BASTERIA, 64: 71-77, 2000 Musculium transversum (Say, 1829): a species new to the fauna of France (Bivalvia, Sphaeriidae) J. Mouthon CEMAGREF, 3bis Quai Chauveau, F-69336 Lyon cedex 09, France & J. Loiseau Hydrosphere, 15 Qiiai Eugene Turpin. F-95300 Pontoise, France Duringa survey ofvarious canals in northern France the bivalve Musculium transversum (Say, 1829) was collected,which speciesis newto thefaunaofFrance. Itinhabits a reach ofthe lateralcanal ofthe Oise River near Apilly (between Noyon and Chauny). M. transversum, a nativeofNorthAmerica,was firstrecordedfromBritainin 1856andnextfromthe Netherlands in 1954. IntheMississippiRiverdensitiesmayexceed 100,000per squaremetre,butinFrance so far numbers reach only aboutone hundred per squaremetre, which maybe due tothe production ofammonia duringthe summer. In the Oise R. lateral canal dominant species associated with M. transversum are characteristic ofthe potamon. Key words: Bivalvia, Sphaeriidae, Musculium, alien species, freshwater ecology, France. INTRODUCTION In the courseofthe last two centuries a large number ofplant and animalspecies, bothvertebratesandinvertebrates, havebeenintroducedintoFrance. Among themolluscs, Dreissenapolymorpha (Pallas, 1771),Potamopyrgus antipodarum (Gray, 1843), and recently also Corbiculafluminea (Miiller, 1774) (discovered only in 1980: Mouthon, 1981a), have oc- casionally causedproblems towatermanagementby theirrapid dispersal andproliferation (Khalansky, 1997). On the other hand, other species have extended their distributionalmost unnoticed. This is particularly the case withLithoglyphus naticoides(Pfeiffer, 1828),which species has migrated southward following the canalisation oftheriver Rhone south ofLyon, with Menetus dilatatus(Gould, 1841), a species ofAmerican origin, which via the British Isles has colonizedall large river basinsin France, and with Emmericiapatula (Brumati, 1838). E.patula from the Dalmatiancoastalarea, discovered in aspring in southern Germany (Boeters & Heuss, 1985) and next in southern France (Mouthon, 1986), has recently been collected in a stream in the departement Vaucluse. In the course of afaunistic survey ofvarious canals in northern France the bivalve Musculiumtransversum(Say, 1829), a species new to thefaunaofFrance, was discovered. This species, from North Americalike Menetus dilatatus, has been recorded for the first timein Britain(England) in 1856asSphaeriumpallidum Gray, 1856(Kerney, 1976, 1999), and next intheNetherlandsin 1954in the IJsselmeer (IJssel Lake, theformerZuiderzee) not far from Amsterdam (Kuiper, 1981; Gittenberger & Janssen, 1998). 72 BASTERIA, Vol. 64, No. 1-3, 2000 SYSTEMATIC POSITION Musculiumtransversumbelongs tothe bivalvefamily Sphaeriidae (suborder Sphaeriacea, order Cyrenodonta/Veneroida, subclass Heterodonta/Eulamellibranchia). Although frequendy classified with the genus Sphaerium Scopoli, 1777 (Herrington, 1962; Ellis, 1978;Clarke, 1981),it hasrecently been includedinMusculiumLink, 1807(Burch, 1975; Heard, 1977; Mackie et al., 1980; Gloer & Meier-Brook, 1994) ofwhich the validity has been confirmed by electrophoretic studies of various enzymes (Hornbach et al., 1980). DIAGNOSIS The following description ofM. transversum(see figs 1-4) has been compiled fromthe accounts ofHerrington (1962), Ellis (1978) and Clarke (1981). Shell elongate, with the anterior part higher than the posterior part. Shell thin, periostracum dull tosomewhatshining. Apex markedly developed, closerto theanterior part oftheshell, butless prominent than in M. lacustre(Muller, 1774) (figs 5-6). Embry- onal shell sometimes separated from the adult shell by a depression as in M. lacustre. Since the number ofspecimens showing this depression varies with the season Gale (1972) and Herrington(1962) consider this character (calyculism) to beoflittletaxonom- ic value. Thesuperior margin infront ofthe apex is straight and forms amarked angle with the posterior margin. The superior margin behind the apex smoothly joins the anteriormargin withoutan angle. Ligament long and straight, exterior. Cardinalplate alsolong and straight, withpoorly developed teeth, lateralteeth thinand almoststraight (figs 3-4). Measurements recorded in the UnitedStates and Britain: 13x9x6 mm.In the Oise canal maximumdimensions are 12x8x6 mm. DISTRIBUTION Musculiumtransversum was discovered in a reachofthe Oise lateral canalbetween the towns of Noyon and Chauny in the municipality ofApilly, departement Aisne (fig. 7). It was not found in various canals connectedwith the Oise lateral canal(St. Quentin canal, Oise-Aisne canal, Sambre-Oise canal, and Canal du Nord).This bivalve seems to have a very limited distribution. However, the Oise river, which is very difficultof access in this sector because ofsteep and soft banks, has not been sampled. BIOLOGICAL AND ECOLOGICAL DATA The majority ofthe data discussed here are extractedfrom work done in the United States. M. transversum is found in a large array of habitats, i.e. lakes, rivers, canals, swamps andswampy areas. It colonizes varioussubstrates, viz. stone, sand, sandy mud, and mud, but itprefers the last (Gale, 1971). In the Oiselateral canalthis bivalve lives onbottoms consisting ofa mixtureofstones, sand, mudand clay at depthsofbetween one and two metres. One does find it also onthe sediment that has been deposited betweenthewooden supporting structures ofthecanalandthemargin ofthebordering road, where water depth does not go beyond 20 cm. Individualsofover 3 mm length Mouthon & Loiseau: Musculium transversum in France 73 Figs 1-6.Shells ofMusculiumspecies. 1-4.M.transversum (Say), (1) non-calyculate form,length 10.5 mm; (2) calyculateform,length7.5mm;(3)rightvalve,internalview,length12.0mm;(4)leftvalve,interiorview, length 12.0 mm. 5-6. M.lacustre(Müll.),(5) non-calyculateform,length8.7 mm;(6) calyculateform, length8.3 mm. Photographsby B. Vollat. BASTERIA, Vol. 64, No. 1-3, 2000 74 Fig. 7. The localityofMusculium transversum (Say) in the Oise River lateral canal (arrow). live essentially in the top layer ofthe sedimentbetween 0 and 2.6 cm. On the other hand, specimens with lengths ofunder 3mmmayburrow to a depth of 16 cm (Gale, 1976). Juveniles embedded deep in the sediment may stay in diapause for a numberof weeks. This strategy enables the species to regulate its populations and to survive pro- longed periods ofless favourable conditions. M. transversum may at times reachconsiderable densities; in theMississippi River Gale (1969) has countedmore than 100,000individualspersquare metre. In theOise lateral canal density has been estimated at only about one hundred per square metre. Itfeeds by filteringphytoplankton, particularly greenalgae and diatomsbut does not seem to exhibit any particular preference (Gale & Lowe, 1971). M. transversum is hermaphrodite and ovoviviparous and is also able to reproduce by means ofself-fertilization(Gale, 1969). According to that author, it may complete its life cycle in approximately one month.Juveniles maybecome sexually mature early in life as soonas they reach a length of 5 mm. Thejuveniles of Mississippi River popu- lations arereleased from thegillsofthe adultsinspring or summeras soonas theyreach an average size of 2.2 mm, and die at the end of the summer or in the autumn. Neverheless, a fewindividualsborn inthe course ofthese seasons survive the winterand die in thenext year. Lifespan is generally under one year and frequently only about six months. Moulhon & Loiseau: Musculiumtransversum in France 75 CHAUNY r pH Cond DO COD BOD5 KJN nh/ N02' N03" PO/ Rot Chi a Phae °c yS/m mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l M9" M9/I 16/06/1998 16.5 8 415 9.6 30 6 0.5 0.5 0.15 13 0.21 0.3 9 17 21/07/1998 20.5 7.8 433 9.5 30 5 1.9 2.1 0.14 11.4 0.15 0.2 22 14 18/08/1998 19.8 7.9 451 8.9 15/09/1998 14.5 8 406 9.4 30 5 1.5 0.9 0.28 14.3 0.21 0.1 10 5 20/10/1998 10.4 7.6 347 11.6 30 3 1.3 0.3 0.15 15 0.15 0.19 9 8 17/1V1998 6.2 7.2 284 10 69 6 1.4 0.5 0.21 11.2 0.31 0.2 5 5 NOYON 16/06/1998 17.9 8 460 9.3 30 6 0.5 0.05 12.8 0.15 0.05 12 24 21/07/1998 20.5 82 474 11.4 30 6 3.2 0.06 11.3 0.4 0.4 24 28 18/08/1998 22.4 7.8 442 15.1 15/09/1998 15.5 8.3 433 10.9 30 6 0.7 0.15 14.5 0.15 0.05 18 26 20/10/1998 10.9 7.6 379 10 30 3 0.2 0.15 13.4 0.15 0.07 13 17 17/11/1998 6.3 7.3 311 10.8 30 7 1.4 0.05 11.2 0.21 0.13 6 8 Cond=conductivity, DO =dissolvedoxygen, COD and BODS=chemical and biological requirementforoxygen, KJN =Kjeldahl nitrogen,Ptot=totalphosphate,Chia=chlorophylla, Phae=phaeopigments. Table 1. Water chemistry andchlorophyll data ofthe waters ofthe Oise River lateral canal (atNoyon) and the St. Quentin canal (at Chauny). As is the case for most freshwater molluscs, M. transversum has numerous predators, i.e. various species of leaches likeErpobdella spec, Glossiphonia complanata (L., 1758) and Helobdella stagnalis (L., 1758), fish like carp and catfish and alsobirds such as duck. This bivalve is alsohost totrematodeparasites ofthegenus Crepidostomium and theoligochaete worm genus Chaetogaster (Gale, 1973). Research into thecauses ofthe dramatic declineofthe populations ofM. transversum in the Mississippi River has revealed that the species is sensitive to various toxic sub- stances, particularly the non-ionized form of ammonia (NH ) (Arthur et al., 1967; 3 Sandusky & Sparks, 1979;Sparks, 1984;Eckblad&Lehtinen, 1991;Wilson etal., 1995). Therefore this organism has been widely used in the U.S.A. as a test organism for detecting the toxicity of thewaterandcontaminatedsediments(Paparo & Sparks, 1977; Zischke & Arthur, 1987). Water samples taken inJuly in the Oise lateral canal have revealedelevated concentrationsofammonianitrogen resultingin high pH valueswhich foster the forming of non-ionized NH ; this may explain the modest population levels 3 ofM. transversumin this habitat.As associates ofthisbivalve one usually observes species typicalofthe potamonsuch as Ferrissia wautieri(Mirolli, 1960),Dreissenapolymorpha (Pallas, 1771),Pisidiumsupinum Schmidt, 1851,Sphaerium rivicola(Lamarck, 1818),and theheavier forms (i.e. those with thick shells and teeth) ofP. nitidumf.crassa Stelfox, 1918, and P. subtruncatumf.incrassata Stelfox, 1918,andalso species more typical of the rhithronsuch asBithynia tentaculata (L., 1758), S. corneum (L., 1758), P. amnicum (Miiller, 1774), P. henslowanum (Sheppard, 1823), and in addition Corbiculafluminea. 76 BASTERIA, Vol. 64, No. 1-3, 2000 CONCLUSION As has been observed for Dreissenapolymorpha and Lithoglyphus naticoides andalso more recently, for Corbiculafluminea, canals are eminently suitablefor invasion and colonisa- tion.These typesofhabitatare rarely subjects offaunisticandfloristicsurveys andmerit more attention from the biologist. Strayer (1999) attributes aEuropean origin tonine species of freshwatermolluscsnow living in North America. On the other hand, as regards western Europe, only the two species Menetusdilatatus and Musculium transversum have their origin in North America. Ifthis discrepancy is alsofound inother groupsofanimalsand plants, research into the causesofthis phenomenon would possibly be ofinterest. ACKNOWLEDGEMENTS The authors are grateful to Dr. J.G.J. Kuiper (Paris) for his valuablecomments and to B. Vollat (CEMAGREF) for the photographs (figs 1-6). Dr. A.C. van Bruggen (Lei- den) andDr. D.S. Brown(London) arejointlyresponsible forthetranslationintoEnglish of the original manuscript. REFERENCES ARTHUR,J.W.,C.W.WEST, K.N. ALLEN& S.F.HEDTKE, 1987. Seasonal toxicityofammonia tofive fish andnineinvertebratespecies. BulletinofEnvironmentalContamination andToxicology38: 324- 331. 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Résumé Aucours d’inventaires faunistiquesréalisés surplusieurs canauxdu Nord de la France,une espèce nouvellepourlafaunemalacologiquedecepays aétédécouverte dans unbief ducanal latéralàl’Oise; il s’agit deMusculiumtransversum (Say, 1829).Cebivalve signaléen Angleterre dès 1856, puis au Pays- Bas en 1954, est originaire du continent Nord Américain. Une description de cette espèce appartenant à la famille des Sphaeriidae, ainsi que différentes données concernantsa biologieet son écologie sontproposées.