Redescription of Corydoras guapore Knaack, 1961 (Siluriformes: Callichthyidae), a midwater Corydoradinae species from the rio Guaporé basin

Abstract

Corydoras guapore was described from the rio Guaporé, Rondônia State, Brazil, based only in three specimens, two of them merely examined alive in an aquarium and apparently not preserved posteriorly. The current location of these two paratypes is uncertain. In the original description, no standard diagnosis was presented and the descriptive information available is scarce and based only in external morphology. Thus, the aim of this study is to provide a redescription of C. guapore based in several topotypes. Corydoras guapore can be distinguished from its congeners by the presence of a short mesethmoid, with the anterior tip poorly developed; posterior margin of pectoral spine with conical serrations directed towards the origin of the spine; and by the lateral portion of caudal peduncle almost entirely blackened. Information about C. guapore ecology and conservation status are also provided.Corydoras guapore foi descrita do rio Guaporé, estado de Rondônia, Brasil, com base em somente três exemplares, sendo dois deles apenas examinados vivos em um aquário e aparentemente não preservados posteriormente. A atual localização desses dois parátipos é incerta. Na descrição original, uma diagnose padrão não foi apresentada e as informações descritivas disponíveis são escassas e baseadas apenas em morfologia externa. Dessa forma, o objetivo desse estudo é fornecer uma redescrição de C. guapore baseada em vários topótipos. Corydoras guapore pode ser distinguida de suas congêneres pela presença de mesetmóide curto, com a extremidade anterior pouco desenvolvida, margem posterior do acúleo peitoral com serrilhas cônicas voltadas em direção à origem do acúleo, e pela porção lateral do pedúnculo caudal quase totalmente enegrecida. Informações sobre a ecologia e status de conservação de C. guapore também são fornecidas.

Redescription of Corydoras undulatus Regan, 1912 (Siluriformes: Callichthyidae), with comments on the identity of Corydoras latus Pearson, 1924

“…[26], obtained Corydoras sensu lato in their phylogenetic analysis as a paraphyletic group composed by seven monophyletic clades. As discussed by Tencatt & Pavanelli [27], one of the most conspicuous groups within Corydoras comprises the species of the lineages 4 and 5, which is basically conformed by Nijssen & Isbrücker’s (1998) “ Corydoras elegans group” species, including C . undulatus , plus C .…”

Corydoras fulleri (Siluriformes: Callichthyidae), a new catfish species from the rio Madeira basin, Peru

“…Convergent colour patterns have apparently played an important part in Corydoradinae evolution, as supported by several studies ( e.g ., Alexandrou et al ., 2011; Britto, 2003; Britto et al ., 2009; Lima & Sazima, 2017; Nijssen & Isbrücker, 1980a, 1980c; Tencatt et al ., 2013, 2019; Tencatt & Britto, 2016; Tencatt & Ohara, 2016a, 2016b; Tencatt & Pavanelli, 2015). While the data gathered by these papers makes it clear that snout shape is one of the most practical ways to differentiate the species with convergent colour patterns, their recognition goes far beyond that.…”

Deconstructing an octogenarian misconception reveals the true Corydoras arcuatus Elwin 1938 (Siluriformes: Callichthyidae) and a new Corydoras species from the Amazon basin

“…Convergence in colour patterns among Corydoradinae has been known for some time (Britto, ; Britto et al, ; Nijssen & Isbrücker, , ) but only recently has a thorough survey identifying convergent taxa across the subfamily been published (Alexandrou et al, ). Since this study, several additional examples of convergent colour patterns in Corydoradinae have been reported (Lima & Sazima, ; Tencatt et al, ; Tencatt & Britto, ; Tencatt & Ohara, , ; Tencatt & Pavanelli, ). These homoplastic colour patterns in Corydoradinae were reported as cases of both Müllerian (Alexandrou et al, ) and Batesian (Lima & Sazima, ) modes of mimicry.…”

“…In the review of Corydoras presented by Nijssen and Isbrücker (1980a), the authors reformulated the groups of species originally proposed by Nijssen (1970), placing C. arcuatus, Corydoras gracilis Among species with homoplastic colour patterns, the snout shape is one of the most important features for distinguishing otherwise cryptic taxa (Alexandrou et al, 2011). However, other morphological traits can also be effective for distinguishing these species, such as the serration pattern on the posterior margin of the pectoral spine and the size of laminar expansions of the infraorbitals (Tencatt et al, 2013;Tencatt & Ohara, 2016a, 2016bTencatt & Pavanelli, 2015). These characteristics explain, for example, how C. gracilis and C. urucu belong to different groups of species despite both having a similar colour pattern and a short, rounded snout.…”