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

Matsui, Masafumi

Ota, Hidetoshi

Pacific Science

ScholarSpace at University of Hawai'i at Manoa

Pacific Science (1995), vol. 49, no. 3: 296-300© 1995 by University of Hawai'i Press. All rights reservedKaryotype of a Ranid Frog, Platymantis pelewensis, from Belau, Micronesia,with Comments on Its Systematic Implications lHmETOSHI OTA2 AND MASAFUMI MATSUI3ABSTRACT: The karyotype of Platymantis pelewensis Peters, 1867, the onlynative, 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 I, 5, 6, 8, 10, and II were metacentric; the re-mainder were submetacentric. Secondary constrictions were evident on shorterarms of pair 7. This karyotype is nearly identical with that of P. papuensisMeyer from New Guinea, but is distinct from two Philippine congeners hithertokaryotyped both in chromosome number and morphology. This suggests thatthe ancestral form of P. pelewensis dispersed from New Guinea or other Mela-nesian islands.THE RANID GENUS Platymantis Gunther con-sists of 37 species distributed in the Philip-pines, Belau (Pelew or Palau), Melanesia(including New Guinea), and western Poly-nesia (Frost 1985, but see Zhao and Adler[1993] for the status of Chinese species as-signed to the genus). The range of the genusis characteristic of that of most other Aus-tralasian frog genera in that it spreads ontovarious oceanic islands (see above) (Inger1954, Darlington 1957, Gorham 1965). It isgenerally supposed that species currently iso-lated on such islands represent past multipleoverseas dispersals and subsequent specia-tions (Brown 1965, Tyler 1979, Gibbons 1985).Gibbons (1985) further surmised that thehighly specialized mode of reproduction inthe genus, involving the direct developmentof embryos (Atoda 1949, Brown and Alcala1982a), has been especially advantageous inthe process of its colonization of oceanicislands.However, there has been little informationregarding the process of divergence amongI This research was partially supported by a Grant-in-Aid from the Japan Ministry of Education, Science, andCulture (A-05740523 to H.O.). Manuscript accepted 27July 1994.2 Department of Biology, University of the Ryukyus,Nishihara, Okinawa 903-01, Japan.3 Graduate School of Human and EnvironmentalStudies, Kyoto University, Yoshida Nihonmatsu-cho,Sakyo-ku, Kyoto 606-01, Japan.Platymantis species: origins and relationshipsespecially of a few, isolated species remainunknown. Of these, P. pelewensis Peters,1867, the only native and endemic amphibianspecies of Belau, western Micronesia, is oneof the most poorly studied species despiteits great biogeographical interest. We haveexamined the karyotype of P. pelewensis forthe first time and discuss its phylogeneticand biogeographical relationships with othercongeneric species from the cytotaxonomicstandpoint.MATERIALS AND METHODSTwo males were collected from NgergoiIsland, ca. 27 km SW of Coror Island, andwere taken live to the laboratory, where theywere injected with colchicine solution (0.1mgjrnl) in their femoral muscles at 0.1 rnljgbody weight. They were sacrificed about 10 hrafter the injection. Bone marrow, extractedfrom the femurs, was subjected to hypotonictreatment in KCI solution (0.05 mol/liter)for 40 min and then rinsed and fixed in Cal-nois's solution (glacial acetic acid: methanol,I : 3). The cell slides, prepared by the air-drymethod, were soaked in 3% Giemsa solutionfor 30 min and then were investigated micro-scopically and photographed. The karyotypewas determined on the basis of five well-spread metaphase cells for each individual.The arm length of each chromosome was296- 414'#W;Karyotype of Platymantis pelewensis-OTA AND MATSUI 297measured on the photoprint using an ironstring. Terminology for chromosomal de-scriptions follows Green et al. (1980). Voucherspecimens were deposited in the amphi-bian collection of the Graduate School ofHuman and Environmental Studies, KyotoUniversity, Kyoto, Japan.RESULTS AND DISCUSSIONBoth males had a karyotype consisting of2n = 22 homologous chromosomes largelyforming a graded series. Of these, the chro-mosomes composing pairs 1, 5, 8, 10, and 11exhibited arm ratios smaller than 1.70 andhence were classified as metacentric. Theremainder exhibited ratios ranging from1.79 (pair 6) to 2.44 and were classified assubmetacentric. Secondary constrictions wereevident on shorter arms of pair 7 (Figure 1,Table 1).Of the 37 valid species of the genus Platy-mantis, only three, P. hazelae (Taylor) and P.dorsalis (Dumeril) from the Philippines, andP. papuensis Meyer from New Guinea, havehitherto been karyotyped (Kuramoto 1985).The karyotype of P. pelewensis is distinctlydifferentiated from those of the two Phil-ippine species both in the chromosome num-ber (P. hazelae has 26 chromosomes and P.dorsalis has 20 chromosomes) and in mor-phology. However, it closely resembles thekaryotype of P. papuensis (2n = 22), fromwhich it differs slightly by having pair 6submetacentric (arm ratio = 1.79) insteadof metacentric (arm ratio = 1.60), and sec-ondary constrictions in pair 7 (Table 1).Platymantis pelewensis was first describedas P. plicifera var. Pelewensis by Peters(1867), who briefly stated that it differs fromP. plicifera Gunther from the Philippines(subsequently designated a synonym of P.corrugatus [Dumeril] by Inger [1954]) only inthe lateral head coloration. However, Inger(1954), on the basis of far more detailedmorphological comparisons, considered thatthe species is most closely related to P.meyeri Gunther from the Philippines (laterdesignated a synonym of P. dorsalis byBrown and Inger [1964]) and P. papuensisand P. rubristriatus (Barbour) from NewGuinea (P. rubristriatus was designated asynonym of P. papuensis by Zweifel [1969]).Gorham (1965), although basically acceptingInger's (1954) account, considered that P.pelewensis is more closely related to P. dor-salis than to P. papuensis on the basis ofmorphological similarity. Since Inger's (1954)work, five species have been added to thegenus from the Philippines, but because oftheir distinct morphological divergencesand specializations (see Brown and Alcala[1963, 1974, 1982b] for further details), Inger's(1954) and Gorham's (1965) assumption ofthe closest affinity of P. dorsalis with P. pele-wensis among the Philippine species appearsstill valid.1728394105116FIGURE I. Karyotype of male Platymantis pelewensis from Belau. Bar equals 10 /lm. Arrows indicate positions ofsecondary constrictions on pair 7.TABLE 1CHROMOSOMAL COMPARISONS OF Platymantis pelewensis WIIH OnmR CONGENERIC SPECIES HIrnERTO KARYOTYPEDSPECIES(LOCALITY: DIPLOID NO.)P. pelewensis P. papuensis P. dorsalis P. hazelae(BELAU: 22) (NEW GUINEA: 22) (PHILIPPINES: 20) (PHILIPPINES: 26)PAIR RELATIVE ARM RELATIVE ARM RELATIVE ARM RELATIVE ARMNO. LENGlH RATIO TYPE LENGlH RATIO TYPE LENGlH RATIO TYPE LENGlH RATIO TYPE1 16.1 ± 0.18 1.27 ± 0.03 m 16.0 ± 0.16 1.26 ± 0.01 m 17.4 ± 0.36 1.08 ± 0.01 m 15.6 ± 0.24 1.27 ± 0.02 m2 12.8 ± 0.19 1.90 ± 0.03 sm 13.2 ± 0.13 1.89 ± 0.03 sm 13.0 ± 0.21 4.19 ± 0.27 st 12.9 ± 0.18 1.70 ± 0.03 sm3 11.7 ± 0.12 2.25 ± 0.07 sm 11.6 ± 0.13 2.27 ± 0.06 sm 12.3 ± 0.13 1.27 ± 0.03 m 11.2 ± 0.26 2.17 ± 0.03 sm4 11.3 ± 0.21 1.95 ± 0.05 sm 11.3 ± 0.14 1.90 ± 0.05 sm 11.6 ± 0.17 2.77 ± 0.10 sm 10.8 ± 0.12 1.83 ± 0.05 sm5 10.4 ± 0.20 1.35 ± 0.02 m 10.2 ± 0.10 1.38 ± 0.02 m 10.1 ± 0.15 1.25 ± 0.03 m 9.9 ± 0.09 1.33 ± 0.02 m6 9.6 ± 0.08 1.79 ± 0.04 sm 9.1 ± 0.06 1.60 ± 0.03 m 8.6 ± 0.14 1.12 ± 0.02 m 5.8 ± 0.12 1.33 ± 0.03 m7 7.1 ± 0.08 2.44 ± 0.11 sm· 7.6 ± 0.10 1.89 ± 0.05 sm 7.8 ± 0.10 1.15 ± 0.04 m 5.7 ± 0.12 2.40 ± 0.06 sm8 5.8 ± 0.16 1.56 ± 0.05 m 5.9 ± 0.08 1.61 ± 0.04 m 7.3 ± 0.11 1.12 ± 0.02 m 5.3 ± 0.08 1.33 ± 0.04 m9 5.5 ± 0.13 1.96 ± 0.06 sm 5.3 ± 0.07 2.08 ± 0.04 sm 6.8 ± 0.16 1.22 ± 0.05 m 5.0 ± 0.09 2.31 ± 0.08 sm10 5.1 ± 0.12 1.48 ± 0.08 m 5.2 ± 0.07 1.42 ± 0.03 m 5.1 ± 0.13 1.14 ± 0.02 m 4.9 ± 0.08 1.26 ± 0.03 m11 4.5 ± 0.09 1.28 ± 0.03 m 4.5 ± 0.05 1.26 ± 0.02 m 4.7 ± 0.08 1.20 ± 0.05 m12 4.5 ± 0.09 1.24 ± 0.04 m13 3.8 ± 0.09 2.99 ± 0.15 smNOTE: Data presented as means ± SE. Abbreviations: m, sm, and st represent metacentric, submetacentric, and subtelocentric chromosomes, respectively. Data for P. papuensis,P. dorsalis, and P. hazelae from Kuramoto (1985).'With secondary constrictions on shorter arms.Karyotype of Platymantis pelewensis-OTA AND MATSUI 299Our comparisons have revealed that P.pelewensis resembles P. papuensis much moreclosely than P. dorsalis chromosomally. Kura-moto (1985) assumed that karyotypes of P.papuensis and P. dorsalis represent two dif-ferently specialized conditions derived fromthe 2n = 26 karyomorph represented by thekaryotype of P. hazelae. He pointed out thatthe karyotype of P. papuensis could have de-rived merely by centric fusion and pericentricinversion, whereas that of P. dorsalis wouldhave been involved in more complicatedchromosomal rearrangements. If this as-sumption is accepted, close chromosomalsimilarity of P. palawensis with P. papuensisbut not with P. dorsalis can be interpreted asindicative of the closer phylogenetic relation-ships of the former two species.Tyler (1979), in discussing historical rela-tionships of Platymantis species in the easternOriental and Pacific regions, provided a sche-matic figure (i.e., fig. 4 : 4) indicating that theancestral form of P. pelewensis had dispersedfrom the Philippines, presumably on the basisof Gorham's (1965) account (see above).However, our results seem to indicate thatthe ancestor of P. pelewensis actually dis-persed from New Guinea or adjacent Mela-nesian islands, similar to ancestors of somereptilian species in Belau (Ota et aI. 1995).Further chromosomal surveys and phylo-genetic analyses of Platymantis species areneeded to verify our hypothesis.ACKNOWLEDGMENTSH.O. is grateful to M. Ota for helping withthe fieldwork in Belau, to M. Toda for labo-ratory assistance, and to R. I. Crombie forliterature.LITERATURE CITEDATODA, K. 1949. Metamorphosis of the"non-aquatic frog" of the Palau Islands,western Carolines. Pac. Sci. 4(2): 202-207.BROWN, W. C. 1965. New frogs of the genusCornufer (Ranidae) from the SolomonIslands. Breviora (218): 1-16.- ,../"" ,BROWN, W. C., and A. C. ALCALA. 1963. Anew frog of the genus Cornufer (Ranidae)with notes on other amphibians knownfrom Bohol Island, Philippines. Copeia1963: 672-675.---. 1974. New frogs of the genus Platy-mantis (Ranidae) from the Philippines.Occas. Pap. Calif. Acad. Sci. (113): 1-12.---. 1982a. Modes of reproduction ofPhilippine anurans. Pages 416-428 inA. G. J. Rhodin and K. Miyata, eds. Ad-vances in herpetology and evolutionarybiology. Harvard University, Cambridge,Massachusetts.---. 1982b. A new cave Platymantis(Amphibia: Ranidae) from the PhilippineIslands. Proc. BioI. Soc. Wash. 95: 386-391.BROWN, W. C., AND R. F. INGER. 1964. Thetaxonomic status of the frog Cornuferdorsalis A. DumeriI. Copeia 1964: 450-451.DARLINGTON, P. J., JR. 1957. Zoogeography.John Wiley & Sons, New York.FROST, D. R., ED. 1985. Amphibian species ofthe world: A taxonomic and geographicalreference. Allen Press, Lawrence, Kansas.GmBoNs, J. R. H. 1985. The biogeographyand evolution of Pacific island reptiles andamphibians. Pages 125-142 in G. Grigg,R. Shine, and H. Ehmann, eds. Biology ofAustralasian frogs and reptiles. SurreyBeatty & Sons, Sydney.GORHAM, S. W. 1965. Fiji frogs (with syn-opses of the genera Cornufer and Platy-mantis). ZooI. Beitr. 25: 381-424.GREEN, D. M., J. P. BOGART, E. H. AN-THONY, AND D. L. GENNER. 1980. An in-teractive, microcomputer-based karyotypeanalysis system for phylogenetic cytotax-onomy. Comput. BioI. Med. 10:219-227.INGER, R. F. 1954. Systematics and zoogeog-raphy of Philippine Amphibia. FieldianaZooI. 33: 183-531.KURAMOTO, M. 1985. Karyological diver-gence in three platymantine frogs, familyRanidae. Amphib.-Reptilia 6: 355-361.OTA, H., R. N. FISHER, I. INEICH, AND T. J.CASE. 1995. Geckos of the genus Lep-idodactylus in Micronesia: Description ofa new species, and reevaluation of the sta-300tus of Gecko moestus Peters, 1867. Copeia.1995: 183-195.PETERS, W. 1867. Herpetologische Notizen.Monatsber. Akad. Wiss. Berl. 1867: 13-37.TYLER, M. J. 1979. Herpetofaunal relation-ships of South America with Australia.Pages 73-106 in W. E. Duellman,ed. TheSouth American herpetofauna: Its origin,PACIFIC SCIENCE, Volume 49, July 1995evolution, and dispersal. Univ. Kans.Mus. Nat. Hist. Monogr. 7.ZHAO, E.-M., and K. ADLER. 1993. Herpe-tology of China. Contrib. Herpetol. (10):1-522.ZWEIFEL, R. G. 1969. Frogs of the genusPlatymantis (Ranidae) in New Guinea,with the description of a new species. Am.Mus. Novit. (2374): 1-19.

Karyotype of a Ranid Frog, Platymantis pelewensis, from Belau, Micronesia, with Comments on Its Systematic Implications

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

OTA, HIDETOSHI

MATSUI, MASAFUMI

Kyoto University Research Information Repository

TitleKaryotype of a Ranid Frog, Platymantis pelewensis, fromBelau, Micronesia, with Comments on Its SystematicImplicationsAuthor(s)OTA, HIDETOSHI; MATSUI, MASAFUMICitationPacific Science (1995), 49(3): 296-300Issue Date1995-07URL http://hdl.handle.net/2433/216882Right© 1995 by University of Hawai'i Press. All rights reservedType Journal ArticleTextversionpublisherKyoto UniversityPacific Science (1995), vol. 49, no. 3: 296-300© 1995 by University of Hawai'i Press. All rights reservedKaryotype of a Ranid Frog, Platymantis pelewensis, from Belau, Micronesia,with Comments on Its Systematic Implications lHmETOSHI OTA2 AND MASAFUMI MATSUI3ABSTRACT: The karyotype of Platymantis pelewensis Peters, 1867, the onlynative, 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 I, 5, 6, 8, 10, and II were metacentric; the re-mainder were submetacentric. Secondary constrictions were evident on shorterarms of pair 7. This karyotype is nearly identical with that of P. papuensisMeyer from New Guinea, but is distinct from two Philippine congeners hithertokaryotyped both in chromosome number and morphology. This suggests thatthe ancestral form of P. pelewensis dispersed from New Guinea or other Mela-nesian islands.THE RANID GENUS Platymantis Gunther con-sists of 37 species distributed in the Philip-pines, Belau (Pelew or Palau), Melanesia(including New Guinea), and western Poly-nesia (Frost 1985, but see Zhao and Adler[1993] for the status of Chinese species as-signed to the genus). The range of the genusis characteristic of that of most other Aus-tralasian frog genera in that it spreads ontovarious oceanic islands (see above) (Inger1954, Darlington 1957, Gorham 1965). It isgenerally supposed that species currently iso-lated on such islands represent past multipleoverseas dispersals and subsequent specia-tions (Brown 1965, Tyler 1979, Gibbons 1985).Gibbons (1985) further surmised that thehighly specialized mode of reproduction inthe genus, involving the direct developmentof embryos (Atoda 1949, Brown and Alcala1982a), has been especially advantageous inthe process of its colonization of oceanicislands.However, there has been little informationregarding the process of divergence amongI This research was partially supported by a Grant-in-Aid from the Japan Ministry of Education, Science, andCulture (A-05740523 to H.O.). Manuscript accepted 27July 1994.2 Department of Biology, University of the Ryukyus,Nishihara, Okinawa 903-01, Japan.3 Graduate School of Human and EnvironmentalStudies, Kyoto University, Yoshida Nihonmatsu-cho,Sakyo-ku, Kyoto 606-01, Japan.Platymantis species: origins and relationshipsespecially of a few, isolated species remainunknown. Of these, P. pelewensis Peters,1867, the only native and endemic amphibianspecies of Belau, western Micronesia, is oneof the most poorly studied species despiteits great biogeographical interest. We haveexamined the karyotype of P. pelewensis forthe first time and discuss its phylogeneticand biogeographical relationships with othercongeneric species from the cytotaxonomicstandpoint.MATERIALS AND METHODSTwo males were collected from NgergoiIsland, ca. 27 km SW of Coror Island, andwere taken live to the laboratory, where theywere injected with colchicine solution (0.1mgjrnl) in their femoral muscles at 0.1 rnljgbody weight. They were sacrificed about 10 hrafter the injection. Bone marrow, extractedfrom the femurs, was subjected to hypotonictreatment in KCI solution (0.05 mol/liter)for 40 min and then rinsed and fixed in Cal-nois's solution (glacial acetic acid: methanol,I : 3). The cell slides, prepared by the air-drymethod, were soaked in 3% Giemsa solutionfor 30 min and then were investigated micro-scopically and photographed. The karyotypewas determined on the basis of five well-spread metaphase cells for each individual.The arm length of each chromosome was296- 414'#W;Karyotype of Platymantis pelewensis-OTA AND MATSUI 297measured on the photoprint using an ironstring. Terminology for chromosomal de-scriptions follows Green et al. (1980). Voucherspecimens were deposited in the amphi-bian collection of the Graduate School ofHuman and Environmental Studies, KyotoUniversity, Kyoto, Japan.RESULTS AND DISCUSSIONBoth males had a karyotype consisting of2n = 22 homologous chromosomes largelyforming a graded series. Of these, the chro-mosomes composing pairs 1, 5, 8, 10, and 11exhibited arm ratios smaller than 1.70 andhence were classified as metacentric. Theremainder exhibited ratios ranging from1.79 (pair 6) to 2.44 and were classified assubmetacentric. Secondary constrictions wereevident on shorter arms of pair 7 (Figure 1,Table 1).Of the 37 valid species of the genus Platy-mantis, only three, P. hazelae (Taylor) and P.dorsalis (Dumeril) from the Philippines, andP. papuensis Meyer from New Guinea, havehitherto been karyotyped (Kuramoto 1985).The karyotype of P. pelewensis is distinctlydifferentiated from those of the two Phil-ippine species both in the chromosome num-ber (P. hazelae has 26 chromosomes and P.dorsalis has 20 chromosomes) and in mor-phology. However, it closely resembles thekaryotype of P. papuensis (2n = 22), fromwhich it differs slightly by having pair 6submetacentric (arm ratio = 1.79) insteadof metacentric (arm ratio = 1.60), and sec-ondary constrictions in pair 7 (Table 1).Platymantis pelewensis was first describedas P. plicifera var. Pelewensis by Peters(1867), who briefly stated that it differs fromP. plicifera Gunther from the Philippines(subsequently designated a synonym of P.corrugatus [Dumeril] by Inger [1954]) only inthe lateral head coloration. However, Inger(1954), on the basis of far more detailedmorphological comparisons, considered thatthe species is most closely related to P.meyeri Gunther from the Philippines (laterdesignated a synonym of P. dorsalis byBrown and Inger [1964]) and P. papuensisand P. rubristriatus (Barbour) from NewGuinea (P. rubristriatus was designated asynonym of P. papuensis by Zweifel [1969]).Gorham (1965), although basically acceptingInger's (1954) account, considered that P.pelewensis is more closely related to P. dor-salis than to P. papuensis on the basis ofmorphological similarity. Since Inger's (1954)work, five species have been added to thegenus from the Philippines, but because oftheir distinct morphological divergencesand specializations (see Brown and Alcala[1963, 1974, 1982b] for further details), Inger's(1954) and Gorham's (1965) assumption ofthe closest affinity of P. dorsalis with P. pele-wensis among the Philippine species appearsstill valid.1728394105116FIGURE I. Karyotype of male Platymantis pelewensis from Belau. Bar equals 10 /lm. Arrows indicate positions ofsecondary constrictions on pair 7.TABLE 1CHROMOSOMAL COMPARISONS OF Platymantis pelewensis WIIH OnmR CONGENERIC SPECIES HIrnERTO KARYOTYPEDSPECIES(LOCALITY: DIPLOID NO.)P. pelewensis P. papuensis P. dorsalis P. hazelae(BELAU: 22) (NEW GUINEA: 22) (PHILIPPINES: 20) (PHILIPPINES: 26)PAIR RELATIVE ARM RELATIVE ARM RELATIVE ARM RELATIVE ARMNO. LENGlH RATIO TYPE LENGlH RATIO TYPE LENGlH RATIO TYPE LENGlH RATIO TYPE1 16.1 ± 0.18 1.27 ± 0.03 m 16.0 ± 0.16 1.26 ± 0.01 m 17.4 ± 0.36 1.08 ± 0.01 m 15.6 ± 0.24 1.27 ± 0.02 m2 12.8 ± 0.19 1.90 ± 0.03 sm 13.2 ± 0.13 1.89 ± 0.03 sm 13.0 ± 0.21 4.19 ± 0.27 st 12.9 ± 0.18 1.70 ± 0.03 sm3 11.7 ± 0.12 2.25 ± 0.07 sm 11.6 ± 0.13 2.27 ± 0.06 sm 12.3 ± 0.13 1.27 ± 0.03 m 11.2 ± 0.26 2.17 ± 0.03 sm4 11.3 ± 0.21 1.95 ± 0.05 sm 11.3 ± 0.14 1.90 ± 0.05 sm 11.6 ± 0.17 2.77 ± 0.10 sm 10.8 ± 0.12 1.83 ± 0.05 sm5 10.4 ± 0.20 1.35 ± 0.02 m 10.2 ± 0.10 1.38 ± 0.02 m 10.1 ± 0.15 1.25 ± 0.03 m 9.9 ± 0.09 1.33 ± 0.02 m6 9.6 ± 0.08 1.79 ± 0.04 sm 9.1 ± 0.06 1.60 ± 0.03 m 8.6 ± 0.14 1.12 ± 0.02 m 5.8 ± 0.12 1.33 ± 0.03 m7 7.1 ± 0.08 2.44 ± 0.11 sm· 7.6 ± 0.10 1.89 ± 0.05 sm 7.8 ± 0.10 1.15 ± 0.04 m 5.7 ± 0.12 2.40 ± 0.06 sm8 5.8 ± 0.16 1.56 ± 0.05 m 5.9 ± 0.08 1.61 ± 0.04 m 7.3 ± 0.11 1.12 ± 0.02 m 5.3 ± 0.08 1.33 ± 0.04 m9 5.5 ± 0.13 1.96 ± 0.06 sm 5.3 ± 0.07 2.08 ± 0.04 sm 6.8 ± 0.16 1.22 ± 0.05 m 5.0 ± 0.09 2.31 ± 0.08 sm10 5.1 ± 0.12 1.48 ± 0.08 m 5.2 ± 0.07 1.42 ± 0.03 m 5.1 ± 0.13 1.14 ± 0.02 m 4.9 ± 0.08 1.26 ± 0.03 m11 4.5 ± 0.09 1.28 ± 0.03 m 4.5 ± 0.05 1.26 ± 0.02 m 4.7 ± 0.08 1.20 ± 0.05 m12 4.5 ± 0.09 1.24 ± 0.04 m13 3.8 ± 0.09 2.99 ± 0.15 smNOTE: Data presented as means ± SE. Abbreviations: m, sm, and st represent metacentric, submetacentric, and subtelocentric chromosomes, respectively. Data for P. papuensis,P. dorsalis, and P. hazelae from Kuramoto (1985).'With secondary constrictions on shorter arms.Karyotype of Platymantis pelewensis-OTA AND MATSUI 299Our comparisons have revealed that P.pelewensis resembles P. papuensis much moreclosely than P. dorsalis chromosomally. Kura-moto (1985) assumed that karyotypes of P.papuensis and P. dorsalis represent two dif-ferently specialized conditions derived fromthe 2n = 26 karyomorph represented by thekaryotype of P. hazelae. He pointed out thatthe karyotype of P. papuensis could have de-rived merely by centric fusion and pericentricinversion, whereas that of P. dorsalis wouldhave been involved in more complicatedchromosomal rearrangements. If this as-sumption is accepted, close chromosomalsimilarity of P. palawensis with P. papuensisbut not with P. dorsalis can be interpreted asindicative of the closer phylogenetic relation-ships of the former two species.Tyler (1979), in discussing historical rela-tionships of Platymantis species in the easternOriental and Pacific regions, provided a sche-matic figure (i.e., fig. 4 : 4) indicating that theancestral form of P. pelewensis had dispersedfrom the Philippines, presumably on the basisof Gorham's (1965) account (see above).However, our results seem to indicate thatthe ancestor of P. pelewensis actually dis-persed from New Guinea or adjacent Mela-nesian islands, similar to ancestors of somereptilian species in Belau (Ota et aI. 1995).Further chromosomal surveys and phylo-genetic analyses of Platymantis species areneeded to verify our hypothesis.ACKNOWLEDGMENTSH.O. is grateful to M. Ota for helping withthe fieldwork in Belau, to M. Toda for labo-ratory assistance, and to R. I. Crombie forliterature.LITERATURE CITEDATODA, K. 1949. Metamorphosis of the"non-aquatic frog" of the Palau Islands,western Carolines. Pac. Sci. 4(2): 202-207.BROWN, W. C. 1965. New frogs of the genusCornufer (Ranidae) from the SolomonIslands. Breviora (218): 1-16.- ,../"" ,BROWN, W. C., and A. C. ALCALA. 1963. Anew frog of the genus Cornufer (Ranidae)with notes on other amphibians knownfrom Bohol Island, Philippines. Copeia1963: 672-675.---. 1974. New frogs of the genus Platy-mantis (Ranidae) from the Philippines.Occas. Pap. Calif. Acad. Sci. (113): 1-12.---. 1982a. Modes of reproduction ofPhilippine anurans. Pages 416-428 inA. G. J. Rhodin and K. Miyata, eds. Ad-vances in herpetology and evolutionarybiology. Harvard University, Cambridge,Massachusetts.---. 1982b. A new cave Platymantis(Amphibia: Ranidae) from the PhilippineIslands. Proc. BioI. Soc. Wash. 95: 386-391.BROWN, W. C., AND R. F. INGER. 1964. Thetaxonomic status of the frog Cornuferdorsalis A. DumeriI. Copeia 1964: 450-451.DARLINGTON, P. J., JR. 1957. Zoogeography.John Wiley & Sons, New York.FROST, D. R., ED. 1985. Amphibian species ofthe world: A taxonomic and geographicalreference. Allen Press, Lawrence, Kansas.GmBoNs, J. R. H. 1985. The biogeographyand evolution of Pacific island reptiles andamphibians. Pages 125-142 in G. Grigg,R. Shine, and H. Ehmann, eds. Biology ofAustralasian frogs and reptiles. SurreyBeatty & Sons, Sydney.GORHAM, S. W. 1965. Fiji frogs (with syn-opses of the genera Cornufer and Platy-mantis). ZooI. Beitr. 25: 381-424.GREEN, D. M., J. P. BOGART, E. H. AN-THONY, AND D. L. GENNER. 1980. An in-teractive, microcomputer-based karyotypeanalysis system for phylogenetic cytotax-onomy. Comput. BioI. Med. 10:219-227.INGER, R. F. 1954. Systematics and zoogeog-raphy of Philippine Amphibia. FieldianaZooI. 33: 183-531.KURAMOTO, M. 1985. Karyological diver-gence in three platymantine frogs, familyRanidae. Amphib.-Reptilia 6: 355-361.OTA, H., R. N. FISHER, I. INEICH, AND T. 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Karyotype of a Ranid Frog, Platymantis pelewensis, from Belau, Micronesia, with Comments on Its Systematic Implications

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