Serological Relationships of the Patagonian Toad Bufo variegatus (Gunther)

Abstract

Bufo variegatus is an intriguing South American toad, usually related to the spinulosus group, a southwestern representative of the so-called “narrow- skulled” line of the genus (Blair, 1972), On the other hand it shows some peculiar morphological traits fairly characteristic of the Eurasian calamita group, e.g. its rounded parotoids, laterally allocated on a line which is internal to the edge of the upper eyelid. Geographical distribution and ecological trends of Bufo variegatus are also interesting, this austral anuran being especially related with the Antar- tandic or Valdivian Nothofagus forest, a biocenotic community relic of the Tertiary times. The Antartandic forest is now restricted to the rainy Chilean environments of the Pacific shores, however in the Oligocenic and Miocenic periods it extended through the Patagonian flats, at present a whole desertic area between the Atlantic coast and the early Cordilleran embossments. A remarkable fossil amphibian fauna has been found there (Scarritt Pocket formation, Upper Oligocene: Schaffer, 1949; Chaffee, 1952). This assembles leptodactvloid frogs still existing in the Chilean batrachofauna (Ca- lyptocephalella or Caudiverhera, Eupso- phus) together with some uncertain forms, e.g. Eophractus, and a small toad, also reported as a telmatobiid frog (Lynch, 1971) but probably belonging to the bufonidr calamita-stock from the northern continent (Tihen, 1962; Estes, pers. comm.). The evidence of a Patagonian calamita-like toad in the Cenozoic Nothofagus biocenosis sounds very suggestive, having in mind the above mentioned morphological similarities between the living Bufo calamita from Europe and Bufo variegatus. Ancestral relationships between Bufo variegatus and the Holarctic and Paleotropical toads have been postulated by Gallardo (1962).