, 69.6 mm SL; C. saladensis, LBP 13164, 51.9 mm SL; C. caboclo, MNRJ 52506, 59.1 mm SL, holotype; C. boiadeiro, LIRP 14133, 42.9 mm SL, holotype. Photographs by B. F. Melo.
Hypothesis of historical biogeography for species of the Cyphocharax saladensis clade highlighting four major river capture events: 1 = Amazon–La Plata; 2 = La Plata–upper Paraná; 3 = La Plata–upper Paraguai; 4 = upper Paraguai–upper Araguaia. Question marks represent unknown relationships and biogeographic histories for putative related species discussed in the text: C. gangamon Rio Tapajós, C. albula Rio São Francisco, and C. jagunco Rio Jequitinhonha.
Contributor Notes
Associate Editor: R. E. Reis.