Aspidoras Ihering, 1907

Tencatt, Luiz Fernando Caserta, Britto, Marcelo R., Isbrücker, Isaäc Jan Hendrik & Pavanelli, Carla Simone, 2022, Taxonomy of the armored catfish genus Aspidoras (Siluriformes: Callichthyidae) revisited, with the description of a new species, Neotropical Ichthyology (e 220040) 20 (3), pp. 1-159 : 6-7

Aspidoras Ihering, 1907

Aspidoras Ihering, 1907:30–31 (original description; type species: Aspidoras rochai Ihering, 1907 , by original designation and monotypy). —Nijssen, Isbrücker, 1976:107‒131 (taxonomic review). —Reis, 1998:161 (diagnosis in identification key). — Britto, 2003:144, 146‒147 (phylogeny; diagnosis). —Reis, 2003:291 (listed). —Ferraris, 2007:108 (listed).

Type species. Aspidoras rochai Ihering, 1907 , by original designation and monotypy.

Diagnosis. Aspidoras can be distinguished from Corydoras and Scleromystax by presenting an exclusive feature among Corydoradinae : base of pectoral-fin branched rays with small laminar expansions on its inner margin, generally more evident on first rays; laminar expansions with irregular margins, forming pointed structures, in some specimens (vs. absence). Additionally, Aspidoras can be distinguished from Corydoras and Scleromystax , with exception of Corydoras pauciradiatus , C. lacerdai and S. virgulatus , by having parieto-supraoccipital fontanel (vs. fontanel absent); from C. pauciradiatus , C. lacerdai and S. virgulatus by presenting extremely reduced to moderately developed pectoral-fin spine (vs. relatively well developed).

Sexual dimorphism. Except for the presence of lanceolate genital papillae in males, presented by all Corydoradinae (see Nijssen, Isbrücker, 1980a; Britto, 2003), no other conspicuous sexually dimorphic feature was observed. In aquarium specimens, it was possible to observe that females tend to be slightly larger and more robust than males (Robert McLure, 2020, pers. comm.).

Remarks. All nominal species of Aspidoras and the summarized results of this review are presented in Tab. 1. After the examination of Aspidoras pauciradiatus from the Branco and Negro river basins, it was possible to conclude that, despite the presence of the parieto-supraoccipital fontanel, A. pauciradiatus is more closely related to the Corydoras from the lineage 5 sensu Alexandrou et al. (2011) than to Aspidoras based on the presence of the following features: (I) pectoral-fin spine well developed (vs. spine extremely reduced to moderately developed); (II) eyes conspicuously larger (vs. conspicuously smaller); and (III) base of pectoral-fin branched rays lacking small laminar expansions on its inner margin (vs. laminar expansions present). Therefore, since both morphological and molecular (see Alexandrou et al., 2011: suppl. fig. 2) evidence support the close relationship between A. pauciradiatus and the Corydoras species from the lineage 5, the most reasonable decision is to reallocate this species in Corydoras , as originally proposed by Weitzman, Nijssen (1970).

Calviño, Alonso (2009) provided the description of two species of Corydoras , C. gladysae and C. petracinii , and the redescription of C. micracanthus Regan, 1912 , proposing the “ C. micracanthus group”, which only includes these three species. The authors discussed the morphological similarities between the species from the C. micracanthus group and Aspidoras , such as short ossified portion of dorsal- and pectoral-fin spines and conspicuously slender body (see Calviño, Alonso, 2009:210). However, the authors refuted the possible allocation of these species to Aspidoras , mainly by the absence of the parieto-supraoccipital fontanel, which is present in all Aspidoras . After the examination of C. micracanthus and C. gladysae specimens, it was possible to confirm that these species do not belong to Aspidoras , not only by the absence of the parieto-supraoccipital fontanel but also by lacking the small laminar expansions on bases of first pectoral-fin branched rays, an apparently exclusive feature of the genus.