太田 英利

Mitochondrial DNA (mtDNA) regions corresponding to two major tRNA gene clusters were amplified and sequenced for the Japanese pit viper, himehabu. In one of these clusters, which in most vertebrates characterized to date contains three tightly connected genes for tRNA(Ile), tRNA(Gln), and tRNA(Met), a sequence of approximately 1.3 kb was found to be inserted between the genes for tRNA(Ile) and tRNA(Gln). The insert consists of a control-region-like sequence possessing some conserved sequence blocks, and short flanking sequences which may be folded into tRNA(Pro), tRNA(Phe), and tRNA(Leu) genes. Several other snakes belonging to different families were also found to possess a control-region-like sequence and tRNA(Leu) gene between the tRNA(Ile) and tRNA(Gln) genes. We also sequenced a region surrounded by genes for cytochrome b and 12S rRNA, where the control region and genes for tRNA(Pro) and tRNA(Phe) are normally located in the mtDNAs of most vertebrates. In this region of three examined snakes, a control-region-like sequence exists that is almost completely identical to the one found between the tRNA(Ile) and tRNA(Gln) genes. The mtDNAs of these snakes thus possess two nearly identical control-region-like sequences which are otherwise divergent to a large extent between the species. These results suggest that the duplicate state of the control-region-like sequences has long persisted in snake mtDNAs, possibly since the original insertion of the control-region-like sequence and tRNA(Leu) gene into the tRNA gene cluster, which occurred in the early stage of the divergence of snakes. It is also suggested that the duplicated control-region-like sequences at two distant locations of mtDNA have evolved concertedly by a mechanism such as frequent gene conversion. The secondary structures of the determined tRNA genes point to the operation of simplification pressure on the T psi C arm of snake mitochondrial tRNAs.

Karyotypes of four East and Southeast Asian species of the genus Mabuya and representatives of three arboreal genera considered to be closely related to the genus (Apterygodon, Dasia and Lamprolepis) are examined. Mabuya rugifera and M. rudis possess 2n = 32 karyotypes, whereas M. longicaudata lacks one small chromosome pair, which makes its diploid number 30. The karyotype of M macularia quadrifasciata from southern Thailand differs from any known scincid karyotypes, including a previously reported karyotype of the conspecific Indian population, in exhibiting a high diploid number (38) and a gradual change in size from large to small chromosomes. This suggests that M. macularia may consist of more than one biological species. Karyotypes of Apterygodon vittatus, Dasia olivacea and Lamprolepis smaragdinus, while exhibiting a close similarity to most Mabuya karyotypes, suggest the occurrence of slight rearrangements involving either the deletion of two small chromosome pairs (A. vittatus), or the change of centromeric positions in medium and small chromosomes (D. olivacea and L. smaragdinus).

The batagurid turtle, Mauremys mutica, is widely distributed in tropical to temperate East Asia. Analyses of morphometric characters and coloration revealed that the southern Ryukyu populations of this species are much diverged from the other populations, presumably as a result of their long geographical isolation. We describe those populations as a new subspecies, M. m. kami. Analysis of geographic variation also suggested that distinctly isolated populations of the central and northern Ryukyus, and Kyoto and Shiga Prefectures of central Japan have originated from animals artificially introduced from the Yaeyama Group, and Taiwan, respectively. We confirmed the absence of ''larger female'' sexual size dimorphism (SSD) in M. mutica unlike most other aquatic batagurids, and further demonstrated variation in SSD pattern between the subspecies: in M. m. kami, the adult male has a significantly greater carapace length than adult females, whereas the adult carapace length does not differ significantly between sexes in the nominotypical subspecies. It is hypothesized that these dimorphic patterns evolved from the widely prevailing ''larger female'' condition through epigamic selection involving forcible copulatory behavior.

A new grass lizard, Takydromus toyamai, is described from the Miyako Island Group, Ryukyu Archipelago. The Miyako population has been considered to be conspecific with T. smaragdinus from the Okinawa, Amami, and Tokara Groups of the archipelago, but it is differentiated from populations of these three island groups by having a greater number of ventral rows (eight) and distinctly keeled temporal scales, and in lacking a white ventrolateral line on head and body. The definition of T. smaragdinus is revised accordingly and a lectotype is designated. A dichotomous key is provided for the Japanese and Taiwanese species of the genus Takydromus.

A diploid member of the parthenogenetic grekkonid species complex Hemidactylus garnotii-vietnamensis was discovered for the first time from Thailand. This, gecko, seemingly unisexual and parthenogenetic, possesses 2n = 2x = 38 chromosomes, showing distinct heteromorphisms. The absence of bisexual congeneric species with a combination of karyomorphs to produce this karyotype indicates the occurrence of chromosomal rearrangements after the initial establishment of a diploid clonal lineage of hybrid origin. Results of karyotypic comparisons of the present sample and the three known triploid species belonging to the H. garnotii-vietnamensis complex suggest that a triploid karyomorph similar to that of H. vietnamensis has first emerged through an insemination of the diploid parthenogen's egg by the sperm from a bisexual species having 44 chromosomes (all telocentric), and that the karyomorph subsequently experienced some minor chromosomal aberrations to produce the karyomorphs of H. vietnamensis and H. garnotii. The origin of the H. stejnegeri karyotype still remains an open question for future studies.

Field observations of the sword-tailed newt, Cynops ensicauda popei (Inger 1947), have yielded preliminary data on life-history traits and reproductive behaviour. In April 1993 the animals were abundant in the breeding ponds and on land. Compared to European species of Triturus, this species has an extended breeding season. Few of the observed courtship encounters progressed to the spermatophore transfer phase. Competitive encounters were frequent. The sexual behaviour of Cynops ensicauda popei is characterised by a short duration of display behaviour and a small repertoire of courtship behaviour patterns. The reproductive behaviour is compared to that of related salamandrids.

The karyotype of Platymantis pelewensis Peters, 1867, the only native, endemic amphibian in Belau, extremely isolated from other congeners, consisted of 2n = 22 homologous chromosomes largely forming a graded series. Of these, chromosomes of pairs 1, 5, 6, 8, 10, and 11 were metacentric; the remainder were submetacentric. Secondary constrictions were evident on shorter arms of pair 7. This karyotype is nearly identical with that of P. papuensis Meyer from New Guinea, but is distinct from two Philippine congeners hitherto karyotyped both in chromosome number and morphology. This suggests that the ancestral form of P. pelewensis dispersed from New Guinea or other Melanesian islands.

A reassessment was made for the status of the poorly known Vietnamese gecko, Gekko palmatus Boulenger 1907, by comparing the holotype and additional specimens of the species with those of the closely resembling G. chinensis Gray 1842 from southeastern China. As a result, it was revealed that the two species differ from each other in several characters such as the size of internasal in-relation to supernasal, and snout-vent length (SVL). On the other hand, the holotype and paratype of G. similignum Smith 1923, a species described from Hainan Island but subsequently synonymised to G. chinensis, showed several characteristics such as the greater scale row count at midbody and smaller SVL when compared with G. chinensis. The types also differed from G. palmatus in having internasal as large as or larger than supranasal, smaller SVL and fewer preanal pores. Therefore, the specific name G. similignum was resurrected as valid.

香港産アカガエル科3種の核型を調査した.Amolops hongkongensisは,雌雄とも中部動原体型7対と次中部動原体型6対からなる染色体数2n=26本で,第7番目の対の長腕に二次狭搾をもつ.この種は核型からみて中国西部産の同属諸種よりもA.rickettiに近い。Rana exilispinosaもまた,雌雄とも染色体数2n=26本であるが,中部動原体型は8対,次中部動原体型が5対で,二次狭搾を欠く.核型からみてこの種はR.spinosaとR.shiniに近く,最近提唱されたQuasipaa亜属の妥当性を支持する.Rana lividaもまた,中部動原体型8対,次中部動原体型5対からなる染色体数2n=26本だが,第10番目の対の長腕に二次狭搾をもつ点で安徽省産と異なる.この種は核型からみてEburana亜属よりもOdorrana亜属の種に近いと思われる.

Karyological investigations revealed that populations of the Hemidactylus garnotii-vietnamensis complex in Hong Kong have 2n=3x=63 chromosomes, of which the two largest triplets consist of biarmed, and the third triplet of one subtelocentric and two telocentric chromosomes. This karyotype more or less differs from those of the two known members of the complex from Asia (i.e., H. vietnamensis and H. stejnegeri), and is almost identical to the karyotype of H. garnotii from the Pacific islands. Although there are slight external differences between the Hong Kong and Pacific islands specimens, it seems appropriate to identify the former as H. garnotii (sensu stricto).

Univariate and multivariate analyses were made for two meristic, 15 morphometric, and eight visceral characters of Cyclophiops semicarinatus on the basis of 143 specimens collected from six islands of the Ryukyu Archipelago, Japan. Results of univariate analyses indicate that the number of ventrals shows a statistically significant variation among the samples, and that the body size in Takarajima population is distinctly smaller than those in the other populations. Results of multivariate analyses, on the other hand, suggest that the Takarajima population has diverged from the others in morphometric characters, but closely resembles the Amamioshima population in male and female visceral characters. Considering the high variability of body size and associated allometric characters generally assumed for small insular populations of vertebrates, these results cannot be interpreted as sufficient supports for the previous assumption of the subspecific separation of the Takarajima or any other populations of C. semicarinatus.

Bisexual populations of the gekkonid genus Lepidodactylus from Belau and other Micronesian islands are reviewed taxonomically on the basis of museum and newly collected materials. Specimens from the Ngerukewid Island Group of Belau, having an entire terminal scansor and a few divided or deeply notched subterminal scansors on digits II to V, are distinct from other Micronesian congeneric populations and are assigned to the species group which has previously been known from New Guinea and other Melanesian islands. The Ngerukewid specimens, however, differ from any other members of this species group in several characteristics such as a relatively few body scale rows; and, hence, it is described herein as a new species, Lepidodactylus paurolepis. Remaining specimens from Micronesia, all having a divided terminal scanser on digits II to V, include the parthenogenetic L. lugubris, one bisexual species, and possible hybrids between them. The bisexual form closely resembles L. lugubris and L. aureolineatus from the Philippines but differs from them in having smaller body, characteristic dorsal pattern, and only barely developed lateral serrations on tail. Because the one extant syntype of Gecko moestus Peters, a species first described in 1867 from Belau but subsequently synonymized with L. lugubris, is apparently conspecific with that bisexual form, we designate this specimen as lectotype and resurrect the validity of the species as Lepidodactylus moestus (Peters).

Genetic differentiation and phylogenetic relationships were examined for populations belonging to six species and one subspecies of the latiscutatus species-group of the genus Eumeces from East Asia by use of allozyme data. Results indicate that the population of Kuchinoshima of the northern Ryukyus, formerly assigned to E. latiscutatus, actually belongs to E. marginatus. This suggests the past dispersal of the species over Tokara Tectonic Strait, which is considered to have existed since the Pliocene. Current outlines for the two subspecies of E. marginatus (E. m. marginatus and E. m. oshimensis) were not supported our data strongly suggested that Okinoerabujima and Yoronjima populations, currently assigned to E. m. oshimensis on the basis of color pattern, are actually more closely related to the nominotypical subspecies in the Okinawa Group. The UPGMA phenogram and the Wagner tree obtained from the genetic distance matrices seem to support Hikida's (1993) recently proposed phylogram constructed on the basis of distance matrix of morphological data in confirming the exclusively close relationships between E. okadae and E. latiscutatus, and E. marginatus and E. stimpsonii. © 1994.

The phylogenetic relationships of populations of Goniurosaurus kuroiwae from the Ryukyu Archipelago, Japan, are resolved using a cladistic analysis and their classification modified accordingly. The resultant phylogeny indicates that five subspecies should be recognized: G. k. yamashinae from Kumejima, G. k. orientalis from Tonakijima, Tokashikijima, Akajima, and Iejima, G. k. kuroiwae from Okinawajima, Sesokojima, and Kourijima, G. k. toyamai subsp. nov. from Iheyajima, and G. k. splendens from Tokunoshima. Goniurosaurus k. yamashinae is the sister taxon of the remainder. Goniurosaurus k. kuroiwae and G. k. orientalis are sister taxa which collectively form the sister group to the lineage composed of G. k. toyamai and G. k. splendens. Goniurosaurus k. yamashinae and G. k. orientalis are designated as metataxa because they are not demonstrably monophyletic or paraphyletic. A discriminant function analysis of the five subspecies shows G. k. yamashinae and G. k. splendens are separated from each other and from the other subspecies by a wide morphological gap. All these lineages were recognized as subspecies because this increases the phylogenetic content of the classification. The ancestor of the G. kuroiwae group may have dispersed into the Ryukyu Archipelago from continental China by way of a late Miocene to early Pliocene landbridge. The paleogeography of the Ryukyu Archipelago suggests that differentiation within G. kuroiwae resulted from the formation of the Ryukyu's contemporary configuration caused by rising Pleistocene sea levels.

A population of the triploid gecko, Hemidactylus stejnegeri Ota and Hikida 1989, was found on an off-shore island of Vietnam for the first time. Chromosomal analyses and multivariate analyses of meristic and morphometric characters revealed that Vietnamese populations are slightly but significantly differentiated from the Philippine and Taiwanese populations. The latter two, on the other hand, are poorly differentiated from each other morphologically. Male phenotypes were found in Vietnamese and Taiwanese populations, and their significance is discussed. © 1993 Taylor &amp Francis Group, LLC.

This paper reviews the distribution and variation of each of the six clonal and one bisexual lineages and their hybrids of Lepidodactylus lugubris in French Polynesia and Easter Island. All 20 animals collected from Easter Island were identified as endemic clone F. In French Polynesia, the other five clones (i.e., clones A, B, C, D, and E) were found, of which clone A was most abundant on almost all surveyed islands. Bisexual populations were found only on Scilly, Tupai, Takapoto, and Ua Pou Islands. Hybrid individuals were characterized by the significantly greater body size, whereas clone C showed smaller body when compared with other clones. In the number of postmental scales contacting the first four right infralabials, clone A was most distinctly differentiated from others. Clone F and bisexual lineage, on the other hand, had statistically significantly greater and smaller numbers of fourth toe subdigital lamellae, respectively, than those of the others.

Using starch gel electrophoresis, we examined allozyme variation at 24 presumptive loci in specimens of Tylototriton andersoni collected from three islands of the Ryukyu Archipelago: Amami-Oshima, Tokunoshima, and Okinawajima. Levels of genetic variability within island samples (H = 0.050-0.082, P = 0.21-0.38, A = 1.25-1.58) are within the intrapopulational range previously reported for other salamandrids. The sample from Okinawajima is different from the Amami-Oshima and Tokunoshima samples with Nei's genetic distance (D) of 0.09-0.12, whereas the level of differentiation between the latter two is lower (D = 0.02). This pattern of genetic differentiation within T. andersoni coincides well with the geological history of the three islands.

Geoemyda spengleriの2亜種,スペングラーヤマガメとリュウキュウヤマガメについて,多数の標本に基づく詳細な比較を初めて行った.その結果によれば,両者の間には著しい差異が存在しており,別種として扱うのが適当と思われる.また,近縁種との比較の結果は,両者が単系統群を構成することを示唆している.

Gonocephalus grandis and G. miotympanum have karyotypes consisting of 2N = 42 chromosomes forming two size groups. The smaller group comprises eight metacentric and 12 telocentric microchromosomes, whereas the larger group has 22 metacentric and submetacentric chromosomes. Slight interspecific differences were recognized in the centromeric positions of a few large pairs. These species are karyologically strikingly different from any other agamids including G. spinipes from Australia, and we suggest the possible presence of a zoogeographic dichotomy between Asian and Australian species currently assigned to the genus Gonocephalus.

Cyrtodactylus consobrinus and C. pubisulcus collected from Sarawak, Malaysia, were karyotyped. These species showed distinct intrageneric differentiation in the diploid chromosome number (2n = 48 and 42, respectively). Chromosomal variation was also recognized within C. pubisulcus: animals collected from the eastern part of Sarawak had a pair of subtelocentric chromosomes among telocentric elements. Specimens from the western part lacked the subtelocentric pair, but had a pair of metacentric chromosomes, Furthermore, heteromorphic sex chromosomes (ZW type) were observed in the latter karyotype. Taxonomic and evolutionary implications of the present findings are discussed.