PL A>. Hial. I : 35-45, t986 PLANT SPECIES BIOLOGYby the Society for the Study of Species Biology

Life History Studies on the Genus TvilUum (Liliaeeae)I. Reproductive Biology of Four Japanese Species

MASASHI OHARAIJ and SHOiCHt KAWANO-"

School of Environmenitil Science. Holckaido University. Sapporo 060. Japan.>Department of Botany. Eaiidty of Science. Kyoto Univer.sity. Kyoto 606, .lapa/i.

Abstract Four Japanese Trillium (Liliaceae) species which are representative perennialherbs of the temperate deciduous forests—7"»77//i//)j kami.schatieum {2.v), T. apetalon (4.v),7. tschonoskii (4.v) antl 7. .smaUH (6.\-)—were studied foi' their reproductive characteristics,e.g., patterns of reproductive resource iilloeation and reproduciive output.

In spite of the ditVerences in ploidy levels (from 2.v- to 6.v), all four species showed verysimilar reproductive traits. It became evident that in response lo the increase in repro-ductive ullocaUon to total leprotluclivc organs (RA), the number of seeds produced perplant (P^) clearly increased. This trend is well in accord with the relationship found in fourNorth American species and also several temperate woodland perennial herbs which occurin closed, stable and predictable environments, and possess typical xenogiinious breedingsystems. Although tbcrc is no conspicuous trend between ploidy levels and PN, one of thesignificant differences noted in this study was in seed weight, which ranged from 2.93 mgin diploids, to 3.42-3.45 mg in tetraploids, and to 4.47 mg in hexaploids.

Keywords: life history, reproductive allocation (RA), reproductive biology, Trillium.

The genus Trillium is one of the representativetemperate woodland elements which currently showdisjunct distributions between North America andeastern Asia including Japan. The genus consistsof approximately 51 species, and nine species arcknown to occur in eastern Asia (Sutnejimu andSamejima, 1962; Freeman, 1975). As for theeight Asiatic species, except for an endemic speciesin the Himalayas, it has been chuitied by a con-siderable number of cytogcneUc studies thai theyform a polyploid series representing their evo-lutionary trends, i.e., 2/(-IO, 15. 20 and 30,including five hybrid derivatives (Haga. 1937, 1951,1952, 1956; Haga and Kurabayashi, 1953. 1954;Haga et al., 1974; Kurabayashi. 1958). However,in spite of the considerable increase in informationon the genus Trillium, very few workers have studiedIheir life history characteristics, including thePatterns of reproductive resource allocation andreproductive output, which have been the subject ofmany recent studies (e.g.. Harper and Ogden, 1970;Gadgil and Solbrig, 1972; Abrahamson and Gadgil,1973; Ogden, 1974; Abrahamson, 1975a, b;Hiekman. 1975; Kawano and Nagai, 1975; Stearns,

1976; Werner, 1976; Wilbur. 1976; Roos andQuinn, 1977; Kawano und Masuda, 1980, Kawano,1981; Soule and Werner, 1981; Kawano ct al.,1982; Cartica and Quinn, 1982; Evenson, 1983:Kawano and Miyake, 1983; Kawano and Matsuo,1983; Waser and Price, 1983; Colosi and Cavers.1984; Jolls, 1984). Furthermore, the evolutionary-ecological trends of differentiation in such re-productive traits in plant species are still notsufficiently understood (Kawano antl Miyake, 1983;Kawano and Nagai, 1986).

The present study, us one in a series of life historystudies on the genus Trillium, was carried out in anattempt to clarify and compare, firstly the repro-ductive allocation pattern and reproductive outputof four Japanese species {T. kamtschatictitn, T.apetalon, T. isclionoskii and T. .mtallii) and, secondlythe overall characteristics of reproductive systemsand their evolutionary trends.

Materials and Methods

For this study, four Asiatic species of the genusTrillititn, i.e., T. katntschatictun Pall. (ln=\Q).

36 Masashi Ohara and Shoichi Kawano

Table !• Sources of malcrials and research sites.

CriteriaTaxa

T. kamt.icliaticuntT. apetaionT. smailii

T. Ischonask'd

Localities

Hakodatcyania,Oshinia, Hokkaido

Tomakomai, Iburi,Hokkaido

Vegetation

Cryptoimria japanica plafi(;ilion itnd broad-leaved deciduous forests;Main associated .species ai-e Qiierciis mof^nolica var. jfrosse.wiTata. Acermono. Anemone flaceida. Corydalis amhif:ua

Rroad-lcavcd deciduous forests and Larix lepioh/ii.s plantation: Mainassociated species arc Acer mono. Qiicrvii.s mongoliva var. f-rassescrmta.Maianihemtim diluiatiim. Smilavina japonica, Cardiocriiiiini eorclaiunivar, ^lehii. l'acliy.saitdra lirniinati.s-

T. apetaion Makino {2n~2Q), T. LsclwnoskiiMaxim. (2/( = 2O), and 7". .snialUi Maxim. {2/i==30)(a species of hybrid origin), were invesllgated altwo localities in Hokkaido, Japan.

The main environmental conditions of the studysites are summarized in Table 1. As shown here,these Trillitm] species occur mostly in mesie broad-leaved deciduous forests developed fn the cool-temperate zone of the Japanese Islands.

The field observations and sampling of theseTriliium species were carried out a( the various sites(Table 1) from 1980 (o 1984.

For the biomass allocation study, planls wereharvcsled a( bolh (he flowering (April-May) and

fruiting stages (July) from different populations in1980 and 1984. For analysis, the plants weredismembered into their component organs anddried in an oven for at least 48 hr at 80^C andweighed.

The number of ovules per ovary was countedunder the dissecting microscope from materialfixed in 70% ethanol. To determine tlie number ofpoiien grains, anthers were collccied beforedehiscence and preserved m paraffin papers untilcxaminaiion. Pollen grains were washed from theiiijihers wiJh 95"/n clhanoJ. jTiounted in giycerine-jelly, and counted under a microscope.

All voucher specimens are preserved in the

M I.I-i 1

Fig, I. Reiadonsfiips beluccn the tndiv'tdim) lolal biomass and reproductive allocalion (RA>lo total rcprodudivc organs in four Tritltinn species at the (lowering stage.

Reproductive biology of Japanese Trillium 37

| , M

tl 1.1

llUL licnxi IliNI

Fig. 2. Relationships between the individual total biomass and reproductive allocation (RA)to total reproduc-tivc organs in four Triliium species at the frLiiting stage. Filled circles,single-scaped individuals; open circles, double-scaped individuals. .

herbarium of Kyoto University (KYOJ, Kyoto,Japan (Utech etal . , 1984).

Results

(i) Rclationship.s hetween individual biomass (Bm)and reprodtietive allocation (RA).

The variation in reproductive allocation in theflowering and the fruiting stages of four Trillinmspecies are presented in Figs. 1 and 2. respectively.The values are expressed as the ratio of the dryweight of total reproductive organs (not onlyflowers, but also peduncles at the flowering stage,

and not only seeds, but also pericarp, sepals andpeduncle at the fruiting stage) to the dry weight oftotal individual biomasscs harvested at bothnowering and fruiting stages. No conspicuoustrend can be recognized between the individualbiomass and reproductive allocation to totalreproductive organs at both flowering and fruitingstages in all four species (cf. Table 2), except for theflowering stage of T. kamtsehatictim in which aweak negative correlation was recognized.

(ii) liclation.slnp.s between individual biomass (Bni)and propagule outpui (P^),

2. Relationships between individual biomass and some reproductive traits of four Trillium species.

CriteriaTaxa

T. kanuschalicnm (2x)T. apc'Uihn (4x)T. txcluino.skii (4x.)T. sniallii (6\)

log Biomass- R A

0.0214^^

0.0420^

log Biomass•log PN

0.8449***0.7538***0.6668***0.6474***

RA log.P;

0.5331***0.7112***0.7251***0.6731***

log PK —log R

-0.9413***- 0.8853*

-0.9358***-0.9037*

Inclines ofregressionlines ( -A)"

-0.7112*'*-0.6146***- 0.6266***

-0.6145***

*P^ 0.001; **P<O.OI; *P<0.C5; NS, non-signilkaiit; I) Probabilily ihat the indine.s ( /)) of regression lines

not overlap with -1 .0 (tested t-)y ft-tSE-to'/N—I-Sx). . : . .

Masashi Ohara and Shoichi Kawano

tK. 3- Relationships between the individual total biomass and the number of seeds producedper plant in four Trillium speeies. 1-illed eircles, single-seapcd individuals; open circles,double-scaped individuals.

Pig. 4. Relationships between ihc reproductive allocation (RA) to total reproductive organsand the number of seeds produced per plant in four Trillium speeies. Filled eiielcs, single-scaped individuals; open circles, doubie-scaped individuals.

Reproductive biology of Japanese Trillium

a

\

Fig. 5. Trade-ofr rclalionships beiwecn energy allocation lo a single seed (RA/ seed no./piant) (RA) and the number of seeds produced per plant (PN) for four Trillium species. Eachdot represents a different sample population. Broken line indicates b^~].O.

Figure 3 .shows the relationships between indi-vidual biomass and the number of seeds producedper pii im. A similar tendency in reproductiveoutput was recognized in all four species, i.e., largerindividuals produced more seeds than smaller ones(cf. Table 2). It is also inlerestinti lo note thai theslopes of the regression lines for all lour speciesshowed rather similar values.

(iii) Relationships between reproductive allocation(RA) and propagute output (Ps,).

Figure 4 illustrates the relationships betweenreproductive allocation to total reproductive organsat the fruiting stage and the number of seedsproduced per plant. Although the slope of theregression line for T. apetahn is slightly steeper thanthose of the oiher three species, all four speciesshowed the same tendency, i.e.. in response to theincrease in reproductive allocation, the number ofseeds produced per piant proportionately increased(cf. Table 2).

(iv) Reiutionsliips between proportional energyullocaiion to a .single propcigiile (RA) andpiopagule ouipiit iP{)

As stated above, it is obvious that the number ofseeds produced per plant is clearly related toreproductive allocation to total reproductive organ.s.

Figure 5 illustrates the relationship between RA toa single propagule (R.\) (not the same as the weightof a propagule) and propagule output (P^). Thereis a conspicLious reciprocity or "trade-otT' relation-ship between RA and P^ (cf. Kawano, 1981; Kawanoet al.. 1982; Kawano and Masuda, 1980; Kawanoand Miyake, 1983; Kawano and Matsuo, 1983).According to Kawano (1981), this trade-off relation-ship can be expressed as, log RA=log C—Alog PN,or R A = C / P S ' ' = C P K - \ where C is a constant,varying with the particular value of />. It has beenshown that three types of plants occur with threedifferent ranges of 6-values, i.e., /}<1.0, />>1.0,and /)—1.0 (Kawano, 1981). As shown in Fig. 5,the slopes of the regression lines are less than —1.0in all four species examined. Thus, these areequivalent to the case of b<l.O. This result againindicates that the number of propagules producedper plant is dependent on the reproductive allocationto total reproductive organs (cf. Table 2).

(v) Reproductive characteristics in four Japanese

Masashi Ohara and Shoiehi Kawano

Table 3. Reproductive characteristics in four Japanese Trillium species.

TaxaCriteria

Chromosome*

Genome*No. of ovules/plant**

(Ploidy)(2n>

No. of pollen grains/plantPollen-ovule ratiosNo. of seeds/plants**

Estimated seedscttiny rale/ovule (%)

Seed weight (nig)**

(1980)

(1984)

0980)(19X4)

Seed weight (rolalive value)

T. kanitscltativtiin

2x10

KiKi225. r ±39.8(158-341)4.2-5.7:- 10'-ea. 2200

101.1 1 39.4(38- 198)

136.8i32.7(77-216)

44.9160.77

2.93^0.301.000

T. apvliiton

4x20

SSUU156.0 + 27.9(113-205)0.6-0.7 xlO-'ca. 400

60.6 - 29.9***(15 116)

139.4 1 49.6(43-269)

89.333.42! 0.84

1.167

7". i.schonoskii

4x20

KsKiTT153.8 - 3LI

(90-222)0.8-1.4:- lO-ca. 700

85.0 I 37.0(29-190)

79.8-33.0(2S-168)

55.2951.89

3.45 ±0.391.177

T. smailii

6x30

K.K^iSSUU216.1 ±42. J(127-293)

1.3- 1.5 10ca. 650

104.3 ; 29.3(43-174)

113.0-1 30.9(57 -182)

48.34

52.294.47 + 0.53

1.526

* After Haga (1937), Haga and Kurabayashi (1953) and Samcjima and Samejima (1962).*• Ranges oT values, mean±S.D.

*** Sampled from a mon(ane population in central Honsliu, Bunao-iotigc in Toyam;) Prelccture.

Trillium.Table 3 summarizes the reproductive character-

istics of the four Japanese Trillium species, includingthe number of ovules and pollen grains per plant,the number of seeds produced per plant (both in1980 and 1984J and the mean seed weight. Asshown here, there lire wide ranges between themaximum and minimum ovule numbers per ovaryin each species. The two tetruploid species, T.iipetalon and T. ischonoskii, produced about ISOovtiles on the average, while T. ka/n/schaticmn(diploid) and T. .tmaJUi (hexaploid) produced morethan 200 ovules on the average. However, asexpected, the number of pollen grains produced perplant in these species was exceedingly high. Notably,T. komisvhaiUiun, which possesses anthers aboutthree times as large as the other three species,produced the highest number of pollen grains, i.e.,ranging 4.2-5.7 > 10-', as compared with the otherthree species (Table 3). T. opeiahn showed thelowest number of pollen grains, tanging 0.6-0.7x10'^. T. i.sclwnoskii and T. smaUi'i possessed0.8-1.4 ylOi' -dnil 1.3-1.5 >]0"* pollen grains perplant, respectively. The ratios of male (pollen) tofemale (ovule) gamets (P/O's) are about 2200;! inT. konitsctuiliciim (2.v), 400:1 in T. apetalon (4.v).7O0'.l in T. j.schonoskii (4.x) and 650.1 in T. smalKi(6.V). The highest P/O nilio is in (he dipJoid, thelowest m Ihe telraploids.

These Trillium species show a relatively highmean seed output, e.g., the average seed output in7". apeiaton is 139 per plant (although much lesspropagutc output, 61 per plant on an average, wasrecorded from a montane popuJation in centralHonshu, Bunaotoge in Toyama Prefecture), 101-136 in T. kamt.schutictim, 79-85 in T. (schonoskii,and 104-113 in 7". .smailii. Furthermore, it isimportant to note that the feciiiidity levei (seedsetting rate per ovule) of these four species, whit-fivaries from 44.91-60.77 (%) in T. kanu.schalicuin,48.34-52.29 (7D) in T. .smailii, 51.89-55.29 {%) inT. i.schonoskii, to a very high rate of 89.33 (%) inT. apdalon, is obviously determined by theavailability of pollinators at the flowering time and/or by their inherent breeding systems (Ohara andKawano. unpubl,).

As for the mean seed weight, one can recognize aconspicuous increase in seed weight in responseto the increase in ploidy levels, i.e. for the dipioidspecies 7". kaintscliaiicutn, ihe seed weighs 2.93 mg,the two teiraploid species, T. apetiilon and T.tschoiwskii, show almost the same seed weight,3.42 mg and 3.45 mg, respectively, and the hexaploidspecies, T. smailii, weighs 4.47 mg. However, asfar as the four Japanese species are concerned,there is no clear correUuion between the number ofseeds per plant and mean seed weight.

Reproductive biology of Japanese TriUiiim 41

100 r

BQ

60

T . KAMTSCHATICUM

FL Ff l

I2K) ClX) (GX)

Fig. 6. Allocalion of dry weight Io Ihe componenl organs for sexual reproduction aspercentages of tlie lotal scxiuil reprotUiciivc effort at both llowcring and fruiting stages infour Trillium species.

OV, ovary; SA, stamen; P, pclal; S, sepal; PED, pedtincle; SD, seed; PER. perlearp.

(vi) Dry matter ullocmionThe allocalion pallerns of dry weight to the

component organs for scxtial reproduction aspercentages of the total .sexual reproductive eflbrtin both nowering and fruiting stages of the fourJapanese Trillium species were examined and arcshown in Fig. 6. In the flowering stages, T. apctalon(4.v). which lacks petals, shows a remarkably highallocation to the ovary; whereas T. kanuschaticum{2.v), which has relatively large petals, shows a highallocation to the petals. In the llowering stage, theHiiocation patterns of dry matter of each speciesare considered to reilect their energy investment toeach reproductive component organ. On thecontrary, no differences were noted in the allocationpatterns at the fruiting stage of the four species.The very high rate of partitioning into the seedswith elaiosomes. i.e., about 75% in all four species,contrasts sharply with the 15% that is invested inthe pericarp.

Discussion

A critical study of the reproductive biology of aparticular species or species group can give usinvaluable information about the significant aspectsof the life history characteristics of plants and their

evolutionary uends tKawano, 1975, 1985). Theresults of the present analyses on various aspects ofreproductive characteristics in four JapaneseTrillium species reveal that in spite of dilTerences inploidy level (from 2.v to 6.v), the four species possessa very similar reproductive strategy. One of themost significant diderence noted in relation toploidy levels was in seed weight, i.e., 2.93 mg (2..V),3.42 mg (4.V), 3.45 mg (4.v) and 4.47 mg {6.v).

This trend detected in four Japanese Trilliumspecies coincides well with the results obtained fromfive congeners of the weedy fox-tait species of thegentis Scniiia (Gramincac). which aiso constitute apolyploid series from diploid (2(/=18) to octoploid(2// = 72) (Kawano and Miyake, 1983). However.the relationsliips between the dry matter partitioningto total reproductive structures (RA) and reproduc-tive output (PN) were conspicuously ditTerent. Thecharacteristic resource allocation patterns found inSctaria. that is. PN is independent of RA. may bedue to their annual growth habit and autogamousbreeding system, which allows these species toalmost attain the levels of saturation in energyallocation, since this trend was also found in manyother weedy or ruderal speeies (Kawano, 1981;Kawano et al. unpubl. and in preparation).

42 Masashi Ohara and Shoichi Kawano

However, further critical studies are needed toconfirm whether such characteristic allocationpatterns found in herbaceous plants are simply dueto (he dilTerenccs in their life forms (annual vsperennial) and/or reproductive life spans (mono-carpic vs polycarpic).

In all four Trillium species examined, the numberof propaguies produced per plant (PN) exhibited aconspicuously increasing trend in response lo theincrcufic in RA fcf. Fig. 4). However, the cor-relations noted between these two variables, i.e..the RA and reproductive output, seem to be chieflydue to the levels of fecundity or efficiency ofpollination caused by pollinator limitation and/orthe breeding system of the planis. The supplyand triinslocation of photosynlhale into fertilizedovules certainly occur via the underground stockorgans, not directly from the leaves, reflecling thefertilization levels of the plants. This trend waslikewise confirmed by us in more than ten NorthAmerican Tiilliuni specrcs (Kawano c£ al., )986;Ohara und Utech. submitted). Kawano et al.(1982) recently showed the presence of somesignificant seasonul changes in the reproductiveoutput (PN) as well as reproductive energy allocationpatterns (RA) in Erythronium japonicum, a liliaceouswoodland perennial. For instance, it was observedthat in a particular year there was a tendency fora higher proportion of energy to be invested inreproductive structures in individuals of lowerbiomass. in other years this tendency, however,became obscured.

This fact strongly suggests that chu pollinationsystem and the brccdint,- system of a particular.species in question no doubt affect the levels offecundity. Indeed, our preliminary breeding ex-periments using these four Japanese Trillium speciesindicate that seed production is strongly determinedby their inherent breeding system and visitingfrequency of pollinators (Ohara and Kawano,unpubl.). Kawano and Nagiii (1982) also con-firmed this phenomenon based on crossing experi-ments in wild populations of Erytlironium japo/iicnm.Since E. japonicum possesses characteristics of atypical outbrecder and no inbteeding occurs in thisspeies (Utech and Kawano, 1975; Kawano et ai..1982 and unpubl.). diflercntial pollination is themo.sl signifkan! fudov in dclerniining the variationin reproductive effort. In short, as noted above,polycarpic woodland perennials translocate theenergy produced by photosynthesis into the pro-paguies through the stock organs (i.e., rhizotnes

and bulbs) in response to the fertilization levels oftiie ovules. Similar cases of pollinator limitationatVecting the fecundity level in plants are also knownin Arisciema iriphyllum, A. urasliima. A. .•ierraiiim,and A. japonicum. North American and Japanesespecies of Juck-in-the-Pulpit (Bierzychudek. 1981;Takasu and Kawano. unpubl.).

Judging from the pollen-ovule ratio found in T.kiimi.schaiicifm (i.e., 2200:1), it is possible to say thatthis is an obviously xenogamous species (Narise,1956). However, remarkable differentiations inthe breeding system in dilTcrcnt local populations arealso known in this species (Pukuda. pers. comm.).However, the breeding system of (he oiher threespecies, with relatively low pollen-ovule ratio(P/O"s) {cf. Table 3), may be regarded as faculta-tively xenogamous or facultatively autogamous(Cruden. 1977). In this respect, it should be alsonoted that they have quite distinct floral displays.That is. 7'. kaml.scluKiciifti has large white petals;on (he olher hand, the pckih yrc enlircJy or partiallylacking in 7'. apetciloti and T. .•iinailii, and thesedifferences are well retlected in the energy allocationpatterns at (he flowering stage (Fig. 6). U has alsobeen shown that in relation to the species' breedingsystems, the P/0 ratio of a species decreases with anincreasing degree of .self-fertilization, i.e., P/O'smay have changed in the process of the evolution ofmechanisms to save energy by minimizing pollenproduction and simultaneously to secure suflicientpollen, assuring maximum fecundity (Cruden.1977). The evoiutionary changes in P/O's mayalso be related lo the decrca.se in energy investmentIo the species" lloral displays and overall sexallocation. Our field observations of pollinatorsand crossing experiments in natural populationsindicate that although Coleoptera. Diptera, etc.were mainly visiting 7". kamt.schaticu/n and T.tsclioiioskii, no effective pollinators have .so farbeen observed in T. apetalon and T. SUHIIIH [cf.Fukuda. 1961, I9fi7). However, it is also notewor-thy that the four Japanese Trillium species aremostly self-compatible, even in 7". kamtschaticiimand T. tschono.skii. Hand-pollinated plants didnot show any significant differences from openpollinated ones in ihcir reproduclive output in allfotir species examined (Ohara and Kawano,unpubl.; cf. Fukuda, 1961, !%7; Uchino. 1980).

As described above, it is evident thiit the re-productive success of plant species is significantlyaflccted by their pollination and breeding meciui-nisms. Our recent findings clearly indicate that

J,

Reproductive biology of Japanese Trillium

not only the density and spatial distribution patternsof individtial plants, but also seasonal changes indensity and foraging behaviour of pollinatorsstrongly affect the levels of fecundity in plantpopulations (Kawano et al., unpubl.). In insect-pollinated species, a large floral display is evidentlyadvantageous in attracting pollinators, and indeed,a reproductive superiority of individuals withnumerous flowers or large heads for attractingpollinators over single, small flowered ones is knownin a North American Trillium species. T crcctum(Davis. 1981), a wild radish species, Raplumiisacanthiformi.s (Kawano and Oda, unpLibl.. and inpreparation), and also a sunflower species,Hcliaiithus amtuu.s (Kawano and Nagai. 1986).If pollinators visit only a limited number offlowers, fruit set will not take place in all flowers ofplants that are non-agamospermous or withoutautomatic selling; and thus the plants are oc-casionally pollinatoi-liniited by virture of lowvisitation (Bierzychudek, 1981; Kawano and Nagai.1982; Koptur. 1984). If plants are self-incompa-tible, a more complex nature of pollinator limitationcan be expected to occur. The fecundity of a self-incompatible species will be considerably affectedby the kinds of pollinators, and the kinds ofpollinator visits, that is, intraplant pollen move-ments result in intrafloral selfing or geitonogamy;on the other hand, interplant pollen movementsresult in xenogamy (Arroyo. 1976). However,resource limitation may also often cause abortionof some developing ovules or ovaries (Stephenson,1981). and may provide a logistical basis for matechoice in plants (Janzen, 1977; Willson. 1979) andsibling competition between developing embryos(Kress. 1981). The reproductive biology of thespecies in the genus Trillium is not sufficientlyknown yet, and further comparative studiesincluding North American species will no doubtprovide us more invaltiable information as to theevolution of life history traits in the genus Trillium,and such studies are now in progre.ss (Kawanoet al.. 1986; Ohara and Utech, submitted).

AclinonledjieniL'nts We tli:ink Dr. Koji Wo for his helpduring this study, and also Dr. F. H. Utech for criticalreading of the manuscript and valuable comnients.Thanks arc also due to Junzo Masuda, Susiimii Miyake,Kaziihito Matsuo, Izumi Noguchi, Hirohito Arai, ToruMatsushima, Hidcaki Nakashima, Seiko Hoshiya,Masako Yanianioto and Shuichi Nakayama for theirlielp in the field woik and pveparation of ihc manuscript.

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Received June 17, J9H6. Aceepted August. 26. 1986.