ON A VERY REMARKABLE FLEA FROM ARGENTINA COLLECTED BY DR. J. M. DE LA BARRERA By H. E. KARL JORDAN (Tring, Herts) With 5 text -figures The rapid increase of our knowledge of the Flea fauna of the Republic of Argentina during recent years is due to Dr. J. M. de la Barrera, Director of the Institute of Hygiene at Buenos Aires, and we students of Siphonaptera in the Tring Department of the British Museum (Natural History) are profoundly grateful to him for the invalu-able collections submitted to the British Museum (Nat. Hist.) for study and report. The latest collection, received in the autumn of 1952, contained, inter alia, a number of interesting species from Bariloche, Nahuel Huapi, Rio Negro, where Dr. de la Barrera has a summer residence. Among these fleas is a species which excels in interest every other new one Dr. de la Barrera has previously discovered. When the specimens were cleared and mounted the very conspicuous and quite unexpected kind of distinction of this species took my breath away, and my two colleagues reacted in the same way : incredible! The Incredible Flea is the subject of this paper. A new species, new genus, new tribe. I name the genus Barreropsylla in appreciation of the great services Dr. de la Barrera has rendered and is continuing to render to the study of Fleas, an order of parasites so closely linked to his researches on the diseases of the wild mammals of his country. I expect that students of Siphonaptera will be as astonished at the somewhat spectacular distinctions of the species as we were, and that the extraordinarily wide gap, in some somatics, between Barreropsylla excelsa and the related species will arouse interest beyond the sphere of Siphonapterology. A short survey of the main characteristics will be sufficient to prove that the species provides an ample field of meditation for the taxonomist and geneticist In evaluating the characteristics of B. excelsa we must bear in mind that the species, apart from its special features, is an American Stephanocircid fitting well into the subfamily of Craneopsyllinae ; there is no doubt about that. Confining the discussion, for the sake of brevity, to four of the obvious distinguishing features of B. excelsa, we can group them into two phylogenetically contrasting categories : (a] Characters ancestral for the Stephanocircidae and (b) characters highly speciali-zed. The first category is exemplified in the postantennal section of the head (usually termed occiput in our writings on fleas) (Fig. 3) : the dorsal margin is medianly somewhat rounded dilated (dt) ; this is an early step in the evolution of a sclerotized band which extends some distance down the side in all other species of the family, Cleopsylla Rothschild, 1914, taking an intermediate position. Similarly primitive ENTOM. Ill, 5. 15
BioStor
