Molecular identification of a cryptic species in the Amazonian predatory catfish genus Pseudoplatystoma (Bleeker, 1962) from Peru

Abstract

Pseudoplatystoma species are highly prized South American Pimelodid migratory catfishes. Until recently, their taxonomy was not clearly established, with discrepancies between morphological and molecular analyses. Here, Pseudoplatystoma species from the Peruvian Amazon were characterized at the molecular level from a sample representing the observed range of their color pattern variations in the study area. Analyses were performed using seven microsatellite loci for 103 specimens and, for part of them (52), using sequences of two regions of their mitochondrial genome [Cytochrome Oxidase subunit I (COI) and Control Region (CR)]. Factorial correspondence analysis and assignment tests based on microsatellite polymorphism showed that the specimens originally identified as P. punctifer belonged to two different gene pools highly differentiated from P. tigrinum. Morphological examination identified two different morphotypes (with and without black stripes), suggesting the existence of two distinct taxa within P. punctifer. This result was corroborated by the ML tree based on CR sequences, where all individuals but four clustered in a similar way as in the FCA and Bayesian assignment tests. For these four individuals, mitochondrial introgression or retention of ancestral polymorphism was likely. In contrast, the ML tree based on COI sequences showed that reciprocal monophyly was not yet achieved for this marker for the two P. punctifer taxa. The existence of three sympatric species of Pseudoplatystoma in the Peruvian Amazon is discussed in relation to their molecular characteristics, color patterns and ecology. Evolutionary scenarios regarding their divergence are hypothesized.

Ontogeny of the digestive enzyme activity of the Amazonian pimelodid catfish Pseudoplatystoma punctifer (Castelnau, 1855)

“…contradictions between this taxonomic revision and subsequent genetic and morphological studies (García-Dávila et al, 2013;Estivals et al, 2015) make drawing conclusions difficult at the species level. In any case, the aforementioned differences in digestive enzyme activity could be attributed to differences in the rearing conditions and feeding regimes.…”

Length-weight relationships of fish from Madeira River, Brazilian Amazon, before the construction of hydropower plants

“…Growth rates and length–weight relationships have been reported for six species in the Madeira River Basin on the Bolivian side: Prochilodus nigricans (Loubens and Panfili, ), Colossoma macropomum (Loubens and Panfili, ), Pseudoplatystoma fasciatum ( P. punctifer , García‐Dávila et al., ) and P. tigrinum (Loubens and Panfili, ), Piaractus brachypomus (Loubens and Panfili, ), Plagioscion squamosissimus (Loubens, ), Pellona castelnaeana (Le Guennec and Loubens, ); and on the Brazilian side: Pellona castelnaeana (Ikeziri et al., ), Roestes molossus (Torrente‐Vilara et al., ), Brachyplatystoma platynemum and Pinirampus pirinampu (Sant'Anna et al., ), however a complete list of LWRs for most of the Madeira River freshwater fish has not been reported previously.…”

Description of the skeletal anatomy of reared juveniles of Pseudoplatystoma punctifer (Castelnau, 1855) with notes on skeletal anomalies

“…After the Buitrago‐Suárez and Burr () revision, two molecular phylogenies of the genus Pseudoplatystoma revealed no differences between P. punctifer and P. fasciatum (Torrico et al., ; Carvalho‐Costa et al., ). More recently, a molecular study conducted in the region of Iquitos proposed that two different species might exist within the P. punctifer clade, the Guyana sequence of P. fasciatum being nested inside one of the two identified clusters and to which the broodstock used in this study corresponds (García‐Dávila et al., ). In view of the skeletal differences found between the results of the present study and the key to the genus of Buitrago‐Suárez and Burr () further studies on this genus are necessary.…”