Section 8 — Cytatoxonomy and Experimental Taxonomy 



8.30. Cytogenetics of South American Amphibians. 



Francisco A. Saez and Brum de Nadir 

 Zorrilla (Montevideo, Uruguay). 



South American species of amphibia offer a 

 wide scope for investigation due to their a- 

 bundance and their distribution in different 

 regions of the continent. Up to present we have 

 investigated more than 80 species belonging to 

 eight families. 



BUFONIDAE; In eleven species of the genus 

 Bufo the diploid number is 2/7 = 22. CERATO- 

 PHRYDAE; in the genus Odontophrynus numeri- 

 cal diversity was found, six species with 2/7 =22 

 and seven species with 24, 30, 42, 44, 50 and 60 

 somatic chromosomes. The genus Ceratophrys 

 is unique because in the same species C. ornata 

 were found four different numbers, 26, 92, 96 and 

 108 chromosomes. The genus Lepidobatrachus 

 presents 2/? = 30. 



LEPTODACTYLIDAE; eight species of the 

 genus Leptodactylus have 2n=22; three species 

 of Pleurodema, 2« = 22; two species of Physalae- 



mus, 2« = 22; two species of Elogia, 2n = 26; two 

 species of Crossodactylus, 2n=22; three species 

 of Eleutherodactylus, 2/7 = 22; three species of 

 Telmatobius, 2n = 22; Calytocephalella, 2/7 = 26; 

 Throropa, 2/7 = 26; Eusophus,2n = 22; Cycloram- 

 phus, 2/2 = 26; and Pseudopaludicola, 2n = 22. 



PSEUDIDAE; one species of the genus 

 Pseudis has 2/7 = 22. 



HYL/DAE; Fifteen species with 2/z = 24 and 

 one with 30. 



MICROHYLIDAE; one species of Elachis- 

 tocleis with 22 chromosomes. 



BRACHYCEPHALIDAE; two species with 

 2/z = 22 and one with 26. 



RANI DAE; R. pipiens and R. palmipes from 

 Costa Rica and Peru respectively with 26 

 chromosomes. None of the studied species shows 

 cytologically differenciated sex chromosomes. 

 Important problems of evolution, geographical 

 distribution and taxonomy will be dealt with by 

 cytogenetical analysis in a future publication that 

 will appear elsewhere. 



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