Anomalies in radulae of Albinaria species from the Greek islands of Kephallinia and Ithaka (Mollusca: Gastropoda Pulmonata: Clausiliidae)

7 Pages·1994·1.2 MB·English

by  Bor, P H F

BASTERIA. 58:27-33, 1994
Anomalies in radulaeofAlbinariaspecies from the Greek islands of
Kephallinia and Ithaka (Mollusca: GastropodaPulmonata:Clausiliidae)
P.H.F. Bor
Valkcnhorst 66, NL 2317CN Leiden, the Netherlands
E. Gittenberger
Nationaal Natuurhistorisch Museum, P.O. Box 9517, NL 2300RA Leiden, theNetherlands
& Th.C.M.Kemperman
Zoomstraat43-11, NL 1078 XHAmsterdam, the Netherlands
While studying 108 radulae ofAlbinariaspeciesin search for diagnosticcharacters, we kept
record ofthe observed malformations, which were classified into seven categories. Next to
longitudinalanomalies, only asinglenon-longitudinalone was found.The results suggestthat
there mightbe (sub)speciesspecific differences in thepercentage ofanomalies.
Key words: Pulmonata, Clausiliidae, Albinaria, radula, anomalies, Greece.
INTRODUCTION
In a paper on abnormalities in the radulaofDrymaeus virgulatus (Ferussac, 1821)
Venmans& Verdcourt(1950: 1) statedthat "very fewreferencesconcerning abnormal
radulae are to be found in the literature on nonmarine mollusca...". Anomaliesin
radula structures ofother molluscan groups had been described by e.g. Adam(1933),
Cawston (1940) and Peile (1922, 1932). At present, more than forty years later, not
much seems to have changed. We could find only five additionalpapers on, or with
references to, abnormal features of radulae (Schilder, 1963; Solem, 1974; Runham,
1975;Falniowsky, 1979;Marshall, 1983:fig. 8d). Thisis surprising, becausethe use of
the Scanning Electron Microscope (= SEM) has madeit considerably easier to study
radulaein much detail.
While studying the systematics and the evolutionary history of the species of the
clausiliidgenus AlbinariaVest, 1867,from the Greek islands Kephallinia and Ithaka,
attentionwaspaid tothe structure ofthe radulae.The mainresultsofthisinvestigation
werepublished by Kemperman (1992: 81-120). Thevarious kinds ofradular anomalies
that were noticed unexpectedly, are dealtwith in thispaper.
Thepulmonate radulahastransverserows with acentraltoothandseveral lateraland
marginal teeth.In principle, the centraltooth consistsofabasalplatewith amesocone,
which may be accompanied by a pair of more or less obsolete side-cusps. The lateral
teethmayalsohave theseside-cusps, whichare calledendo-orectocones, dependingon
theirposition relative to the centraltooth. The marginal teethhave bothkinds ofside-
cusps, with anectocone often split up intoa series of separate cones.
Counting in atransverse row fromthecentral, bilaterally symmetrical tooth(= C) on,
theadjoining asymmetrical tooth(on both sides) is the first lateral(= LI), followedby
thesecondlateral(=L2) etc. The transitionbetween lateralandmarginal (= M)teethis
28 BASTERIA, Vol. 58,No. 1-2, 1994
notalways clear. In Albinariawe used the size ofthe basal plate to distinguish between
bothkinds. In atransverse row ofradularteeth, the C andL teethhave relatively large
basalplates, provided with denticles thatenablethem to perform a hinge-function. By
definitioncounting fromthe centraltooth on, the first toothwith abasalplate decreas-
ing disproportionally insize, is consideredtobethe lastlateral.Theadjoining oneisthe
first marginal tooth(= Ml).
Breure & Gittenberger (1982) describedtherock-scraping radula type,characterised
by a reductionofthe side-cusps onboth sidesofthecentral toothandseveraladjoining
lateral teeth, resulting in a central zone with unicuspid teeth. The Albinaria radula
belongs to this rock-scraping type.
MATERIAL AND METHODS
During fieldtrips on Kephallinia and Ithaka living snails were collectedat many
localitiesandfixatedandconservedin 70% alcohol. The radulaeofspecimens belong-
ing to the following (sub)species were studied:
A. adrianaeadrianaeGittenberger, 1979;
A. a. dubia Gittenberger, 1979;
A. contaminatacontaminata(Rossmassler, 1835);
A. c.periporon Kemperman & Gittenberger, 1992;
A. c. samiensis Kemperman & Gittenberger, 1992;
A. c. odysseus (Boettger, 1878);
A. c. muraria (A. Schmidt, 1868);
A. senilissenilis (Rossmassler, 1836);
A. s.flavescens (Boettger, 1878);
A. s.kolpomyrtensis Kemperman & Gittenberger, 1990;
A.jonicajonica (Pfeiffer, 1866);
A. j. assicola Kemperman & Gittenberger, 1990
Anomalieswere foundin materialfrom the following localities(unless statedother-
wise, thelocality isonKephallinia island); thematerialwas collectedbyE. Gittenberger
(053, 055, 060), G.J.M. Visser(033) and the thirdauthor (remaining localities).
033 A. contaminatacontaminata — along road to Oros Aenos (ca. 13 km ESE. ofArgostoli), 1200 m alt.,
DH6923; 10-11-1985
053 A.adrianaeadrianae—coastalrocks 1 km N.ofPoros, 50 m alt.,DH7924; 09-05-1987
055 A. adrianaeadrianae — gorgeW. ofPoros (type loc.)(= 25.1 km E. ofArgostoli), 25 m alt.,DH8023;
08-05-1979, 21-03-1988
060 A.adrianaedubia— ca. 2.5 km SE. ofXenopoulon,300 m alt., 08-05-1979
294 A. contaminata contaminata—betweenMetaxataandTravliata nearjunctiontoMon.Andreou(= 7.6km
SE. ofArgostoli), on rock-bases alongroad, 145m alt.,DH6021; 23-04-1987
467 A.senilissenilis—500 mSW.ofTsarkasianos (= 16.3km E. ofArgostoli),onsmallrocks alongroad, 570
m alt., DH7125; 03-05-1987
507 A.adrianaeadrianae— gorge3.8km SE.ofPoros(28.3 km ESE.ofArgostoli), onrocks ofN.-face gorge
alongroad, 10m alt.,DH8220; 08-05-1987
539 A. senilis senilis — Mavrata (= 24 km ESE. ofArgostoli), on vineyard-wallin village alongroad to
Thiramones,160m alt.,DH7514; 09-05-1987
544 A.adrianaeadrianae—200 mN.ofPoros(= 25km E. ofArgostoli),onisolatedrockbetweenhousesalong
coastalroad, 1 m alt.,DH8023; 09-05-1987
568 A.adrianaedubia— 1.5kmN.ofArginiaalongtheroad toKapandriti(= 22.3km ESE.ofArgostoli),520
m alt., DH7618; 10-05-1987
Box, Gittenberger &Kemperman: Radula anomalies in Greek Albinaria species 29
578 A.adrianaedubia—2.5km NW.ofAg.Georgios(typeloc.)(= 22.8km ESE.ofArgostoli),on highrock-
faces, 400 m alt.,DH7618; 11-05-1987
579 A. adrianaedubia - 1.5km NW.ofAg.Georgios,275 m alt., DH7717;11-05-1987
585 A. contaminata muraria—IthakaIsl., 3km NNW.ofVathi, onrocks alongcoastofN.-sidebay ofVathi,
5-10 m alt.,DH7448; 12-05-1987
604 A. contaminataodysseus—IthakaIsl.,alongroadtohighland-planes2kmS.ofMoniTaxiarchon(= 5.6km
S. ofVathi),510 malt., DH4174; 13-05-1987
614A. contaminataodysseus— IthakaIsl.,600 mS.ofAgros (= 4.5km W.ofVathi)on rock-face alongroad,
160 malt.,DH7147; 13-05-1987
From 108 specimens the buccal masses wereremoved, macerated in a 20% KOH-
solution, cleaned ultrasonically and mounted for SEM studies. For more detailed
informationonthese procedures, see Kemperman (1992: 85).
RESULTS
In 108 specimens we found oneor more anomaliesin 20% ofthe radulae(table 1).
Sevencategories ofanomaliesare distinguished, concerning the central, thelateral, as
wellas the marginal teeth.In allcases butone, the anomaly is repeated inalltransverse
rows. Thus nearly always entire longitudinal teeth-rows are involved. The following
anomaly types were listed.
(1). Fusion ofteeth. — This was found five times. In four cases two teeth were
involved:L8 andL9 inA.a. adrianae(507) (fig. 1),L5 andL6inA.c.contaminata(033), M3
andM4in A.a.adrianae(544) (fig. 2), andM9 and M10 inA.a. dubia(579) (fig. 12). In a
specimen ofA. a. dubia (578) three mesoconesand three ectocones were present ona
single element (fig. 3), which canbe interpreted as a fusion ofthree marginal teeth.
(2). Dwarfedmesocone.— We found teeth with a dwarfedmesocone intwo speci-
mens. One specimen ofA. a. adrianae(544) has a relatively small mesoconeofC. A
specimen ofA.a. dubia(060) has not only a smallmesoconein C,butalso in L7(fig. 5).
(3). A missing ecto- orendocone. — In a specimen ofA. s. senilis (539) we found a
missing ectocone in L8(fig. 6); thisanomaly was also noticedin M5 ofaspecimen ofA.
a. adrianae(544) (fig. 2).An endoconewas missing in M5 (left and right side ofasingle
specimen) andM3 ofA. a. adrianae(055).
(4). Abluntedor two-topped mesocone.— One specimen ofthe Ithakiansubspecies
A. c. odysseus (604) shows a L3 with a blunted and sometimes slightly two-topped
mesocone(fig. 4). A specimen ofA. a. dubia(579) hada very broadmesoconein M9.
Several shortly but distinctlybifidmesoconeswerefoundinisolatedteethinaspecimen
of.A. a. adrianae(055) (fig. 10).
(5). Amissing mesocone inmarginal teeth.— Themesocone isreducedto theheight
ofthe ectocone. Thisis foundin fourcases. Three specimens ofA. a. adrianae(055 [1],
053 [2]) have anaberrant M4 (fig. 7), M7 and M10, respectively; a specimen ofiA. c.
muraria(585) has anaberrant Ml 1 (fig. 8).
(6). Abroad marginal. — The marginal tooth is exceptionally broad and shows a
protrusion at the base ofthe mesocone(fig. 9). This is found in five cases withintwo
differentspecies. Two specimens of A. a. adrianae(544) havethis anomaly, in M7 and
M9,respectively. InA. contaminataitwasseenin specimens ofthree differentsubspecies,
viz., in M8 ofA. c. contaminata(294), M15of A. c. muraria(585) andM8 ofA. c. odysseus
(614).
30 BASTERIA, Vol. 58,No. 1-2, 1994
Figs. 1-6.AnomaliesinradulaeofAlbinariaspec. 1,A.a. adrianae(loc. 507),fusedL8-L9(1750x); 2,A.a. adrianae(loc.
544),fusedM3-M4(1050x);3,A.a. dubia(loc. 578),three marginalteethfused(1050x);4,A. c.odysseus (loc. 604),
mesocone L3withbluntedapex(1050x);5,A.a.dubia(loc.060),reduced mesocone of CandL7 (700x);6,A.s. senilis
(loc. 539),L8 withoutectocone(1400x).
Box, Gittenberger<2?Kemperman: Radula anomalies inGreek Albinana species 31
Figs. 7-12.AnomaliesinradulaeofAlbinariaspec.7,A.a. adrianae(loc.055),missingmesoconein M4(2400x);8,A.
c. muraria(loc. 585),missingmesocone in M11 (1190x); 9,A. c. odysseus (loc.614), avery broad M8witha basal
protrusion (2800x); 10, A. a. adrianae (loc. 055), L4-7 with some bifid mesocones, notlongitudinallyconstant
(1400x); 11,A. s.senilis(loc. 467),M12witha doubledmesocone (1890x); 12,A. a. dubia(loc. 579),fusedM9-M10
(1400x).
32 BASTERIA, Vol. 58,No. 1-2, 1994
SSuubbssppeecciieess NNrr NN1l NN22 NN33 NN44 NN55 NN66 NN77 NNaa PPaa
aa.. aaddrriiaannaaee 1188 22 11 44 11 33 22 1100 5555
aa.. dduubbiiaa 1133 22 22 11 44 3311
cc.. ccoonnttaammiinnaattaa 1177 11 11 22 1111
cc.. ppeerriippoorroonn 66 00 00
cc.. mmuurraarriiaa 33 11 11 22 6666
cc.. ooddyysssseeuuss 88 11 11 22 2255
cc.. ssaammiieennssiiss 44 00 00
jj.. jjoonniiccaa 22 00 00
jj.. aassssiiccoollaa 88 00 00
ss.. sseenniilliiss 1177 11 11 22 1111
ss.. ffllaavveesscceennss 88 00 00
ss.. kkoollppoommyyrrtteennssiüsI 44 00 00
TToottaall 110088 55 33 55 33 44 55 11 2222 2200
Table 1. Number and percentage ofanomaliesin Albinaria.Nr, numberofspecimens studied; N1-7, category
numberoftheanomaly(seethetext);Na, numberofradulaewithoneormoreanomalies; Pa,percentage ofradulae
withoneormoreanomalies.(NadoesnotalwaysmatchthetotalofN1-7becausesomeradulaehavemorethanone
anomaly).
(7). A doubledmesocone. — Aspecimen ofA.s. senilis(467) hasa M12 which hasa
doubledmesocone(fig. 1 1). The two cusps are almost equal in size.
The numberandpercentages ofradularanomaliesin the various taxa are shown in
table 1.
DISCUSSION
There is notmuch literatureonanomaliesinradular structures. Amost interesting
paperonthissubject was mentionedby Runham(1975: 68), viz. an unpublished Ph.D.
thesisofIsarankura(1966), in whichradularabnormalitiesinvarious gastropod species
are dealtwith. This thesis contains many veryinteresting data.Isarankura dividedthe
observedabnormalitiesinseveraltypes, themost important being 'longitudinal' (involv-
ing one or more longitudinal teeth-rows) and 'transversal' (involving generally two or
Bor, Gittenberger&Kempertnan:Radula anomalies in Greek Albinaria species 33
three transverse tooth-rows). In our research we foundalmost exclusively longitudinal
anomalies.
Itis unclearhow thedefectodontoblasts, which areresponsible for theproduction of
the particular tooth-row(s) originated during the life ofthe animal. Isarankura (1966:
69) concluded that: "longitudinal abnormalities were permanent and probably arose
spontaneously while theothertypes wereonly temporary,forming during orafter deep
dormancy and they could be induced experimentally". He also stated (p. 129) that
"there are indications that severe cold (winter), and heat(cautery) can produce this
[longitudinal] abnormality".
It is unclear whetherand, if so, in what way, the conditionsunderwhich Albinaria
species live, might be relatedto the frequency andtype ofradular anomaliesin these
species. Ourresults, summarizedin table 1, indicatethat there might be (sub)species
specific differencesin the incidence ofradularanomalies.The differences between A.
adrianaeandA. senilisare most conspicuous in this respect. Itis still anopen question,
however, whetherpopulations ofa single subspecies, living under differentconditions
(various altitudes for example), show differences in percentage ofradular anomalies.
ACKNOWLEDGEMENTS
We are very much indebtedto Dr. M.B. Seddonfor supplying us with important
pages of the thesis ofDr. K. Isarankura. J. Goud,J.H.W. KromandA. van Assen are
acknowledged for their most valuableassistance with the SEM.
REFERENCES
ADAM, W., 1933.Notes sur lescephalopodes.II.Anomalies dela radula chez Octopus vulgarisLamarck et
observations surla seriationet l'asymetrie. Bull.Mus. r.Hist. nat. Belg.9(3): 1-8.
BREURE, A.S.H.,&E. GITTENBERGER, 1982. Therock-scraping radula, a strikingcase ofconvergence
(Mollusca).— Neth. J.Zool. 23: 307-312.
CAWSTON, F.G., 1940. Bluntedteeth ofLymnaeidae.— Nature 146: 654.
FALNIOWSKI,A.,1979.AnomaliawbudowiezebalateralnegowtarceLymnaeaauricularia(L.)(Gastropoda,
Basommatophora).— Przegl. zool.23: 261-263.
ISARANKURA, K., 1966. Studies on the replacementofthe gastropodradula. (unpublishedPh.D. thesis,
University ofWales).
KEMPERMAN,Th.C.M., 1992. SystematicsandevolutionaryhistoryoftheAlbinariaspeciesfromtheIonian
islandsofKephalliniaandIthaka(GastropodaPulmonata:Clausiliidae):1-251. (Ph.D.thesis, University
ofLeiden).
MARSHALL,B.A., 1983.Triphoridaeofsouthern Australia. Rec. Aust. Mus. 1983, suppl.2: 89-116.
PEILE,A.J., 1922.Some noteson radulae.—Proc. malac. Soc.Lond. 15: 13-18.
PEILE, A.J., 1932. Radularmalformationsand abnormalities. - Proc. malac. Soc. Lond.20: 103-104.
RUNHAM, N.W., 1975.Alimentarycanal.In: V.Fretter&J. Peake (Eds.)Pulmonates 1.Functionalanatomy
andphysiology:53-104.London, New York,San Francisco.
SCHILDER, F. A., 1963.An abnormalcowry radula. — Proc. malac. Soc.Lond. 35: 129-130.
SOLEM, G.A., 1974. The shell makers. Introducingmollusks: i-xiv, 1-289. New York, London, Sydney &
Toronto.
VENMANS,L.A.W.C.,&B. VERDCOURT, 1950.AbnormalitiesintheradulaofDrymaeusvirgulatus(Fer.),
—Basteria 14: 1-3.