Towards a complete classification of the Neotropical thorny catfishes (Siluriformes: Doradidae)

Abstract

We propose a revised classification of Doradidae based on phylogenetic analyses of sequence data for one nuclear (rag1) and two mitochondrial (co1, 16s) genes, and corroborated by caudal-fin morphology. The molecular dataset comprises 174 doradid specimens representing all 31 valid genera, 83 of the 96 valid extant species and 17 species-level taxa that remain undescribed or nominally unassigned. Parsimony and Bayesian analyses of molecular data support six major lineages of doradids assigned here to three nominal subfamilies (Astrodoradinae, Doradinae, Wertheimerinae) and three new ones (Acanthodoradinae, Agamyxinae, Rhinodoradinae). The maximum parsimony topology of Doradidae was sensitive to ingroup density and outgroup age. With the exceptions of Astrodoradinae and Doradinae, each subfamily is diagnosed by caudal-fin characteristics. The highest degree of fusion among skeletal elements supporting the caudal fin is observed in Acanthodoradinae and Aspredinidae, lineages that are sister to the remaining doradids and aspredinoids (i.e., Auchenipteridae + Doradidae), respectively. Fusion among caudal-fin elements tends to be higher in taxa with rounded, truncate or emarginate tails and such taxa typically occupy shallow, lentic habitats with ample structure. Caudal-fin elements are more separated in taxa with moderately to deeply forked tails that occupy lotic habitats in medium to large river channels.

Karyotype Evolution of Talking Thorny Catfishes Anadoras (Doradidae, Astrodoradinae): A Process Mediated by Structural Rearrangements and Intense Reorganization of Repetitive DNAs

“…According to Takagui et al [2021], the ancestral diploid number for the Doradidae family still remains as an open question, but several lines of evidence support the 2n = 58 chromosomes as a plesiomorphic feature in the family and as the likely ancestral karyotype configuration. Furthermore, this diploid number also occurs in most species of Auchenipteridae [Lui et al, 2009[Lui et al, , 2010[Lui et al, , 2013a[Lui et al, , 2013b[Lui et al, , 2015[Lui et al, , 2021Felicetti et al, 2021;Machado et al, 2021;Santos et al, 2021], the sister group to Doradidae family [Arce et al, 2013;Birindelli, 2014;Sabaj and Arce, 2021].…”

“…Currently, the Doradidae family is considered a monophyletic group by both morphological and molecular approaches, with phylogenetic relationships relatively wellresolved. Six subfamilies are recognized: Wertheimerinae, Astrodoradinae, Doradinae, Achantodoradinae, Agamyxinae, and Rhinodoradinae [Sabaj and Arce, 2021]. The subfamily Astrodoradinae was first proposed by Higuchi et al [2007] and actually comprises 15 species [Fricke and Eschmeyer, 2021] allocated in 6 genera: Anadoras, Amblydoras, Scorpiodoras, Physopyxis, Hypodoras, and Astrodoras [Sabaj and Arce, 2021].…”

“…Six subfamilies are recognized: Wertheimerinae, Astrodoradinae, Doradinae, Achantodoradinae, Agamyxinae, and Rhinodoradinae [Sabaj and Arce, 2021]. The subfamily Astrodoradinae was first proposed by Higuchi et al [2007] and actually comprises 15 species [Fricke and Eschmeyer, 2021] allocated in 6 genera: Anadoras, Amblydoras, Scorpiodoras, Physopyxis, Hypodoras, and Astrodoras [Sabaj and Arce, 2021]. The speckled Anadoras thorny catfishes have a wide geographic distribution, however only 2 species are formally recognized: Anadoras grypus (plus Anadoras insculpitus), which occurs in the Upper and Middle Amazon, from the large Andean tributaries located in Ecuadorian and Peruvian territory to Central Amazonia in Brazil, and Anadoras weddellii (plus Anadoras regani), described from Mamoré, Guaporé, Madeira, Jari, Oiapoque Rivers, Lower Amazon to the Marajo island as well as to the Pantanal basin [Birindelli and Sousa, 2017].…”