Phylogenetic relationships of extant pelobatoid frogs (Anura:Pelobatoidea) : evidence from adult morphology

19 Pages·1998·8.7 MB·

by  Anne M Maglia

QL
668
.E262
M33
1998
Papers
Scientific
Museum
Natural
History
The Kansas
University of
30 October 1998 Number 10:1-19
of Extant Pelobatoid
Phylogenetic Relationships Frogs
(Anura: Pelobatoidea):
Evidence from Adult Morphology
By
Anne M. Maglia
^ Division ofHerpetology, NaturalHistoryMuseum and BiodiversityResearch Center,
^ and DepartmentofEcologijand Evolutionary Biology,
o The UniversityofKansas, Lawrence, Kansas 66045-2454, USA
CONTENTS
>' ^'
a ^';^ ABSTRACT 1
^ RESUMEN 2
1
^ -J INTRODUCTION 2
V HistoricalTaxonomyofthe Pelobatoids 3
T Acknowledgments 5
O t MATERIALSAND METHODS 5
-
CladisticMethodology 5
m Specimens Examined 6
S DESCRIPTION OFCHARACTERS 6
I RESULTS 12
DISCUSSION 13
Relationships withOtherAnurans 13
Supportfor Pelobatoidea 13
Interfamilial Relationships 13
RelationshipsWithin thePelobatidae 13
Conclusions 17
LITERATURE CITED 17
APPENDIX 19
ABSTRACT The phylogenetic relationships of the Pelobatoidea, the most specious clade of basal
anurans,arepoorlyunderstood. 1conducteda phylogeneticanalysisof14extantpelobatoidtaxa (rep-
resenting all recognized extant species of the family Pelobatidae and representative taxa of
Megophryidae and Pelodytidae) and six outgroup taxa by examining alcohol-preserved specimens,
dried skeletons, and cleared and double-stained skeletal preparations. Analysis of73 characters from
primarily adult morphology resulted in the discovery of six most parsimonious trees, each with 251
©NaturalHistoryMuseum,TheUniversityofKansas ISSNNo. 1094-0782
^ SciENTinc Papers, Natural History Museum, The University of Kansas
'^LiJ.
3 -3 steps. The analysis supports Pelobatoidea and Pipoidea as sister taxa. Within the Pelobatoidea,
I
CjOjO^ Pelodytidae is thesistergroup to Pelobatidae, and Megophryidae is thesister taxon to [Pelobatidae +
Pelodytidae]. Within the Pelobatidae, the monophyly of Pelobates, Scaphiopus, and Spea is supported.
Thispapersummarizesandredefinesmorphologicalcharactersthathistoricallyhavebeenused in the
studyofextantpelobatoidsystematicsandaddsnew,informativemorphologicalcharacters.Thisshould
createa framework upon which furtherphylogeneticanalysesofthis group canbeconducted.
Key Words: Anura, Pelobatoidea, Pelobatidae, systematics, phylogenetic relationships, Pelobates,
Scaphiopus, Spea.
RESUMEN Las relaciones de parentesco de los Pelobatoidea, el grupo the anuros basales con mas
especies, son pobrementeentendidas. Pormediodelestudio deespecimenespreservados, esqueletos
secosyesqueletostransparentadosydoblementetefiidos,condujeunanalisisfilogeneticode14taxones
vivientes de pelobatoideos (representando todas las especies vivientes conocidas de la familia
PelobatidaeytaxonesrepresentativesdeMegophryidaeyPelodytidae)yseisgruposextemos.Elanahsis
de 73 caracteres tomados fundamentalmente de la morfologia adulta resulto en el descubrimiento de
seis arboles mas parsimonicos de 251 pasos cada uno. El analisis respalda a Pelobatoidea y Pipoidea
como grupos hermanos. Dentro de Pelobatoidea, Pelodytidae es el grupo hermano de Pelobatidae
mientrasqueMegophryidaeeselgrupohermanode[Pelobatidae+Pelodytidae].DentrodePelobatidae,
la monofilia de Pelobates, Scaphiopus y Spea esta bien sustentada. Este trabajo resume y redefine los
caracteres morfologicos que historicamente han sido usados en el estudio de la sistematica de
pelobatoideosactuales,yagrega nuevoscaracteresmorfologicos. Estodeberia crearunmarcosobreel
cvial otros analisis filogeneticos de este grupo puedan ser realizados.
Palabras claves: Anura, Pelobatoidea, Pelobatidae, sistematica, relaciones filogeneticas, Pelobates,
Scaphiopus, Spea.
INTRODUCTION
The Pelobatoidea, comprising about 95 extant species lution to the phylogenetic placement of the pelobatoids
(Frost,1985)inthreefamiUes(Pelobatidae,Megophryidae, among other anurans; however, many of his characters
and Pelodytidae), is the largest and arguably, the most were not informative in resolving relationships within
poorly studied group of basal anurans. These frogs are Pelobatoidea. Thosecharacterspertinenttopelobatoidre-
distributed throughout the Holarctic Region and extend lationships provided little resolution beyond the family
into the Old World tropics (Duellman and Trueb, 1986). level, and when the results of his analysis were reported
The pelobatoids also are represented by an extensive fos- later(FordandCannatella, 1993),therelationshipsamong
sil record ranging from Late Jurassic of North America thepelobatoid famiUeswereunresolved. Lathrop's (1997)
(Evans and Milner, 1993) to the Pleistocene of North subsequent reanalysis of a portion of Cannatella's (1985)
America; the fossils include fEopelohates, iMacropelobates, data provided suggestions as to the among-genera rela-
fMiopelodytes, and iTephrodytes. tionships, but it did not address the placement of the
Although there are numerous suggestions as to the pelobatoids among other anurans, and it was not able to
phylogenetic placement of the pelobatoids among other elucidate some of the relationships within the family
anurans(e.g.,Brattstrom,1957;Griffiths, 1963;Lynch, 1973; Pelobatidae. Therefore, there is a pressing need to under-
Cannatella, 1985),fewstudieshavefocusedspecificallyon stand the phylogenetic relationships of the extant
pelobatoidsystematics.Henrici(1994)conductedthemost pelobatoids,includingtheirrelationshipswithotherfrogs
inclusivephylogenetic analysis ofthe pelobatoids to date and their inter- and intrafamilial relationships,
by examining both fossil and Recent forms. Her analysis Currently, a separate study in progress (Amy Lathrop,
resolvedrelationshipsamonggenera,butdid notaddress pers. comm.) is designed to address the generic relation-
theplacementofthepelobatoidsrelative tootheranurans ships within the pelobatoid family Megophryidae. To re-
or the relationships within genera. Cannatella (1985) in- duce overlap in efforts, the focus of the present paper is
eluded the extant pelobatoids in his analysis of threefold—(1) to understand the relationships of the
archaeobatrachianfrogs.Usingadultanatomyandtadpole Pelobatoidea with other anurans; (2) to determine the fa-
life-history characters, he was able to provide some reso- milial-level relationships within the group; and (3) to hy-
Phylogenetic Relationships of Pelobatoid Frogs
pothesize relationships of taxa within the family do not form a monophyletic group. He argued that
Pelobatidae. Herein,Iusemorphologicalcharacterstocon- Pelobatidae (including whatisnow Megophryidae, sensu
duct a phylogenetic analysis of extant pelobatoids. A de- Cannatella, 1985) is the sister group to Neobatrachia, and
tailed description and comparison of the adult pelobatid Pelodytidae is the sister to this combined group (Fig. 1).
skeletonhavebeenpresentedelsewhere(Maglia,inpress) He also suggested that Pipidae is the sister group to the
and should serve as a companion to this analysis. Within clade [(Neobatrachia + Pelobatidae) -i- Pelodytidae].
the pelobatoids, I included two representative taxa ofthe Duellman (1975, 1988) and Duellman and Trueb (1986)
family Megophryidae, one representative taxon of asserted, based on the incomplete nature of the cricoid
Pelodytidae,andrepresentativesofallcurrentlyrecognized cartilage,that Pelobatidae (includingMegophryidae) and
extanttaxaofPelobatidae.Becausethephylogeneticplace- Pelodytidae are sister groups (Fig. 1). They also showed
mentofpelobatoidsisproblematic,Iincludedseveraltaxa that, together, these taxa form the sister group of
representing the Pipoidea, Discoglossidae, Bombin- Neobatrachia,basedonthefollowingsynapomorphies: (1)
atoridae, and Neobatrachia {sensu Ford and Cannatella, absence of ribs (also absent in Rhinophrynidae); (2) non-
1993) that serve as outgroups. overlap of the scapula by the clavicle; and (3) absence of
HistoricalTaxonomyofthe Pelobatoids the neopalatine bone. Using molecular evidence. Hay et
al. (1995) hypothesized that Pelobatidae (including
SinceNoble(1931)placedthepelobatoidsintothesub- Megophryinae) and Pelodytidae are sister-taxa and that
orderAnomocoela (whichheconsideredtobeaninterme- together they form the sister group to a clade comprising
diatebetweenpipidsandbufonids), thesystematicplace- all other archaeobatrachians.
m(1e9n5t7)ofatlhseopaellloobcaattoeiddsthheaspbeleoebnactoonitdesnttiooutsh.eBrsautbtosrtdreorm SokBoals(e1d97o7n) tphreopsotasteedofa tchlaesstirfiigceamtiinonalthaantddifavciidaelsnAenrvuersa,
ccaAfpavhoonraatuotirhrmilaelaocsabtciglseoezeruseeibdflziooenastrdsopdi(blreFbiyiredgmas.pitdrt—ae1io.)rvAcAieorHbgveaceedllshidooeasasudcberssoygogaovublnfeeoarudsttss(srkeiiptebaodhilrnscapea.tihteodai,ftRlsahea)teim;hcgoeporen(iAlpd1nohim9tbt5opea8irlht)ovooinegeirchrdytoeesecebahtarlnyearadd-le iftct(anahohltmeneloisyopliteitadhelcweseotorrbuLeaaefsdtlriuolotobiygopodsmbre)se.dl.aemHpyHraresteib,imesdsiuDatuagiieggshvgaceeieosngs(gtdhetle.legoDdy.dsi,tssdOthcoehraoirattgditolevanoietl,sdhts,(e1hiiy9oidn5unace3dgel;vih)uorSdlteapiacvinnrtepdrgdoebtRiortfadna,rnsln1ooycw9imh7edt3raeh)oenie,f
d(ilsecioogpleolssmiadtsi,dsa)n;d rhinophrynids); and Neo(bpaetlroabcahtioaid(sal,l i"neotpeirpmoeiddisa.t"eLagurroeunptw(1i9t7h9),aipniapnoiadt-tleimkpetttoadrpeocloeg,niczaelltehde
baosaartpalehpseaebirrdonafnttroeeuonsrgs.sm,t)eh.HddeGieerapcithrfaeaeflrsisbatsoechosttrsew(urm1egs9aeg6none3fds)ipttsrbehuiudegmlgietaetphesiiavtctmeeoudrtsaahctncehldoaeiptsdea,tldhhovaeobanrpandnetsclos,eoiqbddsausttfaeorramionnodgad-ssl NdtwseieiursotbitbhoniargnttdchrtteeahircevcheleMinaxeaseiss,ssiosttfbirionaicfgteadtrtniahtooeocnmhcepoionefamclDlobtubaioaetntuleiorlnitecmdhlaesoufnfdwAie(inr1tdcP9hih7ion5apug)eostoibboddyfaertSaaersortake(iccopcthliaiipl(nail1gdy9ast7an7hld+)e-
rsehnitneodpharnyneiadrlsyasriedeclborsaenlychreolfattehde alinnde,otfoagrectihfeerr,alrefprroegs- rhinophrynids) and Pelobatoidea.
that diverged from the pipids. Rocek(1980)comparedthedevelopmentofthecraruum
Oneoftheearliestphylogeneticanalysesofanuranre- of Pelobatesfiiscus to several other species of pelobatoids.
l(a19t6i7o)n,shwiphsosuesinmgorppahrosliomgoincyalwaansalpyesrifsoirnmdeidcabtyedIntgheart Tpaatktienrgnionftothaecctoeucnttuamssiynngloeticchuarma,ctheer,etrheectdeedvealcolpasmseinfitcaal-
tionofanuranscomposed ofArchaeosalientia (containing
Pelobatoidea is the sistergroup toneobatrachians, except
Microhylidae, which is the sister group to the clade fEopelobatesandPelobates)andNeosalientia (containingall
[Neobatrachia + Pelobatoidea] (Fig. 1). Inhisanalysis, the otherfrogs). However, thishypothesishasbeencriticized
rhinophrynids are the sister group to the clade (e.g., Cannatella, 1985) because it takes a less than parsi-
[neobatrachians + pelobatoids + microhylids], and the monious view ofanuran evolution.
pipids are the sister group to this combined clade. Kluge Themostthorough analysisofarchaeobatrachianrela-
and Farris (1969) (Fig. 1) also used parsimony analysis to tionships is that of Cannatella (1985) (Fig. 1). His results
suggest that the pelobatoids are the sister group to all suggested thatPelobatoidea is monophyleticand that the
neobatrachians (including microhylids). Their analysis pelobatoids and pipoids are sister groups, and he sug-
suggested that [pipids -i- rhinophrynids] are the sister gested that Mesobatrachia (Laurent, 1979; = Pipoidei of
group to the clade [neobatrachians + pelobatoids]. Dubois, 1983) is monophyletic. Five synapomorphies (all
Lynch (1973) hypothesized that the pelobatoids are a with some level of homoplasy) unite members of
transitionalgroupbetweenarchaicandadvancedfrogsand Mesobatrachia;theseareasfollows: (1)hyaleintwoparts;
ScffiNTiFic Papers, Natural History Museum, The University of Kansas
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Phylogenetic Relationships of Pelobatoid Frogs
(2) cutaneous origin ofthegracilis minor muscle; (3) hyo- clade. It also suggests that within Pelobatidae, Spea and
glossalsinuspartiallyboundbylaminaeofhyalae;(4)pres- Scaphioptis are sister taxa, and Pelobates is the sister to
ence of an accessory head of the gracilis minor muscle; [Scaphiopiis+ Spea].Theseresultsareconsistentwiththose
and (5) concealment of the frontoparietal fontanelle. of Henrici's (1994) phylogenetic analysis of Recent and
Cannatella's(1985)analysisdidnotprovideresolutionfor fossil pelobatoids. She proposed that Pelodytidae and
familial-level relationships within the Pelobatoidea. Al- Pelobatidaearesistergroups,andrecognized Pelobatinae
though the phylogeny resulting from his analysis depicts and Megophryinae as sister taxa within the family
[(Pelobatidae + Pelodytes) + Megophryidae], he stressed Pelobatidae.
thatthiswasaresultofhischoiceofequallyparsimonious Acknowledgments
topologies and not thesingle most parsimonious result.
IthankLinda Trueb,Jude Higgins,ChristopherShell,
Reanalysis ofCannatella's data set by Hilhs (1991) in- andJennyPramukfortheircommentsonthismanuscript.
dicated thatthepelobatoidsareparaphyletic, and thatthe I also thank L. Anah'a Pugener for her comments and for
neobatrachiansare thesistergroup toMegophryidae. He providing the Spanish translation of the abstract. John
also hypothesized that the clade [Neobatrachia + WiensandAmy Henriciprovided thoroughand thought-
Megophryidae]isthesistergrouptotheclade[Pelodytidae fulcommentsthatgreatlyimprovedthispaper. 1amgrate-
H- Pelobatidae],and thiscombinedcladeis thesistertaxon fultoCharlesW.MyersattheAmericanMuseumofNatvi-
to the pipoids. A second reanalysis of a portion of ral History,Jose Rosado at the Harvard MuseumofCom-
Cannatella's (1985) data set was conducted by Lathrop parative Zoology, and Jose E. Gonzalez from the Museo
(1997).Thehypothesisresultingfromheranalysissuggests Nacional de Ciencias Naturales (Madrid) for the loan of
that withinPelobatoidea, Megophryidaeand Pelobatidae specimens.ThisresearchwassupportedbyNSFGrantDEB
are sister taxa, and Pelodytes is the sister to thiscombined 95-21691 to Linda Trueb.
MATERIALSAND METHODS
Cladistic Methodology (Fig. 2). A phylogenetic analysis was performed using
Characterswerecoded for20 taxa representing 11 spe- PAUP Ver 3.1.1 (Swofford, 1993) using ACCTRAN opti-
cies in the family Pelobatidae, two species in the family mizations;alltransformationserieswereweightedequally
Megophryidae,onespeciesinthefamilyPelodytidae,and and were treated as unordered. An heuristic search was
sixoutgrouptaxa (Pipidae: Rhinophnjmisdorsalis,Xeuopiis performed with the topological constraint presented in
laevis; Neobatrachia: Leptodactyhis fiiscus, Limnodyjiastes Figure 2. The resulting tree was rooted using the
fletcheri; Discoglossidae: Discoglossus snrdus; discoglossid taxon, Discoglossits sardus, and the
Bombinatoridae: Bombina orientalis). I examined alcohol- bombinatorid taxon, Bombina orientalis, the most basal
preserved specimens, dried skeletons, and cleared and outgroup taxa included in this analysis (according to the
double-stained skeletal preparations. hypothesesofanuranrelationshipsofDuellmanandTrueb
Seventy-three characters from adult and larval mor- [1986] and Ford and Cannatella [1993]).
phology were defined and included in the analysis. Al-
though several characters are similar to those used by O
:= :=:
CKlaungnea,te1l9l6a6;(Z1w9e8i5f)ela,nd195o6t)h,emroasuttchhoarrsac(tee.gr.s,wHeernerirceid,ef1i9n9e4d; 6 .„ -ii i= 2 -fao 3 e -e 5
and coded directly from specimens for this analys—is. Ten 5 (D Q^ 0} O O
5 3:?:^=:;=
characters were taken directly from the literature Char- o
acters 64-72 (myology and soft tissue) were taken from
Cannatella (1985), and Character 32 (condition of the
stapes)wastaken from Lathrop (1997).Characterdescrip-
tions and illustrations are presented in the next section;
thedata matrix is presented inAppendix.
The monophyly of Pelobatoidea was assumed based
on (1) ossification ofthesternum, (2) presence ofpalatine
processoftheparsfacialisofthemaxilla, and (3) presence
ofadductorlongusmuscle(Cannatella, 1985). Iforced the
pelobatoids to be monophyletic, as well as forcing the
monophylyofthepipoidoutgroup(twotaxarepresented)
and the neobatrachian outgroup (two taxa represented)
Scientific Papers, Natural History Museum. The University of Kansas
To determine robustness of support for each of the Speamultiplicata(KU27622,86662,86664),S.bombifrons
nodes, I calculated Bremer decay indices (Bremer, 1988; (KU5405,73382),S.Jmmmondii(KU176016),S.intennoutam
1994) by rerunning the analysis several times, saving all (KU 79436, 204563), Scaphiopus coiichii (KU 20444, 73384,
trees one step longer than the previous analysis, comput- 209575), S. holbrookii (KU 20439, 145413), S. hiirtMcmN(CKNU
irensgultthseocfontsheenosruisg,inaanldantahleynsics.omIpaalrsoincgaltchuelarteesdulbtosotsotrtahpe 2200407421,;6M01N73C,N9002906)2,41P)e,lobP.atfeistsccuulstri(p(KesUA(M6K8NU8H1194,861192,9240M),CZP.
values foreachofthe resolved clades. s3y1r9i7a0c)u,s M(eKgUop1l4m6/8s56)m,onPt.avnaaral(dtMiCZ 22635,6K29U35,79010),
SpecimensExamined Leptobrachhimhaseltii(KU194712),Pelodytespimctatus(KU
Institutions are as follows: American Museum of Natural 153435,129241, MCZ 1616b), Rhinoplm/nus dorsalis (KU
History (AMNH), University of Kansas Natural History Mu- 69084, 168799), Xenopus kei'is (KU 195934, MCZ 26585),
seum(KU), HarvardUniversity MuseumofComparativeZool- Lvmwdynastesfletcheri(KU186780),Leptodacti/lusfiiscus(KU
ogy (MCZ), Museo Nacional de Ciencias Naturales, Madrid 92957, 166429, 167677, 167678), Bombina orieiitalis (KU
(MNCN). United States National Museum (USNM). 38645,38649, 129703),and Discoglossussardus (KU 183734,
USNM
129239, 10052).
DESCRIPTION OFCHARACTERS
The 73 characters used in this analysis are described 4. Frontoparietal contact with nasal.—The anterior and/
below. RefertoMaglia (inpress),Wiens (1989),andRocek oranterolateral marginofthefrontoparietalextendsto
(1980) for additional descriptions and illustrations of abutoroverlap the nasal.
pelobatoid osteology. 0: frontoparietal and nasal not in contact
1; frontoparietal and nasal in contact
Cranialcharacters (Fig. 3)
5. Occipital foramen.—In the taxa considered, the path-
Frontoparietal — way for the occipital vessels is unroofed, and thus the
1. Ornamentation. 1 considered this tobedistinctive bony or- vessels merely traverse the dorsal surfaceof the poste-
namentationofthefrontoparietals,nasals,maxillae,premax- rolateral corner of the frontoparietal, or it is roofed in
illae. and squamosals. bone to form a canal (= occipital foramen) through the
0: dermal ornamentation absent posterolateral cornerof the frontoparietal (Fig. 3).
1: dermal ornamentation present 0: pathway for occipitalvessels open
2. Supraorbital flange.—This small, lateral expansion 1: pathway foroccipitalvessels roofed inbone
along the dorsolateral margin of the frontoparietal is a 6. Frontoparietalboss.—In a few Spea, this raised ridgeof
thin sheet ofbone that forms a partial roofover the or- bone is present in the anterior interorbital region. See
bitandisbestviewed inventralaspect. Wiens(1989) andZweifel(1956) formorethoroughde-
0: supraorbital flange absent scriptions ofthis morphology.
1: supraorbital flange present 0: frontoparietal boss absent
3. Medial contact of frontoparietals.—The frontoparietals 1: frontoparietalboss present
areeitherseparatefromoneanother,incontactforpart 7. Lateral foramen.—In Pelobates, there is a large foramen
or aU of their medial margins, or are fused. Fusion is in the dorsal third of the lamina perpendicularis, the
with or without a visible median suture. In Pelobates, portion of the frontoparietal that contributes to thelat-
the frontoparietals fuse with no median suture; how- eral wall of thebraincase.
ever, Rocek (1980) found that, developmentally, this 0: lateral foramen absent
aernitsefsrofmrotmhethsrteaeteseipnaXreantoepcuesntaenrdsoRfhoysnsoipfhinc/atniuosn).(differ- 1: lateralforamen present
Nasal
0: frontoparietals notin contact
1: frontoparietals in contact posteriorly only 8. Medial contact ofnasals.
2: frontoparietalsincontactformostofmedialmargins 0: nasals not in contact
3: frontoparietals fused, suture visible 1: nasals in contact —
4: frontoparietals fused, no suture visible, two centers 9. Extent of posterior divergence of nasals. In all taxa
ofossification considered, the nasals diverge laterally from one an-
5. frontoparietals fused, nosuturevisible, threecenters other posteriorly. This divergence is minimal, involv-
ofossification ing only the posteriormost margins, or extensive, in-
Phylogenetic Relationships of Pelobatoid Frogs
—
ant proc vomer
premaxilla
maxilla
— mm
5
' pterygoid
angulosplenial
dentary
Fig.3. CraniumofSpeamultiplicata(KU86662)indorsal(topleft),ventral(topright)andlateral(center)views.Mandibleisshowninlingual(bottomleft)
andlabial(bottomright)views.Graydenotescartilage,blackdenotesforamina.Abbreviations: antproc=anteriorprocessofnasal;c=cartilage;parsfac=pars
facialisofmaxilla;f=foramen;frontopar=frontoparietal;spheneth=sphenethmoid.AdaptedfromMaglia(inpress).
volvingat least halfofthe length ofthe nasal bones. cess, thatextendsventrallytoward theparsfacialisof
0: posterolateral divergence of nasals minimal (less the maxilla.
than one third the length ofnasals) 0: maxillaryprocess ofthenasal absent
1: posterolateral divergence of nasals extensive (at 1: maxillary process ofthe nasal present
least halfthe length ofthe nasals) Preniaxilla
— —
10.Shapeofanteriorprocess. Theanteriormarginofthe 12. Width of alary process. In anterior view, the alary
nasal forms a thin, blunt, rounded process that over- process of the premaxilla is either thin (less than a
lies the septum nasi, except in Spea, in which it forms fourth the width ofthe premaxilla) orwide (at leasta
a sharp point (e.g.. Fig. 3). third the width of the premaxUla).
0: anterior process ofnasalblunt 0: alaryprocessonefourthorlesswidthofpremaxilla
1: anterior process ofnasal—pointed 1: alaryprocessonethirdorgreatervW—dthofpremaxilla
11. Maxillary process of nasal. In some taxa, the nasal 13. Premaxillaarticulationwith maxilla. Inventralview,
possesses a lateral sheet of bone, the maxillary pro- thepremaxillaeitherabutsthemaxillaorformsasmall
SciENTinc Papers, Natural History Museum, The University of Kansas
posterior projection, the lingual process (Mendelson, 0: 23 maxillary teeth
et al., in press), that lies medial to the lingual margin 1: 25 maxillary teeth
ofthe maxilla. 2: 26 maxillary teeth
0: premaxillaabutsmaxilla,nolingualprocesspresent 3: 33 maxillary teeth
1: premaxilla medially overlaps maxilla, lingual pro- 4: 35 maxillary teeth
cess present 5: 40 maxillary teeth
—
14. Shape ofpars palatina. The pars palatina ofthe pre- 6: 42 maxillary teeth
emnaxsilla iseitherofuniformdepth (Fig. 3),oritbroad- 87:: 5408 mmaaxxiillllaarryy tteeeetthh
laterally.
9: 85 maxillaryteeth
0: pars palatina ofpremaxilla nearlyuniform depth —
15.N1u:mpbaersrpoaflparteimnaaxoifllparreymatxeeitlhl.a—bIrnotahdeetnasxalactoenraslildyered, 20. Ptoesntdosrbdiotraslaplrloycefsrso.m tThheismaixsilalsamjaulslt pprooscteersisorthtaot tehxe-
orbit.
theaveragenumberofpremaxillaryteethrangesfrom
nine to 20. 0: postorbital process ofthe maxilla absent
0; 9 premaxillary teeth 1: postorbital pro—cess ofthe maxilla present
1: 11 premaxillary teeth 21.Preorbitalprocess. Thisisasmallprocessthatextends
2: 12 premaxillary teeth dorsally from the maxilla justanterior to the orbit.
3: 13 premaxillary teeth 0: preorbital process ofthe maxilla absent
4: 15 premaxillary teeth 1: preorbital—process ofthe maxilla present
5: 16 premaxillary teeth 22. Pars facialis. This is a sheet of bone in the anterior
6: 18 premaxillary teeth portion of the maxilla that extends dorsally to invest
7: 19 premaxillary teeth the lateral margin of the planum antorbitale (Fig. 3).
8: 20 premaxillary teeth— 0: parsfacialisofthemaxillaabsent(orpoorlydeveloped)
16. Height of alary process. In anterior view, the alary 1: pars facialis of the maxilla present
—
processofthepremaxillaextendsdorsallytothelevel 23. Maxillary foramen. This small foramen pierces the
of the anterodorsal margin of the maxilla or beyond
pars facialis ofthemaxilla (ortheunderlyingconnec-
themarginofthe maxilla.
tive tissue ifthepars facialis is absent).
0: alary process extends dorsally to the level of the 0: absent
maxilla
1: present
1: alary process extends dorsallybeyond the level of —
maxilla 24. Pterygoidprocess. Inventralview,thissmallprocess
—
17. Condition of septum nasi. The septum nasi is either extendsposteromedially from theparspalatina ofthe
maxilla to articulate with the anterior ramus of the
cartilaginous or ossified for at least half of its length;
insome taxa, theanterior margin forms a small plate pterygoid.
that extends dorsoventrally between the alary 0: absent
cartilages ofthe nasal capsule. 1: present —
0: septum nasi cartilaginous 25. Palatine process. This isa smallprocessthatextends
1: septum nasi ossified forat least halfits length medially from the pars facialis of the maxilla to ven-
2: septum nasi ossified, forming plate anteriorly trallyinvesttheplanumantorbitale.Althoughthishas
Maxilla been considered to be the neopalatine {- palatine)
18. Posteriorextentofmaxilla.—Inventralview, themax- fused to the maxilla by some authors (e.g., Zweifel,
illa extends posteriorly to a level equal to about half 1956; Rocek, 1980), Wiens (1989:49) described the on-
the length of the orbit (Fig. 3) or extends posteriorly togeny of this element and showed that it is part of
formorethanthreefourths the length ofthe orbit. the maxilla.
0: maxilla not extending posteriorly beyond half the not distinct from vomer
length ofthe orbit distinct from vomer
1: maxillaextendingposteriorlyformostofthelength absent
oftheorbit Parasphenoid
— —
19. Number of maxillary teeth. The average number of 26. Ridge on body. When present, this is a raised, V-
maxillary teeth ranges from 23 to 85. shaped ridge on the posteromedial parasphenoid.
Phylogenetic Relationships of Pelobatoid Frogs
—
0: parasphenoid ridgeabsent 32. Condition of stapes. This character was taken from
1: parasphenoid ridge—present Lathrop's(1997)reanalysisofCannatella's(1985)data.
27. Posteromedial process. This small process extends 0: stapes absent
posteriorlyfromthebodyoftheparasphenoid;insome 1: stapespresent,extendingentirelengthofearcavity
taxa, it overlaps theventromedial margin ofthe fora- 2: stapesgreatlyelongate(muchlongerthanearcavity)
men magnum. 3: stapesreduced (notextendinglengthofearcavity)
0: posteromedial process ofparasphenoid absent Pterygoid —
1; posteromedial process ofparasphenoid present 33. Ventral flangeofanteriorramus. In some taxa, there
Vomer — is a thin, sheetlike process that extends ventrally for
28. Postchoanal process. This process extends laterally muchoftheposteriorhalfoftheanteriorramusofthe
from the body of the vomer to invest ventrally the pterygoid.
planumantorbitale.Whenelongate,itcomesintocon- 0: ventral flange ofpterygoid absent
tactwiththepalatineprocessoftheparsfacialisofthe 1: ventral flange ofpte—rygoid present
maxilla in some taxa. 34.Auxiliarydorsalprocess. Thepterygoidarticulateswith
postchoanal process ofvomerabsent themaxilla bysimplyabutting itvia thelateralmargin
postchoanalprocess ofvomer short oftheanteriorramus, orithasa secondaryarticulation
postchoanal process ofvom—erelongate via a small auxiliary dorsal process that extends from
29. Dentigerous process ofvomer. Among the taxa con- the dorsolateral margin of the anterior ramus. See
sidered,therelativepositionofthetooth-bearingpor- Mendelson et al. (in press:fig. A2) for illustration and
tion ofthe vomervaries. furtherdiscussionofthischaracterinothertaxa.
0: dentigerousprocessofvomeranterior toposterior 0: absent
margin ofplanum antorbitale 1: present
1: dentigerous process ofvomerat thelevelofposte- Squamosal —
rior margin ofplanum an—torbitale 35.Conditionofzygomaticramus. Thezygomaticramus
30 Number of vomerine teeth. The average number of of the squamosal, when present, extends anteroven-
vonierine teethvaries from zero to 15. trallyfromtheregionofthecristaparotica.Theramus
no zomerine teeth isshortorlong;whenlong,itarticulateswiththemax-
3 vomerine teeth illa (in most taxa).
4 vomerine teeth 0: zygomatic ramus of the squamosal absent
5 vomerine teeth 1: zygomaticramus ofthe squamosal short
6 vomerine teeth 2: zygomatic ramus of the squamosal long (half or
7vomerine teeth moredistance to dentigerous process ofmaxi—lla)
8 vomerine teeth 36. Condition of the otic ramus of the squamosal. The
9 vomerine teeth oticramusofthesquamosalbarelyoverlapsthecrista
14 vomerine teeth parotica orformsanoticplatethatinvestsmostofthe
15 vomerine teeth lateral halfofthe crista parotica.
Prootic/exoccipital — 0: otic ramus barely overlapping lateral margin of
31. Anterior margin ofprootic foramen. In the taxa con- crista parotica
sidered, the posterior margin of the prootic foramen 1: otic ramus formingoticplate —
isalways formed bybone. However, theanteriorhalf 37.Squamosalcontactwithfrontoparietal. Insometaxa,
may be formed completely by cartilage, formed by the frontoparietal and squamosal each possess plate-
bone except for the most anterior portion, or formed likepostorbitalprocessesthatmayarticulatedorsalto
completelybybone. theoticcapsule.
0: anterior margin of prootic foramen completely 0: frontoparietal and squamosal not in contact
formed by cartilage 1: frontoparietal and squamosal in contact
1: anteriormarginofprooticforamenpartiallyformed Quadratojugal —
by bone 38. Quadratojugal. In some taxa, the quadratojugal is
2: anterior margin of prootic foramen completely absent from the maxillaryarcade.
formed bybone
0: absent
Plectra! apparatus 1: present
10 SciENTinc Papers, Natural History Museum, The University of Kansas
—
44. "Webbing" ofsacrum/urostyle. Thesearesmallbony
platesthatextendbetweentheposteromedialmargins
of the sacral diapophyses and the urostyle (Wiens,
1989; Fig. 4). Although these havebeenconsidered to
be postsacral transverse processes by some authors
(e.g.,DuellmanandTrueb, 1986),Wiens(1989:48)sug-
gested that they were homologous with the posterior
webbing found on the presacral vertebrae.
0: "webbing" ofsacrum/urostyle absent
1: "webbing" ofsacrum/urostylepresent
—
45. Fusionofribstotransverseprocesses. In the taxa ex-
amined,distinguishableribsarepresentinlarvaeand
adultsofDiscoglossussarcitisandBojnbmaorientalis.Ribs
aredistinguishablein the larvaeofXenopms laevis,but
areindistinguishablyfusedtothetransverseprocesses
ofadults. Ribsarenotdistinguishableinallothertaxa
examined (including Rhinophnjnus dorsalis).
0: ribs distinguishable in larvae and adults
styleFiigl.lu4s.tratDionrgsCahlavraicetwerof4t4h:e"powsetbebriionrg"preosfacsraaclruvneir/tuerborsatey,les.ac(rAu)m,Staatned0u.r—o- 1: ribs distinguishable in larvae only
Discoglossussardus(KV129239);(B)Statel.—Speamultiplicata(KU86664). 2: ribs not distinguishable—inlarvae oradults
"Webbing"isdenotedbyarrow. 46.Relativelengthofurostyle. Todeterminetherelation-
POSTCRANIALCHARACTERS ship of urostyle to presacral vertebrae lengths, these
Axial skeleton elementsweremeasuredonseveralindividualsofeach
species and compared as an average ratio of snout-
39. Posterior exterit ofspinalprocesses. ventlength.Inalltaxaconsidered,thecombinedlength
0: spinal processes reach the level of of the presacral vertebrae is about 35% SVL, and the
postzygapophyses urostyle length is as long as (= 35% SVL) or much
1: spinalprocessesextendposteriorlybeyondmargin shorter than (s 23% SVL) the combined length of the
ofpostzygapophyses
— presacrals.
40.Comparativelengthoftransverseprocesses. Inmany 0: urostyleaslongorlongerthancombined lengthof
taxa, thetransverseprocessesofVertebraII arelonger vertebrae
presacral
than those ofthe other presacral vertebrae. 1: urostyleshorterthancombinedlengthofpresacral
0: transverse process ofVertebra 11 longest vertebrae
1: transverse process ofVertebra 11 not longest Anteriorappendicularskeleton
—
41. UncinateprocessesontransverseprocessofVertebra111. 47. Relativelengthofscapula. Todeterminetherelation-
0: uncinate process of transverse process of Vertebra ship of scapula to coracoid lengths, these elements
III absent weremeasured onseveralindividualsofeachspecies
1: uncinate process of transverse process ofVertebra andcomparedasanaverageratioofsnout-ventlength.
III present The relative length of the coracoid is similar among
42. Lateralextentoftransverse processes. taxa (approximately 13% SVL). The relative length of
0: transverseprocessesofVertebraeV-VIIInotextend- the scapula is about the same in every taxon (= 16%
ing beyond lateral margin ofpostzygapophyses SVL); however, in Discoglossus sardus, Pelodytes
1: btreaynosnvderlsaeteprraolcmesasregsionfoVferptoesbtrzayegVa-pVoIpIhlyesxetsending psuhnocrttaetrus(,= 7an%dSXVeLn).opus laevis, the scapula is relatively
43. Condition ofsacral diapophyses. 0: scapula shorterthan coracoid
0: length of sacral diapophyses less than or equal to 1: scapula slig—htlylonger than coracoid
width 48. Bony sternum. In the taxa considered, the sternum
1: lengthofsacraldiapophyseslongerthanwidth,an- consistsofacartilaginousplatewithorwithoutabony
teriorand posterior ends rounded stylus (Fig. 5A, B).
2:lengthofsacraldiapophyseslongerthanwidth,an- 0: bony stylus absent
teriorand posterior ends pointed 1: bony stylus present