A major revision of the genus Puntius
that contains the barbs of South and SE Asia has been proposed by three ichthyologists in a paper published in the June 2012 edition of the scientific periodical Ichthyological Exploration of Freshwaters
Some of our very well-known aquarium fish are presently classified in this genus; eight are included in our profiles (do a scientific name search for Puntius to list them). This recent study only deals with the species from South Asia, roughly being the Indian subcontinent, but further studies of the SE Asian species will almost certainly occur in the future.
Puntius is what biologists refer to as a catch-all genus, which means that any new species sharing the general characteristics are added with the understanding that future revision may significantly alter their placement. Some 30 newly-discovered species from South Asia alone have been added in the last two decades, and there are 220 nominal species now residing in Puntius, of which 120 are considered valid; 78 of these live on the Indian subcontinent, and are the focus of this study. The characin genera Hyphessobrycon and Hemigrammus are another huge catch-all, with over 200 South American tetra species, and work has begun by various scientists to discipher the characidae family complex bit by bit.
Biologists today have more tools at their disposal than did those during the early and mid-20th century. New fish were then primarily classified on the basis of dentition, fin rays, and internal physiology--and sometimes colouration and pattern entered the description. Present-day scientists use cladistic analysis and chromosomal DNA to determine the ancestry of modern species. Many fish are therefore being reclassified into clades that more accurately represent their evolution. Cladistics comes from the Greek klados, meaning "branch," and is the method of classifying species of organisms into groups called clades that contain one original ancestor and all its direct descendants but nothing else.
The referenced paper proposes five new genera for the South Asian species in Puntius
. As an example, the Black Ruby Barb, Puntius nigrofasciatus, will now be in the new genus Pethia
, the name derived from the generic vernacular name for small cyprinids in Sinhala, one of the languages used in Sri Lanka off the coast of India. This species will in fact be what is called the type species, meaning that it holds all the specific characteristics that will be found in any other species that may be added to this genus from now on; 23 Puntius species are proposed for Pethia
. The species epithet will change to nigrofasciata
in order to agree with the gender (feminine) of the genus name. Other than changing gender to agree with the genus, the first name given to a valid species must remain, as governed by the International Commission on Zoological Nomenclature. The species epithet nigrofasciatus
was originally given to this species by its first describer, Gunther, in 1868. The species was at that time placed in the genus Barbus
, where it lived until being moved to Puntius by Pethiyagoda in 1991, a reclassification suggested previously in 1978 by Taki, et al. [this is mentioned in our profile].
For those interested in reading the scientific paper, here is the link: http://www.pfeil-verlag.de/04biol/pdf/ief23_1_12.pdf
Some may find it interesting to read the various characteristics that separate these fish into distinct individual species.