Karyotypes of Two Species of the Genus Ptychozoon (Gekkonidae: Lacertilia) from Southeast Asia

HIDETOSHI OTA AND TSUTOMU HIKIDA

Abstract: Karyotypes of two Ptychozoon species, P. kuhli and P. lionotum from Southeast Asia are investigated for the first time. The results showed the occurrence of extensive chromosomal differentiation between the two species. Taxonomic implications of the present results are discussed. Key words: Lacertilia; Gekkonidae; Ptychozoon kuhli; Ptychozoon lionotum; Karyotype

During the last decade, Australian and RESULTS American gekkonids have been intensively No sex chromosome heteromorphism was karyotyped, providing fruitful material for evident in each animal. The karyotype of research on the mechanism and the process of P. kuhli consisted of 42 chromosomes in chromosomal evolution in reptiles (Bickham, a graded series. Of these, pairs 1 and 2 were 1984; King, 1981, 1987; McBee et al., 1987). regarded as metacentric and subtelocentric, However, karyological data for geckos from respectively, whereas the remainder were acro- other regions are quite meager. For instance, centric elements (Fig. 1a). Thus, the funda- most of the Asian members have not been mental number (NF) was calculated as 46. On examined yet, or have been examined only with the other hand, P. lionotum had 34 chromosomes the old-fashioned testis-sectioning method which forming two discontinuous size-groups. The may produce wrong data (Gorman, 1973). larger group accommodated six pairs, of which Moreover, species identifications for several pairs 1, 3, 4, 5 and 6 were metacentric, and pair previously karyotyped animals have proved to 2 submetacentric. The smaller group consisted be misleading (Kupriyanova et al., 1989). of 22 acrocentric chromosomes (Fig. 1b). Thus, the accumulation of reliable data for Thus, NF was also 46. oriental gekkonids is an urgent necessity to test the hypotheses proposed on the basis of data DISCUSSION for Australian and American species. In the present study, we investigated karyo- On the basis of a morphological comparison, types of two species of Ptychozoon, a genus Smith (1935) stated that P. lionotum is very endemic to Southeast Asia, for the first time. closely allied to P. kuhli. However, he deferred The results showed the occurrence of extensive the taxonomic conclusion on the validity of the chromosomal differentiation within the genus. former for further detailed studies. Later, Taylor (1963), while noting that they actually MATERIALSAND METHODS resemble each other, listed several external One male of P, kuhli from Sepilok Forest characteristics to differentiate these forms, and Reserve, Sandakan, Sabah, Malaysia, and three regarded each of them as representing a good males of P. lionotum from Thailand (detailed species. The present results indicate the occur- localities unknown; imported by pet dealers) rence of extensive karyological differentiation were karyotyped by bone-marrow air-dry between P. kuhli and P. lionotum, and strongly method following Ota et al. (1987). Each support Taylor's (1963) conclusion. slide was investigated after being stained in 2% From the coincidence in NF value between Giemsa solution for 30 minutes. The karyo- karyotypes of the two species, it seems likely type was determined for each individual on the that the Robertsonian modifications took place basis of more than 15 well-spread cells. in the process of their differentiation. Further Voucher specimens were deposited in the investigations on chromosomes of the other herpetological collection of the Department of three congeners (Wermuth, 1965), as well as Zoology, Kyoto University (P. kuhli: KUZ with advanced banding techniques, are required 8793; P. lionotum: KUZ 8253, 9328 & 9331). to correctly outline the karyological divergence within the genus Ptychozoon. Accepted 24, Sep. 1988 Considerable chromosomal variation among 140 Jpn. J. Herpetol. 12 (4). 1988

Fig. 1. Karyotypes of male Ptychozoon kuhli (a) and male P. lionotum (b). The scale represents 10μm. OTA AND HIKIDA-LIZARD KARYOTYPE 141 closely resembling species or populations have Essays in Honor of M. J. D. White. p. 262-285. been reported for several gekkonid genera from Cambridge University Press, Cambridge. Australia and America (Bickham, 1984; King, KING, M. 1987. Chromosomal evolution in the 1981, 1987; McBee et al., 1987; Moritz, 1987). Diplodactylinae (Gekkonidae: Reptilia). I. Evo- lutionary relationships and patterns of change. The present results indicate that such differenti- Aust. J. Zool. 35 (5): 507-531. ation also exists in the Asian members, and KUPRIYANOVA,L. A., I. S. DAREVSKYAND H. OTA. further demonstrate the high chromosomal 1989. Karyotypic uniformity in East Asian variability of the family Gekkonidae. populations of Hemidactylus frenatus (Sauria: Gekkonidae). J. Herpetol., in press. ACKNOWLEDGMENTS.-Wethank T. Hidaka, M. MCBEE, K., J. W. BICKHAMAND J. R. DIXON. 1987. Ishii, M. Kon, K. Otsuka, S. Furukawa, B. A. Male heterogamety and chromosomal variation Fauziah, R. Goh, R. F. Goh, L. Saikeh, V. Chey, in Caribbean geckos. J. Herpetol. 21 (1): 68-71. and the staff of the entomological section of the MORITZ, C. 1987. Parthenogenesis in the tropical Forest Research Center, Sepilok for providing gekkonid lizard, Nactus arnouxi i (Sauria: Gekko- valuable company and continuous support during nidae). Evolution 41 (6): 1252-1266. the fieldwork in Sabah. This work was partially OTA, H., M. MATSUI, T. HIKIDA AND S. TANAKA. supported by a Grant-in-Aid for Oversea Researches 1987. Karyotype of a gekkonid lizard, Euble- from Japan Ministry of Education, Science and pharis kuroiwae kuroiwae. Experientia 43 (8): Culture (No. 62041049). 924-925. SMITH, M. A. 1935. The Fauna of British India, LITERATURECITED including Ceylon and Burma. Reptilia and BICKHAM, J. W. 1984. Patterns and modes of Amphibia. II.-Sauria. Taylor and Francis, chromosomal evolution in reptiles. In: A. K. London. 440 p.+1 pl. Sharma and A. Sharma (eds.), Chromosomes in TAYLOR, E. H. 1963. The lizards of Thailand. Evolution of Eukaryotic Groups. Vol. 2. p. 13-40. Univ. Kansas Sci. Bull. 44 (14): 687-1077. CRC Press, Florida. WERMUTH, H. 1965. Gekkonidae, Pygopodidae, GORMAN, G. C. 1973. The chromosomes of the Xantusiidae. In: R. Mertens, W. Hennig and Reptilia, a cytotaxonomic interpretation. In: H. Wermuth (eds.), Das Tierreich. Vol. 80. p. i- A. B. Chiarelli and E. Capanna (eds.), Cyto- xxii 246 p. Walter de Gruyter & Co., Berlin. taxonomy and Vertebrate Evolution. p. 349-424. Academic Press, New York. Department of Zoology, Faculty of Science, KING, M. 1981. Chromosome change and speci- Kyoto University, Kitashirakawa-Oiwakecho, ation in lizards. In: W. R. Atchley and D. Sakyo-ku, Kyoto, 606 JAPAN Woodruff (eds.), Evolution and Speciation,

要旨東南アジア産トビヤモリ属(Ptycho- zoon)2種の核型太田英利・疋田努化が生じていることがわかった。今回の結果の東南アジア産トビヤモリ属のPtychozoon 分類学的意義について考察した。 kuhliとP.lionotumの核型を初めて調べた。そ (606京都市左京区北白川追分町京都大学理の結果,これら2種の間に,著しい染色体の分学部動物学教室)