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R# VENUS (Jap. Jour. Malac,) Vol. 41, No. 2 c19s2): 150-153

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Chromosome Numbers of Two Species in the (, Basommatophora)'

Shigemi KoMATsu (Mukaishima Marine Biologieal Station of Hiroshima University,

Mukaishima-cho, Hiroshima-ken 722)

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The ehromosomes of two species in the EIIobiidae were studied by use of the aceto-orcein squash me'hod using gt)nadal tissues. The chromosome numbers of

Ellobium ehinense were 2nb=36 and n--18. The karyotype of E. chinense consisted

of 18 pairs of metaeentrics. A haploid number of n=18 was also observed in

Metampus castanews.

appreciation for the eentinuing guidance Introduction of Professor A. Inaba, Director of Mu-

Cytological studies have been eon- kaishima Marine Biological Station of

dueted on a Iarge number of basom- Hiroshima University.

matophoran and stylommatophoran gas- Materials and Methods tropods. Observed haploid ehromosome

numbers have ranged from n==15 to The specirnens used in this study were

n=21 in approximately 140 species re- as follows:

presenting 10 families (Patterson, 1970). Melutmpt{s castaneus (MUIdfeld): In the basommatophoran family Ellobii- Collected from Fujii River, Fuku-

dae, ehromosome numbers of n!=17, 18 yama City, Hiroshima Prefecture

and 19 have been reported among the in June, 1978 and May, 1979.

10 speaies studied so far (Meyer, 1955; Eltobium chinense (Pfeiffer) : Col-

Natarajan, 1958; Natarajan and Burch, Iected from Kiya River, Shimono-

1966; Burch, 1960, 1967). This paper seki City, Yamaguchi Prefeeture

reports the ehremosome numbers of two in March, 1979.

additional ellobiid species: Melampus Gonadal tissues were examined by the

castaneus and Ellobitt7n chinense. aeetQ-oreein squash method as deseribed

The author would like to express his in Komatsu and Inaba (1982). " ' .arme contTibutionfrom the MukEigKima M Biological Station. No. 193.

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恥 151

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む 磁 逡 L ’ ま ”‘ 1 ， ・ 1 i葛 蜜 鶏篇 慕毒 翻 1／ x葺 X ’嘉 z t き n ’ ’ @ き ， モ “ 葱こ羅灘招 欝幾 慧鮮 灘 婁1 鼈灘 冠1 轟 溝：鯉蜘 瞳：1瀕麟：鱗齢懐嘉愛

、 ． L Metampus く Fig castane κ s ， chromosomes at prometaphase of lst spermato t e ハ マノ ィ ノ 、 ガ イ ， 第 1 精 母 細 胞 前 中 期 染 色休 Figs． 2 −4． Ellobtum chznense オ

、 イ 2 、 カ chromosomes at spermatogonial metaphdbe 精 原細 胞 の染 色 体 3 ．chromosomes 期 at prometaphase of lst spermatocyte 第1精 母 細 胞 目 I ﾌ 染 色 体 4 ．Kdry

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152 VENUS: VoL 41, No. 2 (1982)

Table 1. Chromosome numbers of the Ellobiidae. -; -(f -( 7]- " E t)" vC 2}l va th tsXD SiU op L UH 6 st t--t-ttt-ttttt .-... tttt t ttt ' ....-ttt ...... Species n 2n Source Reference ttt Natarajan, 1958 Ilythia Plicata 17 34 India

P. scarabaeus 18 Solomon ls. Burch, 1967 Meyer, 1955 Rhytia myosotis 18 Europe [==Ovatella myesotis] Burch, 1960 R m. mar:ylandica 18 U. S. A,

1958 Cassidula m"stegina 17 34 India Natarajan,

Natarajan and Burch, 1966 C. vespertitienis 34 New Caledonia

1960 Detracia noridana 18 36 U. S. A. Burch, Natarajan, 1958 MelamPus ceilonicus 18 36 India M. bidentatus lineatus 18 36 U. S. A. Burch, 1960 Natarajan and Burch, 1966

1966 M. cofuus 19 38 U. S. A. Natarajan and Burch, ' tttttttttt tt tt ttt ....--..- ' ttt--ttttt tt ttt-

[ ]: synonyrn used by the investigator.

Chromosome nomenclature follows that actemzing the lower taxa.

of Levan, Fredga and Sandberg (1964). In the family Ellobiidae, chromosome

numbers have been reported foT 10 Observations species and subspecies, ranging from the 1. Melampus castaneus (MUIdfeld) n-17 to n=19 (Table 1). Because

number of n=18 Some meiotie divisions were observed haploid ehromosome

study for two species in the squash preparations. Eighteen observed in this n--17 to n==19, chTomosomes were counted in the pro- is within the range of

Ellobiidae also have metaphase of lst spermatocyte (Fig. 1). it appears that the a eonservatiye na'ure in cytelogical 2. (Pfeiffer) n=-=19, Meiotic divisions were observed in characters. The highest number,

reperted for an ellobiid was found in May. From the squash preparatiens, the cofieug numbers of this species were only one speeies, Melampus (Na- ehremosome - 1966). NataraJan determined to be 2n-36 and n=18 (Figs. tarajan and Burch,

reported that one in- 2, 3). The size range of the diploid and Burch (1966) had 38 ehromosomes at the dia- eomplement was from 2.3 ptm to 1.1 pm. dividual of the spermatocyte, although The karyotype of this species eonsisted kinensis it was doubtful whether it was an in- of 18 pairs of metacentries

Discussion was obviously a tetraploid.

Karyotypes in the Ellobiidae have Patterson (1970) has stated that in reported only for Me- the Gastropoda eytological characters been previously

lineatus are eonservative among the ]ower taxa, lampus bidentatus (Natarajan

Bureh, 1966). It consisted of 7 e.g. families and genera. Chromosome and

metacentrics and of numbers are constant within families pairs of 11 pairs submetacewttrics. Hovsrever, the karyo- and genera and variation in haploid

chromosome numbers seldom exceeds ± 2 type of Ellobium chinense consisted of

bivalents from the basic numbers ehar- 18 pairs of metacentrics.

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Komatsu: Chromoseme Numbers of Ellobiidae 153

To reveal the cytological relationships tropoda). Ven?ts, Jap. J. Malacol.,

within the Melamfms, further 41(1): 47-60.

comparison of the karyotypes should be Levan, A., K. Fredga and A. A. Sand-

made. berg 1964. Nomenelature for eentro-

merie position on ehromosomes. Here- ee ts ditas (Lztnd), 52: 201-220. -? .. y( 1 l fftMcstde fi E ab'Iovagts Meyer, K, O. 1955. Naturgeschiehte

ig = iV U {- 7ptJll!, LtlreMCD ff L-)$LneC X der Strandschnecke Ovatella myosotis

o-CenzaLft:. reMC'rk, A't :717 E h"( n= (Draparnaud). Arch. Mollzeskenk, 84

18)tJ)ij l .` ab"I 2n=36, n=18u(SfoDk. rifi (113): 1-43. -;. i, " ;ij'I e[)vaWom, lsXJ'a)[PutN'Eayvatsts Natarajan, R. 1958. Chromosomes of

k ip ma,diiiZ ig. some estuarine basommatophorous (Mol]usca: ) from Literature cited Portonovo. J. geol. Soe. Indin, 10(2):

Bureh, J. B. 1960. Chromosome studies 103LI07.

of aquatic pulmonate snails. IVucletts, Natarajan, R. and J. B. Burch 1966.

3; 177-208. Chromosomes of some Arehaeopulme- Bureh, J. B. 1967. Cytological relation- nata (Mollusea: BasommatophDra). ships of Pacifie gastropods. Ven?ms, Cytologia, 31(2): 109-116. Jap. J. Malacol. 25(314): 118-135. Patterson, C. M. 1970. Choromosomes

Komatsu, S. and A. Inaba 1982. Chro- of mollusks. P7`oc. Symp. Moll., II, mosome numbers of 14 species in the Mar. biol. Assoc. Indin, 1969: 635- Neritidae (Gastropoda, Arehaeogas- 686.

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