In this work Tamsiella amazonica nov. sp. a new species of Nayades of the genus Tamsiella HAAS, belonging to the Juruá River, an affluent of the Solimões River, between Taumaturgo and Fóz do Bréu, Brazil, is described. At the same time an analysis and new regrouping of the existing genera of Monocondylaeinae, is made, giving some considerations about the geographical distribution of its genera in South American waters and its probable phyletic relationship

Bonetto, A.

English

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AT,IAZO\ I.\\'\ III ÌI ')')4 23() Iiit'I, Aug 72 articular apparatus, and certain other characteristics of the genus. As an outcome of theseinvestigations we introduce some changes to the scheme proposed in 1966. In fact, thearticular apparatus of the genus as revealed by T. amazonica - T. tamsiana DUNKER weknow only through the literature - reveals deep differences from that which ischaracteristic of the tribe Monocondylaeini, being very near to that characterizing theFossulini.In our example of T. amazonicø a substantial reduction of the teeth and aconsiderable modification of the articular area, coincides on the whole with HAAS 'description. Likewise, it is easy to see that the nacreous layer covers only the inner faceof the teeth as a result of modifications of the hinge line. The rest of the teeth and thearticular cavities, reveals a thick prismatic layer.Because of this we consider that the genus Tamsiello HAAS must not be included inthe tribe Monocondylaeini but in the Fossulini, because although there are somedifferences in the form and sculpture of the teeth and cavities théy are of the samegeneral form. In Fossula the tooth is more or less quadrangular and projects Ìittle, whilein Tamsiella it tends to be triangular and projects more conspicuously. Furthermorealthough these characters are of less importance, we point out that T. amazonica tends tobe bilaterally flattened and thai the folds of the periostracum are extremely reduced.Some.radial lines are present corresponding to the microscopic sculpture (the "puckeredradiating impressed lines" of MARSHALL ). There is no posterioi ridge, the þosteriorslope is smooth, and there are no coloured lines. These details not only support thephyletic separation proposed by HAAS , but also lead to place Tamsielia in anintermediate position between the typical Monocondylaeini and ihe genus Fossula. Thesuggested relationships can be indicated as follows :lherÌngella Haasica DiplodontitesFossulaA new species of Monocondylaeinae fromthe Amazoubasin, and someconsideratiolìs on this subfamily in the hydrographic systems ofSouth Americaby Argentino A. Bonetto *)*-¡ ¡"1o* of the scientific. Research career of the National council of scientific andTechnica.l Research (Repdblica Argentina)'2)4As is well known Nayades of the subfamily Monocondylaeinae constitute a very.characteristic g.oup anO ui" easily set apart from ihe rest of the neotropical Mutelacea, onthe basis of the presence of artiäular elements in the hinge. These usually consist of oneo¡- *ã.. roundéd-projá.tio"r or toothed bosses, and provide a reliable and precisediagnostic feature in all well developed specimens'In this whete group; ;; ;; pàirt"o out in 1966, two tribes -ca1 be distinguished :ruonà.ånoyiueini änd iràr*rinì,'based o1 the nature of the articulating apparatus of theshells. Generally the "rti;i;;il; teeth of the Monocondylaeini are well developed a-nd. ofthe rounded_pro¡e"tion typ., "uro the whole apparatus -. including the articulatingcavities- is covered ;y iñ.'nacreous layer. In^the Fossulini, the teeth are less welláã".iãp.¿ and the artiáütar ãrea is defined by dep-ressions and projections incesed on theñ;;f th" hinge, and-ifls pãssi¡re to distiirguiih over all thearticular surface a thickpiìr-uti. layer,"i.é. it is not cävered, as in the previous S9uP, !y the.nacreous layer'So far as the positián of-tft" Nionocondylaeinae ñithin the subfamily Mute-lacea.isconcerned, it must ¡"'làiri.¿ ãui trtut it is isolated, and it is difficult to establish itsrelationship to the other subfamilies.ORTMANN "onri¿ri.i if to ¡e ttre most primitive of the South American Mutelaceabecause of the articular'apparatus, but thii suppositi-on is,based exclusively on thepresumed relationship ¡.t*Ë." the two fig g1o-ups-.9f South American Nayades thatORTMANN united i" ;";iúl; ia"o" ltamíty"ttrtuietiaae¡. Accotding to him.the mostmodern forms are tirore *itñ an edentàte hinge (Mutelinae), which were derived fromforms with a hinge pt-iá.¿ wittr wett develoled'teeth (Hyriinae). However, as it was.rtuUfirfr.¿ Uy fAñ.OtrfZãnJAONeffo(tSO:),itiereis nocloserelationship between theseÀtåri;., tfràlís to say ¡etween the Hyriiàae (: Hyriinae of ORTMANN ) *.tti..h . have aheterodont tringe; anliitã-irr'."toóioae pmudetinae of ORTMANN) which have anedentate hinge, or " iti"g; *itü i"eUiy Oe*ìoped teeth as in the Monocondylaeinae. Thefamity Mycetopidae, toïnicn the l\ionoconàylaeinae. belong,.shows clear and indubi-table relationstrips witt litã tutnif' Mutelidäe of Africa' These together fo.rr.n lfesuperfamily Mutetacea,'wftiiã tftã iått of the Nayades of the world are united in thesuþerfamily Unionacea. r-- .^^.^..^^^-+. It seems ,.uronubià to suppose that these Nayades represent. a group of .recentdifferentiation, deriveJfrãm thãse with the basic edentate hinge which is characteristic ofit " ,.*uining lVfutef u"ãu, und they could_rep_resent the perfecting of the system to be seenin an incipieñt form in the $enus Leila GP"AY 'ThefindingofanewspeciesofthegenusTamsíellaHAASintheJuruáRiver,anaffluent of the solimões River in thp sta[e of Acre,.Brazil, that.will be described under.the name of rømsiella amazonica nov. sp., provided úhe opportunity to study in detail theTamsiella umazonicø nov. sp.Diagnosis : Shell of moderate thickness. Outline suboval to subtrapezoidat with theanterior margin.somewhat acutely and the posterior margin blunty rounded. Dorsal andventral margins curved in .a more or less regular mannei, the dorsal rherging with thepos-terior margin by an obtuse angle. The valves are flattened laterally, and havõ a smoothsyrfacg without posterior corrugations. There is a slight antero-ventiál gap. periostracumthin, lightly ,,clothlike" in the terminology of MARSHALL, without giois, and showingin isolated areas some .,,puckered radiating impressed lines'i similar tõ, though less welidefined than those of the genus Anodontites. The colour of the periostracum ís yellowishochre. The nacreous layer of the inner surface is bluish white'in colourancl moderately,iridescent.Prismatic area of considerable width and best developed towards the middle of theventral edge, though this varies a little in the different paratypes. Ligamental scartriangular as is typical of the Mutelacea. Anterior muscle icar moderate'ly impressed,posterior scar lightly impressed. Two or three little rounded impressions can be seencorresponding to the retractors, arranged in a series towards the umbone cavity.Monoco!ramsieuaLeilaAnodontites22sThe articular apparatus is constituted by feebly developed Uyt !3eu and triangularcavities. In the right "^f"äif.ärã"irï.-"lf u.,ä rftãtpiooth - almost a spine --' adjacent toan elongate, somewhat'ùiä"ì"r* ""tctr orientîäd"in'un ut*ott horizontal position infronr of and below rh".piäìtäîr"ä"iiy'.i!rr",;;"bo;; ihis notch' widening posteriorlv'is contiguous with , "it;;i; ';i;;;i;'" " "i trr. trirge line that perhaps represents aî"¿i.åti.-v second tooth' r -. !^-:^-r-. ^r o orirIntheleftvalvethearticulatingelementsconsistanteriorlyofaslightlvmodifiedareaof the hinge line that Oãã, rot coîstitute " tJiï;th-i;iiá*äO ¡V thõ ariiculating notchwhich lies somewhat ";i'ili; unã-u*t.nO, t.t*..["f.ãst to thã anterior extremitv ofrhe umbone. Behind iliJ';;;¿t äriig;ily;ieh.tîrJfì;^t.r articular tooth than that of*t "f.tîJi:r"XJrï.. of the valves is smoorh w*hour a posrer.iorddge. There.are nocoloured lines in this position such as are usual in this su'bfamily. soft parts unknown'*.å:åîtJ-ÏtiiS"riiiitå¡ rhe varves varies a litre in dirrerenr paratvpes, being sometimesmore elripsoi¿ur o, .r.,ååïä;ä;ith.";t;i "r ü'ã î"iåiviã, ¡i''t ¡*äv' being higher andmore rounded than å';;";{'i"r^¡nlto to*rüno. itt"" äeíelopm.ent of the articulatingapparatus is also somewtrat varia¡te nut .orr.*iäiosìnlenerat *it¡ tit. description of theholotype. ft is.remarlça¡fãinul in spe"imens.tuis ittin S?,,' in length the differe'tiatlon ofthe articutar uppurutu*î*;;;ìt;" fe distinguishàd, *h"t.ut iñ typical Monocondvlaeathe tooth is distinct '.*ï l. ,i"i, *maff lnfiviãuuü' ffl"tt are aist' variations of lessinterest in the cotour.il"h; ä;.;;nd in [he ridses and sculpture ol the periostracum'whereas in tte lrluîei;;;; . whole the'ri"ur" uru¡rv no impressions of retraclormuscres, three such #ï;äly q"r.nt ¡. rï*lüUi-i*í"o'¡'o' Àtttrougir these differsomewhat in number ano oispoJition in the îTf;;t;;t"fpes they are present in allexamPles'Locality:AllthematerialisfromtheJuruáRiver,anaffluentoftheSolimõesRiverinthe state of Acre, il;*;; iila raumaturio ïl¡'t*' do Bréu' t.]rai is to av in theneighbourhoo¿ .t tnå'tãrä;t';ith-Þ;tú unà' Boliuiu' These were-coltecteclbv PRICE iti1956, and given ro "; f*';;iy ïy t¡. urttrotili.r oi ilrå cãeroi Museum o[ Belém' Pará'Brazil, to whom we gi;;ffi;;d wh.ere the holotype is being deposited'Dimension of some sPecimens :Diplodontites of which only two species ate known, occurs in the basin of the OrinocoRiver and the head waters of the Amazon and Magdalena Rivers. The genus Fossulaoccurs in most of the la Plata basin (Paraguay, Upper paraná and UruguayRivers) beingremarkable in that its occurrence is limited to stretches of fast flowing water with a hardor rocky bottorrl. and it disappears in the lower and middleportions of these rivers. It isfound also in the São Francisco and Paraguassú Rivers in the state of Bahía, from where anew species was recently described. It is an interesting fact that to date Fossula has notbeen found in the Amazon River.*)The genus Tamsiella was hitherto known only from the Chirgua River, near PuertoCabello, which is a head water of the Orinoco River. The new species comes from theJuruá River, in Taumaturgo, i.e. in the neighbourhood of the border with Perír, therebyconsiderably extending the distribution of genus. This also tends to confirm thèsuggestion that the apparently limited known distribution of many genera is a result oftheir tendency to establish themselves in localized areas, such as the upper reaches ofdifferent rivers.*) PILSBRY and OLSSON described int944 a new species of þt¡ssulu, in the GuaricoRiver, at Barbacoas' state of Guarico, Venezuela, The photograph of the type is notclear, especially on the articular apparatus, and the description is very poõr, beingpossible it will be another species of the genus Tamsiella HAAS.SummaryIn this work ramsiella amazonicû nov_. sp. a new species of Nayades of the genusTamsiellø HAAS, belonging to the Juruá River, an affluent of the solimões River,between Taumaturgo and Fóz do Bréu, Brazil, is described.At the same time an analysis and new regrouping of the existing genera ofMonocondylaeinae, is made, giving some considerations about the geographical distri-bution of its genera in South American waters and iis probable phyletic relationship.Holotype 1Paratype 1"Paratype 2Paratype 3Paratype 4Paratype 5Paratype 6Length10,817,537,12b,bo4,934,052,97Height7,825,344,964,733,722,942,r272,3470,9169,6671,L275,4672,6971,3836,4434,6636,6537,8937,3237,7734,68VoLength Diameter VoLength3,942,612,6r2,521,841,531,03ResumoNêste trabalho descreve-se Tamsiella amazonica nov. sp,, uma espécie nova de Nayadesdo gênero Tømsíella HAAS, proveniente do Rio Juruá, àfluente d'o Rio solimões, entreTaumaturgo e Fóz do Bréu, Brasil.No mesmo tempo executam-se uma análise e um novo reagrupamento dos gênerosexistentes de Monocondylaeinae, apresentando-se consideraçoes -sôbre a distr"ibuiçãogeográfica dos gêneros daquela famflia em águas sulamericanas e sôbre as suas relaçbesfiléticas prováveis.Soure consideratiorrsof NaYades of theon the geographical distril¡utiotlsu b familY M onoc ot.r dY1 ae in ae ')26BibliographyAD-4Mq, H., 1870 : List of additionat species of land and fresh-water shells collected byMr. E. BARTLETT in eastern perú. -proc. zool. soc. London, rgTo :874-876.BAKER , H.B., 1930 ¡ The mollusca collected by the University of Michigan-Williamsonexpedition in Venezuela. VI. - Occ. Pap. Mus. Zool. Univ. Michigan. 210 : 1-9b.BONETTO,4.,4., 1963 :Contribución al conocimiento de Leila blainuilleana (LF,A).-Physis, 24 (61) : 11-16.'1S9_6 , Espécies de la subfamilia Monocondylaeinae en las águas del sistema del Río dela Plata. - Arch. Moll. 95 (112) : B*74.BONETTO , A.A. & EZCURRA ,I.D., 1969 : Notas Malacológicas, I. - physis, 24 :r7-2LDUNKER , W., 1858 : Einige neue Species der Naiaden. - Mal. Bläit. 5 : 225-229.ExceptforMonocondylaea,mostgeneraofsubfamilylrave'alimitednumberofspecies, most being *onãiypi"' Many äppéar to have very local or restricted areas ofdistribution. fn" gnu, M;íiiondylaea iras a considerable number of soecies which aredistributed throughout the principal ,iu"r. ,yrtã*rìi-Sãutit America" Iheringella andHaasica (which should p;;;"ãly bË united in-a single genus) occur in tìre upper ParaguayRiver and extend to*ur¿r"it" iíuuJ *ut".. ot tnã ¿ïaãon Riutt in Bolivia' a region whichhas trausitory contacts with the Upper Paraguay River'))1HAAS , F,, 1930-1931 : Versuch einer kritischen Sichtung der südamerikanischenNajaden. - Senckenbergianâ, 72 (415) : 775-1-95 (1930); 13 (1) : 30-62 (1931);13(2) : 87-110 (1931).-, 1969 : Superfamilia Unionacea. - Das Tierreich, 88 : 1-663'IHERING , H. von, 1893 : Najaden von São Paulo und die geogtaphische Verbreitung derSüßwasser-Faunen von Südamerika. - Arch. Naturg., 1893 (1) : 45-140.-,1910 : über brasilianische Naja4¡n. - Abh. senckenb. naturf. Ges., 32 : 111-140.-.f Sf f : Molluscos, in Annexo No5, Commissão de Linhas Telegráphicas Estratégicas de'Matto-Grosso ao Amazonas : 1-14.. Rio de Janeiro.LEA , L, 1834-L874 : Observations on the genus Unio. - Philadelphia'MARSHALL , W.8., 1922 : New pearly fresh water mussels from South America' - Proc.U.S. Nat. Mus.. ti1 : 1-9"-,7925 : Microscopic sculpture of pearly fresh water mussels shell. - Proc. U.S. Nat.Mus., 67 : t-L4.OLAZÀRRI ,J., !964: Primer haÌlazgo de Fossula en la cuenca del Río Uruguay'-Com. Soc. Malac. Uruguay, 1 (6) : 150-155.OLSSON , A.A. & WUR"TZ-,'C.È., 1951 : New Colombian Naiades, with observations onother species. - Notulae Naturae, 239 : !-9,ORBIGNY , 4.D., 1835 : Synopsis terrestrium et fluviatilium molluscorum in suo perAmericam Meriodionalem itinere. - Mag. Zool., (Y) Nr. 61 : 44 pp'-,1835-1843 : Voyage dans I'Am6rique M6ridionale. V, 3 Mollusques : 1-758.ORTMANN ,4.E., 1921 : South American Naiades, a contribution to the knowledge'ofthe freshwater mussels of South America. - Mem. Carnegie MuS., 8 : 457-670.Pittsburgh.PILSBRY , H.4., 1893 : Notes on the genera of Unionidae and Mutelidae. - Nautilus, 7 :30.PILSBRY , H.A. & OLSSON ,4.4., 1944 : A Venezuelan Species of Fossula. -Nautilus,57 : 89.PARODIZ , J.J. & BONETTO , A.4., 1963 : Taxonomy and zoogeographic relationshipsof South American Naiades (Pelecypoda : Unionacea and Mutelacea), - Malacologia, 1(2) :779-273.SIMPSON , C.T., 1900 : Synopsis of the Naiades, or pearly fresh water mussels. - Proc.U.S. Nat. Mus., 22 :5I-7044.-,7974: A descriptive catalogue of the Naiades or pearly fresh water mussels. -BRYANT WALKER , Detroit : I-XI, 1-1540.STRAND , 8., 1932 : Miscellanea nomenclatoria zoologica et palaeontologica, III' -Folia ZooI. Hydrobiol., Riga, 4 (1) : 133-147.Author's Address iI'.f ':.i/l¡5 Cm.Dr. Argenti4o A. BonettoInstituÍo Nacional de LimnologlaJosé Maciá 1933143SANTO TOMÉ (Pcia. Santa Fé)REPUBLICA ARGENTINA.Plate I. - Holotype of TømsieLla amazonica n. sp.Iæ-228a)ïçr.t /3\\ lirg.PlateI[._Detailso{thehingeorg.aniza'tionof:aundb,TaynsieLlaamazonicøn'sp.ic and. d, FOSU:;i;;:;';it';; ù'o;b ' it'ti' corrientes' Argentina230

A new species of Monocondylaeinae from the Amazon basin, and some considerations on this subfamily in the hydrographic systems of South America

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