Discovery of the Costa Rican poison frog Dendrobates granuliferus in sympatry with Dendrobates pumilio, and comments on taxonomic use of skin alkaloids. American Museum novitates ; no. 3144

Abstract

21 p. : ill. (some col.) ; 26 cm.Includes bibliographical references (p. 19-21)."Dendrobates granuliferus, previously thought to be a characteristic endemic of Pacific-side rain forest in the Golfo Dulce region, was found in sympatry with Dendrobates pumilio on the Caribbean coast of southeastern Costa Rica, near the Panamanian border. The sympatric frogs were easily separated by features of coloration and skin texture. Relative abundance in microsympatry was about 100 pumilio:4 granuliferus. Inasmuch as Dendrobates pumilio is sometimes strikingly polymorphic within populations, the initial identifications were tested with bioacoustical, skin-alkaloid, and allozyme data. These comparisons negate the possibility of intrapopulational polymorphism and are consistent with the determination of the rare species as D. granuliferus. Previous inferences that D. granuliferus and D. pumilio are sister species are neither supported nor repudiated by present data. Interpopulational and even individual variation in the skin toxins of these species is extraordinary and probably reflect dietary differences as well as genetic factors. Current knowledge of the dendrobatid alkaloids is briefly reviewed in a systematic context. With a few exceptions, skin chemistry has not been useful in supporting taxonomic differentiation of closely related species. But underlying genetic mechanisms for alkaloid sequestering (and synthesis?) support the monophyly of a suprageneric group of aposematic dendrobatids (tropical poison frogs). Within this group, the monophyly of Phyllobates (true dart-poison frogs) and of Phyllobates + Dendrobates is supported by alkaloid data. The monophyly of Minyobates (dwarf poison frogs) also is corroborated, although in this case the alkaloid character is one of loss and especially in need of further study"--P. [1]-2