Plagioscion is a genus of freshwater ray-finned fishes belonging to the familySciaenidae, the drums and croakers. They are found in tropical and subtropical South America where they inhabit fresh and brackish waters.[2][3] Some species (notably P. squamosissimus and P. surinamensis) are important food fish and support major fisheries.[4]
Depending on the exact species, they reach up to about 30–80 cm (1.0–2.6 ft) in length.[2] In general, the various species are similar and are not easily separated by meristics or colour.[3]
Plagioscion sometimes occur in schools.[4] They are predators and the adults are essentially piscivorous.[2][4] The largest in the genus, P. squamosissimus, mainly feeds on fish smaller than 15 cm (6 in), but may take ones up to about 60% of the length of the Plagioscion itself.[4]
Although the family Sciaenidae primarily is marine, there are four genera with freshwater species in South America. In addition to Plagioscion, this is Pachypops, Pachyurus and Petilipinnis.[3][4]
Plagioscion is a combination of plagio, meaning "oblique", and scion, the modern Greek name of Umbrina cirrosa, which Gill preferred over sciaena because he did not like the sound of Cynosciaena. Gill did not explain what palgio was alluding to but he did mention that the crest and margin of the preoperculum were "oblique, nearly parallel".[8]
Species
FishBase currently recognizes 7 species in this genus.[2] The validity of P. casattii and P. surinamensis are questionable (both possibly junior synonyms of P. squamosissimus).[3] In contrast, genetic analysis indicates that two currently unrecognized, cryptic species exist.[9]
^ abcdeGoulding, M (1980). The Fishes and the Forest: Explorations in Amazonian Natural History. University of California Press. pp. 179–181. ISBN0-520-04131-3.
^Cooke, G.M.; N.L. Chao; L.B. Beheregaray (2012). "Marine incursions, cryptic species and ecological diversification in Amazonia: the biogeographic history of the croaker genus Plagioscion (Sciaenidae)". Journal of Biogeography. 39 (4): 724–738. Bibcode:2012JBiog..39..724C. doi:10.1111/j.1365-2699.2011.02635.x. S2CID54678480.