Nematognath fish collected during the Macarena expedition

Abstract

This is the second installment in a series giving a systematic account of the nematognathous fishes collected during the Expedition to the Southern Macarena Mountains, January 10th to March 23rd, 1959. As work on this collection has progressed, it has become more and more apparent that the fish fauna of the headwaters of the Guaviare River is of a very special interest, containing many forms that have not been reported from any other part of the world. All in all, our knowledge of the fauna of the Orinoco System and specially of its fishes is still very far from satisfactory, and it is fervently to be hoped that a more thorough and extensive investigation can be initiated as soon as possible, especially of the Colombian part of this immense river system. In this paper, several forms are described as new to science. It is indeed in some cases with a certain reluctance that the author describes for instance a new Pimelodella; but when the material at hand cannot be identified with any species described, there is no other way open. The same is the matter with the small pimelodid catfishes without a free orbital rim. These are certainly in need of a revision, as are many other South American groups of fishes; such an eminent scientist as Professor G. S. Myers, of Stanford University, would like to see the number of genera considerably reduced. The author does not doubt that there are very good reasons for such an opinion, but lacks the very extensive material from most of South America that would be necessary for such an undertaking; until a revision is made and published, the only thing that can be done is to describe as new those forms that do not agree with the definition of any genus hitherto known, in the hope that a detailed description may be of some service to future investigators.