Morphological variation and the definition of species in the snake genus Tropidophis (Serpentes, Tropidophiidae)

8 Pages·2002·4.2 MB·

by  S Blair Hedges

Bull. mil. Hist. Mus. Loud. (Zool.)68(2): 83-90 Issued28November2002
Morphological variation and the definition of
species in the snake genus Tropidophis
(Serpentes, Tropidophiidae)
BLAIR HEDGES
S.
DepartmentofBiology, 208MuellerLaboratory, ThePennsylvaniaState University, UniversityPark.
Pennsylvania 16802, USA. [email protected]
SYNOPSIS. Historically, the definition ofspecies in the Neotropical snake genus Tropidophis has been difficult because of
intraspecificvariationinscalationandapaucityofspecimensofmosttaxa.Therewere 13speciesrecognizedatthetimeofthe
lastreviewin 1960.butadditional specieshavesincebeendiscoveredandataxonomicreviewandupdate isneeded. Dataon
morphologicalvariationarepresentedhereandusedtoclarifythestatusofthedescribedtaxa.Becausemanytaxaareallopatric
withtheirclosestrelatives,itisnecessarytomakedecisionsastotheirstatusasspeciesorsubspecies.Asagaugeofspeciesstatus
inthegenus,characterdivergence in ten pairsofclosely related sympatric specieswasexamined.Typically,such speciesare
differentiatedbytwonon-overlappingcolourpatterndifferences,often incombinationwithadiagnostic(non-overlapping)or
overlapping difference in scalation. Using thiscriterion, seven taxapreviously consideredas subspecies are hereelevated to
speciesstatus,whereassevenothertaxaareretainedassubspecies,althoughinsomecasestheyareallocatedtodifferentspecies.
Asaresult,thegenus Tropidophisisconsideredheretocomprise29species,26ofwhichareWest Indianand 15 ofthoseare
restrictedtoCuba.
INTRODUCTION TmelanurusandthoseplacedbySchwartz(1957)inthesemicinctis
group. However, their success was in recognizing the utility of
colourationandpatterncharacters,andthatspeciesdiagnosisinthis
Tropidophis are typically small, stout-bodied snakes ofthe family genus often requires consideration ofmultiple characters, some of
Tropidophiidae that occur in South America and the West Indies. which may not be individuallydiagnostic.
ThisfamilyisamemberoftheprimitivesnakeInfraorderHenophidia This is not a comprehensive revision of the genus but rather a
(Underwood, 1967). Asrecognizedhere, there are 29 valid species taxonomicupdate,motivatedbythemanychangesthathaveoccurred
oi'TropidophisandallbutthreeoccurintheWestIndies,whereCuba sincethatlastmajorreview(Schwartz&Marsh, 1960)andtheneed
(15 species) is thecentreofdiversity (Table 1). They are nocturnal to summarize what is known of morphological variation in the
andfeedmostly on sleeping lizards(especiallyAnolis), butalsoon genus. Another motivation is toaddress arecurring problem in the
frogs (especially Eleutherodactylus); other nocturnal snakes may
systematicsofthisgroup:determiningthespeciesstatusofallopatric
impinge on Tropidophis ecologically. All are viviparous and most populations andtaxa. In the process, taxapreviouslyconsideredas
are terrestrial, although several Cuban species are arboreal and subspeciesare hereelevatedtospeciesstatus, someareassignedto
gracile in habitus. They exhibit a diversity ofcolour patterns that different species, andothers are left unchanged.
include spots (mostly), bands (saddles), and stripes. They have the
unusualabilityofbeingabletochangetheircolouration,physiologi-
cally(Hedges.Hass&Maugel, 1989).Typicallytheyarepalerwhen MATERIALS AND METHODS
active (at night) anddarkwhile inactive. Speciesdistributionstend
to be greatly restricted, with species endemic to single islands or
islandbanks,andoftentosmallareasonanisland.However,species Thedatapresentedhereinarealmostentirelyfromthe literature,or
density can be high, and as many as six species are sympatric in wereusedinpublishedstudies(butnotnecessarilypublishedinthe
some areas ofCuba. form here). Mostderive from the raw datasheetsofthe late Albert
Historically, the taxonomy of Tropidophis has been difficult to Schwartz, used primarily in several publications (Schwartz, 1975;
study because of small numbers of specimens and a paucity of Schwartz&Garrido, 1975;Schwartz&Henderson, 1991;Schwartz
diagnostic characters. For example, two of the earliest described & Marsh, 1960; Schwartz & Thomas, 1960; Thomas, 1963).
species, T maculatus and T pardalis, have been confused repeat- Schwartz's Cuban specimens are in the American Museum of
edly.Boulenger(1893)andStull(1928)commentedontheconfusion Natural History and his other material is almost entirely in the
of these species by Cope (1868), whereas Schwartz and Marsh collectionoftheMuseumofNaturalHistory,UniversityofKansas.
(1960) latercommentedon theirconfusion by Stull! Most ofthese Inadditiontothosedata,IhaveincludeddatafromspecimensIand
early problems in Tropidophis taxonomy stemmed from the use of colleagueshavecollectedduringthelasttwodecadesoffieldwork,
characterslaterfoundtobe unreliable, suchasthekeelingofscales and which, forthe mostpart, formedthebasisofseveral published
or hemipene morphology. It was not until Schwartz and Marsh studies: (Hedges, Estrada& Diaz, 1999; Hedges & Garrido, 1992;
(1960)assembledalargenumberofspecimensandcollectedexten- Hedges&Garrido, 1999;Hedges&Garrido,2002;Hedges,Garrido
sivedataonproportions,scalationandpatternthatthesystematicsof &Diaz, 2001). Thismaterial isintheNationalMuseumofNatural
thisgenusbecamereasonably wellknown. Althoughitwasalarge History(Smithsonian)andinCubancollections(NationalMuseum
study,itwasnotcomprehensivebecauseitomittedspeciesrelatedto ofNatural History, Havana; Institute ofEcology and Systematics,
©TheNaturalHistoryMuseum.2002
84 S.B. HEDGES
Table1 Species,speciesgroups,anddistributionsofsnakesofthegenus Garrido, 2002). Thedifference involvestheelevationofsometaxa
Tropidophis. previouslyconsideredas subspecies. Below, Idiscuss the utility of
Species SpeciesGroup Distribution different characters used, my reasoning in determining species
boundaries, and the taxonomic issues involved in each geographic
T. battersbyiLaurent taczanowskyi SouthAmerica area. The phylogeny and biogeography of species in this genus,
T. bucculentiisCope melanurus NavassaIsland usingDNAsequencedata,isdiscussedelsewhere(S. B. Hedges.S.
TT..ccaaynmusanCeonpseisBattersby mmeellaannuurruuss GBraahnadmaCsayman C. Duncan, A. K. Pepperney, in preparation). The species group
T. celiaeHedges,Estrada,andDiaz melanurus Cuba status(Table 1)isbasedonthatwork,butotherwisethefocusofthis
T.curtusGarman melanurus Bahamas current assessment is the definition of species boundaries, not
T.feickiSchwartz maculatus Cuba phylogenetic relationships.
T.fuscusHedgesandGarrido pardalis Cuba
T.galacelidusSchwartzandGarrido pardalis Cuba Characters
T.greenwayiBarbourandShreve haetianus TurksandCaicos
TT.. hhaaredtyiianSucshCwoarptezandGarrido hpaaredtailainsus CHiusbpaaniola Variation in 20 characters among the 29 species of Tropidophis is
T. hendersoniHedgesandGarrido pardalis Cuba showninTables2-4.Theyaregroupedintothoseinvolvingpropor-
T.jamaicensisStull jamaicensis Jamaica tions(Table2),scalation(Table3),andpatternandcoloration(Table
T.maculatusBibron maculatus Cuba 4).Ingeneral,sexualdimorphismin Tropidophisisnotpronounced
T.melanurusSchlegel melanurus Cuba and therefore data from both sexes can be combined, with the
T. morenoiHedges,Garrido,andDiaz maculatus Cuba exception ofbody size, which shows slightdifferences. Characters
T.nigriventrisBailey pardalis Cuba
T.pardalisGundlach pardalis Cuba thatIhavefoundtobeoflimitedvaluehavebeeneliminated.These
T.parkedGrant melanurus LittleCayman includefourthatarecommonly scored in snakesystematics: upper
T.paucisquamisMiiller taczanowskyi SouthAmerica andlowerlabialsandthepre-andpostoculars.Allfourarevariable
T.pilsbryiBailey pardalis Cuba withinspeciesandinalmostallcases,notdiagnostic. Upperlabials
T. schwartziThomas melanurus CaymanBrae areusually9-10andlowerlabialsusually9-12inall species. In T.
T. semicinctusGundlachandPeters maculatus Cuba melanurusandsomerelatedspecies,labialcountstendtobehigher,
T. spiritusHedgesandGarrido pardalis Cuba
T. stejnegeriGrant jamaicensis Jamaica althougheven inthosecasesthereisoftenoverlap.Thereis usually
T. stullaeGrant jamaicensis Jamaica one preocular and 2-3 postoculars in Tropidophis, although some
T. taczanowskyiSteindachner taczanowskyi SouthAmerica species occasionally have two preoculars and as many as 4
T. wrightiStull pardalis Cuba postoculars; however, variation in ocularscales does not appearto
beoftaxonomicutility.Examplesofexceptions,asnotedbySchwartz
Havana). In nearly all cases, museum numbers and localities of and Marsh (1960), are T. pardalis (usually 2 postoculars) and T.
those specimens are listedin thepublications and therefore are not maculatus (usually 3 postoculars), although such differences are
repeatedhere. rarelydiagnostic.Stull(1928)consideredtheforkingofthehemipenis
Insomecases,summarydatapresentedinthetablesofSchwartz (bifurcate versus quadrifurcate) to be a diagnostic character but
and Marsh (1960) donotagree with those intheraw datasheetsor Schwartz and Marsh (1960) could not identify any species or
withdatamentionedinthetextofSchwartzandMarsh,presumably specimens with a quadrifurcate condition. Also, such a character
because of typographical errors in their tables. Some of the data would notbe very useful in this groupbecause oflimited material
presented later in Schwartz and Henderson (1991), such as the and scarcityofspecimens withproperlyevertedhemipenes.
ventralrangeofT.canusandcaudalrangeofT.maculatus,appearto Schwartz scored several other characters in Tropidophis, but I
be derived from those typographical errors. Although these errors havealsofoundthemtobeoflimitedv&alueindiagnosingtaxa.Inthe
are minor, the summary data presented in this paper were taken caseofrelativetaillength (Schwartz Marsh, 1960),itisusefulin
directly from Schwartz's raw data sheets, to avoid any confusion, distinguishing T. canusfrom T curtus (seebelow)butotherwiseis
andsupplementedwithadditionaldata.Also,somecharacterswere difficult to score because of tail damage in some specimens, and
notscoredby Schwartz in some species (e.g., parietal contactin T. overlappingofratios.Thecolourofthetailtip(paleversusdark)was
feicki, T. melanurus, T. semicinctus,etc)oratall (e.g.,ratiosofeye useful in distinguishing Cayman Islands Tropidophis from T.
length to headwidth and head width to neck width, andaspects of melanurus (Thomas, 1963), and other trends are noticeable, but
colourpattern).Inthosecases,specimensathandwereexaminedto differencesbetweenjuvenilesandadults,andintraspecificvariabil-
hfiallvienotbhseegravpesd.Iahnadvceolelxeacmteidne1d2porfetsheervsepdecmiaetse:riT.alcaonfumso,sTt.fteaixcak,i,anTd. ity,Nmoawkecointsaidleesrsinugsetfhuel2ch0artaacbtuelra.ted characters, maximum snout-
fuscus, T. greenwayi, T. haetianus, T. maculatus, T. melanurus, T. vent length (SVL) is useful because some species differgreatly in
pardalis, T.pilsbryi, T. stejnegeri, T. stullae, andT. wrighti. body size, and most individuals encounteredare adults. Tworatios
Because this is not a comprehensive revision, there was no (Table2)thatIhavefoundtobeofutilityareeyelength/headwidth
attempt to survey all collections for holdings ofTropidophis orto (i.e., relative size of the eye) and head width/neck width (i.e.,
examine all available material. Itis anticipatedthat such an under- distinctiveness ofthe head). Both ratios are larger in the arboreal
taking willbe attempted in the future. gsrpaecciileesCTubfaenicskpie,ciTess(eTm.ifcuisnccutsu)st,haatnidspTo.sswirbilgyhtair,boarenadl(inHeadngoetshe&r
Garrido, 1992). Unfortunately, both show variation within species
RESULTS AND DISCUSSION and sample sizes still are small.
Despitetheintraspecificvariabilityinthescalecharacters(Table
3), some are useful when considered simultaneously with other
The conclusion of this taxonomic update is the recognition of 29 characters. Ventral and midbody scale row counts are perhaps the
species of Tropidophis (Table 1). This is an increase ofabout six most useful whereas caudal counts and posterior scale row counts
species over the number recognised earlier this year (Hedges & are the least useful. Contact of the two parietal scales can be
)))) )
SNAKEOFTHEGENUS TROPIDOPHIS 85
Table2 Variation inproportionsofsnakesofthegenusTropidophis.
Max SVL(mm) Eyediameter/ Headwidth/
Species males females headwidth neckwidth Samplesize1 References2
T. battersbyi na3 na na na 1 1
T. bucculentus 360 596 0.19-0.24(2) 1.50-1.55(2) 4 2-5
T. canus 363 338 na na 20 2,6
T. caymanensis 470 438 0.26(1) 1.59(1) 13 2-3.7
T. celiac na 344 0.28(1) 1.31(1) 1 8
T. curtus 357 354 0.25(1) 1.35 (1 93 2-3,6
T. feicki 411 448 0.28-0.32(4) 1.76-2.24(4) 29 2-3.9
T.fitscus 287 304 .30-.33(2) 1.83-1.99(2) 8 10-11
T.galacelidus 187 405 0.28(1 1.45(1) 6 2-3.6, 12
T. greenwayi 313 301 0.23 (1 1.35(1) 16 2-3.6
T.haetianus 534 552 0.22-0.25 (8) 1.28-1.52(8) 158 2-3,6, 13
T. hardyi 303 334 0.26-0.31 (2) 1.30-1.49(2) 8 2-3.6, 12
T. hendersoni 302 315 0.28( 1 1.45(1) 1 14
T.jamaicensis 338 306 0.20-0.21 (3) 1.47-1.54(3) 23 2-3,6
T. maculatus 327 347 0.23-0.32(5) 1.30-1.92(5) 25 2-3,6
T. melanurus 770 957 0.21-0.26(8) 1.28-1.77(8) 100 2-3, 15
T.morenoi na 295 0.24-0.27(2) 1.39-1.52(2) 2 16
T. nigriventris 184 227 na na 4 2.6. 12
T.pardalis 264 287 0.24-0.27(4) 1.26-1.63(4) 161 2-3.6
T.parkeri 422 512 0.24(1 1.95(1) 21 2-3,7
T.paucisquamis 101 283 0.24-0.28(3) 1.53-1.71 (3) 3 2-3
T.pilsbryi 295 260 .24-.25(2) 1.59-1.62(2) 8 2-3,6, 10
T. schwartzi 385 321 na na 17 2-3. 7
T.semicinctus 383 408 0.30-0.34(2) 1.70-1.88(2) 26 2-3,9
T. spiritus 320 372 0.24-0.37(4) 1.35(1) 4 17
T. stejnegeri 395 529 0.22-0.28(3) 1.39-1.48(3) 23 2-3.6
T. stullae 260 248 0.23-0.25(3) 1.78-1.86(3) 4 2-3.6
T. taczcmowskyi 3054 243 0.27-0.30(2) 1.46-1.51 (2) 3 3, 10, 18
T. wrighti 330 323 0.32-0.34(7) 1.77-2.24(7) 17 2-3,9
'numberofspecimensusedformostmeasurementsandcounts,unlessotherwiseindicatedinparentheses.
:primarysourcesofthedatareportedinthisandothertables: I (Laurent, 1949).2(AlbertSchwartz,unpublisheddata).3(S. B. Hedges,unpublisheddata),4(Thomas. 1966).5
(1B2ai(lSecyh,wa1r93t7z),&6Ga(rSrcihdwoa,rt1z97&5).Ma1r3sh(.ScIh9w6a0r)t.z.7(19T7h5o)m.as1,4(1H9e63d)g,es8&(HeGadrgreisdoe.lu2i0,02)1.9991)5.(9Sc(hSwcahrwtazrt&z.T1h9o5m7a).s.10I9(6H0e)d.ge16s(&HeGdagrersideot.al1.9,922)0.01)1,I (1A7ns(eHledFgoensg.&unGaprurbildios.he1d99d9a)t,a),18
(Stull, 1928).
'datanotavailable
4sexnotdetermined
diagnostic in some comparisons (Hedges & Garrido, 2002). but common in others (e.g., T. pardalis).
problems arise in how different people score the character (e.g., Thedorsal groundcolourofmostspeciesisashadeofbrownor
whenaninterparietalispresentandscalesbarelytouch).Asalready grey, andoften variable within species. I once collectedtwo speci-
noted, the keeling of the dorsal scales is often variable within mensofT. pilsbryiin the same rockpile in Cuba, and was initially
species.Manyspecieshaveweaklykeeledscalesthatarenoticeable misled into thinking they were different species because one was
onlyabovetheventregionandaredifficulttoscoreconsistently,and brown and the othergrey. On the other hand, T. stullae is consist-
depend sometimes on condition of preservation. However, some entlypaletananddiffersfromtheothertwoJamaicanspecies,which
species consistently have smooth scales and others (e.g., T. aredarker.Also,twoboldlyspottedspeciesthatoccursympatrically
melanurus) have distinctly keeled scales. in westernCubacanbedistinguishedby, amongotherthings, their
Colour and pattern variation (Table 4) has been important in dorsalgroundcolour: greyishpinkin T.feickiandyellowtoorange
Tropidophis taxonomy, in part because the snakes are frequently in T. semicinctus. Although most species are spotted, those in the
spottedandthisprovidesyetadditionalcharacterstocount. Infact. melanurus group often have narrow lateral stripes as well as a
SchwartzandMarsh(1960)consideredcolorationandpatterntobe middorsal stripe. The absence ofmiddorsal spot contact occurs in
the most reliable characters, in combination with scalation, for two related species, T. maculatus and T. semicinctus, and the two
'separating and combining' taxa. Except for T. feicki, which has Bahaman species T. canus and T. curtus are unitedby thepresence
crossbands,mostspecieshave2-12rowsofbodyspots.Ihaveused ofananteriolateral(faceandneck)stripe.Ventralpatternisdiagnos-
theSchwartzandMarsh (1960) methodsofscoringbody spotsand ticforT.nigriventris(almostcompletelydark)andinseveralspecies
spot rows. Spot rows include those on the dorsum and venter, all thatlackaventralpattern,butotherwisemosthavedifferentdegrees
aroundthebody(both sides)whereasbody spotsarecountedalong ofspottingandflecking.
onerowofspots(usuallyjusttoonesideofmiddorsalregion)from
behind the head tojust above the vent. Typically, the largest and Species boundaries
most distinctive spots are those near the middorsal region. This
reaches an extreme in species ofthemelanurusgroup where some Most taxonomists discern the presence of sympatric species by
individuals have only those two spot rows present, resulting in covanation of multiple characters from individuals of a single
widely varyingrow counts (e.g., 2-10). Occipital spots sometimes locality, indicating lack of gene flow between the species. For
fused to form a white neckband, are diagnostic ofseveral species example, in a series ofdark and pale snakes found together, two
(e.g., T. celiae, T. galacelidus, T. pilsbryi, T. stejnegeri) and are species wouldbe indicatedifall ofthe dark snakes alsohad small
)
86 S.B. HEDGES
Table3 Variationinscalationofsnakesofthegenus Tropidophis. (Numbersandcharacterstatesinbracketsrepresentrareorinfrequentoccurrences;Y=
yes,N=no;othernotationasinTable2.
Dorsalscalerows
Parietal Keeled
Species Ventrals Caudals Anterior Midbody Posterior contact dorsals
T. battersbyi 200 41 21 23 17 N N
T. bucculentus 183-186 28-32 24-25 25-27 17-19 N Y
T.canus 170-183 29-35 21[20.22,23] 23[22] 16-21 N/Y Y[N]
T. caymanensis 183-200 33-38 23-27 23[25] 17[19] N N/Y
T. celiae 203 30 25 27 19 Y N
T. curtits 146-173 22-37 19-27 23-25 17-22 N[Y] Y[N]
T.feicki 217-235 34^11 23-25[19,21] 23-25 17-19 N/Y N
T.fuscus 160-185 30-36 21-24 23 15-19 N Y
T.galacelidus 177-186 29-35 25-27 25-27 19-20 N Y
T.greenwayi 155-165 26-30 23-25 25-27 17-19 Y N
T. haetianus 170-194 27-39 23-27 25-27[23,29] 17-19[21] Y[N] N
T. hardyi 153-172 31-48 20-24 23-25 18-20 N/Y N/Y
T. hendersoni 190 33 23 25 19 N Y
T.jamaicensis 167-181 28-36 23-27 25-29 15-23 N/Y N
T. maculatus 189-208 28-40 22-25 25[23] 17-21 N/Y N/Y
T. melanurus 188-217 31^44 24-27[19] 27-29 17-21 N Y
[24,25,26,30] [16,22,23,24]
T. morenoi 198-199 42-44 23 23 17 N N
T. nigriventris 144-150 25-26 23-25 23-25 18-22 N N
T.pardalis 140-157 23-34 21,23 23,25 17-21[16] N/Y N[Y]
[19,22,24,25] [21,22,24]
T.parked 199-212 33^41 25[23,24] 27[25,26] 17[18.19] N Y
T.paucisquamis 170-178 37-40 21 21 17 Y N
T.pilsbryi 160-169 26-31 22-25 23-25 17-21 N N/Y
T. schwartzi 191-205 31-39 25 25[26] 17[15] N Y
T.semicinctus 201-223 33-41 21.23[22,24,25] 25[21-24] 17-20 N/Y N
T. spiritus 183-200 35-39 21-23 23 17 N N
T. stejnegeri 181-190 30-38 25-27[23] 25,27[26] 17-19 N/Y Y
T. stullae 166-170 31-34 25 25 16-19 N N
T. taczanowskyi 149-160 25-27 23-25 23 19-21 Y Y
T. wrighti 192-215 36-45 21-23 21-23 17[16.18,19] N N
headsandfewerspotsthanthepalesnakes(thus,bodycolourwould SympatricspeciesofTropidophisoccuronlyinCuba. Inwestern
be covarying with head size and spot number). In the case of Cuba, the following six species have been found in the general
allopatric populations, it is typically assumedthatcharacterdiffer- regionofCanasf,HabanaProvince: T.celiae, T.feicki, T.maculatus.
encessimilartoorgreaterthanobservedbetweensympatricspecies T. melanurus, T. pardalis, and T. semicinctis. In central Cuba, the
indicate that the two forms are different species. Thus, the 'yard- followingsixspecieshavebeenfoundinthevicinityoftheTrinidad
stick'usedforassessingallopatricpopulationsischaracterdivergence mountains: T. galacelidus, T hardyi, T melanurus, T. pardalis, T.
betweencloselyrelated,sympatricspecies.Thisistheprinciplethat semicinctis, and T spiritus. In eastern Cuba, the following four
I use here in assessing species status within Tropidophis. It is a species are known from the region ofBaracoa, Guantanamo Prov-
practicalspeciesconceptbutisbasedontheobservationthatspecies ince: T.fuscus, T. melanurus, Tpilsbryi, andT. wrighti. Toidentify
are reproductively isolated from each other, as noted by Darwin thelevelofcharacterdivergenceassociatedwithspeciesdifferentia-
(1859)andlaterarticulatedbyMayr(1942)asthebiologicalspecies tion in Tropidophis, I now focus on four clusters of sympatric
concept. species, eachofwhich are membersofthe same species group: (1
Thereasonthataparticulardegreeofdifferentiationisnecessary, feicki/maculatus/semicinctis,(2) celiae/melanurus, (3) pardalis/
ratherthanaminimaldiagnosticdifference,concernsthe'reality'of galacelidus/hardyi, and(4)fuscus/wrighti/pilsbryi.
speciesinevolution.Almostallspeciesarefragmented(structured) Incluster(1),TmaculatusandT.semicinctisareclosestrelatives
tosomedegree,andmanypopulationscanbediagnosedbyoneora accordingtoDNAsequenceevidence(S.B. Hedges,S.C. Duncan,
few nucleotide differences or minor morphological differences. A. K.Peppemey,inpreparation)andaredistinguishedprimarilyby
However, through time, such populations frequently combine and colourpattern:thenumberofbodyspots(nooverlap)andnumberof
separate again as part of the reticulate nature of gene flow and spotrows(nooverlap).Allscalecountsinthosetwospeciesoverlap,
evolution within species. It is only those populations that have althoughT.semicinctistendstohaveahighernumberofventrals.In
differentiated sufficiently, genetically and/ormorphologically, and the case of T. feicki and T. maculatus, there are non-overlapping
presumably reflecting a length of time, that evolve reproductive differences inventral counts,body spots, and spotrows. Consider-
isolation from other populations. Thus, to assign species status to ing T.feickiand T semicinctis,thegroundcolourandspotrowsare
diagnosable,butephemeral,populationsduringonesliceoftime is non-overlapping, and the ventral counts are different but overlap
arbitraryfromanevolutionarystandpoint.AlthoughFrostandHillis slightly.
(1990) recommended abandoning the use of quantitative criteria Incluster(2),T.celiaeandT.melanurus,whicharecloserelatives
(molecular and morphological) for discerning species status of according to DNA sequence evidence, completely overlap in all
allopatricpopulations,theydidnotproposeanythingtoreplacethat scalecounts,althoughparietalcontactmightbeconsidereddiagnos-
procedureandthusfew haveheededtheirrecommendation. tic ifthere were more than one specimen of T. celiae. Otherwise.
SNAKEOFTHEGENUS TROPIDOPH1S 87
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vO VD vO (N vO - — sO — — 0O\D — vOO.O'OI\000\220,(Ni \°0f00<Ni(NvOOOi — OO^t
O - — n -
|-~ r— O — VD a\ \c ~— vp oo — -- r^ooinr-^o oo on On ^o ^- oo
inI mI viI C—M <nI (NI O 4- u-i m m -4- in
*u->Ou^N-vO oi,oirJiOiO\i-TNtlcNi\it i|ONitCi\^lONlriJ\iOolo'itoi\(lNit^iNt
c« tooI lmI-oNoIto^ooon_- " ^rr-\OfNooooi/ir--oor-~ino>n^DONOoo\Or<-,
fi> <j a fc .a a ~>: ? c ^ Q -^^^ O^r-.':r^--."i^^ ^^e* ^^ -^d 'S 'C .£S 8 *
i^2 •o ^^e, oo oojj -c j: -S, e 5 S e cn,ci.
88 S.B. HEDGES
abouttheonlycharactersthatdistinguishthesetwospeciesarebody Navassa Island
sniuzmebaenrdoafspbeocdtyssopfoctso)l.orIantciaosne(et.hge.,renaedcekrbiasnwdonindeT.ricnegli,atehaenpdrehsiegnhceer FourspecimensofT bucculentusareknownfromthis small island
between Hispaniola and Jamaica, but apparently no snakes have
ofenlargedovainthesmallholotypeofT. celiae,anddetailsofthe
pattern, indicate it is not ajuvenile T. melanurus (Hedges et ah, b(Peoewnelsle,en1i9n9o9v).erS1i0n0ceyeiatrwsaasnddetshcursitbheedspbeyciCeospiesc(o1n8s6i8d)e,retdheerxetihnacst
1999).
In cluster (3), there are no molecular data available for T. bwietehnoctohnesridsepercaibelse.cMoonsftuswihonoahsatvoeietsxaspmeicnieedsstthaettusypaensderrieelsa,tiinocnlsuhdi-p
gwailtahceTlipdaursdaalnids.T.Hhoawredvyiertotchoenafsisromcitahteiironspiescsiuepspgorrotuepdabsysotchieatfiaocnt ingme,havenotedaresemblancetoT melanurus(Thomas, 1966),
that there are no diagnostic (non-overlapping) scale or pattern althoughStull(1928)insteadconsidereditasubspeciesofTpardalis.
characters that distinguish T. hardyiand T. pardalis. This problem Thereisnooverlapinventralcountsbetween T bucculentusandT
was noted in the original description (Schwartz & Garrido, 1975). melanurus, andalmostnooverlapincaudalcounts. Althoughthere
However, T. hardyi has a higher number ofventrals, even though aspppeecairmetnobinetphaettAecrnaddiefmfyeroefncNeastubreatlwSeceinenthceestw(Pohislpaecdieelsp,hitah)edsiifnfgelres
overlapping with T. pardalis, and it is a larger species with a from the otherthree specimens (National MuseumofNatural His-
distinctly smaller head. The latter character caused Schwartz and
tory, Smithsonian) intermsofventralpigmentation (Bailey, 1937).
Garrido to associate (as a subspecies) T. hardyi with the small-
headed T. nigriventris. The third sympatric species ofthis trio, T. Based on the diagnostic scalation differences alone, I would con-
galacelidus, canbe distinguishedfrom theothertwo speciesby its sider T. bucculentus as a valid species. The unusual geographic
higher number of ventrals, dorsal spots, and spot rows (all non- location of a species with apparent Cuban affinities, on Navassa
Island, is remarkable. With the exception of the anole (Anolis
overlapping).
DNA longiceps), other species on Navassa have affinities with nearby
Inthecaseofcluster(4), sequenceevidenceplaceallthree
togetheras close relatives. Tropidophisfuscus and T.pilsbryihave Hispaniola(Powell, 1999;Thomas, 1966),whichislogicalbasedon
no completely diagnostic scale differences, although the combina- thewesterlydirectionofoceancurrents.However,theeasterntipof
tionofventralscalecountsandmidbodyscalerowswilldistinguish CubaisfurthereastthanNavassa.andoceancurrentsflowsoutherly
thespecies.Also,T.fuscushasamoregracilebodyshape.Thethird throughtheWindwardPassageseparatingCubaandHaiti.Dispersal
species, T. wrighti,isdiagnosedfromtheotherspeciesbyitshigher ofonrtthhoeseorciugrirnenotfsTisbtuhcucsuploesnstiubsle(aannddAi.stlhoengmiocsetpsl)ikoenlyNeaxvpalsasnaatainodn
ventral counts, and fewer dorsal spots and spot rows (all non-
possibly the gecko Sphaerodactylus notatus on the Morant Cays
overlapping).
southeast of Jamaica. The locally changing direction of water
Tosummarize,ofthetencombinationsofcloselyrelated,sympatric
currentsduring ahurricane may alsohave aidedin the dispersal of
species, nearly all were distinguished by at least two non-overlap-
ping differences in colour pattern, or (less frequently) body these taxa.
proportions. In addition, there was usually one other difference
Cuba
(eithernon-overlappingoroverlapping)inscalation.Moredistantly
related species ofTropidophisoften have two (ormore) non-over- With 15 describedspecies.Cubaisthehotspotofspeciesdiversity
lappingdifferencesinscalation,inadditiontoanyotherdifferences. in the genus. Recently, two subspecies described by Schwartz and
Thissuggestsatemporalsequenceincharacterdifferentiation,with Garrido (1975) were elevated to species status and a new species
colour pattern and body proportion differences accruing first, fol- was described from eastern Cuba (Hedges & Garrido, 2002).
lowed by scalation differences. Ideally, one would like to use CharacterdifferencesamongmanyoftheCuban specieshavebeen
moleculardataaswellforassessingdifferentiation,although tissue discussed above (see 'Species Boundaries'), and I consider all 15
samplesstillarenotyetavailableformanytaxa.Usingthismorpho- species to be valid. Also, I am aware ofmaterial that likely repre-
logical criterion for assessing species status in Tropidophis, I will sents additional, undescribed species. Undoubtedly, more species
nowreview thecurrentstatusofthetaxa in thisgenus. will be discovered.
TworemainingtaxaareconsideredsubspeciesofT.melanurus:T.
Hispaniola m. dysodes and T m. eriksoni (Schwartz & Thomas, 1960). The
formerisknownfromthreefemalespecimensfromnearLaColoma,
Only one species (T haetianus), with three subspecies, occurs on PinardelRioProvince,andthelatterisrestrictedtoIsladeJuventud.
Hispaniola: T h. haetianus (most ofisland), T h. hemerus (distal ThesetaxadifferfromT.m.melanurusprimarilyinsizeofthedorsal
portion of the Tiburon Peninsula in Haiti) and T. h. tiburonensis spots and in having bolder, darkercolouration, with T. m. dysodes
(extreme eastern portion of the Dominican Republic). Although havingthedarkestpigmentationofthethreesubspecies.Theventral
Schwartz andMarsh (1960) and Schwartz (1975) have considered counts of T. m. eriksoni are low for the species, but there is
theJamaicantaxatobesubspeciesofThaetianus,geneticevidence considerableoverlapwiththeothertwotaxa.Consideringthatthere
has shown that they are more closely related to the Cuban species arenodiagnosticdifferencesinbodyproportionorscalation,andthe
(Hass, Maxson & Hedges, 2001) and thus are removed from T colourationdifferences, althoughreal, are notastrenchantasthose
haetianus (see below). Also, the Cuban specimens ofT haetianus distinguishingsympatric.closelyrelatedspecies(e.g., T maculatus
discussedbySchwartzandMarsh(1975)andSchwartzandGarrido and T. semicinctis),Iaminclinedtoleavetheirstatusassubspecies
(1975)havebeenremovedfromthatspecies andassignedtoanew unchanged until additional datawarrantareconsideration.
species, T hendersoni (Hedges & Garrido, 2002). Because the
subspeciesofHispaniolanThaetianusareparapatricandapparently Jamaica
intergrade(Schwartz, 1975),andbecausetheircharacterdifferentia-
tion is less than that ofsympatric species, I suggest retaining their The three Jamaican taxa, originally described as full species, are
current taxonomic status as subspecies. It is possible that genetic closerto Cuban taxathan to T. haetianusbased on immunological
studies in the future may further clarify their status. Thus, T. data(Hassetal,2001)andDNAsequencedata(S.B.Hedges,S.C.
haetianusisconfined toHispaniolaandcontainsthree subspecies. Duncan, A. K. Pepperney. in preparation). However, they form a
SNAKEOFTHEGENUS TROP1DOPHIS 89
single genetic and morphological group (jamaicensis group), and difference,overall, betweenbarbouriandandrosi. Whenconsider-
are distinguished morphologically from the Cuban species at the ingthe'speciesboundary'charactersnotedabove,thereisinsufficient
species level, although they are closest to species of thepardalis justification at present to recognize these taxa as distinct species.
group. The question then remains as to whether they should be Additional specimens and genetic analyses will be necessary to
treatedasasinglespecies(Tjamaicensis)orthreeseparatespecies: betterresolvegeographicvariationinnorthernBahamanTropidophis.
T. jamaicensis, T. stejnegeri, and T. stullae. However, using the Untilthen,Isuggestherethatandrosiandbarbouriberecognizedas
morphological criterion for species status, I recommend the latter. subspeciesofT curtus: T. curtusandrosi(newcombination)andT.
Eachofthesethree taxacan bediagnosedbasedon scalation,body curtusbarbouri(newcombination).
proportions,andcolourpattern, andthey areasdifferentfromeach Tropidophis greenwayi lanthanus is a subspecies found in the
otheras sympatric species in Cuba. Inbody size, T. stejnegeri(529 CaicosIslandsandisdistinguishedbycolorationdifferencefromthe
mmSVL)isconsiderablylargerthanT.stullae(260mmSVL),with nominate subspecies on nearby Ambergris Cay (Schwartz, 1963).
T.jamaicensis (338 mm SVL) being intermediate in size. Ventral However, the difference concerns 'interspace stippling' and not
counts ofT. stejnegeri do not overlap with those ofT. stullae, and actual numbersofspotsorspotrows.Therearenodiagnostic scale
counts of T. jamaicensis are nearly completely non-overlapping count differences, and the presence oftwo postoculars in the two
withtheothertwotaxa.Tropidophisstejnegerihaskeeledscalesand knownspecimensofTg. greenwayiisnotremarkablebecausehalf
occipital spots whereas the other two taxa are smooth scaled and of the specimens of T. g. lanthanus also have two postoculars, at
lack occipital spots. Additionally, dorsal ground colours differ, least on one side ofthe head. More material of T. g. greenwayi is
being yellowish-grey (T. stejnegeri), chocolate brown (T. needed, in addition togeneticanalyses, beforethe species statusof
jamaicensis) andpaletan (T stullae). A middorsal stripe ispresent T g. lanthanus can be accurately assessed. I suggest that the latter
in T. stejnegeriand T. stullaebutabsentin T.jamaicensis.Thehead taxon continue tobe recognizedas asubspecies.
ofT. stejnegeriispointedbutthatofT. stullaeisdistinctlysquared- Thus, Tropidophisofthe Bahamas Bank are placed here in three
shaped. species: T. greenwayi(Turks andCaicos), T. canus (Great Inagua),
and T. curtus (northern and central Bahamas). The question as to
The Bahamas Bank whethersome BahamanspeciesalsooccurinCubahasbeenraised
in the past, primarily because oftwo old specimens (Schwartz &
Six taxa are currently recognized from the Bahamas Bank: Marsh, 1960). The first is the type of T. curtus, purportedly from
Tropidophis canus androsi Stull (Andros Island), T. c. barbouri 'Cuba' (Garman, 1887). However, morphologically it agrees with
Bailey (central Bahamas, from Eleuthera to Ragged Island), T. c. snakes from New Providence, Bahamas, andthe specimen number
canusCope (Great Inagua), T. c. curtusGarman (New Providence, (MCZ6114) isclose toothernumbers in thatcollection from New
Bimini Islands, and Cay Sal Bank), T. g. greenwayi Barbour and Providence. Also, the origin ofthe specimen was investigated and
Shreve (Ambergris Cay), and T. g. lanthanus Schwartz (Caicos found to be 'without definite history' (Stull, 1928). Thus, I agree
Islands). Schwartzand Marsh (1960) considered all except the last withStullinconsideringthisspecimentobefromNewProvidence.
twotobesubspeciesofasinglespecies(T. canus)andthatarrange- TheotherspecimenisAMNH2946from'Nuevitas,Cuba'(noother
ment has since been followed. However, it is worth reviewing information). As noted by Schwartz and Marsh (1960) it agrees in
morphological variation in T. canus in the context of our current morphologywithsnakeshereconsideredasTcurtus.Althoughthey
understandingofspecies definitions in the genus. Recent evidence considered the provenance of the specimen to be correct, partly
from DNA sequences has shown that T greenwayi is most closely because of the confusion surrounding the holotype, I raise the
related to T. haetianus (Hispaniola) and unrelated to the complex question here that it also may be an error. The specimen numberis
currentlyconsidered under T. canus. closetoseveral T. curtusfrom Andros Island(AMNH 2925-2927)
AmongthefoursubspeciesofT.canus,T.c.canusstandsoutboth apparentlycatalogedataboutthesametimeanditsscalecountsfall
morphologicallyandgeographically.Itisisolatedinthesouth,being withintherangeofcountsofsnakesfromthatisland.ThusIconsider
separated from the northern taxa by islands apparently lacking the range ofT curtustobe restrictedto the Bahamas.
Tropidophis: Crooked, Acklins, Mayaguana, and Little Inagua. It
hasahighernumberofventrals (170-183). One specimen (1%)of The Cayman Islands
thenortherngrouphas 173 ventrals; allothers havefewerthan 168
ventrals. Anteriorand midbody scale rows in T c. canus typically Currently there are three subspecies ofT. caymanensis recognized
are 21-23 whereas they are typically 23-25 in the northern taxa, from the Cayman Islands (Thomas, 1963) and they differ in scale
althoughthereissomeoverlap.ThetailsofT.c. canusaredistinctly rowcounts,ventralcounts,andcolourpattern. Eachisendemictoa
shorter,averaging 11%(9.4-12.1),comparedwith 13%(11.0-15.2) singleisland,andthereisnoevidenceofintergradation.Atthetime
inthenortherntaxa. Rowsofbodyspotsnumber6-8 in T. c. canus they were last reviewed (Thomas, 1963), a more conservative
whereastheyaretypically 10ormorein the northern taxa; overlap definitionofspeciesboundariesinthegenusprevailed.Althoughno
consists ofnine specimens (10%) ofnorthern taxa witheightrows newmaterial hasbeenexaminedhere, the level ofdifferences seen
and two (2%) with nine rows, and one (5%) T. c. canus with nine among these taxa would suggest that they are distinct species.
rows.Thisdegreeofdifferenceisthesameorgreaterthanthatseen Tropidophiscaymanensis(GrandCayman) isdistinguishedfrom T
betweensympatricspeciesofTropidophisinCuba,andthereforethe parkeri (Little Cayman) by its lower anterior and midbody scale
northern taxa shouldberemovedfrom T canus. rows (23-25 versus 25-27), lower number of ventrals (183-200
The status ofthe three northern Bahaman taxa is problematic at versus 199-212), andalarger, darkercephalicpattern. Tropidophis
this time. Clearly there isgeographic variation amongthese forms. caymanensis is distinguished from T schwartzi(Cayman Brae) by
Forexample,andrositendstohaveahighernumberofventralscales its larger body size (maximum SVL = 470 mm versus 385 mm),
thantheothertwotaxa,althoughthereisconsiderableoverlapwith loweranteriorscalerows(23 versus25), lower,albeitoverlapping,
barbouriand some with curtus. Within one taxon (curtus), snakes number ofventrals (183-200, x= 192, versus 191-205, x= 198),
fromBimini aredistinctly largerthan those from NewProvidence. fewertailspots (4-8,mode=6versus5-9,mode=8)andalarger,
BothBailey(1937)andSchwartzandMarsh(1960)notedverylittle darker, cephalic pattern. Tropidophisparkeriis distinguishedfrom
.
90 S.B. HEDGES
T.schwartzibyitshighermidbodyscalerows(27versus25),higher Cope,E.D.1868.AnexaminationoftheReptiliaandBatrachiaobtainedbytheOrton
numberofventrals(199-212,x=203versus 191-205,x= 198),and ExpeditiontoEcuadorandtheupperAmazon,withnotesonotherspecies.Proceed-
ingsoftheAcademyofNaturalSciences, Philadelphia20:96-140.
alarger, darkercephalic spot(Thomas, 1963). Darwin,C.1859.TheOriginofSpecies.JohnMurray,London.
Frost,D.R.&Hillis,D.M.1990.Speciesinconceptandpractice.Herpetologica46:
South America 87-104.
Garman,S. 1887.OnWestIndianreptilesintheMuseumofComparativeZoology.
AlthoughStull(1928)andSchwartzandMarsh(1960)attemptedto Cambridge,Massachusetts.ProceedingsoftheAmericanPhilosophicalSociety24:
relateoneormoreoftheSouthAmericantaxatoWestIndianspecies 278-286.
groups, I do not envision a close relationship. For example, the Hasosf,WCe.sAt.,IMndaixasnonam,pLh.iRb.ia&nsHaenddgerse,ptSil.eBs.:2i0n0s1i.ghRteslaftrioomnsahlipbsumainndidimvmeurngoelnocgeyt.imIens:
keelingofthedorsalscalesinT. taczanowskyiisgreaterthanIhave Woods CA and Sergile FE, eds. Biogeography ofthe West Indies: patterns and
seen in anyWest Indian taxon. In thecaseofT.paucisquamus, the perspectives. BocaRaton.Florida:CRCPress. 157-174.
lownumber(21)ofmidbodyscalerowsandadistinctivepatternof Hedges,S.B.,Estrada,A.R.& Diaz,L.M. 1999.A newsnake(Tropidophis)from
mniodteddorbsyalScshtrwiapretazndanbdloMtacrhesshi(s1n9o6t0)l.ikTehaenyonWleysktnIonwdinanspsepceciimeesn,oasf west&erGnaCrurbiad.o,CoOp.eHi.a11999929.:A37n6e-w38s1peciesofTropidophisfromCuba(Serpentes.
Tropidophiidae). Copeia 1992: 820-825.
iT.ncblautdtienrgsbtywioharsowbseeonndtehsecrviebnetderon(lLyauarsenhta,vi1n9g49s;ixPerroewzs-Soafntsopsots&, cent&ralCuba..1J9o9u9.rnAalnoefwHesrnpaekteoloofgyth3e3:ge4n3u6s-4T4r1o.pidophis (Tropidophiidae) from
Moreno, 1991).ThefactthattheventersofT.paucisquamusand T. & . 2002. A new snake ofthe genus Tropidophis (Tropidophiidae) from
EasternCuba.JournalofHerpetology36: 157-161.
taczanowskyi have both been described as consisting ofblack and , & Diaz, L.M. 2001. A new banded snake of the genus Tropidophis
yellow spots andbands (Stull, 1928) is noteworthy; such apattern (Tropidophiidae)fromNorth-CentralCuba.JournalofHerpetology35:615-617.
andcolouration is notknown in West Indian taxa. This might also ,Hass,C.A.&MaugelTK.1989.Physiologicalcolourchangeinsnakes.Journal
suggestarelationshipatleastbetweenthesetwospecies. Molecular ofHerpetology23:450-455
phylogeneticevidence(S.B.Hedges,S.C.Duncan,A.K.Pepperney, Laurent,R. 1949.Note surquelquesreptilesappartenantalacollectionde 'Institut
RoyaldesSciencesNaturellesdeBelgique.III.Formesamericaines.BulletinInstitut
in preparation) places T. paucisquamus outside ofthe West Indian RoyaldesSciencesNaturellesBelgique. Bruxelles25: 1-20.
clade, reinforcing the morphological distinction. Examination of Mayr,E.1942.Systematicaandtheoriginofspecies.ColumbiaUniversityPress.New
additional specimens, and genetic data from T. battersbyi and T. York.
taczanowskyi,areneededtoclarifytherelationshipsoftheseSouth Perez-Santos,C.&MorenoAG.1991.SerpienlesdeEcuador.MuseoRegionaledi
ScienzeNaturali.Torino,Italy.
Americanspecies.Untilthen,availableevidencesupportstheplace- Powell,R. 1999. HerpetologyofNavassaIsland.WestIndies. CaribbeanJournalof
ment of the South American species in a separate species group Science35: 1-13.
(taczanowskyigroup). SchwartzA. 1957.A new speciesofboa(genus Tropidophis) fromWesternCuba.
AmericanMuseumNovitates(1839): 1-8.
. 1963. A new subspecies of Tropidophis greenwayi from the Caicos Bank.
Breviora. MuseumofComparativeZoology(194): 1—6.
Acknowledgements. IthankR.Hendersonforprovidingaccesstothe .1975.VariationintheAntilleanboidsnakeTropidophishaetianusCope.Journal
raw scalecountdataandnotesofA. Schwartz; L. Diaz, A. R. Estrada, A. ofHerpetology9:303-311.
Fong,O.H.Garrido,andL.Moreno,fordataonspecimensintheirposses- &Garrido,O.H.1975.AreconsiderationofsomeCubanTropidophis(Serpentes.
osifonN;aRt.urTahlomHaisstfoorryas(sSimsitatnhcseoniinatnh)e,fieMlud;steheumstafoffsoCfotmhpeaNraattiiovnaelZMouosleougmy Boi&daeH)e.ndPreorcseoend,inRg.sW.of1t9h9e1.BiAomlpohgiibcailanSsocainetdyreopftiWlaesshoifntghteoWnes8t8:In7d7i-es9.0.University
ofFloridaPress.Gainesville.
(Harvard), and Natural History Museum (London), forloan ofmaterial or &Marsh,R.J. 1960.Areviewofthepardalis-maculatuscomplexoftheboid
accesstothecollections.Thisworkwassupportedbygrantsfromthe U.S. genusTropidophis.BulletinoftheMuseumofComparativeZoology123:49-89.
NationalScienceFoundation. &Thomas,R. 1960.Fournewsnakes(Tropidophis. Dromicus.Alsophis)from
theIsladePinosandCuba.Herpetologica16:73-90.
Stull, O.G. 1928. A revision ofthe genus Tropidophis. Occasional Papers ofthe
MuseumofZoology, UniversityofMichigan: 1—49.
REFERENCES Thomas,R. 1963.Cayman Islands Tropidophis(Reptilia. Serpentes).Breviora, Mu-
seumofComparativeZoology: 1-8.
.1966.AreassessmentoftheherpetofaunaofNavassaIsland.JournaloftheOhio
Bailey,J.R. 1937.AreviewofsomerecentTropidophismaterial.Proceedingsofthe HerpetologicalSociety5:73-89.
NewEnglandZoologicalClub16:41-52. Underwood,G.1967.AContributiontotheClassificationofSnakes.BritishMuseum
Boulenger,G.A.1893.CatalogueofsnakesintheBritishMuseum(NaturalHistory). (Natural History) Publication No. 653. Trustees ofthe British Museum (Natural
Vol. I. LongmansandCompany,London. History),London. 179pp.