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Rubens Pasa

  • Biodiversity Journal, 12 (1): 0147-0153

    Francisco de Menezes Cavalcante Sassi, Manolo Fernandes Perez, Marcos Aurélio da Silva, Karine Frehner Kavalco & Rubens Pasa
    Can geometric morphometrics work for species clusterization on the armored catfish Hypostomus Lacépède, 1803 (Siluriformes Loricariidae)?
    https://doi.org/10.31396/Biodiv.Jour.2021.12.1.147.153

    ABSTRACT
    Studies with geometric morphometrics are efficient to clusterize and delimitate fish species. The armored catfish family (Loricariidae) is the second with more species and the Hypostomus genus can be highlighted as the most representative. By that, we present a geometric morphometric analysis in seven Hypostomus species from Paranaíba river basin (Brazil), testing which view for this technique were able to clusterize more efficiently the species. We found that lateral, frontal and ventral views were capable to form species-clusters with few overlaps in the PCA analysis. With the dorsal view overlapping all species, except for Hypostomus nigromaculatus, we consider that this view cannot be used for the geometric morphometric analysis. Hypostomus presents a complex taxonomy, with several cryptic species, and geometric morphometrics can be used as a complementary tool on Hypostomus taxonomy. Therefore, further analyses were required to evaluate the contribution of each landmark in species clusterization.

  • Biodiversity Journal, 11 (4): 0807-0814

    Rosana de Mesquita Alves, Igor Henrique Rodrigues Oliveira, Rubens Pasa & Karine Frehner Kavalco
    A new species of genus Psalidodon Eigenmann, 1911 related to the P.  paranae complex (Characiformes Characidae) from Upper Paranaíba river basin, Brazil, supported by genetic and morphometric data
    https://doi.org/10.31396/Biodiv.Jour.2020.11.4.807.814
    https://www.zoobank.org/References/d67e864a-1fd4-4641-9d8d-bbada5bbfd2d

    ABSTRACT
    The genus Psalidodon Eigenmann, 1911 (Characiformes Characidae) is a fish group with great diversity, expressed at the chromosomal, genetic and taxonomic level. The genus is marked by events of allopatric and vicariant evolution, by the formation of complexes of species and by wide geographical distribution. Both in these fish and other organisms, the association of studies with molecular markers and geometric morphometric techniques are useful in delimiting significantly evolutionary units (ESU). In this work, we performed maximum likelihood estimates (MLE) from mitochondrial Cyt b gene sequences and canonical variables (CVA) from 13 landmarks in eight populations of P. aff. paranae Eigenmann, 1914. The analysis of Maximum likelihood resulted in the structuring of populations in two different clades, one of which was composed only of individuals from a small population inhabiting a stream with approximately two km of length, demonstrating their clear distinction from the other populations. The analysis of canonical variation demonstrated the complete structuring of this population, and the position of each clade in the morpho-space was congruent with the topography observed in the MLE. Based on the results found, the existence of a new endemic species of the genus Psalidodon is evident.

  • Biodiversity Journal, 10 (4): 307-314

    Rubens Pasa, Caroliny Helena Moreira Fernandes, Renan Rodrigues Rocha & Karine Frehner Kavalco
    Distribution and morphological diversity of Astyanax rivularis Lütken, 1874 (Teleostei Characiformes) in the upper São Francisco River basin, Brazil
    https://doi.org/10.31396/Biodiv.Jour.2019.10.4.307.314

    ABSTRACT
    Astyanax S.F. Baird et Girard, 1854 (Teleostei Characiformes) is one of the most well characterized of the neotropical ichthyofauna and is composed of fish with great ability to adapt to different environmental conditions and a wide spectrum of interaction in fish assemblages due to its structure and population density. This study presents the geographical distribution and morphological diversity of Astyanax rivularis Lütken, 1874, a fish historically complex and extremely diverse, in tributary streams of the left side of upper São Francisco River.