Japanese Journal of Herpetology 11(1): 1-4. 1985.

Karyotype of an Asian Ranid , latopalmatus

Masafumi MATSUI* and Takeshi SETO**

ABSTRACT: The karyotype of a torrential ranid, Staurois latopalmatus from Sabah, Borneo, is analyzed from gutt epithelium. The karyotype is of ancestral ranid type, 26 chromosomes consisting of sharply disjunct 5 large and 8 small pairs.

INTRODUCTION

Recently, Wu and Zhao (1984) reported the karyotypes of Staurois mantzorum and S. liangshanensis from southwestern China. The Staurois, however, is strictly confined to torrential from the Philippines and Borneo (Inger, 1966), and the Chinese treated by Wu and Zhao (1984) should be placed in another ranid genus, (see discussion). In view of this fact, only 4 (liana, Ooeidozyga, Altirana, and Amolops sensu Inger, 1966)) of 12 genera of the family Ranidae from the Asian region (Gorham, 1974) have hitherto been karyologically investigated (Morescalchi, 1973; Kuramoto, 1980; Wu, 1984; Wu and Zhao, 1984). The knowledge of chromosomes from 'real' Staurois, therefore, is still completely lacking. We here report the results of a karyological examination of Staurois latopalmatus (Boulenger, 1887), which is endemic to Borneo.

MATERIAL AND METHODS

A male Staurois latopalmatus was collected from a stream near Kampong Poring, Sabah. In the field, the frog was intraperitoneally injected with 0.1ml of colchicine solution (2mg/ml) per gram of body weight. After 24hr, the was sacrificed and the entire digestive tract was taken out, treated with hypotonic solution, and fixed and stored in Carnoy's solution. Chromosome preparations were made from the intestinal epithelia by the squash method as described by Kezer and Sessions (1979).

* Biological Laboratory, Yoshida College, Kyoto University, Sakyo, Kyoto 606 JAPAN 606京 都市左京区吉田二本松町,京 都大学教養部生物学教室 ** Department of Biology, Faculty of Education, Shimane University, Matsue 690 Japan. 690松 江市,島 根大学教育学部生物学教室

1 2 爬虫両棲類学雑誌

Fig. 1. Karyotype of male, Staurois latopalmatus from Sabah,

Borneo. Scale equals 10μ.

RESULTS

The diploid number was 26, like most other species of the family Ranidae. The karyotype consisted of 5 pairs of large elements and 8 pairs of small homologues (Fig. 1; Table 1). There was a clear dichotomy in the size between large and small pairs. The chromosomes of the large group were characterized by metacentric (Nos. 1 and 4) and submetacentric structure (Nos. 2, 3 and 5). The small group included 3 metacentric (Nos. 6, 9 and 11), 4 submetacentric (Nos. 7, 10, 12 and 13), and 1 subtelocentric pairs (No. 8). No evidence of heteromorphic pairs of chro- mosomes was detected in this male.

DISCUSSION

The genus Staurois has long been misunderstood to contain torrential frogs whose larvae are characterized by a large abdominal sucker (e. g., Liu, 1950; Liu and Hu, 1961). Inger (1966) elucidated the relationships between adult and larval forms of frogs formerly collectively included in the genus Staurois. He thoroughly reviewed the taxonomic history of related genera and split the genus Amolops from Staurois on the basis of differences in larval morphology. The genus Staurois (s. str.) should be confined to three species of torrential frogs occurring in the Philippines and Borneo whose larvae lack a specialized abdominal sucker. By contrast, frogs with a larval form provided with a large abdominal sucker belong to the genus Amolops, which includes many species and has a much wider range, including continental China. Current Chinese authors still confuse these two genera and assign the name Staurois Vol. 11, No. 1, 1985 3

Table 1. Relative length and arm ratio(mean±one standard deviation) of chromosomes of a male Staurois latopalmatus measured on 3 well-spread metaphase plates. Abbreviations for type of chromo- somes are: m=metacentric; sm=submetacentric ; st=subtelocentric.

to frogs with gastromyzophorous larvae. This taxonomic treatment is out of date and the two species of 'Staurois' karyologically investigated by Wu and Zhao (1984) should be regarded as members of Amolops. The diploid chromosome number 2n=26 found in Staurois latopalmatus is a basic diploid number in the family Ranidae (Morescalchi, 1973). This number, as well as two sharply distinct size groups (5 large and 8 small pairs), is regarded as fun- damental and ancestral among the Ranoidea. Of the three known species of the genus Staurois, S. latopalmatus here reported is most distinctive, having peculiarly webbed outer fingers. The species, therefore, has long been placed in a separate genus, Si- momantis, yet no specialized karyotype has been proved even in this distinct species. This suggests that the karyological divergence has occurred inconspicuously in the genus Staurois notwithstanding marked morphological specialization such as distinct transverse grooves on digits. Most of the species in the other three Asian genera of the family Ranidae hitherto karyologically studied (=Seto, 1965, Morescalchi, 1973; Ooeidozyga=Kuramato, 1980; Altirana=Wu, and Zhao, 1984) also possess generalized 26 chromosomes. This is in strong contrast to a marked karyological radiation in the African ranid genera reported by Bogart and Tandy (1981), and the Asian genera seem to be karyologically more conservative than African members. 4 爬虫両棲類学雑誌

ACKNOWLEDGEMENTS

We thank T. Hidaka, Y. Johki, H. Momose and Md. Jaya for kind help in the field survey. The field trip was financed by an Overseas Scientific Research Grant from the Ministry of Education, Science and Culture, Japan. This report is a contribution from the Forest Department of Sabah.

LITERATURE

Bogart, J. P, and Tandy, M. 1981. Chromosome lineages in African ranoid frogs. Monitore Zool. Ital. (N. S.) Suppl. 15: 55-91. Gorham, S. W. 1974. Checklist of world up to January 1, 1970, New Brunswick Museum, Saint John, N. B. 173p. Inger, R. F. 1966. The systematics and zoogeography of the amphibia of Borneo. Fieldiana: Zool. 52: 1- 402. Kezer, J. and Sessions, S. K. 1979. Chromosome variation in the Plethodontid salamander, Aneides ferreus. Chromosoma 71: 65-80. Kuramoto, M. 1980. Karyotypes of several frogs from Korea, Taiwan and the Philippines. Experientia 36: 826-827. Liu, C. -C. 1950. Amphibians of western China. Fieldiana: Zool. Mem. 2: 1-400. Liu, C. -C, and Hu, S. -C. 1961. Chinese Tailless Batrachians. Ka-sue-chu-ban sha, Peking, 364p. Morescalchi, A. 1973. Amphibia. pp. 233-348. In: Chiarelli, A. B. and Capanna, E. (eds.), Cytotaxonomy and Vertebrate Evolution. Academic Press, London and New York. Seto, T. 1965. Cytogenetic studies in lower vertebrates, II Karyological studies of several species of frogs (Ranidae). Cytologia 30: 437-446. Wu, G. 1984. Karyotypes of Scutiger boulengeri (Pelobatidae) of Sichuan and Altirana parkeri (Ranidae) ofXizang. Acta Herpetol. Sinica 3(1): 33-36. Wu, G. and Zhao, E. 1984. Two rare karyotypes of anurans, the karyotypes of Staurois mantzorum and S. liangshanensis. Acta Herpetol. Sinica 3(4): 5-10.

要 旨

ア ジア産 アカガエル科の一種,Staurois latopalmatusの 核型 松井 正 文 ・瀬戸 武司

マレーシア連邦 サバ州(ボ ルネ オ島)産 の渓流性 の ア カ ガ エ ル 科 の一種,Staurois lato- palmatusの 核 型を腸上 皮細胞で調べた。 核型 はアカガエル科の中で祖先 タイプとされ るもの で,は っき りと大 きさの異な る大型5対,小 型8対 の合計2n=26本 の染色体か ら構成 され て いた。