Occasional Papers of the Museum of Zoology the University of Michigan

Number 729 May 31,2000

OCCASIONAL PAPERS OF THE MUSEUM OF ZOOLOGY THE UNIVERSITY OF MICHIGAN

TI-IE ETHERIOIDEA REVISITED: A PHYLOGENETIC ANALYSIS OF HYKIID RELATIONSHIPS (MOLLUSCA BIVALVIA: PALEOHETERODONTA: UNIONOIDA) By Daniel L. GraP

MSTKACT. - 7Xe Ell~c.n'oidc,ciiwi~ited: a Pl~yylogcnrlzcanalysis oJ'I1yriid rclrifion- ships (Moll~isca:Hii~nlr~in: Palcoheierorlon/n: (Jnionoida). Orc-. Pap. MILS.Zool. Uni~c Mic-11. 729: 1-21, 2 PC.;. Alrriost all lieshwatrr pearly rr~ussels(Order Unionoitla) llavc one oS two types of parasitic larvae, either gloclridi;~or lasidia. 'The most widely acccpted hypothesis of Srcshwatcr mussel highel- classificatio~ldivides the ordcr- into lwo superfamilics, the U~iionoidcaand Etherioidca [= Muteloidca], based solely upon larval typc. To test this hypothesis, specifically the I-clatio~l- ships of the Hyriidae (which have glochidia), a morphological data set compilcd horn both lat.v;rl and adult lik histo~ystages was analyzed phylogenetically nsing prrsirnony. Results indir;ltc that llyriitls, dcspitc their development including a parasitic gloc\~iclium,sharc a more recent comrnon ancestor with the Ethcrioidca than with any uniorioit1e;tn. Thc Ethc~ioidca,(I-Iyriidae, (Iridinidac, I'.tlreriid;rc)), is c1i:rgnoscd by at least Lliree adult anatomical synapomorphies. The lasidium- typc larva is I~ypothcsizcdto be derivctl koni glochidia. The bcaring of these results on the biogeography, character evolution, and classificaliorl of the Unionoitla is discusscd. Kcycvords: /ierhwater pearly rrruvrel~~,EIyrzidac, Irtdinidae, Ethwiidne, P3/~<,r;uidea, Goriclwwnnril/~n,d,nrorf,Iio/ogic-nl j~l~ylogcncfics, cla.s.tzficntion

INTRODUCTION Recently, lher e has beell an increased awareness of the phylogenetic paradox created by disparity amvng evolutionary hypotheses derived from diflercnt scmaphoronts. This is especially so among marine invertebrates (p.g., Strathmann and Eernisse, 1994; Wray, 1996). Phylogenies recov-

*Museum of Zooloky and Department of Biology, U~llivcrsityof Michigan, Ann Arbor, Michigan 48109-1079, U.S.A. ered using adult rnorph~lo~gyrnay not necessarily reflect the same evolu- tiona~yhistory suggested by comparisons of larval orjuvenile characters (Wiley, 1980). Such is also the case among freshwater pearly mussels (Bivalvia: Unionoida). The order has been divided into two superfami- lies based solely upon larval type- the Unionoidea have glochidia, the Etherioidea (= Muteloidea) have lasidia (Parodiz and Bonetto, 1963;Boss, 1982). The objective of this paper is to phylogenetically re-evaluate the inonophyly of the Etherioidea, based upon both larval and adult characters. A study of these taxa is timely in light of the lack of phylogenetic testing afforded the etherioideans and the recent nomenclatural revi- sion proposed by Ibbat (199'7). Thc Order Unionoida is comprised of 6 nominal families, depending upon the authority (e.g., Ortmann, 1912a, 1921; I-Iaas, 1969a, 1969b;I-Ieai-d and Guckert, 19'71; Davis and Fuller, 1981; Boss, 1982) : Margaritiferidae, Unionidae, Hyriidae, Iridinidae (= Mutelidae), Mycetopodidae, and Etheriidae (Table 1). This order is probably monophyletic, diagnosed by their restriction to freshwater, ovovivipary, and a parasitic larval stage that must infect an appropriate host to complete its metamorphosis (Boss, 1982). But, with the exceptions of the Margaritifcridae and Unionidae (Lydeard et ctl., 1996; Graf and 0 Foighil, in press), the inlerrelationships of these families have not been tested phylogenetically. Until the 19601s,the Margaritiferidae and Unionidae were considered to cornpose the Unionoidea, whereas the remaining families fell into the Etherioidea (Ortmann, 1912a, 1921; Thiele, 1934; McMichael and Hiscock, 1958). The Unionoidea was diagnosed by (1) presence of a supra-anal aperture dorsal to the excurrent aperture, (2) having inner demibranchs that connect to the visceral mass distant from the labial palps, (3) having a slightly incomplete diaphragm (z.e., co~nposedonly of the deinibranchs without pallial fusion) dividing the mantle cavity, and (4) use of the outer pair of demibranchs (or both pairs) as marsupia Sir brooding (Ortmann, 1912a). According to Ortmann (1921), the Etherioidea, ie., I-Iyriidae, Iridinidae, Mycetopodidae, and Etheriidae, was diagnosed by (I) pallial f~~sionbetween the incurrent and excurrent apertures (thus, a complete diaphragm), (2) having inner demibranchs with an anterior attachment adjacent to the labial palps, and (3) use of only the inner pair of deinibranchs for brooding. Further enforcing this separation was the zoogeography of the two taxa- unionoideans on the northern continents, etherioideans with a Gondwana distribution (Ortmann, 1921). Subsequent work by Parodiz and Bonetto (1963), however, empha- sized the discordant distribution of larval types among these taxa. While non-parasitic life cycles have been reported for a small number of freshwater mussel genera (Howard, 1915; Parodiz and Bonetto, 1963; Kondo, 1990), most have laivae that are parasitic upon fish or, infrequently, am- No. 729 Hyriid Kelationships 3 phihians (Watters, 1994b). Parasitic mussel larvae fall into two general types. Whereas the Unionoidea possess only glochidia, the Etherioidea spnsu Ortmann had either glochidia or lasidia. Glocllidia arc srnall (70-350 pm), cornposed of a single adductor muscle and ~nantlecells enclosed by a calcareous, bivalved shell. They attach to host tissue by clamping their valves over exposed gill or fin epithelium. The host tissue encysts the mussel larwae (Arey, 1921), arid it is within this cyst that the glochidia undergo metamorphosis into j~~vcniles(Kat, 1984; C;raf, 1998). Glochidia geiierally belong to one of two morphological varieties: ( 1 ) sub-circular to sub-ovatc and unhooked or (2) sub-triangu- lar and hooked (Colter (~rnl., 1921), although there is variation within these types (e.g., I'otc~tnilus;Roe and Lydcard, 1998). Lasidia are also small (85-150 pm, not including the 'larval thread') but arc tri-lobed larvae with ;I nnivalvc, uncalcificd shell. Just as with the glochidia, they come in two So:orms: (1) lasidium-type and (2) haustorium-type (Bonetto and Ezcurra, 1965a). Although differing in morphology the fundamental distillctioil I-~etweenthe two types is that whereas the former attaches to the host by forming cysts, the haustorium-type attaches via tubular appendages (Fryer, 1954, 1961; Parodiz and Bonetto, 1963). Parodiz and Bonetto (1963: 185) argued that, "Tlic two different types of larvae, i.e., glochidiurn and lasidi~rm,cannot be considered to be dcr-ivcd one f'rom the other or from ally hypothetical direct ancestry." They advocated the re-assignment of the Hyriidae (the only Etherioidea to have glochidia) to the Unionoidea, and this scheme has been largely Sollowed in subsequence classificatiolls (Table 1): Unionoidea = Margaritifc'cridae,Unionidae, and Hyriidae; and Etherioidea senszl Parodiz and Bonetto = Iridinidac, Mycctopodiclae, Etheriidae. The rclativcly recent consensus that classificationsshould bc compriscd of uatural taxa reflecting their pattern of phylogeny requires that supraspecific groupings be mo~lophyletic(i.~., include all of the descen- dents of a common ancestor) and suggests that these should be diagnos- able by shared, derived homologies (i.e., synapomorphies) (Wiley, 1980). rIhc 7 systematic hypothesis of Parodiz and Bonetto (1963) suggests that the Unio~loidcaand Etherioidea are each monophylctic, as diagnosed by their larval type, but this has never been tested phylogenetically. Rather, classification has bccn largely authoritarian. 111 order to test the monophyly of' thc Etherioidea sensu Parodiz and Bonetto (1963) and the place~nentof the Hyriidae among the Unionoidea, I coded 38 shell and soft-anatomy characters of 18 taxa for cladistic analysis r~nderthe optirnality criterion of nlaximum parsimony. Results indi- Table I. Summary of the Parodiz and Uonetto (1963) sttpragcncric taxonomy of the Unionoida along with thc gcncra inclrlded in the prescnt phylogcnctic analysis. This scheme has bcen followed in most subsc- quent classifications (Haas, 1969~1,19GSb; I-leard and (;ucltcrt, 1971; Boss, 1982; Vaught, 1989; Kabat, 1997), but it rep!-cscnts a shift from the view before the work of Parodiz and Bonetto (1963) that the Hyriidae should be placed among the Etherioidea (Ortmann, 1912~1, 1921; Thiele, 1934; McMichacl and Niscock, 19.58). Also provided arc the large-scale distributions of the genera analy~ed(Bi-own and Lomolino, 1998).

Taxon Distribution

Uriionoidca Unioriidac Unio Palcarctic - Ethiopian Elliptio Neal-ctic I,n.rnpsilis Nearctic I'yg~znodon Nearctic P[~rrqsia India Ck(~ndidieria Ethiopian Margiritiferidae Marqa~itifra I-Iyriidae Cr~slulir~a Neotl-opical Diplodon Neoti-opical Hy ridella Australian l/,l(.~unio Australian

Etherioidea (= Muteloidea) Etheriidae Ltheria Ethiopian Aco~(crec~ Neotropical Mycetopodidae Anodontites Neotropical Myc-c.lupod(c Ncouopical Iridinidac (= Mutelidac) Mutph Ethiopian Iridina (= Pleiodon) Ethiopian cate that the Unionoidea is not monophyletic and that the Hyriidae is part of a natural taxon when included among the Etherioidea. This has implications not only for the classification of the Etherioidea, but also the historical biogeography and character evolution of the freshwater pearly mussels as a whole.

METHODS AND MATERIALS

Rather than limit the analysis to either adult or larval characters, a combined evidence approach (Kluge, 1989) was applied that included No. 729 Hyriid Relationships 5 morp11o1ogical and life history traits of both semaphoronts. One to six representatives of each of the six lamilies where chosen for analysis (Table I),with an emphasis on genera representing different infi-afamilial taxa. Also included was the marine Neot%onia, the solitary surviving genus of the once-diverse Trigonioida (Bivalvia: Paleoheterodonta) . Neotr~goninis the presumed sister-group to all freshwater mussels (Thiele, 1934; Taylor et nl., 1969; Healy, 1989; Hoeh et al., 1998; but see Newel1 and Boyd, 1975 and Morton, 1987). Thirty-eight characters were coded from the literature and corrobo- rated by persolla1 examination of specimens deposited in the University of Michigan Museum of Zoology, Ann Arbor, Michigan, USA. The specimens examined and accompanying literature references are listed in Appendix 1. The characters analyzed include those of the shell (1-ll), gross soft-anatomy (12-22), brooding and life histoiy (23-34), and larval (35-38), and these are principally the characters deemed significant by previous mussel systematists (e.g.,Ortmann, 1912a; Parodiz and Bonetto, 1963; Heard and Guckert, 19'71). Character diagnoses are listed in Ap- pendix 2. Table 2 shows the matrix used in this analysis. Inapplicable characters (e.g.,marsupial characters in non-brooding taxa, hinge characters in eden- tulous taxa, etc.) were coded as dashes ('-'), and missing data with ques-

T'II~c2. Adult and larval unionoid ~norpholo~gydata matrix. Oindicates the plesiomorphic condition of-the Paleohetcrodorrta. Character diagnoses can bc found in Appcndix 2. 6 Ckaj' OCC. I+~(?J tion marks ('?') . When a particular character varied intragenerically, the character state of the type species was given precedence, rather than as- suming monophyly of the genus and coding the character as polymor- phic. Phylogenetic analysis (branch-and-bound) was performed with PAUP* (Swofford, 1998). Dashes were treated as missing data rather than as a new state. Neotrigoniawas designated as the outgroup, and the ingroup was constrained to be monophyletic in order to root the phylogeny. Char- acter transformation series were traced using MacClade 3.07 (Maddison and Maddison, 1997) and PAUP*. To gauge the 'robustness' of each node, Bremer Support-Decay (Bremer, 1995) values were calculated using TreeRot (Sorenson, 1996), and a bootstrap analysis (200 replicates, heuristic searches with 10 random sequence additions each) was performed using PAUP*.

RESULTS

Parsimony analysis recovercd a single, most-parsimonious tree 62 steps long (25 parsimony informative characters, CI= 0.625, RC= 0.561) (Fig. 1). The Margaritiferidae (= Mar,urilz$era) is sister to the remaining Unionoida. The other families are recovered as monophyletic with the exceptions of the "Unionidae" and the "Mycetopodidae" (= Etheriidae; see below). The Hyriidae are sister to the Etherioidea senslc Parodiz and Bonetto (1963), not the "Unionoidea." Thus, parsimony analysis of the characters traditionally employed to diagnose unionoid taxa rejects the hypothesis that glochidia diagnose a monophyletic clade composed of the Margaritiferidae, Unionidae, and Hyriidae. The bootstrap 50% consensus tree (not shown) differs from Fig. 1 in that the ~~niollidscollapse into a polytomy. The (Ilyriidae, (Iridinidae, Etheriidae)) clade, however, is resolved by the bootstrap analysis. Fig. 2 illustrates all character translormations, and these are also described in Appendix 3. The recovered phylogeny finds no support for a monophyletic "Mycetopodidae" (Fig. 1). I-Ieard and Vail (1976a), finding no soft-anatomical synapomorphies to distinguish Ethrria from mycetopodids, syn- onymized Etheriidae with Mycetopodidae. Kabat (1997) demonstrated that, of the two, Etheriidae has priority. Parodiz and Konetto (1963) rec- ognized several subfamilies within the "Mycetopodidae," but the monophyly of these has not been tested.

DISCUSSION

The phylogenetic reconstruction 01 Parodiz and Bonetto (1963; also Haas, 1969a, 196910; Heard and Guckert, 1971) divided the Unionoida into two "clades" based on larval type. That hypothesis is rejected by the No. 729 Hyriid Relationships

Neotrigorria

2MargaritiJkra - MARGARITIFERIDAE 6 4 Pj~garzodnn - Lanrpsilis I Elliptio 1

5 4 I'arreysia 80 Grandidieria

2 I Diplodorr 2 Castalincr

Fig. 1. Single trcc ~rccovcrcdhy parsi~nonyanalysis (62 steps, (;I = 0.625, KC= 0.561). Taxonorrry 1.cf1cc.t~the classific;rrion listccl in Tablc 1. Thc "Unioniclae," "Myccropoditlac," ;rntl "Unio~~oitlca"arc shown not to be monophyletic. Thc rcvisctl taxonomy of ~11c Erl~crioitlcais listctl in T~ble3 and drpicted in Fig. 2. Nrrnlbers above the brancllrs indicate I)r;~nclilengths, tllosc brlow arc Urerncr-Decay and bootstrap values, respectively. present analysis of the characters that have been considered important by pas1 rnussel systematists. In thc most parsimonious reconstruction, glochidium-type parasitic larvae are considered syrlapomorphic at the ordinal level - a glochidium is the primitive state among the Unionoida. In thc lineage leading to the (Iridinidae, Etheriidac) clade (= Ethcrioidea sen,.su Parodiz and Bonetlo) , the glochidium was modified into a lasidium (Fig. 2). This is in direct contradiction to Parodiz and Bonetto (1963) who could not irnagirle one larval type being derived from the other (see quote above). The definition of the Etherioidea should be expanded to includc he Ilyriidae. The Etherioidca, i.e., (Ilyriidae, (Iridinidae, Etheriidae)), is synony- Castalirra

Acostea J

Fig. 2. Cladograin depicting cliaractcr transformations and ~hcrevised taxonomy of' the Ethcrioidca. Character nrrmbrrs rcfcr to thosr listed in Appendices 2 and 3. Sliacled boxes indicate cha~acteracquisition (gray and hlack Sor statcs 1and 2, rcspectivcly), white I~oxesidenti'j character losses (character state 0). Unambiguous character transfbrma- tions (CI= 1.0) are marked by an arrow ('*'). mous with the Mutelidae of Ortmann (1912a, 1921), Thiele (1934), and McMichael and Hiscock (1958). That clade is diagnosed by at least three morphological synapomorphies: pallial closure above the excurrcnt aperture [character 18, see Appendices 2 and 31, attachment of thc inner demibranchs to the visceral mass near to or in contact with the labial palps [15], and pallial fusion between the incurrcnt and excurrent apertures creating a complete diaphragm [17] (Fig. 2). Within the Etherioidea, the tendency for complete fusioil of the inner demibranchs to the visceral mass [I41 and parasitism via a glochidium [35,36] are plesiomorphic; No. 729 I-Iyriid Relationships 9 they define natural taxa with levels of universality higher than the Etherioidea. Kndobranchy (the use of only the inner demibranchs for brooding) is also plesiornorphic among the Etherioidea, according to the present analysis (Fig. 2, character 25). This result, however, hinges 011 the position of Grnndidieria and the apparent paraphyly of the Unionidae (Fig. I). While parsimony analysis of this data set weakly supports the paraphyly of the Unionoidea, more extensive molecular phylogenetic analyses support the monophyly of (MargaritiSeridae,Unionidae) (e.g.,GraSand 0 Foighil, in press). Presuming the Unionid-ae are monophyletic, the endobranchous condition of Grandidieria, as well as certain other unionids (e.g.,Moncetin; Kondo, 1984), should not be considered homologotis with that of the Etherioidea. Thus, endobranchy may be a fourth synapornorphy diag- nosing the (Hyriidae, (Iridinidae, Etheriidae)) clade. The inclusion of' the Hyriidae among the Etherioidea is circumstan- tially supported by the biogeography of the clade. The Unionoida is an a~icier~tgroup, the extant fiimilies extending perhaps as far back as the Triassic (Henderson, 1935; Haas, 1969b). It is expected that the evolution of an ancient, continental taxon would reflect the break up of Pangaea. This expectation is born out in the phylogeny recovered here. While there is evidence for Mesozoic etherioideans in North America (Pilsbry in Wanner, 1921; Morris and Williamson, 1988), the present-day Etherioidea are limited to the southern Gondwana continents. U~lionoideansoccur almost exclusively on the northern coiltinents (Table 1). Etherioideans and unionoideans are syrnpatric only in areas of sec- ondary contact: Central America, Africa, and Southeast Asia. The results of' this analysis bear directly upon the taxonomy of the Unionoida. A revised system of the Etherioidea, based on this and other studies as well as Kabat's (1997) nornenclatural revisions, is presented in Table 3. An important aspect of this classification - equally as important as the hierarchical arrangement of taxa within it - is its rejectability. It is based upon explicit statements of character homolo

Ethcrioidca Deshayes, 1830 Etheriidae s.s. Ethcriinae s.s. - Etheriu I~mai-ck,1807; Acotlrrea d'orbigny, 1851; Pse~~domulleric~ Anthony, 1907. (Heard and Vail, 197Ga; Yonge, 1978) Mycetopodinae Gray, 1840 - Mycetoj~odad'Orbigrry1835; Myrc!lojOodellaMarshall, 1927. (Pal-odizand Borietto, 1963) Monocondylaeinae Modell, 1942 - iMonorondylaea d'orbigny, 1835; I?Tnmic(~Scans, 1932; Fossula Lea, 1870; Tamrirlla Haas, 1931. (Parodiz and Bonctto, 1963) Anodontitinac Modell, 1942 - An,odor~lzlrsRr-~~guii.~-e, 1792. Iridirridac Swainson, 1840 Iridininac s.s. - Mutrla Scopoli, 1777;As1)alharia Bourguignat, 1885 [= Spc~lhol~sis Simpson, 19001; Iridinn Larriarck, 1819 [= I'lriodon Conl-ad, 18341. (Haas, 1SG9b) ?? Lcilinae Morrctcs, 1949 - Leilr~Gray, 1840. I-Iyriidae Swainson, 1840 Hyriinac s.s. (Parodiz arid Bonetto, 1963) I-Iyr-iini5.s. -Prisodon Schumache1; 1817 [= Hyricr Lalnarck, 18191 ; Paxyor%on Schumacher, 1817. (hstaliini Parodiz and Bonetto, 1963 - (,'mlnlia 1,arnarck , 1819; C;astalin,n von Ihering, 1891; (,'(~llonaiaSinipson,1900; C(~ctnlielloSimpson,1900. Diplodontini Parodiz and Boneito, 1963 -UijOlodonSpix, 1827; ~ijllodonlitvt Marshall, 1922. Velesunioninac Ircdale, 1934 - Klrtu7zio Ircdale, 1934; Microdon,fio Tapparone- Canefri, 1883; Alathyria lrcdalc, 1934; Wvstral7~71ioIredalc, 1934. (McMichacl and Hiscock, 1958) Lortiellinac Ircdalc, 1934 - Lortirlla Iredale, 1934. Hyridellinac Iredalc, 1934 - Hyridrllr~Swainson, 1840. Ct~cumerunioninaeIredale, 1934 - C~i,r~rncc>r~~n,ioIrcdalc, 1934; Viqrlrs Sirnpson, 1900.

ACKNOWLEDGMENTS This research was undel-taken as part of a larger study for my Pl1.D. preliminary cxami- nation in the Biology Departrncnt of the University of Michigan. 1 wot?ld like to thank my examination committee (Williarn Fink, George Kling, and Diarrnaid 0 Foighil) fbr their comlnerrts and suggestions. Thanks are also extended to J. kt,T. Lee,J.-I<. Park, J. Sparks, and two anonymous reviewers for their suggestions ancl comments . Most especially, I would like to thank my Lriend Shanc Webb for his time arid assistance and John B. Burch for loaning me his personal copy of Haas (1969a). All that being said, any errors present are solely my own. LITERATURE CITED hey, L. B. 1921. An experimental study on glochidia and the factors turdel-lying encyst- ment. Journal of Experimenral Zoology 33: 463.499. No. 729 Hyriid Relationships 11

Artcaga, S. E. 1994. El lasidiu~r~de Acostaea nuoli Dcshayes, 1827 (Mollusca: Bivalvia: F,thcriidac) y su importancia para la ubicacian taxonomica cle esta especie. Boletin Ecotl-opica 27: 1-9. Rakcl; F. 1.:. 1928. The freshwater Mollusca oSWisconsin. Wisconsin Geological and Natu- I-al Histol-y Survey Bullrtin 70: 1-495. Bloomct; H. H. 1932. No(cs on thc anatomy of sonie African Naiades- Pal-t I. Procccd- ings of the Malacological Society of London 20: l6bi-173. ISlootncr, 1-1. 11. 1933. Notcs on the anatomy oSsomc African Naiades- Part 11. Proceed- ings of the Malacological Socicty of Idondon 20: 237-241. Uo~~clto,A. A. 1951. Acel-a dc las fortnas Iarvales dc Mutelidac Ortmann. Jornadas Icticas 1: 1-8. Uonctto, A. A. 196la. Investigacionrs accl-a tlc las formas larvales ell el genel-a "I)ij,lodonn y su aplicacion a los estudios sistcmaticos. Dircccion Genet-al dc Kcc~rrsosNatrrrales, Provincia dc Santa Fc Ministerio de Agricultura y Ganadcr-ia. 48 pp. l\onctto, A. A. 196111. Notas sobre los generos Crwtalina y Castnlin cn cl Parana Mcdio c Inl'c~.ion Dirccciori (;cl~e~-aldc liccul-sos N;cturales, Provincia dc Santa Fc Ministerio tic Ag1.icu1tul.a y Ganacleria. I I pp. Bonetto, A. A. l962a. Notas sobre L)iplodor~rhr~rr-ltanus (Orb.) y I)il~lodor~rl~uaroiru\ (Orb.). Dircccion Gcncral dc Recursos Naturalcs, Provincia clc Santa Fe Ministel-io dc Agricult~~l-ay Ganadct-ia, Prrblicacion Tecnica (10): 35-44. Bonctto, A. A. 1962b. Espccics del genera "iMycrlo~)orlri'cn cl sisterna liitlrogralico dcl Rio dc 121 Plats. Rcvista del Musco Argcntino dr Cicncias Nat~lralcsRcrnardino Kivadavia, (:icnci;ls Zool6gicas 8: 173-182. Bonctto, A. A. 1963. C:ontribucirin al conocimie~ltode Lcilc blr~in,vilkcrn,cl(Lea) (Mollusca: Pclccypod;~). Physis 24: 11-16. Uonctto, A. A. arrtl I. D. Ezcul-I-;i. 1'362. El desarrollo de lasitliurn dr Anodon,titrs /mapcsiali.s Ji)rbr!sinn,zrs(1.c~) (Moll. 1,arncll.). Pl~ysis23: 195-203. Uonetto, A. A. ant1 I. D. Ezcurr;i. 1965a. Estuclio cot~~pal'atiodc las forrnas Iatvales de Mutelidae Ortmarin y su signification sistcrnatica y zoogeogl-alica. Anais Do 11 Congresso Laiino Amcricano dc Zoologia (S. Paulo, 1962). p. 55-71. Bonctto, A. A. and I. D. Ercurra. l965h. Notas malacologicas. 111. 5) la escultura dcl pcriostraco en cl gcrrcl.o Anodontitrc. 6)(-1 lasidium dc Anodorctitr,.t I7rip~zru.s(Spix). 7) el l;rsicIium de Myretof~odr~silicpo.\u (Spix). l'hysis 25: 197.204. l3oss, I<. ,]. 1982. Mollusca. Irr: S.P. Parker (cd.), Synopsis and C:lassificatio~~of Living Organisms 1 : 945-11 66. McGraw-Hill Book Company, Ne\vYo~-k. Brc~ncr;I<. 1995. Branch support arrd tree stability. Cladistics 10: 295-304. Brown, J. I-I. and M. V. 1.onrolino. 1998. Biogeography, 2nd Edition. Sinauel- Associates, Inc., Sundcrlar~d,Massachusctts. Cokcl; R. E., A. E Shi~-a,11. W. Clark and A. U. Howard. 1921. Nat~rralhisto~y and propagation of li-eshwatcr ~n~~sscls.Bulletin of tllc U.S. Bureau oSFislieries 37: 77-81. Cox, I,. li. 1969. Gcncri~lfcaturcs of the Bivalvia. Irt: K. C. Moot-e (ed.), Trcatisc on Inver- tebrate Paleontology, Part N, Mollusca, 6. Volrrnre 1: Kivalvia, pp. N2-N129. Uxrivc~-sity oS ILnsas I'ress, I,awl.cncc, IG~nsas. Ikragh, T. A. 1998. Order T~rigonioida.In: P. L. Bccsley, G. J. B. Ross, and A. Wells (eds.), Moll~lsca:the So~~thcrnSynlhcsis. Fauna of Australia 5: 294296. CSIRO Publishing, Mclbourl~c,Australia. L)avis, (;. M. and S. L. H. Fullcn 11181. (;cnctic relationships arnong Kecent Unionacca (Uivalvia) of North A~ncrica.Malacologia 20: 217-253. l'arl-is,]. S. 1989. Tlrc Kctention Indcx and the Kcscalcd Consistency Index. Cladistics 5: 417-419. F1.yc1; 6. 1954. Dcvclopmcnt in a rrl~~telidLamellibranch. Nature 183: 1342-1343. FI-ycr,G. 1961. Tlrc dcvclopniental history ot Mtctela hourg-crig.r~,nti(Ancey) Bourguignat (Mollusca: Bivalvia). Philosophical 'Transactions of' the Royal Society of' 1.onclon B 244: 259-298. Gould, S. J. and C:. C. .Jones. 1974. The pallial ridgc of' Ncotrigonin: lilnctional siphons without mantle fusion. Veliger 17: 1-7. Gmr, D. L. 1998. Sympatric speciation of freshwater ~nusscls(Bivalvia: Unionoidca): a model. Amcl-ican Malacological Bulletin 14: 35-40. Graf, L). I.. and 1). 6 Foighil. In press.. The evolution ~I'rcproductivecharacters among the Srcshwatcr pearly mussels (Mollusca: Bivalvia: Unionoicle;~)of North America. Journal oTMoll~~scanStudies. 1.1. aas,. . F. 1969a. Superfamilia Unionacea. In: R. Martens ;nld W. I-lcnnig (eds.),Das Tierrich, 1,iekrung 88, 663 pp. Walter de Gruyter and Co., Berlin. I-Iaas, F. 1969b. Superfamily Unionacea. In: R. C. Moore (cd.),Treatise on Invertebrate Paleontology, Part N, Mollusca, 6. Volume 1: Riv;tlvia, pp. N4ll-N470. University of

Hcaly, J. M. 1989. Sper~niogcncsisand spermatozoa in the relict genus Ncott-igolrirc: rcl- cvancc to trigonioid relationships, particularly Unionoidca. Marine Biology 103: 75- 85. I-lcard, W. H. and U.J. Dougherty. 1980. An ;ln;ltornic;tl rcdcscription of i'L(!iodon ((hm(.n,~zia) spekii (Pclccypoda: Mutclidac: I'leiodoninae) . Malacological Review 13: 45-53. Heard, W. H. and R. H. Guckci-t. 1971. A re-evaluation of the Reccnt Union;lcca (l'clecypoda) olNorth Amel-ica. Malacologia 10: 333-355. Heard, W. 1-1. and V.A. Vail. 1976a. Anatomical systenratics ofEtl~c>t-in(~llif~/icn (I'clccypoda: Mycc~opoclidae).Mal;icological Review 9: 15-24. I-Icard, W. M. and V.A. Vail. 1976b. The systematic position of U11io crrffrr (Pclccypoda: Unionoida: Unionidae). Zoologica Mricana 1 1: 45-58. Henderson, J. 1935. Fossil non-marine Mollusca of Norllr Amc~.ica.Geological Society of A~nericaSpecial Papcrs 3: 1-313. I-loch, W. It., M. B. Black, R. (;. Gustafson, A. E. Bogiln, It. A. Lut7 and K. C:. Mijcnhock. 1998. Testing alternative hypothcscs of Nrolrf,gonio (Bivalvia: TI-igonioida) phylogcnctic relationships using cytoclrron~ec oxidase subunit 1 DNA sequences. Malacologi;~ 40: 267-278. Howard, A. D. 1915. Some cxccptional c;~scsof bl-ccding ;lmong thc Unionidae. Nautilus 29: 4-1 1. Jones, El. A,, R. 11. Simpson and C. L. Humphry. 1986. The I-eproductive cyclcs and glochidia of fresh-water ~nusscls(Bivalvia: Hyriidae) of the Maclwy River, northern New South Wales, Australia. Malacologia 27: 185-202. Jupiter, S. D. and M. Ryl-nc. 1997. Light and scanr~ingelectron microscopy of the cn~b~yos ancl glochidia larvae of the Austl-alian frcshwatcr bivalve Hyridrlla d(pr(:.\.src(Hyriidae). Invel-tebratc Kept-oduction anel Development 32: 177-186. ICabat, A. li. 1997. Correct f'amily names for the freshwater "muteloid" bivalves (Unionoida: Etherioidea). Occasional Papcrs on Mollusks 5: 379-392. Iht, P. W. 1984. Parasitism and the Unionacca (Bivalvia). Biological Reviews 59: 189-207. I

Idckvrc,(;. and W. C. (krtis. 1912. Stuclics on tlre reproduction and XI-tilicialpropagation ~Sfresliwatcumusscls. Bulletin ol the U.S. Bureau of Fisheries 30: 105-201. I,ydc;~rd,(:., M. Mulvey and G. M. Davis. 1996. Molecular systerilatics and evolution of rcpr-oductivc traits in North An~ericanfi-eshwater unionacean rnusscls (Mollusca: Rivalvia) as infcl-red fi-om 16s rRNA gcnc scqucnccs. Philosophical Transactions of rllc Royal Society of Lontlon B 351: 1593-1603. Matldison, W. P. ancl D. R. Maddison. 1997. MacClade: Analysis of Phylogeny and Charac- ter Evolutiotl, Version 3.07. Sinauer Associates, Irrc., Surrdcrl;lnd, Massachusctts.

McMicllacl, 1). F, and I.D. Hiscock. 1958. A rno~iograph- - of frcshwatcr musscls (Mollusca: I'clccypoda) of the Australian region. Australian Jotu-nal of Marine and Freshwarel- Research 9: 372-508. Morris, P. J. and P. <;. Willianisori. 1988. Plriodon (Conrad) (Biv;rlvia Mutelidae I'leiotloninac) ko~nthe 1,atc C:rctaccous of Montarra- a 1" North-American I-ccol-dfor the Mutclitlae. ,Journ;tl of I'alcotology 62: 758-765. Morton, B. 1987. Fllnction;~lrnorpholo,q of N(,olrigwn,in mnl;quri/crrpa (Rivalvia:Trigoniacca), wit11 ;I cliscussion ol phylogcnctic affinities. 1Zccords of rhc AUSLI-alianMuscu~n 39: 339-354. Newcll, N. 1). atrtl I). W. Boyd. 1975. P;~rallclevolution in carly trigoniaccan bivalves. Bullc~iriof the hcl-ic;ui Museum ofN;~turalHistory 154: 53-162. (3 Foighil, I). anel D. I.. GI-af. In PI-css. Prodissoconch rrlorpl~ologyof thc rclict marine p~lcohetcroclon~Nootrigon,ia rnorgantncrn (Mollusca: Bivalvia) indicates a non-plank- ronic ~x~j~~vcnilc01110gerry. Jour~ialof the Marine Biological hsociation, U.I<. Ortm;tnn, A. E. 1910a. A new system ofthc Unionidac. Nautilus 23: 114-120 Ol.t~n;lnn,A. E. 1910h. Thc systc~naticposition of thc unionid-genus Purrry.r~n.Niultilns 23: 131)-142. 01-tm;~nn,A. I<. 1910c The discharge of glor1iidi;t in rhc Uniotliclac. Nautilus 24: 94-95. Ortrriann, A. E. 1910cl. The m;irsupi~unof the Anodontinae. Biological Bulletin 19: 217. Ortm;mn, A. E. 1911 a. Tllc an;ltonrical structure of certain cxotic Najadcs coinparcd with that of the Nor-th Amel-ican lol-ms. Nautil~~s24: 103-108, 114120, 127-191. OI-LI~;III~,A. E. 191 lb. Thr classification ofthc European Naiades. Nautilus 25: 5-7,20-23. Ortrnann, A. l<. 191 Ic. Monogl-;~phof the Nyjadcs of Pc~lnsylv;~riia.Part I. Anatomical investigations. Part 11. 'rhe systeln of Nortlr hcrican Najadcs. Memoirs of the Chr-ncgic Ml~scum4: 279-347. Ortlnann, A. E. 19 12;~.Notes rlpon the fanrilics and gencr;i of thc Najadcs. Annals of thc (:arnegie Museum 8: 222-365. Ortnrann, A. E. 1912b. The ;tnatolny of the Najad I-lylz'rlrlln ~usimlic(1.anlar-ck) (= Dzplodon nrt.c.lr(~1i.s).Nal~tilrls 25: 100-103. Ortrn;~nn,A. 1'. 1918a. The anatomy of two aft-icanNayadcs, lirzio cnflerand Sf)ntlzn wohlhPr,i. N;u~tilus31: 75-78. Ort~nalin,A. E. 1918h. Thc idcntity ofthc Nayad-gcnus Nod~tlrr~iciConrad with Cinio liet~ius. Nautilus 31: 128-131. Ort~narrri,A. E. 1921. South American Naiadcs; ;I contl-ihution to the knowledge of the l'rcsl~watcrrrlussels of South Arncrica. Merrioirs ol the Carnegie Museum 8: 451-(570. l'arotliz, J. J. ar~tlA. A. Bonctto. 1963. Taxoliorny and zoogeographic relationships of the So~lthAmcric;ln N;~i;~dcs(I'clccypoda: Unionacca and M~~telacca).Malacologia 1: 179-214. l'ilsbry, M.A. ;incl,J. Kcquaert. 1927. The aquatic nrollusks of tlic Belgian Congo, with a geographical and ecological account of Congo malacology. B~lillctir~of rlic Arncrican Muscum of Natural History 3: 69-602. Roc, I<. J. and C:. 1.ydcarcl. 1998. Molccrilar systematics of the freshwater musscl gcnus I'olnnril~us (Bivalvia: Unionidac). Malacologia 39: 195-205. Koscnbcrg, G., G. M. Di~vis,(;. S. Kuncio arid M. (;. Harasewych. 1994. Prclimina~yriboso- 14 Gruj' Occ. P(~,brr.v

ma1 RNA phylogeny of gastropod and unionoidcan bivalvr ~nollusks. Nautilus Supplime~~t2: 1 11-121. Iiosenberg, G., S. Tillier, A. Tillier, G. S. I<~~ncio,K.T. Hanlon, M. Massclot and (:. J. Will- iams. 1997. Ribosomal RNA phylogeny of selected major clades in the Mollusca. Journal of Molluscan Studies 63: 301-309. Smith, R. J. 1998. Order Unionoida. In: 1'. L. Recslcy, G. J. B. Ross, and A. Wells (eds.), Mollusca: the Southern Synthesis. Fauna of Austl-alia 5: 296-298. CSIRO Publishing, Melbourne, Australia. Smith, D. C. 1979. Marsupial anatomy of the dcmibranch of Ma?xctr~tt$eramarg/~ritz/n (Lin.) in northeastern North America (Pelecypoda: Unionacca). Journal of Mollus- can Studies 45: 39-44. Smith, D. C. 1980. Anatomical studies on A4nrg/~~itifcramargu,rilq~r~~ and CumbtrI/~~ndin mon,odonla (Mollusca: Pclccypoda: Margal-itifci-idae). Zoological*]onrnalof the Idin- nean Society 69: 257-270. Srnith, D. C. 1983. On the so-called mantle muscle scars on the shells of the Margaritif'eridac (Mollusca, Pelecypoda), with observations on the mantle-shell attachment in the Unionoida and Trigonioida. Zoologica Scripta 12: 67-71. S~lnlcy,S. M. 1970. Relation of shell form to life habits in tlrc Bivalvia. Memoil-s of thc Geological Society of America 125: 1-296. Sorenson, M.D. 1996. Trceliot. University of Michigan, Ann Arbor. Stasek, C. R. 1963. Synopsis and discussion ofthc association ofctcniclix and labial palps in the bivalved Mollusca. Veliger 6: 91-97. Strathmann, R. I<. and D. J. Ecrnissc. 1994. What molcctllar phyloxenies tell us about the evolutioll of larval forms. American Zoologist 34: 502-512. Swofforcl, D. L. 1998. I'AUP*: Phylogenctic Analysis Using Parsimony, version 4.0. Sinallel- Associates, lnc., Sundcdand, Massachusetts. Taylor, J. L)., W. J. Iknnedy and A. Hall. 1969. The shell structure and niineralo~yof the Bivalvia. Iritrocluction. Nuculacea - TI-igonacea [sic]. Bulleti~lofthe British Museum of Natural Histroy (Zoology), Supplenient 3: 1-125. Tevesz, M.J. S. 1975. Stlucturc and habits of the "living fossil" pclccypocl Neotrig(~n2o.Lcthaia 8: 9'21-327. Thiele, J. 1934. I-landbuch der Systcmatischen Weichticrkunde, Pal-t 9: 779-1022. Jena, Gustav Fischcn Vaught, I<. C. 11189. A (:lassilication of the Living Mollusca. Amel-ican Malacologis~s,Inc., Melbourne, Florida. von Ihering, H. 1910. ~bcrBrasilianische Najadcn. Sc~lckenhergischeNaturforchende Gesellschaft, Abhandlungcn 32: 113.140. Wanner, H. E. 1921. Some faunal remains from thr Trias of York County, Pennsylvania. Proceedings of the Academy of Natural Sciences, I'hiladelphia 73: 30-36. Wattcrs, G. T. l994a. Form and function ofunionoidear~sliell sculpturc and shape (Rivalvia). Amcrican Malacological 11: 1-20. Wattcrs, G. T. 1994b. An Annotated Bibliography of the Reproduction and Propagation ol the Unionoidea (Primarily of North America). Ohio Biological Survey Miscellaneous Contribution 1. Columbns, Ohio. Wilcy, E. 0. 1980. Phylogenetics: the Theory and Practice of Phylogenctic Systematics. Wiley and Sons, Inc., Ncw York. Wray, G. A. 1'396. Parallel evolution of'nonfceding la13~aein cchinoids. Systematic Zoology 45: 308-322. Yongc, C. M. 1962. On Etherin elliptica Lam. and the course of evolution, including the assumption of monomyarianism, in the family Etheriidae (Rivalvia: Unionacea). Philosphical Transactions of the Royal Society o1.London B 241: 423-458. Yonge, C. M. 1978. On the monomyarian, Acostaea riuoli and evolution in the family Ethcriidae. Journal of Zoolo

AI'I'ENDIX 1: MATElU4L EXAMINED

The fi)llowing is a catalog of the general analyzed, the specimen lots examined, and relevant literature references to anatomical descriptions of larvae and/ or adults. Genera arc listed alphabetically. All specimens are deposited in the University of Michigan Museum of Zoology (UMMZ), Ann Arbor, Michigan. An asterisk ("g') identilies the type species of each genus.

Acostc~ecid'orbigny, 1851. - *A. rivoli (Deshaycs, 1827) UMMZ 112660 Amazon Rivcr, Sotrth America. - Yonge (1978), Arteaga (1994). Anodontitcs Bruguierc, 1792. - :';A. crispata (Brug., 1792) UMMZ 11239 1 upper Datrlc liiver, Ecuador. A. lraf,rsialis (Lain., 1819) UMMZ 112429 Rio Grandc do Sul, Brazil. - Ortmann (1921), Bonetto and Ezcurra (1962, 1965b). (;ccstcrlina von Ihcring, 1891. - '"C. martensi (von Ihcring, 1891) UMMZ 110907 Rio Grande do Sul, Brazil. C. undosa (von Martens, 1885) UMMZ 110905 Sao Palllo, Brazil. - Ortmann (lglla, 1921), Bonetto (1961b). niflodon Spix, 1827. - "D. ellipticum (Spix, 1827) none examined. 1). pamnensi.c (Lea, 1834) UMMZ 248835 Buenos Aircs, Argentina. 11. Jontainianu,.~ (d'Orbig~ry,1835) UMMZ 111280 Rio Grande do Sul, Brazil. - Ortnlann (1921), Bonctto (1951, 196la, 1962a). IXllifltio RaGnesquc, 1819. - $'E. crns~iden,~(Larn., 1819) UMMZ 129451 Missis- sippi Kiver, Wabasha Co., Minnesota, USA. E. dilalala (Kafinesque, 1820) UMMZ 205584 IGalarnazoo River; Jackson Co., Michigan, USA. - Ort~nann (1912a), Bakcr (1928). IClheria Larnarck, 1807. - '''1:'. elliplica (Lam., 1807) UMMZ 43223 Whitc Nile Rivcr; Africa. - Yonge (1962), Heal-d and Vail (1976a). C:mndirli(viccBourguignat, 1885. - :':C;. hurtoni (Woodward, 1859) UMMZ 248778 1,akc Tanganyika, Zanrhia; UMMZ 110105 Lakc Tanganyika, Zaire. - Bloomer (1933), Icondo (1990). tlyridrlln Swai~lson,1840. - "H. nu.strulis (Lam., 1819) UMMZ 111296 Australia. H. dej~rc:scr(I.am., 1819) UMMZ 111827 Paranlalta River; New South Wales, Australia. - McMicllacl and Hiscock (1958),Jones et al. (1986),Jupiter and Ryrne (191-)7). In'din,a I.:u~rarck, 1819 [= Plriodon Conrad, 18341. - *I.cjxolica Idam.,1819 UMMZ 111973 Africa. I. ouatus Swainson, 1823 UMMZ 112006 Scncgal. - Heard and Dougherty (1980). I,crrrrf~.sili,slb-lfincsque, 1820. - "L. ovaln (Say, 1817) [= L. cardium Raf., 18201 UMMZ 50637 St. Joseph River, Berrien Co., Michigan, USA, UMMZ 130005 Mississippi Kivcr, Wabasha Co., Minnesota, USA. - Ortmallrl (1912a),Bakcr (1928), Krae~ner(1 970). Mayrrt~l{/i.r~rSch~u~naclirr, 1816. - *'M.margarilz/ua (Idinn.,1758) UMMZ 4338 St. 1,awrcnce River, NewYork, USA. M. hcmbeli (Conrad, 1838) UMMZ 107633 Alexandria, Rapides Parish, Louisiana, USA. - Or~mann(1911b, 1912a), Smith (1979). Mutela Scopoli, 1777. - "M. dubia (Gmclin, 1793) UMMZ 111979 Nile River, Africa. M. nnilotica (Cailliaud, 1823) UMMZ 111984 Mahmoudich, Egypt. - Bloomer (1932), Fryer (1954, 1961). Mycc.topodu d'Orbigny, 1835. - "M. solen,iJorrnis d'orbigny 1835 none examined. M siliquosu (Spix, 1827) UMMZ 112645 Maraiion, Pcru. - Ortrnann (1921), Bonetto (1962b), Bonetto and Ezcurra (1965b). N~olrigoninCossmann, 1912. - pectinnta (Lam., 1819) none examined. N. margaritcccea (Lam., 1804) UMMZ 253004 Thsmania. - Tevesz (l975),Morton (1987), Darragh (1998), 0 Foighil and GraP (in press). ParrvysinConrad, 1853. - "P. corrugata (Miillel-,1774) UMMZ 110263 Sri 1,anka. - Ortnlann (191Ob, 191la), Pilsbry and Bequaert (1927). bgar~odonCrosse and Fischer, 1894. - "1-1 grandis (Say, 1829) UMMZ 205535 Portage Creek, Kalamazoo Co., Michigan, USA. P c(LL(~ru(:t(~(S.ay, 1187) UMMZ 101840 Framingham, Middlesex Co., Massachusetts, USA. - Ortmann (1912a), Baker (1928). Unio Philipsson, 1788. - "U. pictorwn (Linn., 1758) UMMZ 79230 Birmingham, England; UMMZ 79213 River Saale, Jena, Germany. U. rr~[fer Ihauss, 1848 UMMZ 60409 Irene, Transvaal, South Africa; UMMZ 234710 Lundi River, 14 nli S Ghiredzi, Zimbabwe. - Ortmann (1912a, 1918a, 1918b), Heard and Vail (1976b). VuGsunio Iredale, 1934. - "V arnl~ipa(Philippi, 1847) UMMZ 11 1839 Murray River, Australia. - rtmann (1912b),McMichael and Hiscock (1958),Bonctto and Ezcurra (1965a). No. 729 Hyriid Relationships 17

APPENDIX 2: CHARACTER DIAGNOSES

The key to the characters and their states as used for character analysis follows. Literature cited refers to relevant discussions of character evolution. See Mcthods and Materials for an explanation of the phylogenetic methodology. 111 all cases, 0 is hypothesized to be the plesiomorphic condition of the Palcoheterodonta. Shell C;hnracters

1. Hinge type: 0 = schizodont; 1 = raxodont (Thiele, 1934; but see discussions in Cox, 1969 and Morton, 1987). 2. Development of posterior (lateral) hinge tccth: 0 = well-developed; 1 = re duced or absent. 3. Morphology of posterior (lateral) hinge terth: 0 = smooth; 1 = serrate (von Ihering, 1910; Ortmann, 1921). 4. Developme~ltof anterior (pseudocardinal) lliilgc teeth: 0 = rubust, generally with two teeth on the left, one on the right, 1 = delicate, generally with one on the left, two on the right; 2 = reduced or absent. 5. Angle between posterior and anterior hinge tccth: 0 = obtuse; 1 = acute. 6. Morphology of anterior (pseudocardinal) hinge teeth: 0 = tab-like; 1 = peg- like. 7. Shell shape: 0 = bilaterally symmetrical; 1 = asyrnmetrical due to cementation. 8. Adult adductor scars: 0 = dimyarian; 1 = nlonomyarian (Yonge, 1978). 9. External shell: 0 = sculptured; 1 =smooth (Stanley, 1970; Watters, 1994a). 10. Beali (urnbo) sculpture: 0 = absent, concentric or double-looped; 1 = angular or zig-zag (including 'radial') (Bonrtto, 1962a; Watters, 1994a). 11. Mantle muscle scars: 0 = present; 1 = absent (Smith, 1983).

12. Ctenidial morphology: 0 = filihranch; I = lamellibranch (Morton, 1987; Smith, 1998). 13. Association of ascending lamcllae of outer demibranchs with the mantle: 0 = completely free (unfused) or free posteriorly, but separation of the inti-abranchial from the suprabranchial chamber is achieved by a 'pallial ridge' or 'diaphragmatic septum'; 1 = fused to mantle along entire length or nearly so (Gould and.Jones, 1974; Smith, 1980). 14. Association of ascending lamellac of inner demibranchs with the visceral mass: 0 = tending to be free of the visceral mass except at the anterior end; I = tending to bc complete fused to the visceral mass. 15. Anterior attachment of the inner dcinibranchs to the visceral mass: 0 = distant from labial palps; 1 = in contact with or adjacent to the labial palps (Stasek, 1963). IG. Pallial fusion ventral to the incurrent aperture: 0 = absent; 1 = short. 17. Pallial f~~sionbetween the incurrent and excurrent apertures: 0 = absent; 1 = present. 18 Graf occ. Pu$m.s

18. Pallial fusion dorsal to excurrent aperture: 0 = absent; 1 = present but re- opening to form a supra-anal aperture; 2 = present but witliout a supra-anal aperture. 19. Pallial hion between supra-anal and excurrent aperture: 0 = equal in length or longer than excurrent aperture; 1 = distinctly shorter that1 the excurrent aperture (Ortmann, 1912a). 20. Diaphragm formed by fusion of mantle with ctenidia: 0 = imperforate; 1 = perforate (McMichael and Hiscock, 1958). 21. Ctenidial filament morphology: 0 = homorhabdic (ctenidia smooth); I = heterorhabdic (ctenidia plicate) (Heard and Vail, 1976a). 22. R/Iantle ventral to the incurrent aperture: 0 = smooth or weakly elaborated; 1 = elaborated with conspicuous papillae or a ribbon-like flap (Ortmann, 1912a; Ikacmer, 1970).

Bmoding and Lzfe HHory Chnractrrs

23. I-Iabitat: 0 = marine; 1 = freshwater. 24. Parental care: 0 = none, fertiliration is external; 1 = female broods embryos and larvae in ctenidial marsupium (Coker et al., 1921; Kat, 1984). 25. Demibranchs occupied by marsupium: 0 = all four; 1 = inner pair only; 2 = outer pair only (Heard and Guckert, 1971). 26. Outer marsupial demibranch: 0 = entire demibranch marsupial or nearly so; 1 = a restricted portion of the demibranch marsupial (Ortmann, 1912a). 27. Inner marsupial demibranch: 0 = entire demibranch marsupial or nearly so; 1 = a restricted portion of the demibranch marsupial (Ortmann, 1921). 28. Interlanlellar connections of non-marsupial demibranchs, including those of' m.n lLS. ,.. 0 = none or scattered; 1 = complete septa; 2 = perforated septa. 29. Interlamellar connection of marsupial demibranchs: 0 = absent or scattered; 1 = perforated septa; 2 = complete septa. 30. Marsupial water tubes: 0 = undivided; I= divided by lateral septa ('tripartite') (Ortmann, 1910a, 1910d, 191lc). 3 1. Interlamellar sepca of marsupium: 0 = without a swelling protruding into the water tubes; 1= bearing a 'marked swelling' (Ortmann, 191 la). 32. Edge of marsupium: 0 = remains sharp when gravid; 1 = expands greatly when gravid (Ortmann, 1911c) . 33. Ventral extent of marsupium: 0 = ventral margin of marsupium does not extend past the non-marsupial portion; 1 = ventral margin of marsr~pium extends past the non-marsupial portion (1,efevre and Curtis, 1910). 34. Larval discharged: 0 = larvae discharged out the excurrent aperture with the respiratory current; 1 = larvae discharge through the ventral margin of'the dernibranch and out the incurrent aperture (Ortmatln, 1910~;1911~; Icraemer, 1970).

35. Larval type: 0 = fi-ee-living; 1 = parasitic; 2 =secondarily non-parasitic (Lcfcvre and Curtis, 1912; Parodiz and Bonetto, 1963; Kondo, 1990). 36. Parasitic larval type: 0 = glochidium; 1 = lasidium (Parodi~and Bonetto, 1963). No. 729 Hyriid Relationships 19

37. Clochidium morphology: 0 = unhooked; 1 = hooked (Ortmann, 1912a, 1921; Parodiz and Bonetto, 1963;Jones et al., 1986). 38. Lasidium morphology: 0 = attaches by tubular appendages (haustorium-type); 1 = attaches by forming a cyst (lasidium-type) (Fryer, 1961; Parodiz and Bonetto, 1963). ~"UJ‘ Orr. P(r11c.r~

APPENDIX 3: CI-IARACTER TRANSFORMATIONS AND STATISTICS

The following is an accounting of the character transfortnations suggested by this phylogenetic analysis. The character numbrrs are the same as in Appendix 2. An srefers to the number of transformations (i.e., steps) each character under- goes; CI and RC are the (hnsistency and Kescaled Consistency Indices, respectively. A dagger ('t')indicates that the RCis taken to be unitywhen the Retension Index is undefined (Farris, 1989). Nomellclature follows the taxouomy listed in Table 3, and character transformatio~lsare mapped in Fig. 2.

Shell Clzaract~~s

I. Synapomorphy of Jridina (s= 1, (;I = 1.0, RC1 .0t). 2. There are three independent reductions in M(~rgarit{fir-a,Pygan,odon, and (Iridinidae, Etheriidae) (s=3, (:I=0.333, RC= 0.222). 3. Arises as independent synapotnorphies of' both Neotrigon,in and Castalinn (s = 2, CI= 0.500, RC= 0). 4. Independent synapomorphies of Pumqsia and (Dzl)lodorr, (Hyrjdella, Mksun,io)), with two independent transformations to 2 in 1'ygn.nodon and (lridinidac, Etheriidae) (s= 4, CI = 0.500, XC= 0.375). 5. Arises as independent synapomorphies of both ElIijilio and Crzstirlina (s = 2, CI = 0.500, KC = 0). 6. Arises as independcnt synapomorphies of M(~rgam'tijkra,Elliptio, and Ca.stnli~zcr (s = 3, CI= 0.333, RC= 0). 7. Synapornorphy of (Ethmkz, Acostaen) (s= 1, CI= 1.O, RC = 1.0). 8. Autapomorphy of Acostnea (s= 1, (:1=1 .O, IiC = 1.Ot). 9. Synapomorphy of the Unionoida with an reversal to Oin (h~ndidieria(s= 2, CI = 0.500, RC = 0). 10. Synapomorphy of (Pameysia, ( GmndidiPm'a, Etherioidca) ), with independent reversions to Oin Velesunioand (Iridinidae, Etheriidae) (s=3, (:I=0.333, RC = 0.167). 11. Synapomorphy of ("Unionidae," Ethel-ioidea) (s = 1, CI= 1.0, RC= 1.0).

12. Synapornorphy oP the Unionoida. (s= 1, (:I= 1.0, RC= 1.0t). 13. Synapomorphy of ("Unionidae," Etherioidea) (s = 1, CI= 1.0, RC = 1.0). 14. Arises independently as synapomorphies of (Parreysia, (Gmndidieric~, Etherioidea)) and Laml~silis(s= 2, CI= 0.500, RC= 0.375). 15. Synapomorphy of the Etherioidea (s = I, (:I= 1.0, RC= 1.0). 16. Arises independently as synap~morphi~sof the lridinidae and Castnlina (s= 2, CI= 0.500, RC= 0.250). 17. Synapomorphy of the Etherioidea (s = 1, (;I= 1.0, IiC= 1.0). 18. Synapomorphy of ("Unionidae," Etherioidea). Transibrmation to 2 in the Etherioidea and reversion to 0 in the Etheriidae (s = 3, (71 = 0.667, RC = 0.600). 19. Synapornorphy of Qliptio (s= 1, CI = 1.O, RC = 1.Ot). No. 729 Hyriid Relationships

20. Synapomorphy of (H)lridella, Velesunio) (s= 1, CI= 1.0, RC= 1.0) 21. Synapomorphy of (Etheria, Acostaea) (s= 1, CI= 1.0, RC= 1.0). 22. Synapomorphy of Lampsilis (s= 1, CI= 1.0, RC= 1.01.).

Brooding and Lfe History Characters

23. Synapornorphy of the Unionoida (s= 1, CI= 1.O, RC = 1.0t). 24. Synapornorphy of the Unionoida (s= 1, CI= 1.0, RC = 1.01). 25. Sytlapornorphy of (Grandidimia, Etherioidea) , and 2 is a synapomorphy of (Un,io, (Elliptio (Lampsilis, Pyganodon))) (s= 2, CI= 1.0, RC= 1.0). 26. Synapornorphy of Lampsilis (s= 1, CI= 1.0, RC= 1.01). 27. Synapornorphy ofHyriidae (s= 1, CI= 1.0, RC= 1.0). 28. Synapolnorphy of ("Unionidae,"Etherioidea). Reversion to Oin the Hyriidae, but with 2 a synapomorphy of (Hyridella, Velesunio) (s= 3, CI = 0.667, RC = 0.500). 29. Synapomorphy of ("Unionidae," Etherioidea), with independent transformations to 2 in (Elliptio, (Lampsilis, Pyganodon) ) and (Iridinidae,Etheriidae) (s= 3, CI= 0.667, RC= 0.533). 30. Synapomorphy of Pyganodon (s= 1, CI= 1.0, RC= 1.0t). 31. Synapomorphy of (Iridinidae, Etheriidae) (s= 1, CI = 1.O, RC = 1.0). 32. Synapomorphy of (Pyganodon, Lampsilis) (s= 1, CI = 1.O, RC = 1.0). 33. Syilapomorphy of Lampsilis (s= 1, CI= 1.0, RC= 1.0t). 34. Synapomorphy of Lampsilis (s= 1, CI= 1.0, RC= 1.01).

Larval Characters

35. Synapomorphy of the Unionoida, with a transformation to 2 in Gmndidieria (s= 2, CI= 1.0, RC= 1.01.). 36. Synapomorphy of (Iridinidae, Etheriidae) (s=1, CI= 1.0, RC= 1.0). 37. Arises as independent s~mapomorphiesof in figanodon, Unio, and the Hyriidae (s=3, CI= 0.333, RC= 0.111). 38. Synapornorphy of the Etheriidae (s= 1, CI= 1.0, RC= 1.01).