The chromosomes of three odor frogs, Luetuosae- group of Rana were analyzed by conventional, as well as Obanding and silver staining techniques. The three species here examined all had 26 chromosome karyotypes encompassing 5 large and 8 small homologous pairs. Differences among them were found in gross shapes of chromosomes and positions of secondary constrictions. Generally speaking, karyotypes of R. andersonii and R. grahami resembled each other, while the karyotype of R. tiannanensis differed from the former two in several respects.Analyses of karyotypes by C-banding technique indicated that, centromeric areas of every chromosome and interstitial parts of some chromosomes of each species were hetero-chromatinized, and differences of distribution of heterochromatin were found among species. In early metaphase plates of R. andersonii, much more heterochromatinized areas were observed, and when it reached late metaphase, the numbers of heterochromatin sections in each chromosome pair reduced to a limited level, e. g. centromeres and a few interstitial parts.The active nucleolar organizer regions (NORs) were localized in long arms of pair No. 10, in connection with secondary constrictions for R. andersonii and R. grahami as in other odor frogs previously reported, but in the long arm of pair No. 6 for R. tiannanensis.The cytogenetic and taxonomic implications of the findings were discussed based on comparisons with each other, and with published literature.
Allozymes of eleven species of Megophryinae in China were examined electrophoretically to investigate genetic diversity and phylogenetic relationships. Fourteen enzymes, presumptively coded by 24 loci were detected to be variable. Gene frequencies of each population at each locus were presented. The commonly used measure of genetic diversity, the average heterozygosity (H) were calculated based on gene frequencies. The results indicated that Megophryinae had a high level of genetic diversity in amphibians, an average H of 0.18, ranging from 0.058 to 0.28. Nei's (1978) genetic distances(Nei's D) were calculated for all possible population pairs. A dendrogram of 13 populations representing 11 species, 3 genera of Megophryinae were derived and presented by using UPGMA, based on Nei' s D. The assignment of Ophryophryne as a distinct genus were supported by an average Nei's D of 1.4067 which separated O. microstoma from all other populations.Subdivision of Brachytarsophrys from Megophrys was not supported by this study. Within Megophrys, three groups were recognized: (1)M. lateralis, M. giganticus and M. longipes; (2)M. palpebralespineosa, M. boettgeri and M. parva;(3) M. minor and M. kuatunensis. Three populations of M. omeimontis were closely related and share a clade independent from all other Megophrys, and B. feae as well.
