FOLIA Vol. 17(2): 49–52 MALACOLOGICA ISSN 1506-7629 The Association of Polish Malacologists & Faculty of Biology, Adam Mickiewicz University Poznañ 2009 doi:10.2478/v10125-009-0008-x DEVELOPMENT OF CLAUSILIAR APPARATUS IN VESTIA GULO (E. A. BIELZ, 1859) (GASTROPODA: PULMONATA: CLAUSILIIDAE) ANNA SULIKOWSKA-DROZD Department of Invertebrate Zoology and Hydrobiology, University of £ódŸ, Banacha 12/16, 90-237 £ódŸ, Poland (e-mail: [email protected]) ABSTRACT: Formation of clausiliar apparatus in Vestia gulo (E. A. Bielz) was analysed and illustrated with SEM photographs. The sequence of formation of apertural barriers is the following: 1) inferior and spiral lamellae, 2) superior lamella, subcolumellar lamella, clausilium, principal palatal plica, 3) lunella and other palatal folds. Under laboratory conditions the closing apparatus developed during two weeks. The shell development in V. gulo was compared with literature data on another clausiliid, Herilla bosniensis. Adaptivesignificanceof the rapid development of apertural barriers is discussed in relation to the reproductive biology of Clausiliidae. KEY WORDS: Vestia gulo, Clausiliidae, clausiliar apparatus, apertural barriers, shell development, sexual maturity INTRODUCTION The sophisticated system of apertural folds, char- complex in gastropods, has been described in Herilla acteristic of clausiliids, is built during the growth of bosniensis (L. Pfeiffer, 1868), subfamily Alopiinae theultimateshellwhorl. This closing apparatus is of - (EDLAUER 1941). It has also been found that clausiliar ten termed clausiliar apparatus (see NORDSIECK apparatus develops rapidly, and the process takes only 2007). Its structurehas a high taxonomic valueand is 2–3 weeks (LIKHAREV 1962). useful for identification of species. Apertural barriers In this paper the formation of clausiliar apparatus are believed to reinforce the aperture, provide pro- in another species – Vestia gulo (E. A. Bielz, 1859) tection against desiccation or predators, protect the (subfamily Baleinae) is described and illustrated. In V. pneumostomeorstabilizetheshellwhenclimbing gulo theclausiliar apparatus consists of: 1. clausilium vertical surfaces (SUVOROV 1991, POKRYSZKO 1997). (plateand stalk), 2. lamellae(spiral,superior, infe - On the other hand, formation of teeth or folds is rior, subcolumellar); 3. palatal folds (principal plica costly in terms of calcium and energy expenditure and lunella) (Fig. 1F) (for detailed description of and may result in delayed growth and sexual maturity. adult clausiliar apparatus in V. gulo see LIKHAREV The sequence of development of clausiliid aper- 1962). tural barriers,which areprobably among themost METHODS Specimens of Vestia gulo, collected in Kroœcienko kepttill theultimatewhorl formation. According to (Pieniny Mts, Poland), were kept in the laboratory at theshapeof aperturethesnailswereclassifiedas juve - the Department of Invertebrate Zoology and Hydro- nile(J – beforeformationof ultimatewhorl), subadult biology, University of £ódŸ (for description of labora- (SA – during formation of ultimatewhorl) and adult tory cultureseeM ALTZ &SULIKOWSKA-DROZD 2008). (A – with thickened lip). Then, the animals were killed Juveniles (50 specimens hatched in laboratory) were in boiling water and their soft parts were removed. To 50 Anna Sulikowska-Drozd show the development of apertural barriers, parts of and at thePolytechnicof £ódŸ. Thenomenclatureof the shell wall were cut out. SEM photographs were clausiliar apparatus follows NORDSIECK (2007). taken at the Department of Physics, University of £ódŸ RESULTS Thejuvenileshellof V. gulo has an open umbilicus, thecolumellaabout 0.9–1 whorl from theultimateap - and a square aperture with thin edges (Fig. 1A). erturemargin.Theedgesof theaperturearestillnot Based on the development of lamellae the subadult connected on the parietal wall. At stage SA-4 all the phase can be divided into several consecutive stages parts of theclausiliar apparatus arepresent(includ - (Table1). Thechangein theapertureshapeandthe ing lunella), the spiral lamella is so long that it usually completesealingof theumbilicus arethefirst signs of joins the superior lamella (some adult specimens re- theultimatewhorl formation (stageSA-1, Fig. 1B). tain the gap between these two lamellae). The aper- Then(stageSA-2) thefirst lamellaearebuilt:spiral ture edges are now connected, however the lip is still and inferior (Fig. 1C). At this stage, the inner end of very thin and fragile (Fig. 1E). The pointed end of the the spiral lamella reaches much deeper inside the clausilium plateis short and not upturned.Soon the shell than the inner end of the inferior lamella. At inferior and subcollumellar lamellae come to reach first, thelamellaearenotprominent,theyarepaper- the aperture margin, and sometimes additional -thin and low, they thicken and gain length during interlamellar folds are built on the columellar wall. later stages. At the next stage (SA-3) the superior The lip thickens, and the callus is formed parallel to lamella develops, primary as a small protrusion (Fig. it. Insidetheshell,theinnerendsof theinferiorand 1D). At thesamestagea very thin, leaf-shaped spiral lamellae are situated approximately at the same clausilium can be observed, as well as the distancefrom theaperture.All thelamellaeandfolds subcollumellar lamella and the first palatal fold – have now reached their ultimate thickness, and the principal plica. The clausilium stalk separates from shell formation has been completed (Fig. 1F). Table1. Vestia gulo. Development of apertural barriers Stages Umbi- Spiral Inferior Superior Principal of shell Aperture shape Clausilium Lunella Lip licus lamella lamella lamella plica development J open straight – – – – – – – Juvenile SA-1 closed oblique, narrow –– – – – – – Subadult SA-2 closed oblique, narrow + + – – – – – Subadult SA-3 closed straight, broad ++ ++ + + + – thin, not Subadult (pear-shaped) (separated joined on from spiral parietal lamella) side SA-4 closed straight, broad ++ ++ ++ ++ ++ + thin, Subadult (pear-shaped) (usually joined on joined parietal with spiral side lamella) A closed straight, broad +++ +++ +++ +++ +++ +++ exanded Adult (pear-shaped) (usually with inter- joined lamellar with spiral teeth lamella) + an initial stage of structure development; ++ middle stage of structure development; +++ ultimate stage of structure development Development of clausiliar apparatus in Vestia gulo 51 Fig. 1. Vestia gulo. Development of ultimate whorl: A – juvenile; B – subadult (SA-1); C – subadult (SA-2); D – subadult (SA-3); E – subadult (SA-4); F – adult; cla – clausilium, clast – clausilium stalk, inf – inferior lamella, sp – spiral lamella, subc – subcollumellar lamella, sup – superior lamella 52 Anna Sulikowska-Drozd DISCUSSION In V. gulo, likein most clausiliids, theshellgrowth lamella. In V. gulo this lamella is built significantly is restricted to juvenile phase of life cycle. Balea per- later than the spiral lamella. versa (Linnaeus, 1758) is the only exception in that it Clausiliids start to reproduce only after the shell can grow during its reproductivelife(B AUR &BAUR growth has been completed (LIKHAREV 1962). The 1992). Under laboratory conditions the average time formation of thickened lip is the sign of reaching ulti- needed to complete the shell growth varies between mate size. Formerly, it was also regarded as tanta- three and six months, depending on the species mount to attaining sexual maturity (LIKHAREV 1962), (MALTZ &SULIKOWSKA-DROZD 2008). In V. gulo the however it was found that reproductive system de- average time needed to complete the growth from veloped a few months later (SCHILTHUIZEN &LOM- hatching was 148 days, thequickestgrowth took 81 BAERTS 1994, GIOKAS &MYLONAS 2002, MALTZ &SULI- days (SULIKOWSKA-DROZD, unpublished data). For- KOWSKA-DROZD 2008). mation of the ultimate whorl lasted ca. two weeks. Theultimatewhorl formation is costly in termsof This process is also very rapid in natural populations energy and calcium expenditure. Moreover, the aper- of V. gulo (SULIKOWSKA-DROZD, in preparation). turemargin at this stageis thin and fragile.During Theformation of clausiliar apparatus in V. gulo can the body whorl formation, lamellae easily break at a be compared with results of EDLAUER’s study (1941) touch. Any major damageat this stageresultsin defor - on Herilla bosniensis. According to EDLAUER (1941) at mation of shell, such as double mouthed shells, or thebeginningof theultimatewhorl formation theap - others – various cases of shell deformation in clau- erture becomes more narrow; resulting in the mantle siliids have been described in detail by JACKIEWICZ edge folding and creating wrinkles or pockets, which (1965). takepart in theformation of lamellaeandclausilium. In clausiliid development the body whorl formation In H. bosniensis the sequence of lamellae development precedes the maturation of the reproductive system, is as follows: 1) inferior lamella, 2) spiral and superior which is also energy demanding (MALTZ &SULIKOW- lamellae, 3) clausilium, 4) subcolumellar lamella, 5) SKA-DROZD 2008). Themain advantageof such a devel- principal palatal plica 6) lunella and other palatal opment strategy rests on the reduction of time re- folds. According to LIKHAREV (1962) thesamepattern quired to finish the shell growth (formation of the ap- of the development of lamellae and main palatal plica ertural barriers) and shortening the period when the occurs in other clausiliids, but the building of lunella shell is most susceptible