Consensus on the taxonomic system and phylogenetic relationships for the anuran genus Fejervarya has yet to be established. Morphological characters in this genus are generally unsuitable for species identification. To carry out molecular species identification and solve phylogenetic problems, we collected 67 Fejervarya specimens from 12 Asian countries and sequenced part of the mitochondrial (mt) Cytb gene. We also sequenced the mt 12S and 16S rRNA genes and seven nuclear genes (BDNF, CXCR4, NCX1, RAG-1, RAG-2, Rhod, and Tyr) for 25 Fejervarya taxa. These molecular markers appear to be adequate for the identification of species. We subjected the molecular data molecular to phylogenetic analyses. In the resulting trees, topotypic F. limnocharis and "F. multistriata" (from China) formed a clade. On the other hand, neither "F. limnocharis" from the Japan mainland nor "F. limnocharis" from eastern Taiwan formed a clade with the real F. limnocharis, and the genetic divergences were larger than the species threshold for frog taxa proposed in previous studies (> 3% for 16S). These results may suggest that "F. multistriata" is a junior synonym of F. limnocharis, or that only some of the populations now recognized as "F. multistriata" correspond to F. limnocharis. Our results also suggest that several cryptic species may be included among the widely distributed Fejervarya species. Finally, our datasets support paraphyly for the genus Fejervarya, although alternative phylogenetic topologies, including Fejervarya monophyly, were not rejected by KH and SH tests.

To elucidate genetic divergence and evolutionary relationship in Fejervarya cancrivora from Indonesia and other Asian countries, allozyme and molecular analyses were carried out using 131 frogs collected from 24 populations in Indonesia, Thailand, Bangladesh, Malaysia, and the Philippines. In the allozymic survey, seventeen enzymatic loci were examined for 92 frogs from eight representative localities. The results showed that F. cancrivora is subdivided into two main groups, the mangrove type and the large- plus Pelabuhan ratu types. The average Nel's genetic distance between the two groups was 0.535. Molecular phylogenetic trees based on nucleotide sequences of the 16S rRNA and Cyt b genes and constructed with the ML, MP, NJ, and BI methods also showed that the individuals of F. cancrivora analyzed comprised two clades, the mangrove type and the large plus Pelabuhan ratu / Sulawesi types, the latter further split into two subclades, the large type and the Pelabuhan ratu / Sulawesi type. The geographical distribution of individuals of the three F. cancrivora types was examined. Ten Individuals from Bangladesh, Thailand, and the Philippines represented the mangrove type; 34 Individuals from Malaysia and Indonesia represented the large type; and 11 individuals from Indonesia represented the Pelabuhan ratu / Sulawesi type. Average sequence divergences among the three types were 5.78-10.22% for the 16S and 12.88-16.38% for Cyt b. Our results suggest that each of the three types can be regarded as a distinct species.

The rice frog (Fejervarya limnocharis) species complex is widely distributed, from India to Japan, and most prevalently in Southeast Asia. Conspicuous morphological variation has been reported for this species complex throughout its distribution range. In the present study, we used mtDNA gene sequence and allozyme analyses to infer evolutionary affinities within this species complex using eight populations (Sri Lanka; Bangkok and Ranong in Thailand; Taiwan; and Hiroshima, Okinawa, Ishigaki and Iriomote in Japan). We also conducted crossing experiments among four populations from Japan, Thailand, and Sri Lanka in order to find out more about the reproductive isolating mechanisms that might exist among the East, Southeast, and South Asian populations of this species complex. The crossing experiments revealed that the Sri Lanka population is reproductively isolated from the Hiroshima, Bangkok, and Ranong populations by complete hybrid inviability, and that the Bangkok population may be reproductively isolated from the Hiroshima population by partial hybrid inviability. Thus, it is not unreasonable to regard the Sri Lanka population as a species separated from F. limnocharis. The mtDNA and allozyme data showed that the Ranong population is most closely related to the Bangkok population in nuclear genome, but more similar to the Okinawa and Taiwan populations in mtDNA genome. The present, preliminary survey may raise questions about the species status of these particular populations and also about the nature of the biological species concept.

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