Not all cory enthusiasts have accepted the reclassification of the "
Brochis" species. Scientifically officially the genus
Brochis is now considered synonymous with Corydoras. I'll try to explain.
The scientific taxonomy of all species of animal is governed by the International Commission of Zoological Nomenclature (ICZN). [There is a similar process for botanical species too.] There are strict rules governing the scientific name assigned to a species. These are set out in the
Code which is online here:
code.iczn.org
If a proposed change to the nomenclature of a species occurs in a scientific paper/study that complies with the Code, the proposed change occurs with the publication of that study/paper. Subsequent change is still possible, again provided it complies with the Code and scientific evidence.
To the specifics, and here I will copy a summary I prepared a couple of years back.
The Callichthyidae [the name is derived from the Greek
kallis (= beautiful) and
ichthys (= fish)] is a family of catfish (the zoological order Siluriformes). There are two subfamilies, Callichthyinae and Corydoradinae. The latter holds 90% of the species, more than 170 described to date, and this is where we find all the cory-like catfish; until fairly recently, these were classified within one of three genera,
Aspidoras, Brochis and
Corydoras. The name of the genus
Corydoras, which was erected by B.G.E. Lacepede in 1803, is derived from the Greek
cory [= helmet] and
doras [= skin, incorrectly used here for "armour"]; it refers to the dual row of overlapping plates (instead of scales) along the body, comparable to a suit of armour.
With the benefit of DNA this classification has been regarded as needing revision, and in 2003 Dr. Marcello R. Britto proposed one on the basis of his thorough phylogenetic examination of the subfamily.
Britto (2003) resurrected the genus
Scleromystax and moved three cory species (
C. barbatus, C. macropterus, C. prionotos) into it. [Planet Catfish today lists eleven species in this genus; two are actually synonymous,* five are new and as yet undescribed (being identified by a “C” number), and one is
C. lacerdai which is still accepted in Corydoras.] These species constitute a monophyletic clade, and are thus a distinct genus. Britto also revised the two tribes of the subfamily Corydoradinae. The tribe Aspidoradini, previously constituted only by the genus
Aspidoras, is composed of
Aspidoras and
Scleromystax; the species in these two genera share traits not shared by any
Corydoras. The tribe Corydoradini, which previously included the genera
Brochis and
Corydoras, is now composed only of the genus
Corydoras.
The anatomical differences that previously separated the three
Brochis species [
Brochis splendens (the Emerald “Cory”),
B. britskii and
B. multiradiatus] from
Corydoras are no longer considered sufficient to create a distinct genus given the phylogenetic analysis. These “Brochis” species belong to a clade shared by four
Corydoras species, namely
C. aeneus, C. zygatus, C. rabauti and
C. eques . Britto (2003) consequently effected the synonymization* of
Brochis with
Corydoras. Ferraris (2007) followed this and moved the three
Brochis species into
Corydoras, and thus they are now known as
Corydoras splendens, C. britskii and
C. multiradiatus respectively. This classification has been accepted as valid in the California Academy of Sciences database [
Eschmeyer's Catalog of Fishes] and Fishbase.
Britto determined that the species in
Corydoras, of which Fishbase lists 158 described to date (2015), were not monophyletic and he proposed a number of taxonomic changes to this subfamily that results in nine clades, i.e., nine different genera. The afore-mentioned genus
Scleromystax is one of these clades.
Subsequent ichthyological studies on new described corydoradidae species [Shimabukuro-Dias, Oliveira & Foresti 2004; Britto, Lima & Hidalgo 2007; Britto, Wosiacki & Montag 2009; Tencatt, Vera-Alcaraz, Britto & Pavanelli 2013; Barriga Salazar 2014; Sarmiento et al. 2014; Tencatt et al. 2014; Tencatt & Pavanelli 2015; Tencatt & Evers 2016; Tencatt & Ohara 2016; Tencatt et al. 2016; DoNascimiento et al. 2017] have concurred with Britto’s basic proposal. If you search any of the species in
Eschmeyer's Catalog of Fishes you will find references to all these studies.
Alexandrou & Taylor (2011) followed Britto’s concept and have also proposed substantial revisions which include the described species and all known undescribed “C” species: “It is clear from the molecular phylogeny that the Corydoradinae are in need of taxonomic revision. The need for this revision has been recognized for some time (Isbrucker, 2001), although it is only now that the genetic relationships among species are clear, allowing species to be grouped into phylogenetically meaningful and monophyletic groups. Here we present suggestions for revision of Corydoradinae (both formally described and undescribed taxa). This is intended as an outline proposal for a future taxonomic revision, and does NOT represent a formal revision. All species should continue to be referred to as
Corydoras, Aspidoras or
Scleromystax until a thorough peer-reviewed revision incorporating both morphological and genetic data has been published.”
This paper is available online for no charge [see link below]. Aside from the ichthyological propositions, this study provides a comprehensive discussion around the mimicry we find in so many of the cory species. The section headed “Ecology of the Corydoradinae” is well worth a read for those wishing to explore this mimicry.
Definitions
A
taxon (plural taxa) is a group of organisms given a formal taxonomic name, such as a species, a genus (which is a group of one or more species that share specific traits that are unique to those species within the genus) and a family (the genus or group of genera that share other unique characteristics that make them distinct from all others).
A
monophyletic (sometimes holophyletic)
taxon is one that includes the most recent common ancestor of a group of organisms, and all of its descendants; a monophyletic group constitutes a clade. A
paraphyletic taxon is one that includes the most recent common ancestor, but not all of its descendants. And a polyphyletic taxon is one that does not include the common ancestor of all members of the taxon.
Mimicry is the similarity between two species, which may be in appearance, behaviours, etc.
*
synonymous, synonymization: The scientific classification of all animal life on earth is governed by the Code of the International Commission of Zoological Nomenclature. Except in rare cases where other factors prevent it, the name assigned to any species must be the first name given to that species as a distinct taxon. When the genus name of a species must be changed according to new understanding, and the genus species are to be included with species from another genus, the oldest genus name predominates, and the discarded name is termed a synonym.
References
Alexandrou, Markos A. and Martin I. Taylor (2011), “Evolution, Ecology and Taxonomy of the Corydoradinae Revisited,” online at
http://www.academia.edu/5890874/Evolution_ecology_and_taxonomy_of_the_Corydoradinae_revisited
Britto, M. R. (2003) “Phylogeny of the subfamily Corydoradinae Hoedeman, 1952 (Siluriformes: Callichthyidae), with a definition of its genera,”
Proceedings of the Academy of Natural Sciences of Philadelphia, volume 153, pp. 119-154. An abstract is online:
A phylogenetic hypothesis of relationships within the callichthyid subfamily Corydoradinae is proposed based on 83 characters. The monophyly of the subfamily is well supported, as are those of two included genera, Aspidoras and Brochis. However, the monophyly of Corydoras, as traditionally...
www.bioone.org
Eschmeyer's Catalog of Fishes, online:
Ferraris, C.J.Jr, (2007), “Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types,”
Zootaxa, No. 1418, pp. 1-628. Online:
http://www.mapress.com/zootaxa/2007f/zt01418p300.pdf
