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R# VENUS (Jup. Jour Malac.) Vol. 4S, No. 2 (1989):S5...95

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Generie Position of Kaliella･ yaeya･mensis Pilsbry, 1901

(: Helicarionidae)

Rei UEsHIMA

(Institute of Biolog'ical Sciences, University of Tsukuba, Tsukuba,

Ibaraki, Japan 305)

Abstract: Live materials of a helicarionid speeies Kaliellct yaeyamensis

eollected from various localities

and its genital and radular features are deseribed. Although the present

speeies has been assigned to the Para･kaliella of the tribe Eueonuli,

subfamily Euconulinae, this species is transferred to the genus Liardetia (s,s.) of the tribe Mierocysti of the same subfamily on the basis ef genital and eon-

chological features, L. yaeyameresis distributes at least from Ryukyu Islands

to Caroline Islands through Formosa. As several related taxa, probably

eonspecifie, are known from various loealities, its distribution range would be

extended further. Local differentiation within this speeies is reeognized from

the morphological variation in the penial stimulator.

Introduction

Katiella･ yaeyamensis Pilsbry, 1901 is a small helicarionid described from

Yaeyama Islands and reported also from Formosa (Pilsbry 1905). This species,

as well as other Japanese minute helicarionids, was first alloeated in the genus

"widely KaLiella whieh was thought as a distributed" genus at that time (Pilsbry

1901). Habe's (1946,1957) anatomical studies revealed that Japanese heli-

carionids formerly classified in Kalietta actually belonged to distinet groups.

``Kalielta" Following Habe's view, Kuroda (1958) divided -Japanese into two

groups; Trochoehtamys Habe 1946 and ParakalieUa Habe 1946, and he pointed

"Kalietta" out that yaeyamensis was conchologically distinguishable from those

two groups. However, Kuroda (1963) later plaeed this speeies in Parakalielta

without any explanation and this alloeation has been followed by subsequent

authors (Azuma 1982, Minato 1988).

During the review of Japanese Helicarionidae, many live speeimen$ of this

species available for anatomieal studies were eollected not only from the type

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86 VENUS: VoT. 48, No.2(1989)

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Ueshima: Generic position of Kalielta yaayamensis 87

loeality, but also from Minami-Daito Island and Formesa. Although the present

species has been assigned to Parcticatiella which belongs to the Tribe Euconuli

ef the subfamily Euconulinae, its genital features indicate that the present

species is a member of the Tribe Microcysti of the same subfamily. Therefore,

the present speeies eannot be retained in ParakalieZla, The following account

presents this evidenee and provides anatomical features of this species and new

generic assignment.

Materials and Methods

Materials dissected:

Ishigaki Island, Yaeyama Islands: Mt. Omange, Hoshino (37 specimens, 30

Mareh 1984); Nagura (3 specimens, 31 Mareh 1984); Palm Park,

Yonehara (2 specimens, 31 Mareh 1984). Iriomote Island, Yaeyama Islands: Nakano (26 specimens, 28 March 1984) ;

Toyohara (2 specimens, 27 Mareh 1984).

Minami-Daito Island, Daito Islands: Kyuto (12 specimens, 5 November 1986,

collected by T. Kurozumi).

Forrnosa (Taiwan): Ken-Ting Park (6 specimens, 22 August 1985); Cape

Wolanpi (1 speeimen, 20 August 1985).

General methods of dissection and scanning electron micrograph were carried

out according to the methods described in Ueshima and Kurozumi (1988), except

several specirnens collected from Ishigaki Island which were dissected alive in

a saline.

Observations

Genitat-ia (Figs. 1-4) :

Hermaphroditic gland (ovotestis) is small, censisted of mainly two clusters of clavate alveoli (each cluster is sometimes divided further into two in large

specimens as shown in Fig. 2), embedded in mid-gut gland. Hermaphroditie

duct is slender, rather short, weakly convoluted. Talon is small, frequently

embedded in albumen gland. Carrefour is small but prominent. AIbumen g}anq

is triangular, rather small for heliearionids, eonsisted of large.loosely cemented

cells. Uterus is well developed, extremely swollen by pregnancy. Upper region ttttt tttttt tttt t ttt t tt tttt-tt

Figs. 1-3. Genital organs of Liardetia (s,s.) yaayamensis. =JK t; }= tfOthdeX 1. Mt, Omange, Hoshino, Ishigaki, Island (showing an individual dissected alive in a saline) ; 2. Cape Wolanpi, Formosa ; 3. Kyuto, Minami-Daito Island (A. showing the natural condition in which penial complex is compactly folded and surrounded by a thin sheath; B. penial complex with its sheath cut out). Scale line 1 mm, AG, albumen gland; At, atrium;BC, bursa copulatrix;C, carrefour;Em, emryo; EC, epiphallic caecum; Ep, epiphallus; HD, hermaphroditic duct ; HG, herma- phroditic gland or ovotestis; P, penis; PA, penial appendix; Pr, prostate; PRM, penial retractor muscle ; PUO, post-uterine oviduct ; T, talon ; Ut, uterus ; VD, vas deferens.

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88 VENVSt VoL 48, No. 2 (1989)

= =}' Fig. 4.Internal structures Qf penis of Liardetia (s.s.) yaayamensis. X t; ifDltgCDNutIYue A. a typical specimen collected from Ken-Ting Park, Formosa ; B, C. specimens with secondary horny stimulator collected from Kyuto, Minami-Daito Island ; D. a specimen with large beaky horny stimulator but no secondary stimulator collectedfrom Kyuto, Minami-Daito Island. Scale bar 250 ptm in A, 100 pm in B, C and D. BHS, beaky horny stimulator; EC, epiphallic caecum; PA, penial appendix; PPd, penial pad ; SHS, secondary horny stiTnulator ; VD, vas deferens.

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Ueshima: Generic positien of Kolietla yaq),amensis 89

of uterus which attaches to prostate is small, slender, defiated, always empty,

refiexed backwards at the end of prostate and then becomes abruptly swollen

to contain eggs or embryos. This embryo-containing region (cerresponding to

free oviduct of other helicarionids) is large, thin-walled, completely separated

from sperm duct, and followed by empty regiQn called post-uterine oviduct

(Baker 1938). Post-uterine oviduct is slender, thin-walled, does not have

glandular zone nor internal pilaster. This species is ovoviviparous, All examined

specimens ineluding young materials have one to ten eggs or embryos in uterus.

Eggs in uterus do not have ealcareous shell nor outer layer, Embryos become

progressively grown from top to bottom and the largest embryo found near

the gonopore has about 2 whorls. Prostate is small for helicarionids, consisted

of numerous acini, contjnues from carrefour to the beginning of vas deferens.

Vas deferens is slender, simple, entering the apex of epiphallus beside the

epiphallic caecum. Epiphallus is slender, s!ightly broader than vas deferens, 'is with a prominent epiphallic eaeeum. Basal region of epiphallus which re-

cognizable from outside as opaque white region has much gland eells than other region and is probably homologous to eorona of Philonesiae (Baker 1938).

Epiphallic caeeum is large, about twice the diameter of epiphallus, inwardly

eurved, with rounded apex, having ne prominent strueture internally. Penial retraetor muscle arises from the diaphragm, and inserts on the apex of penis.

Penial appendix loeating near the insert,ion of penial retracter muscle is short

but more slender when the is living (Fig. 1), tapers towards its apex,

lacking pilaster or stimulator int,ernally. In a single specimen eolleeted from

!shigaki Island, penial appendix is found to be everted. Upper half of penis is rather slender, having weak internal pilasters in several speeimens. Mid

portion of penis is swollen, thick-walled, internally containing horny stimulator

and one or two large penial pads (Fig. 4). Beaky horny stimulator whieh

locates just below the penial pad is small, inwardly curved and its tip is peinting

towards gonopore. As this beaky stimulator is found in all specimen examined

and attaehing to the thick wall of penis tightly, this structure is probably persistent. In most of the specimens collected from Minami-Daito Island, a secondary horny stimulater is found just above the beaky stimulator. Thi's secondary stimulator is large, recurved, with blunt or truncated tip. The phenb-

type with the secondary horny stimulator is dominent in Minami-Daito Island

but is never found in other localities. Basa} region of penis is rather slender,

thin-walled, lacking pilaster or stimulator internally. A thin sheath attaching

around the mid portion ef penis surrounds upper half of penis, penial appendix,

epiphallus and epiphallic caecum that are eompactly folded (Fig. 3A). This

sheath called penis sheath by Baker (1938) seems not to be homologous to thick

muscular penis sheath of higher helicarionids whi ¢ h surrounds only a part of

penis or epiphallus (this sheath is cut off and not shown in Figs. 1, 2, 3B, so

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90 VENUS: VoL 48, Ne. 2 (1989)

Fig. 5. Radula ef Liardetia (s, s.) yaeyamensis: showing a specimen collected from Mt. Omange, Hoshino, Ishigaki Island, = A i} } tfOta= A. marginal teeth ; B. central teeth and latero-marginal transition showing the shape of basal plates ; C. outermost marginal teeth ; D. central teeth and latero- marginal transition in slightly worn rows. Scale bar 10 ptm.

that detailed structure of penial eomplex can be seen). BuTsa copulatrix locating

en male side is small, as long as or slightly shorter than penis, thin walled,

lacking any pilaster, and enters into baBe of penis. In all specimens examined,

bursa copulatrix is connected to uterus orli post-uterine oviduct with thin membrane alld fine fibers (Figs. 1, 3). Although white slimy mass, probably sperm fluid or degradation product of allosperm, is found in bursa copulatrix

of some speeimens, horny spermatophore is not found. Taken together with

internal structure of epiphallus, this species probably does not produee horny

spermatophore, Atrium is short.

Radula (Fig. 5):

Radula has 87-108 rows of teeth and each row is constituted aecording to

the following formula:

C/3 + 5-6 L13 + 23-32 M/2-4

Central teeth are tricuspid, squarish, with broad basal plate. Lateral teeth are

also trieuspid, usually 5 in number. First and second laterals are closely

similar to centrals in size and shape, each having a large entocone whieh is

almest equal to ectocone, rather symmetrical but the inner-lateral side of basal

plates are reduEed, Transition from lateral teeth to marginal teeth is gradual,

involving the following steps of asymmetricalization; narrowing the breadth,

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Ueshima: Generic position of Koliella ptaeyamensis 91

decrease in the prominence of entocone which beeomes located more posterior and centerwards shift in angles for the mesocene. Marginal teeth are narrow,

lack entocone, with large ectocones that are almost equal to the mesocone in

size, bicuspid in early several teeth but mostly tricuspid. Among trieuspid

marginals, multicuspid ones sometimes observed. Size of marginals gradually

decreases towards the outside. Outermost marginals are frequently multicuspid.

Discussion

The classification of Heliearionidae is first proposed by Blanford and Godwin- Austin (1908) and has been modified by Thiele (1931), Baker (1941), Zilch {1959-1960) and Selem (1966) as available anatomical data have increased. In

this paper, I follew the system of Solem (1966). Although the present species was assigned to the genus PaTakaliella whieh

belongs to the Tribe Eueonuli of the subfamily Euconulinae, the present species

should be placed in the Tribe Microeysti of the same subfamily because of

having sepaTate gonoduct, bursa copulatrix on male side and ovoviviparity.

0ther features of the present species sueh as conical spire, presence of penial

appendix and horny stimulator illside the penis fit the characteristics of the 'those genus Liardetia Gude, 1913 (Baker 1938). Radular teeth is also agree with "Kaliella" of the genus Liardetia. Therefore, yaeyesmensis should be trans-

ferred to the genus Liaraetia. Baker (1938) divided the genus Liardetia into

three subgenera. The present species is plaeed in the widely distributed sub-

genus Liardetia (s.s.) because of having rounded periphery and dullish shell

surface.

L. sp. from Minami-Daito Island whieh was reported by Sorita (1985) is

apparently conspecific with L. yaeyamensis beeause of the same conchological

features and having large epiphallic caecum (called flagellum by Sorita). 'to Sorita's figure of genitalia is drawn as if vas deferens was fused free

oviduct and bursa copulatrix was loeated on female side. Although I examined

the rnaterials from the same island (see Fig. 3), such genital features were not

collfirmed. As vas deferens is connected to oviduct by fine fibers and the opening

of bursa copulatrix is close to the separation of oviduct, discrepancy is probably

due to Sorita's misjudgement. Baker (1938) assigned the specimens from

various localities to L. sculpta CMoellendorff, 1883) and dissected the materials

from Caroline Islands. Baker's descriptions on L. sculpta quite agree with L.

yaeyamesis not only in its conchological features but also in anatomical features,

espeeially in having large epiphallic caecum (called fiagellum by Baker) and

occurrence of the phenotype with more than one horny stimulator as found in

the specimens from Minami-Daito Island. As the latter two genita] features

``scutpta" are unique and have not been found in other congeners, L. at least 'is' from Caroline Islands undoubtly conspecific with L. yaeyamensis and the

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92 VENUS: VoL 48, No.2(1989)

c･

4oeN , e

;. e fl>2;!5 .ttt:- 3oo A 69,iei 0 2oo A / k ''' 'i'' 1oe 'f 5. ng .Q, - " s.

".-1 Oe fu a g': lfll'i-･gil ss. :'scrts-", "oe £ )gy '211 : ,ox$ ' 100s t". .

e 1000E 1200 1400 160" 18t

Fig. 6. Geographic distribution of Liardetia (s, s.) yaayamensis and its related taxa. = - i> } tfNocifiiil;tfiotevemb5irhi e:lecalities of the specimens which can be assigned to L. yaayamensis on the basis of both anatomical and conchological features; O:localities of L. yaaya- mensis whose anatomical data are not available; x.'... : locaYities of L. sculpta "dotiolum" reportecl by Baker(1938); []:localities of L. reperted by Benthem- Jutting(1950). Locality numbers 1, Minami-Daito 1$., Dal'to Islands; 2, Ishigaki Is., Yaeyama Islands; 3, Iriomote Is,, Yaeyama Islands; 4, Formosa; 5, Ponape Is., Caroline Islands.

distribution range of the latter speeies is extended far to Paeific Islands. L.

scutpta to which the materials from Pacific Islands were assigned by Baker

C1938) was originally described from Macao, China (Moellendorff 1883). Conchologically L. sculpta closely resembles to L. yaeyamensis espeeially in its

stTong eoarse rib-striae which die out about halfway between periphery and

columella

species is also supported by biogeographical data beeause land mollusean faunas

of southern China (ineluding the type loca}ity of L. scutpta), Formesa and

Yaeyama Islands (the type locality of L. yaeyamensi$) share many common genera and the closely related speeies groups (Kuroda 1941, 1959, Habe and "doliotum'' Chinen 1974). Small helicarionid from Java which was assigned as L.

by Benthem Jutting (1950) has also similar shell sculpture and seems better ･yaeyamensis te be referred to L. sculpta or L. rather than L. dotiotum with

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Ueshima: Generic position of Keliella yaeyamensis 93

finer growth lines. Judging from conchological features, all these materials from

various loealities are probably consisted of a single species with extensively

wide distribution range. However synenymization of L. yaeyamensis with L.

sculpta is not warranted and the former name is tentatively used for Japanese

and Paeific materials until the specimens of the latter species collected from

its type loeality can be disseeted. In order to clarify the relationships between

L, ya･eyamensis and its al]ied taxa, further materials available for anatomical

studies are required. ･yaeyamensis Although L. exhibits slight intra-populational variation in shell

shape, size and sculpture, there is no sign of prominent inter-populational

differentiation in shell morphology. As mentioned above, most of the specimens

collected from Minami-Daito Island have additional horny stimulators. Sueh

a phenotype is characterist･ie to the population of this island, and has not been

found in Yaeyama Islands nor Formosa. Furthermore, in a specimen collected

from Minami-Daito Island whieh lacks the additional stimulator, a beaky

stimulator is unusually enlarged (Fig. 4D). These observations indieate that

the degrees of ceratinization in penial stimulator is muc.h ellhaneed in Minami-

Daito Island population than in Yaeyama Islands and Formosa populations,

hence local differentiation within L. yaeyamensis does occurs. L. sp. (aff.

boninensis) also exhibits the stmilar pattern of loeal differentiation; only the

population of Minami-Daito Islands is differentiated from those ef other Japa-

nese localities in both eonchological and anatomical features (Ueshima, un-

published.) . It should be noteworthy that Baker (1938) also found the phenotype

of L. yaeya,inensis from Caroline Islands (reported as L. sculpta) with more

than one horny stimulator like the specimens of Minami-Daito Island. Although

additional stimulator of L. yaeyamensis can be considered as apomorphic character,

whether the occurrences of such specialized phenotype in such faT remoted islands should be explained by the genetic sirnilarity between L. yaeyamensis of these

island populations or by convergent evolution is not clear, In any cases, L.

yaeyamensis from Minami-Daito Island is different frem those of neighboring

regions, Considering the pattern of local differentiation in Liardetia, it is

supposed that Daito Islands have been isolated from other regions for a long

time enough to produce the endemic forms or that the origin of the land Enail

fauna of the Is]ands are different from those of neighboring regions.

Acknowledgentents;-I thank Dr. Kazuo Haga, Institute of Biological Seiences, Uni-

versity of Tsukuba, for his critieal reading of the manuscript. Thanks are also

extended to Dr. Katura Oyama of Toba Aquarium for his kindly supplying some

literatures and useful eomments. Specimens from Minarni-Daito Islund were kindly

provided by Mr. Taiji Kurozumi of Okinawa Prefeeture.

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94 VENUS ： Vol ，48， No ．2 （1989）

要 約

国 内外 の 各地 （模 式 産 地 を 含 む ） か ら 得 られ た コ ス ジ キ ビ の ．軟体 部 を 検 討 し ，そ の 生 殖 器 と 歯舌 の

し コ x ジ ビ こ Euconulinae Euconuli の ハ マ ビ 形態 を 記 載 た 。 キ は ， れ ま で 並 科 族 リ キ 属 Parakatiella 一 の ・ ニン ビ − 員 と し て 扱 わ れ て き た が ，軟体 部及 び 殻 の 特 徴 か ら ， 11亜 科 Microcysti族 の ボ キ 属 Liar

detia s s （．．） に 所 属 を 変 史 し た 。

コ ス ジ キ ビ は 少 な く と も 八 重 山諸 島 か ら南 大 東島，台湾 を 経 て カ ロ リ ソ 諸 島 に 至 る 広 い 範 開 に 分布 “ マ し ， 同種 と思わ れ る も の は 中 国 大陸 ， ジ ャ ワ ， リ ア ナ 諸 島 か ら も報 告 さ れ て い る の で ， こ れ ら 近 ” ． の の こ 似種 と 比 較 検 討 が 進 め ば ，木 種 分 布 は さ ら に 拡 大 さ れ る と が 予 想 さ れ る 。

な お コ ス ジ キ ビ の 陰 茎 の 内部形 態 に は 種 内変異 が 認 め られ ，特 異 な表．現型 の 出現 す る 産 地 が 限 定 さ ． ’ れ て い る こ と か ら ，種 内分 化 が 生 じ て い る 可 能 性 が 示 唆 さ れ た 。南 人 東 島 の 個 体 群 は ，八 重 山 諸 島 ，

い 力 卩 ン の 台湾 の 個 体 群 と は 著 し く 異 な っ て る が ， リ 諸島 か ら 報 告 さ れ た も に 似 た 表現 型 が 出 現 し ，

い 生 物 地理 学 的 に 興味あ る 問 題 を 提起 し て る 。

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