The cytogenetics of the ornamented pygmy frog (Microhyla fissipes), painted chorus frog (M. pulchra) and narrow-mouthed frog (M. heymonsi) were studied in the aspect of chromosome numbers, morphology and nucleolus organizer region (NOR) locations. For this present study, we provided the karyotype and idiogram of these three species by conventional and Ag-NOR staining techniques. The 10 male and female samples of those three species were collected in Northeast Thailand. The metaphase chromosome preparations were prepared from the bone marrows by the standard protocol. To stain the chromosomes, 10% Giemsa s and 50% silver nitrate were applied. The results showed that all three species had the same diploid chromosome number of 2n=24, and fundamental numbers (NF) were 48 in both males and females. The chromosomes of M. fissipes were comprised of 16m+6sm+XY (X and Y were metacentric chromosomes). M. pulchra had chromosomes consisting of 12m+12sm and M. heymonsi had chromosomes comprising of 18m+6 with no obvious difference in size of sex chromosomes for the two species. M. fissipes and M. pulchra had the same NORs adjacent to the subcentromeric on the long arm of chromosome pair 9, while M. heymonsi had the NOR location on the short arm of chromosome pair 2 close to the centromere. For this case, we suggested that chromosome morphology and the NOR location is still a useful cytological character for taxonomic and evolutionary studies.

SummaryChromosomal relationship between humans and dusky langurs (Trachypithecus obscurus, 2nϭ44) was established by chromosome painting using chromosome specific DNA probes of the human chromosome 1 and 19 which each gave hybridization signals on two non-homologous dusky langur chromosomes. The results show that the human chromosome 1 and 19 probes hybridized to three regions of dusky langur on the autosomes 6 and 8. The human chromosome 1 probe hybridized to one region on the dusky langur chromosome 6 and two regions on the dusky langur chromosome 8, where the human chromosome 19 probe hybridized with the same pattern but on different regions. Hybridization patterns of human painting probes on dusky langur, when compared with the data of other species in the same genus suggest that the alternating hybridization pattern of the conserved segments homologous to human chromosomes 1 and 19 on dusky langur chromosomes 6 and 8 is the result of the translocation followed by the pericentric inversion. Moreover, the present research also indicates that the dusky langur's chromosomes 6 and 8 have the same hybridization patterns as other Asian colobines. Key words Trachypithecus obscurus, Chromosome painting, Reciprocal translocations.The dusky langur (Trachypithecus obscurus) is also called the dusky leaf monkey belongs to the family Cercopithecidae, subfamily Colobinae. There are three groups of colobine monkeys: the colobus monkeys of Africa, the langurs and the odd-nosed monkeys of Asia. T. obscurus is a species of Asian langurs distributed throughout South-east Asia. However, it can be found only in the southern part of Thailand. The classification and taxonomy of colobines has not been yet settled and is subject to continued revisions (Napier and Napier 1967, 1985, Groves 1970, Oates et al. 1984, Vogel and Winkler 1990. For instance, there is no consensus even on the number of genera and species. The dusky langur is either classified in the genus Trachypithecus (Oates et al. 1984) or the genus Presbytis (Napier and Napier 1985). The scheme of Oates et al. (1984) was used as the classification system which put dusky langur into the genus Trachypithecus.In the previous studies using the classical staining, the diploid numbers of both African (genus Colobus) and Asian (genus Presbytis) colobines were demonstrated that they are to be 2nϭ44 (Chiarelli 1963, Ushima et al. 1964. All chromosomes can be divided into two groups; the metacentric and the submetacentric according to their centromeric index, with the exceptions that the Asian langurs have a pair of small acrocentric chromosomes while the African colobines have

Summary Localization of nucleolar organizer regions (NORs) of four gibbon species in Thailand was studied. Blood samples were taken from 1 male each of the following 3 species: white-handed gibbon (Hylobates lar), pileated gibbon (H. pileatus), and white-cheeked gibbon (Nomascus leucogenys): and 1 female of the dark-handed gibbon (H. agilis). These were subjected to standard whole blood T-lymphocyte culture. The samples were harvested by colchicine-hypotonic-fixation-air-drying technique and were followed by the Ag-NOR banding technique. The results showed that the H. lar had NORs on chromosome pair 13 (submetacentric chromosomes) while the H. agilis had NORs on chromosome pair 10 (submetacentric chromosomes) and H. pileatus had NORs on chromosome pair 15 (metacentric chromosomes). In addition, the N. leucogenys showed 5 positions with NORs on chromosomes pairs 23, 24 (acrocentric chromosomes) and the Y-chromosome (submetacentric chromosome). These results are useful to confirm marker chromosomes of gibbons and also comprise basic genetic information for these animals.

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