Cytogeography of the Adiantum pedatum Complex (Pteridaceae, Subfamily Adiantoideae)

2005·2.4 MB·English

by  Nakato, Narumi

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ISSN 1346-7565 Acta Phytotax .Geebot. 56 (1) :85-96 (200S)
Cytogeographyof the Adiantum pedatum Complex (Pteridaceae,
SubfamilyAdiantoideae)

NARUMI NAKATOiand MASAHIRO KATo2

JNarahashi I-363 ,Higashiyamato ,7bkyo 207-O031 ,Japan; 2Department qfBiologica Slciences G,raduate Scheol
ofScien cUnei,versit oyf71)k ]7-i3o-, JHbngo, 7bk}io 113-O033, Japan
A chromosomal survey revealed that Japanese pepulation sof the Adiantum pedatum complex
(Pteridac esuabefa,mily Adiantoidea ei)nclud efour cytotypes: diploid osf 2n = 58 (x = 29) and 2n = 60
(x = 30) ,and tetraploi dosf 2n = 118 and 2n = 120 (x = 30) .The few Nonh American plants we analyzed
were diploi d(2 n= 58) and triploid (2n = 87) (x = 29), The two tetraploid cytotypes in Japan and the
trip]oid from Canada are new cytotypes for this complex. In Japan ,diploi dwsith 2n = 60 are widely dis-
tributed at all elevations throughout Hokl(aido, Honshu and Shikoku .Diploid swith 2n = 58 are
known from only two lowland sites in eastem Hokkaido. Tbtraploi dpslant swith 2n = 1 18 and 120 are
rare in the high mountains of central Honshu and a tetraploi dplan twith 2n = 118 is known from a low-
lan dsite in centra] Hokkaido .Asian members of the A. peclatum complex have a base chromesome num-
bers of both x = 29 and 30, whereas North American plant asre known to have enly x = 29 as a base num-
ber .Since x = 30 is considered to be ancestral in Adiantum, j tis inferr etdha tthe x = 29 cytotype in the
A, pedatum complex originated in Asia and plant swith this number late mrigrated to North America,
Other possibili tairee sthat plant wsith x = 30 went extinct in North America ,or they have yet to be found.
Key words: Adiantum pedatum, base chromosome number, cytogeography, cytotype, polyploidy.
The Adiantum pedatum L. complex (Pteridaceaete,traploid based on x = 29 in North America (Table
subfamily Adiantoideae) is a typical example of 1) .Pari set al. (199 0ma)de a preliminar ysystematic
taxa distribut eddiajunctl iyn temperate eastern Asia study of thc complex based on chloroplast DNA
and North America, a distribut ipoantter nknown variation, cytology, and isozyme electrophoresis,
since the lat e18th century (Chri 1s9t1O ,BoufTbr d& and suggested that there are at least three diploid
Spongberg 1983, Kato & Iwatsuki 1983), The com- species, one each in eastern Asia, western Nerth
plex shows three remote centers of distribution; America. and eastern North America. Paris &
eastern Asia, western North America and eastern Windham (1988 )and Paris (199 11,993) reported
Nerth America (Hult 61n968, Sugawara 1975, that the North American complex comprises three
Fomin 1986, Kurata & Nakaike 1987, Lin 1990, distin cstpecies; Adiantum pedatum sensu stricto
Kato 1993, Paris 1993, Khullar 1994). The histori-(2x i)n eastern Nonh America ,A. aleuticum (Rupr.)
cal biogeograph oyf the complex remains uncertain. Paris (2x )in western and rarely in eastern North
Cytological lAy. ,pedatL{m include dsiploid bsased America, and A. viridimontanum Paris (4, rxe)strict-
en x = 29 and 30 in Asia, and a diploi dand a ed to serpentine areas in Vermont, eastern North
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FIG　l　Somatlc　chromobomes ⊥n　the　Adiantumpedat“m　complex 　For　detalle　cdolEeLtion 　data　see　Table　2　A　D　Japanese　p］dnts　A
　 山plold（2n　＝58），no　2155　B　d夏plold〔2n＝ 60〕，　no　1923　C　teヒraplold （2π＝ ll8）nθ i666　D　tetrdploid（21t＝12〔〕），　no 　i471
　 EFNorth 　Amor且can 　plant　sE　dlplold（2n；58）no 　f823 ）tnplold （2n ＝87）n（） 1670　Sしdle　bar＝10μm
一
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Results Discussion
America. By contrast, the systematics and cytotax- and
onomy of the Asian entities have not been well
investigat ebdu,t two base chromosome numbers Chromosome counts
have been recognized, based on a small number of Chromosome counts obtained in thi sstudy are sum-
'fable
counts (Ihbl 1e) .[[b gain a greate runderstanding of marized in 2, XNb confinmed four cytotypes in
this complex, we undertook a survey of the chro- Japanes eplants T.hey are diploid wsith 2n = 58
mosomes in the complex, based mainly on plants in (fi vpleant sfrom two localiti edsip)l,oid sof 2n = 60
Japan, (54 plant sfrom 41 lecaliti etset)r,aploids with 2n =
1 1 8 (thr peleant sfrom two locaiiti eansd) ,tetraploids
Materials and Methods with 2n : 120 (thr epelants from two localities)
(Fig s1 .& 2). In previou sstudies of Japanese
Material ussed in the present study were collected Adiantum pedatum, Kurit a(1 960) and Mitui (1968)
from 47 localiti e(s65 individual si)n Japan and recorded n = 29 (2x x, = 29) ,whereas Mitui ( 1976),
three localit i(efsi viendividual isn) North America Nakato (i nMitui 1976) and Kawakami (1979 1,981)
(Tabl 2e). For mitotic chromosome observations, reported n = 30 or 2n = 60 (2x x, = 30) ([fa b1l).e
root tips were pretreat ewidth a O.O02M solution of From outside Japan, diploids with x = 29 were
8-hydroxyquinoli fnoer 3-6 hr, fixed in 45% acetic reported from the Sikkim Himalaya and North
acid fbr 15 min, macerated in a mixture of IN HCI America, a tetraploid with x = 29 from Verrnont,
and 45% acetic acid (3: 1f)br 1 min at 60℃ and eastern U,S.A. ([Ela 1b)l ,eThe two Japanes etetra-
,
then squashed in 2% aceto-orcein. Spores were p]oid swith 2n = 118 and 2n = 120 are newly report-
embedded in Eukitt (O. Kindler, Germany), and ed cytotypes for the A, pedotum complex. As fbr the
the equatorial diamete rwas measured for 20 sam- North American plant s(= A. pedutum sensu stricto),
'
ples per specimen, Cytologic avloucher specimens two individua lfsrom Massachusett asnd two from
are deposite din the herbariu mof the University Vermont were fbund to be diploi dw,ith 2n = 58,
of Tokyo (Ti). which is consistent with previous chromosomal
studies from North America ([Il a1b) l.Oene indi-
ttttttt-Jt-t t.L.ttt -
s t t,.'
FIG. 2. Explanator ydrawings of chromosomes, A. tetraploid (2 n= 1 l8) of Fig. 1C. B. tetraploid (2n = 120) of Fig, 1D. Scale bar =
10pm.
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vidual from eastem Canada was a triploi dw,ith 2n 1990) at a relatively low elevation of 240 m.
= 87, or x = 29, and is also a new cytotype in this [Ietrapl ocyitodtypes with 2n = 120 were fbund
.]n
complex. a montane andesite area (Yamad a& Kato 1991)
at 1480 m (no 1.709) ,and in an area of intermingied
Distrihutio nofthefo cuytrotly{pes in lapan black-shal sec,halstein and sandstone (Yamad &a
Figur e3 is a cytogeographic map of the Adiantum Kato 1991) at 1750 m and 1800 m (no s1.472,
pedatum complex, based on the present and previ- 14Z3) ,where Adiantum pedntum reaches it shighest
ously publishe dstudies shown in [ktble s1 and 2. elevation in Japan. Population no. 1709 was in
The imprecise chromosome counts by Mitui (n = c. relatively rich soil, 15-20 cm thick i,n a deciduous
29, 1975) and LOve & L6ve (2n = c. 58, 1964) are fbres t(mainl Cyereidiphyltttmy'apon aincdu msev-
excluded. Figure 4 shows the altitudinal distributioneral species ofAcer), and populatio nnos. 1472 and
of the fOur cytotypes in Japan .Diploid sof 2n := 1473 were in the lower zone of a montane conifer-
60 were fbund at a wide range of elevations, from ous fores t(Abie sveitchii Lindl.) ,The Japanese
20 to 1500 m, in a variety of hal)itat ssu,ch as forest tetraploid stherefore occur in various geological
fioor sand fores tedges and openings in broad- formations ,By contrast, the North American
leave ddeciduou sand mixed forest san,d also on tetraploid A. viridimontanum (2n = i16, x = 29) is
rocky slopes and stone walls in semi-open places, restricted to exposed serpentine areas at 200-800 m
Diploids with 2n = 58 were collected on the edges (Par &is Windham 1988, Paris 1993).
of coniferous and deciduou sbroad-leaved mixed Since the Japanese tetraploi dcytotypes are
fbrest sat 20 m and 80 m elevation in Hokl(aido. restricted to a much narrower range than the
Kurit a(1960 r)eported a diploid of x = 29 from diploid sth,ey seem to be of relatively recent origin
Mt. Buko, Saitama Prefecture ,which is a lime- as in the case of an American tetraploid (Adiantum
stone region. However, the two localit iofes the 2n viridimontanum; Pari s& Wincham 1988) .The tetra-
= 58 diploids in eastern Hokkaido are not calcare- ploids with 2n = 120 are likel yto have arisen by
Qus; Abashiri (nos .2164, 2166) is in a siltstone chromosome doubling of a 2n = 60 diploi dw,hile
region, and Kitami (no s2J,5S 215a 2159) belongs the 2n = 118 tetrapioid asppear to be either allote-
to the Sorach igeologi cgroup consisting of schal- traploi dderiyativ oefs a hybri dbetween the 2n = 58
stein (wollaston ibtaes)a,l tlava ,chert, mudstone and 2n = 60 diploids ,or an aneuploid of the 2n =
and sandstone (Sato h& Hata 1990). 120 tetraploid. The occurrence of the tetraploids
Tbtrapioid swith 2n = 118 were found at one (2n = 118 and 1 20) in central Honshu are certainly
locali tiyn central Honshu and one in Hokkaido, correlated with severe environments at high e]eva-
while tetraploids with 2n = 120 were found at two tions .It may be that they originated there. The rela-
sites in central Honshu, The 2n = 118 cytotype in tionshi pof the tetraploids with 2n = "8 on Honshu
Honshu (no s1,665, 1666) was collected from the and Hokkaido is still uncertain. They may have
fores tfloo rat 1550 m in a sandstone-mudstone originated independently ,because thei rlocalities
area (Yamad &a Kato 1991) in the upper zone of a are about 1OOO km apart.
broad-leaveddeciduous forest[mainlCyercidi-

pdyllumJ'oponicum Sieb .& Zucc. and Ulmus lacini- External monphology and spore size of Jinpanese
ata (Traut vMa.y)r] mixed with conifers (AbiesCJ'tOmpes
homolepi sSieb ,& Zucc.) T.he tetraploi wdith 2n = The Nomh American Adiantumpedatum sensu stric-
1 18 (no .1787) in Hokl<aid owas found in a thicket to (2x) A,, aleuticum (2x )and A. viridimontanum
along a path in a limestone area (Sato h& Hata (4x )are discriminat efdrom each other by such
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morpho]ogical characters as the form of the leaves Japanese cytotypes, however, we could not find
and pinnul esegments, the depth of the segment diagnost ichcaracters to distingui tshhem, The form
sinus, the length of the segment stalk and false of the segments, the size of the segment sinus and
indusi arh,izome differenc eansd, spore sizes (Paristhe lengt hof segment stalk and fals eindusi aare
& Windham ]988, Paris 1991, 1993). When we ex- variable, in particula rin the 2n = 60 diploid st;he
amined the external morphology of the four variation in these characters in the 2n = 60 diploids
sor 120' 150' leD' 15r nor gl. Set
e sp D
1or
po
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"F
. .g ci}
6or
eOq
1
e 't' 45'
-s"---4--

3e'
etae" I ))bA
e
15.
at
ee
Fia. 3. Distributi oofn cytotypes of the Adiantumpecintum complex. Solid linc sindicat deistributi roannges. Dotted line corresponds
to magnified maps ofJapan. Material scited in Tables 1 and 2 arc used.
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TABLE 1 , Summary of publishe dchromosome numbers in thc Adiantum pedatum complex.
Locality Chromosome PloidyReference
numbern
2n
EASTERN ASIA

HIMALAYA
Sikkim 29 2x Nlerma in Mehra 1961
JAPAN
Habero, Hoklcaid ePrefecture c. 293e 2x2x2x2x2x2Mxi2tx2uxi 21x975
Yahiko N,iigat Parefecture Mitui 1976
Myokosan, Niigat aPrefectur ea,lt. 14SO m 606060 Nakato in Mitui i976
Yoro-keikoku ,Chiba Prcfectur ea,lt, 150 m Nakato in Mitui 1976
Itsukaich i[,fokyo Prefectur ea,lt .5SO m Nakate in Mitui 1976
Bukosan. Saitama Prefecture 29 Kurita 1960
Otsuki ,Ylamanash iPrefecture, alt. 500 m 606060 Nakato in Mitui 1976
Eiheij iF,ukui Prefectur ea,lt. 300 m Nakato in Mitui ]976
Hiroshima City ,Hiroshima Prefecture Kawakami 1979 & 1981
WESTERN NORTH AMERICA

Graham Isl .Q,ueen Charlott eIsls ,C,anada 2ga 2x2x2x2x2x2Txlaylo r& Mul]igan 1968
Big Bend, Briti sCholumbia C,anada c. 5sa5sa LOve & LOve 1964
Big Bend, Albert aC,anada LOve & LOve 1976
Vanceuver, Canada 292ga29 Manton & Sledge 1 954
Washington,U,S.A. Wagner inFabbri1963

Califerni aU,.S.A. Whgner 1963
EASTERN NORTH AMERICA

Mont Alber tG,aspe ,Quebe cC,anada 2gb2gb 2x2x2x2xC2oxd2yx &4 xM2uxl2lxi4gxa n1982
Mont Albert ,Gaspe, Quebe cC,anada Cody 1983
Ile Bizard ,Quebec ,Canada 58 L6ve & LOve 1976
Gatineau Park, Quebec ,Canada 29292958c2954I+2IId Cody & Mulligan 1982
[Ibront oO,ntario ,Canada Britte n1953
Exete rWildflower Gard. ,Exeter .U.S.A, Cody & Mulligan 1982
Belvider eMt., Vermont, U,S.A. ll6 Pari s& Windham 1988
Breidentha lBiol. Reserve ,Baldwin City ,Kansas, U.S.A. Rabe & Haufle 1r992
Breidentha lBiol, Reserve ,Baldwin City, Kansas, U.S.A. Rabe & Haufiei 1992
Brcidentha lBiol. Reserve ,Baldwin City ,Kansas, U.S.A, 116e Rabe & Haufler 1992
ORIGIN UNKNOWN or DOUBTFUL
Origin unknown (cul itn .Ibkyo Univ .of Education) 2929f29g2922h 2x2x2x2x2Mxitui 1968
Origin unknewn (horticul sttruairn)al Wagner 1963
Origin unknown (cul ti.n Niles ,Michigan, U.S.A.) Wagner & Boydston 1978
Origin unknown (cul itn .Univ. of Kansas, U.S.A.) 58 Paris & Windham 1988
CostaRicah Gbmez 1971

a: As Adianturn pedatum var. (or ssp.) alezaticum. b: As A, pedatum ssp, calderi. c: n = 56tl+1I Yn = 57II+2I and n = 55Il+2I+1IV
were also recorded. d: Chromosome count from dipioi dmutant, e: Autotetraple iodbtained by selfing from diploi dmutant; 58 chro-
mosomes were also recorded at mitosis in the gametophyte .Asf :A, pedatum f. miniature. g: As A, pedat"m var. suop"milum. h:
Doubtfu1 for both localit aynd chromosome number.
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TABLE 2,Summary of chromosome counts in the Adiant"m pedat"m complex obtained in the prese nsttudy.
Locatity (Number ofindividuals examined in parentheses) Chromosome Ploidy Vbucher"
number (2n)
JARANFutatsuiwa,
Abashiri ,Hokkaido Prefectur ea,lt .20 m (2) 5858606060620x121x826x026x0262x0f266x0446,x0 226x10266x602b6x026x026x026x026x026x026x026x026x02lx128x620x620x2x4x2x2x2x2x2x2x2x2x4x4x2x2x2x2x2x2x2x2x2x2x2x2x2x
Kitakami, Kitami, Hokkaido Prefectur ea,!t. 80 m (3) 2issb, 2is6b, 21sg
Iwaobctu, Syari-cho H,okkaido Prefectur ea,". 40 m (1) 2162b1793b177gb,
Uryu-cho, Hokkaido Prefectur ea,]t .200 m (1 )
Jozankei ,Sapporo, Hokkaido Prefectur ea,tt. 340 m (3) ]7s4, ns6b
Asarigawa-onsen, Otaru ,Hokkaklo Prefectur ea,lt. 170 m (1) 11J317s7b24591896244J166020202i33,
Tbuma-syonyudo, Tbuma-cho, Hokkaido PreC'eetu raelt,. 24e m ( 1)
Owani-onsen, Owani-rnachi ,Aemori Prcfectur ea,lt, 300 m (1)
Ti,usonji H,iraizumi-cho ,Iwate Prefectur ea,lt. 90 m (1 )
Sakunami, Sendai ,Miyagi Pre fecture a,] t. 31O rn (1)
Kawasaki-machi, Shibata-gun M,iyagi Prefectur ea,lt .820 m (1)
Houhara-machi, Ylarnagat aY,amagata Prefectll raclt,. 470 m C1 )
Haguro-san, Higashitagawa-gun, Yamagata Prefectur ea,lt 150 rn (3) 2134, 2138
Atsushiokanou-mura .Fukushima Prefectur ea.lt. unknown (2) 1486, l555
Iwatsuk{-machi, Kitakara F,ukushima Prefectur ea.lt. 65a m (2> 1558, 1592
Yanaizu ,Kawanuma-gun, Fukushima Prefectur ea,lt. 220 m (1) 227sb10631724lss3bJ5662470165316oob166sb,
AsN'ano-rnac hKia,mitsuga-gun ,Tbchigi Prefectur ea,lt. 300 m (1)
Doai, Minakami-machi, Tone-gun, Gunma Prefectur ca,lt. 700 m (1)
Mitsuishi-yama ,Kimitsu ,Chiba Prefectur ea,lt, 200 m (1)
Mt. Mutsuishi ,Okutama-machi, Tbkyo Prefectur ea,lt. 1400 m <1)
Inoue ,Hanno, Saitam aPrefectur ea.lt .180 m (1)
Yakeyama, Tsukui-machi ,Kanagawa PTcfcctur ea,]t. 1020 m (1)
SasanodairaH,akushu-machi,YhmanashiPrefecture, 1500 (1)
alt. m
Hirogawara, Ashiyasu-mura .Yamanashi Prefectur ea,lt. 1550 m (2) 1666
Kamosawa, Tabayama-mura, Yamanashi Prefecture, alt. 580 m (1) J5801550,
Aoki-kosen ,Nirasaki Y,hinanash iPret'ectu rue]t,. 1 l40 m (2) 1551
lwadono, Otsuki ,\amanashi Prefecturc, alt. 390 m (l) 6e 15521986198419872150b182517091472,
Aikawa-machi, Sado-gun, Niigat aPrefectur ea,lt. 180 m (1) 60
Niibo-mura, Sado-gull N,iigata Prefecture, alt. 1OU rn (1) 6e
Ogi-machi, Sado-gun, Niigata Prefectur ea,lt. 20 m (1) 60
Zenzan{i. Ueda, Nagano Prefectur ea,lt. 58e m (1) 60
Shiokawa, Oshika-mura, Nagano Prefectur ea,lt. 1360 m (1) 60120120
Nerikura-kogen ,Azumi-mura, Nagano Prefectur ea,lt. 1480 m (1)
Oshika-mura ,Nagano Prefectur ea,lt. 1750m, 1800 m (2) 1473
Taira-mura ,Higashitonami-gun [,[byama Prefectur ea,lt. 330 m {2) 60 ipssb, igs6
Kandadani, Wajima, Ishikawa Prefecture, alt. 11Om, 170 m (2) 60 ig2ob,lg23b
Kakuma-machi, Kanazawa, Ishikawa Prefectur ea,lt. 160 m (3) 60 1935b, 1936, 1937
YUgiri-toge, KanaLawa, I$hikawa Prefeeture, alt. SOO m {1) 60 155419072429IP59,
Eiheij iE,iheiji-ch oY,Oshida-gun ,Fukui Prefectur ea.lt. 300 m (1) 60
Akame-machi, Nabari, Mie Prefecture, alt. 300 m (1) 60
Shirakawago ,Shirakawa-inur aG,ifu Prefectur ea,lt, 520 m (2) 60 Ig6ob
Murou-mura, Uda-gun, Nura Prefecture, alt. 360 m (1) 60 242523J7166gb246522sib,
Koya-san, Ito-gun ,Wakayama Pfefectur ea,lt 790 m (1) 60
Nishinoshima ,Oki-gun, Shimane Prefectur ea,lt. unknown (1) 60
Arnedaki, Kokufu-chQ, Iwami-gun. Tbttori Prefecture, alt ,300 m (1) 60
Katsuura ,Kotomami-cho, Kagawa Prefecture, alt. 300 m (2) 60 2283
Kaminanokawa, Agawa-mura, Kochi Prefectur ea,lt. 80e m (1) 60 2316b
EASTERN NORTH AMERICA

Leveret tPond .Massachusetts U,.S.A., alt. unknown (2) 585887 2x2x3x 1313, i492
Jericho C,hittende nCo., Vermont, U.S.A., alt. 340 m (2) 1823, l824
Mt. Albert ,Gasp6 Peninsu]a C,anada, alt. unknewn (1) i670
a: Specime nnumber of N. Nakato. b: Specime nexamined fo rspore length.
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1800 E
iSE]oo e:2n=58
1500
o O:2n=6o
t:
2n=11s
AEv-a=---"(
D:2n==12o
oo
1000
o
oo oo

o
goo

g
500
o8 oOoe8 o ooas
8soo
200100 o
A e
o
33 34 35 36 37 38 39 40 41 42 43 44 45
LAT1TUDE (eN)

FIG. 4, Altitudin aanld latitudi ndailstributi oofn four cytotypes of the Adiantumpedoturn complex in Japan .Material sin fable s1 and
2, except for those whose altitudes ure unknown, are cited.
include tshe variation of other three cytotypes com- tra lfor Adiantum? Tryon & Tryon (1982 )argued
pletel (yFi g5.). that n = 30 is more frequent than n = 29 in the
Spore size in the North American Adiantum genus ,and the base number x = 29 in several species
pedatum sensu stricto (2x w)as 34-40 pm, 37-47 pm is a second series of chromosome numbers. We
in A. aleutic:um (2x a)nd 45-58 ym in A. viridimon- reviewed all previous chromosome counts of
tanum (4x ),The spores of the tetraploid A. viridi- Adiantum. Of the 150-200 species in the genus
montanum are therefb rlearge rthan the spores in the (Copela 1n9d47, Lin 1990, Tryon 1990), chromo-
diploi sdpecies (Par i1s993) I.n contrast no clear difi some numbers have been reported for 67 species (or
ference sexist among the Japanese cytotypes; the specjes complexes). Forty two speeies (63% )have
mean (± SD) was 40.2 ± 2.3 pm in the 2n = 58 x = 30, eight (12%) have x = 29, eight (12% )have
diploid s(N = 60) ,43,5 ± 3.5 pm in the 2n = 60 both x = 29 and 30, three (4%) show only aneu-
diploid s(N = 320) ,45.0 ± 2.8 ym in the 2n = 118 p]oidy ,and the counts for the remaining six (9%) are
tetraploi d(sN = 40) .Mature spores in the 2n = 120 only approximate (Chiaru g1i960, Fabbri 1963,
cytotypes were unavailable and could not be deter- 1965, LOve et at. 1977, Goldbla t1t981, 1984 ,1985,
mined, 1988, Walker 1984, Goldblat t& Johnson 1990,
1991,1994,1996,1998,2000,2003,Takamiya

qitogeography 1996). [[hus the base number x = 30 is predominant
The genus Adiantum has the same base numbers, x in the genus.
= 29 and x = 30, as the A. peclatum complex (Lovis A recent molecular phylogeny revealed that
1977,Walker1984).Whichbase is Adiantum (PteridaceaAdei,antoideae)
number ances- and
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April 2005 NAKMO & KMO, Cytogeegraphy ot'Adiantum pedanim 93
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FIG. 5. Fertil e(A-K) and sterile (L) pinnule sof some vouchcr specimens. A-C, Japanese 2n = 58 diploid A,, no. 2156. B. no. 2155.
C. no. 2166, D-H Japanes e2n = 60 diploi dD no l660. E. no. I551. E no. V553. G. ne. I959 .H. no. 2316. I .Japane s2en = l18
tetraploid ,no. i665. J. Japanese 2n = 120 tctrnploid ,no. i473. K. North American 2n = Sg diploid ,no. 1313. L. North
Amencan 2n = S7 triploid ,no. I670. Scale bar = 5 mtn.
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94 APG Vl)I,56

Vittariaceae (inc]ud iVn?gittar iAan,troph.yum, An alternative explanation is that plant swith x = 30
Polytaenium and Ananthacorus) form a mone- became extinct in North America, leaving behind
phyletic group, which is successively sister to only diploid wsith x = 29. This scenario seems less
Meridaceae (includ 7ibnengitis P,tatyzoma ,Pteris, likel tyhan an eastward migratio onf only the x = 29
Onychium, Bommeria, Notholaena ,Hemionitis, cytotype,
Doryopteris, Cheilanthes, Pellaea and Atlgyro- In a prelimina rryeport based on unpublished
chosma) and to Coniogramme (Pteridace Cahee,i- data, Paris et al. (1990 d)escribe gdeographica land
lanthoideae )in al 1ML, MP and NJ tree s(Haseb eet chromosomal isolati nmgechanisms to have been
al, 1995), Other phylogenie salso showed that importan tin the diyergence of the three diploid
Adiantum and allied genera are rooted by Conio- species of the A, pedatttm complex in North
gramme (Cran eet al. 1995 ,Schneide ret at, 2004), America (i. et.he, eastern North American A. pedti-
As te base chromosome number, Vittariacea heave tttm, the western and eastern North American A,
x = 30. Pteridaceae have x = 29 and 30 with some alettticum, and the Asian `A. peciatum') .Our results
exceptions, apparently derive dfrom aneuploidy indica ttehat chromosomal isolatio lnikel yoccurs in
(7inen ixt =i 2s2, and Platyzo,n xa =, 38) ,and Cbnio- Asia, but not between Asia and North America,
gramme has x = 30 consistently (Lovi 1s977, Walker Outside Japan, Adiantttm pedatum occurs
1987). These data strongly imply that the ancestral widely in continental Asia ,fror nFar East Russi aand
base number in Pteridacea eis x = 30, from which x Korea to China ,Bhutan ,Nepal, India ancl Pakistan
= 29 and other aneuploid numbers diverged. It is (Fig .3), No chromosomal data are availab]e for
likel ythe same in theA. pedatum complex. this larg earea except for a single chromosome
Present and previou osbservations show that in count of n =: 29 from Sikkim (Verma in Mehra
the Adiantum pedatt{m complex both the assumed 1961) .To understand bette rthe systematics and
ancestral (x = 30) and derive d(x = 29) diploi cdyto- biogeograph yof the whole A. pedatum complex
types occur in eastern Asia (Japa nea,stern Hima- and in particula rto test the proposed eastward
laya), thederived Cx 29)is
whereas only cytotype = migration, extensive comparative rnorphological,
in North America. The Adiantum pedatum com- molecular phylogenet iancd, phylogeograph ainac]y-
plex occurs mainly in cool temperate zones and is ses are needed.
one of the northernmost elements of the genus (Fig.
3). It is likel tyhat durin gpast geologi ctimes asso- We thank the lat eZ. Kaneda, S, Mitani ,N. Sahashi ,A.
Tanaka,Y Watano K.Yamaoka fdr living
ciated with climatic changes, the A. pedatum com- and providing
plex or an A, pedotum-li kanecestor migrate drepeat- materials, and T, Sate for valuable informatio onn local-
itie isn Hoklcaido T.hanks are also due to C. A. Pari sfbr
in
edly southward and northward, resulting changes sending American material and invuluabl ceomments en
in distribut rianogne, Eastward and westward migra- an earlier version of this paper.
'tlioanr must have occurred also in changing but simi-
Transpaciffilcoristic References
climatic zones. exchanges
between eastern Asia and North America occurred
via the Bering land bridg eduring the late lrbrtiary Boufford, D. E. & S. A. Spongberg .1983. Easter nAsian
and Quaterna r(yHulte 1n968 ,Hong 1983 ,Kato & - eastern North American phytogeographic arlela-
Iwatsuki1983,Wen 1999,Tiffuey& Manchester tionships: history from the time of Linnaeus to the

2001, Xiang & Solti 2s001) .We propose that the x twentieth century, Ann, Missouri Bot. Gard. 70:
423-439.
= 29 diploid(s o)riginated within the x = 30 diploid Britto nD,, M, 1953, ChrDmosome studies on fems. Amer.
populatio nisn Asia ,then spread to North America. J. Bot 40: 575-583.
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