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| Phenacogaster lucenae Souza, Mattox, Vita, Ochoa, Melo & Oliveira, 2023 |
Abstract
Phenacogaster is the most species-rich genus of the subfamily Characinae with 23 valid species broadly distributed in riverine systems of South America. Despite the taxonomic diversity of the genus, little has been advanced about its molecular diversity. A recent molecular phylogeny indicated the presence of undescribed species within Phenacogaster that is formally described here. We sampled 73 specimens of Phenacogaster and sequenced the mitochondrial cytochrome c oxidase subunit I (COI) gene in order to undertake species delimitation analyses and evaluate their intra- and interspecific genetic diversity. The results show the presence of 14 species, 13 of which are valid and one undescribed. The new species is known from the tributaries of the Xingu basin, the Rio das Mortes of the Araguaia basin, and the Rio Teles Pires of the Tapajós basin. It is distinguished by the incomplete lateral line, position of the humeral blotch near the pseudotympanum, and shape of the caudal-peduncle blotch. Meristic data and genetic differentiation relative to other Phenacogaster species represent strong evidence for the recognition of the new species and highlight the occurrence of an additional lineage of P. franciscoensis.
Keywords: Biodiversity, Characinae, mitochondrial DNA, Neotropical freshwater fishes, Phenacogasterini
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| Phenacogaster lucenae A MZUSP 126754, holotype, 26.7 mm SL, Brazil, Pará, Novo Progresso, Xingu basin, stream affluent of Rio Curuá B LBP 30738, paratype, 38.1 mm SL, Brazil, Mato Grosso, Primavera do Leste, Xingu basin, Rio Culuene, Córrego Xavante C LBP 25217, paratype, 30.6 mm SL, Brazil, Pará, Altamira, Xingu basin, Rio Treze de Maio. |
Phenacogaster lucenae sp. nov.
Phenacogaster sp. Xingu: Souza et al. 2022: 9, figs 3, 5
[molecular phylogeny; cited in figures also as Phenacogaster sp. Xingu].
Diagnosis: Phenacogaster lucenae is distinguished from all congeners except P. tegata (Eigenmann, 1911), P. carteri (Norman, 1934), P. napoatilis Lucena & Malabarba, 2010, and P. capitulata Lucena & Malabarba, 2010 by having an incomplete lateral line (vs. complete lateral line). It differs from P. tegata by the presence of a round or slightly longitudinal oval humeral blotch near the pseudotympanum and distant from the vertical through dorsal-fin origin (vs. humeral blotch longitudinally elongated distant from pseudotympanum, closer to vertical through dorsal-fin origin). The new species differs from P. carteri by having a humeral blotch in males and females (vs. absence of humeral blotch in both sexes) and from P. napoatilis and P. capitulata by having a humeral blotch in both sexes (vs. absence of humeral blotch in males). In addition to the incomplete lateral line (vs. complete), P. lucenae differs from P. retropinna Lucena & Malabarba, 2010 by the anal-fin origin at vertical through base of first or second dorsal-fin branched ray (vs. anal-fin origin located posteriorly to that point), and from P. ojitata Lucena & Malabarba, 2010 by the round caudal peduncle blotch slightly reaching over the middle caudal-fin rays (vs. a diamond-shaped caudal peduncle blotch and further extending over the middle caudal-fin rays).
Etymology: Phenacogaster lucenae is named in honor of Dr. Zilda Margarete Seixas de Lucena, an eminent ichthyologist who has significantly contributed to our knowledge of Phenacogaster taxonomy. A noun in genitive case.
Camila S. Souza, George M. T. Mattox, George Vita, Luz E. Ochoa, Bruno F. Melo and Claudio Oliveira. 2023. Molecular Species Delimitation and Description of A New Species of Phenacogaster (Teleostei, Characidae) from the southern Amazon Basin. ZooKeys. 1164: 1-21. DOI: 10.3897/zookeys.1164.102436
