Subfamily Serrasalminae or Family Serrasalmidae?

By Frank Magallanes, OPEFE

Photo (left) demonstrate different body forms of the pirambeba S. rhombeus (top) P. nattereri (bottom). 

INTRODUCTION

The systemic of the Characiformes has long been (and continues to be) a difficult task to undertake. They were recognized as a homogeneous group in 1844 by German ichthyologist's Müller and Trochel. The Viennese Kner and his student Steindachner (between 1858-1915) followed by describing accurately a number of species without paying much attention to the classification. It was not until much later that Carl H. Eigenmann (considered to be the Father of Characoidologist) established the natural classifications of characins from South America. His principal manuscripts were posted between 1910 and 1927. He was then followed by one of his students Dr. George S. Myers. Within recent modern times a series of anatomical studies was completed by S. Weitzman, T. Roberts, and others helped establish the critical position of several groups, which led to the recognition of many families within the suborder (a recognition that would not have been accepted during Eigenmann's time). The research revealed the importance, as well as the complexity, of the Characiformes, and is presently considered as a key-group among teleosts. Included in this huge grouping to be discussed specifically at this website are the Serrasalmin which includes the pacus, silver dollars, pirambebas and of course, the true piranhas. The first authoritative division of the Characoids into several families (16) was done by S. Weitzman, in Greenwood et al. (1966). The French ichthyologist J. Géry (1972) would modify this order in a later manuscript.

Piranha and Pirambeba have distinctive body differences which become apparent as maturity sets in. These differences are the key reason why South American natives call non-true piranhas by other names. It is only outside South America (or S. A. non-fishing city dweller's) that the name "piranha" is loosely applied to all species within the subfamily Serrasalminae.

HISTORICAL IMAGES COURTESY OF ADRIEN LEROY

GENERAL EXPLANATION

The name Serrasalminae means saw-salmon-family the saw or serration pertaining to the scutes (or serrated keel) found on the belly of these fishes. Both carnivorous (single row teeth per jaw) and the vegetarian (double row teeth per jaw) practice mimicry. Perhaps this has much to do with the ecological home they inhabit and survival.

The epithet "piranha" is perhaps the most over used common name on fishes that could not even be scientifically called piranhas. It has been used for Serrasalminae vegetarian fishes and other related forms. In order to properly understand what a piranha is, one must do some research into common names and how they are applied. The Piranha Book, edited by Dr. G. S. Myers, (pg 26, TFH Publications Inc.,1971) covers what the usage of common names should be defined as. I recommend the research student use that reference to understand common name usage.

I frequently use the loose term piranha when I am discussing the "carnivorous" group as a whole, since this is the name more closely associated with the fish. For specifics, I prefer the Brazilian pirambeba for the species not genus Pygocentrus. For the true piranhas placed in genus Pygocentrus I use the epithet Caribe or Piranha. Caribe pertains to the Spanish Venezuelan piranhas but is a much more loose application since many of the piranha-like forms are also called that. But if you get a native fishermen and try to pin him down he will simply distinguish the more innocuous species with another name or the true caribe as caribe. The same holds true for epithet piranha. The native fishermen will give another name for the piranha-like and use the name piranha for the most dangerous ones in genus Pygocentrus. One last thing, native fishermen do not use scientific names in describing their fishes, we do! So we must be careful when attaching a common name to a scientifically described fish.

It has been common practice for biologists, news media and laymen to describe vegetarian fishes (pacus and tambaqui) in the genera Colossoma or Piaractus as belonging to the "piranha family" they are not! Pacus, and piranhas are all members of the Characidae family that hosts well-over 2,000 species of fish. The Characidae family (loosely called tetras) are delineated into groups or subfamilies.

There have been several unsuccessful attempts to split the sub-family into 2 groups; Mylinae (pacus and such) and the Serrasalminae (piranhas and associated forms) during the course of ichthyologic history. Norman (1929) lumped the both groups into one subfamily naming it Serrasalmoninae, but got the spelling wrong (should have been Serrasalminae.) His basis was certain characters found on both species. But the problem was much deeper than simple character assimilation. It was the advent of Phylogenetic and DNA evidence which now prevents such delineation. DnA research has also been used to separate the species with results proving confounding. Some species merged to the surprise of experts. A good case is the species Catoprion mento (the wimple piranha), this species is closest (sister) to Pygocentrus in genetic terms. Ichthyologists over the centuries have kept this particular species separate in its own ranking, but with genetics it puts it closer to the true piranhas. The wimple piranha is a good example of a species having the surname "piranha" while it is NOT a piranha by scientific definition. Most recently, genus Metynnis was discovered to be closely aligned with genus Pygocentrus using Phylogenetic and DNA sequencing.

Other species like P. denticulata , which is a piranha, have unique, specialized teeth which help it remove seed husks, much like a pacu's teeth.

TWO SCIENTIFIC OPPOSING VIEWS REGARDING CLASSIFICATION

JACQUES GÉRY

ANTONIO MACHADO-ALLISON & WILLIAM L. FINK