Fettuccia, DC. a * da Silva, VMF. a and Simões-Lopes, PC. b

Transcription

1 ID Artigo: envio: 12/08/2009 Digrmdor: Dniel cuomultimidi pulicções e-mil: Non-metric chrcters in two species of Sotli (Gry, 1866) (Cetce, Delphinide) Fettucci, DC. * d Silv, VMF. nd Simões-Lopes, PC. Lortório de Mmíferos Aquáticos INPA. Av. André Arújo, 2936, Aleixo, CEP , Mnus, AM, Brzil Lortório de Mmíferos Aquáticos LAMAQ, Deprtmento de Ecologi e Zoologi, CCB, Universidde Federl de Snt Ctrin UFSC, CP 5102, CEP , Florinópolis, SC, Brzil *e-mil: fettucci@hotmil.com Received Decemer 7, 2007 Accepted August 27, 2008 Distriuted August 31, 2009 (With 12 figures) Astrct Anlyses of non-metric chrcters of the skull nd cervicl vertere were performed mong smples of dolphins of the genus Sotli from the north, northest nd south Brzilin cost (S. guinensis) nd lso smples from the Amzon River Bsin (S. fluvitilis) s prt of n osteologicl descriptive study. The results demonstrted tht there ws higher percentge of occurrence of fenestre in the occipitl region (66%) nd cervicl ris in the cervicl vertere (87%) in the riverine species. The vomer in wide shpe ws more frequent in the riverine species (57%), followed y the intermedite (32%) nd nrrow shpe (11%), tht ws found to e more frequent in the mrine species (66 to 76%). In reltion to the lcerte nterior formen, it ws oserved tht n open/elongted shpe is more common in the riverine species (88%). Most smples in the mrine species present this formen divided y spike shped projection (72 to 98%). The ventrlly visile loction of the hypoglossl formen ws more often oserved externlly displced in S. guinensis (88 to 98%), while in S. fluvitilis, most smples (87%) presented this formen internlly displced to the jugulr notch, nd not visile in ventrl view. The fluvil species seems to present neoteny (or mintennce of juvenile chrcters in dults) in reltion to the position of the pterygoids nd in development of lcerte nterior formen. Keywords: Morphology, Sotli, osteology, skull, cervicl vertere. Crcteres não métricos ns dus espécies de Sotli (Gry, 1866) Resumo Este é um trlho osteológico descritivo entre exemplres do gênero Sotli d cost Norte, Nordeste e Sul do Brsil e exemplres fluviis d ci mzônic, nlisndo crcteres não métricos no crânio e ns vérters cervicis. A frequênci de ocorrênci de fenestrs n região occipitl (66%) e de costels cervicis (87 %) foi mior n espécie fluvil (S.fluvitilis). N espécie fluvil, form do vômer lrgo foi mis frequente (57%), seguid d form intermediári (32%) e estreit (11%). A form do vômer estreito foi mis frequente n espécie mrinh (S. guinensis) (66 76%). Em relção o forâmen lcerdo nterior, foi oservdo que form ert/longd é mis comum n espécie fluvil (88%). N espécie mrinh, miori dos exemplres present este forâmen dividido por um projeção em form de espinho (72 98%). A loclizção do forâmen hipoglossl visível ventrlmente foi mis oservd em S. guinensis (88 98%), enqunto que em S. fluvitilis, miori dos exemplres (87%) presentou este forâmen deslocdo internmente à reentrânci jugulr, não podendo ser oservdo em vist ventrl. A espécie fluvil prece presentr neoteni (ou mnutenção de crcteres juvenis no dulto) em relção o posicionmento dos pterigoides e o desenvolvimento do forâmen lcerdo interior. Plvrs-chve: morfologi, Sotli, osteologi, crânio, vérter cervicl. 1. Introduction The genus Sotli (Gry, 1866) ws until recently considered monospecific, however recent moleculr genetics (Cunh et l., 2005; Cllero et l., 2007), nd geometric morphometric (Monteiro-Filho et l., 2002) studies reveled the existence of two species: the mrine species Sotli guinensis (P.J. vn Bénéden, 1864) (gry dolphin) nd the riverine species Sotli fluvitilis (Gervis, 1853) (tucuxi). Brz. J. Biol., 69(3): ,

2 Fettucci, DC. d Silv, VMF. nd Simões-Lopes, PC. The mrine species is rodly distriuted long the tropicl nd sutropicl Atlntic cost of South nd Centrl Americ, hving een recorded from Florinópolis, Snt Ctrin, Brzil (27 35 S nd W) (Simões- Lopes, 1988; Boroi, 1989) to Hondurs (15 58 N nd W) (d Silv nd Best, 1996). The riverine species is endemic to the Amzon Bsin, occurring from Belém (t the mouth of the Amzon River), in Brzil, to the rivers of Peru, Colomi nd Ecudor (Boroi et l., 1991, d Silv nd Best, 1996). Osteologicl descriptions for the genus Sotli hve een pulished y Mirnd-Rieiro (1936); Csinos et l. (1981); Boroi (1989); Menezes nd Simões- Lopes (1996); d Silv nd Best (1996); Alves Júnior nd Monteiro-Neto (1999); Avil et l. (2002); Fettucci nd Simões-Lopes (2004), Simões-Lopes (2006). With the exception of Simões-Lopes (2006), these studies were minly sed on trditionl studies of morphometrics. There re no previous comprtive studies using non-metric chrcteristics such s, for exmple, the com- prison of forms or presence nd sence of determined chrcters for this genus. Therefore, this study ims to compre the two species of the genus Sotli using nonmetric chrcters. 2. Mteril nd Methods A totl of 149 specimens were nlysed from five distinct Brzilin sttes: Mmml Collection of Ntionl Institute for Amzôni Reserch (INPA), Mnus, Amzons (AM); Emilio Goeldi Museum (MPEG), Belém, Prá (PA); Aqutic Mmmls Lortory (LMA) of the Deprtment of Ecology nd Zoology, Federl University of Snt Ctrin (UFSC), Florinópolis, Snt Ctrin (SC); s well s the Osteologicl Archive of the Assocition of Reserch nd Preservtion of Aqutic Ecosystems (AQUASIS), Cuci, Cerá (CE) (Tles 1-4). The INPA collection contins riverine specimens (S. fluvitilis) from the Amzons Stte (AM), mrine specimens from the cost of the Ampá (AP) nd es- Tle 1. List of Sotli fluvitilis nlysed from the northern region (Amzon Stte, Brzil), deposited t INPA s mmmls collection. F - femle, M - mle, I - indeterminte gender. N = 44. Collection Sex Age Loclity Collection Sex Age Loclity INPA 005 I dult Jpurá River INPA 054 M clf Amzons River INPA 007 I dult Tefé Lke INPA 055 I dult Amzons River INPA 008 I dult Tefé Lke INPA 056 F dult Amzons River INPA 009 M juvenile Negro River INPA 057 F dult Amzons River INPA 015 F clf Jpurá River INPA 059 M juvenile Mrchntri, Solimões River INPA 016 I dult Jpurá River INPA 060 M juvenile Mrchntri, Solimões River INPA 017 M dult Jpurá River INPA 062 F dult Tefé Lke INPA 018 I clf Jpurá River INPA 065 M clf Jpurá River INPA 020 I dult Jpurá River INPA 067 I dult Jpurá River INPA 024 I dult Jpurá River INPA 069 F dult Negro River/ Anvilhns INPA 026 M juvenile Purus River INPA 071 F dult Jpurá River INPA 029 F juvenile Tefé Lke INPA 072 I dult Prá River INPA 038 F clf Jpurá River INPA 073 F dult Purus River INPA 039 M immture Jpurá River INPA 074 M dult Purus River INPA 040 F dult Amnã Lke INPA 080 M clf Ctlão, Negro River INPA 041 M dult Negro River/ Anvilhns INPA 081 M juvenile Clin Lke, Mncpuru INPA 043 M juvenile Jpurá River INPA 082 F clf Tpjós River INPA 047 M dult Juruá River INPA 093 M dult Tocntis River/ Tucuruí INPA 050 F immture Amnã Lke INPA 097 F juvenile Negro River INPA 051 M clf Amzons River INPA 113 M dult Solimões River INPA 052 M dult Amzons River INPA 149 I dult Cori Grnde River INPA 053 F dult Amzons River INPA 151 I dult Cori Grnde River 2 Brz. J. Biol., 69(3): , 2009

3 Non-metric chrcters in Sotli Tle 2. List of Sotli guinensis nlyzed from northern region (Ampá nd Prá Sttes, Brzil), deposited t INPA nd MPEG mmmls collections, respectively. F - femle, M - mle, I - indefinite gender. N = 26. Collection Sex Age Loclity Collection Sex Age Loclity INPA 120 M juvenile Amzons Estury INPA 133 M juvenile North of Ampá INPA 121 M juvenile Amzons Estury INPA 134 F dult North of Ampá INPA 122 M juvenile Amzons Estury INPA 135 F clf North of Ampá INPA 123 M dult North of Ampá INPA 136 M clf North of Ampá INPA 124 F juvenile North of Ampá INPA 137 M clf North of Ampá INPA 125 F juvenile Amzons Estury INPA 138 F juvenile North of Ampá INPA 126 M juvenile North of Ampá INPA 139 F juvenile North of Ampá INPA 127 M clf North of Ampá INPA 140 M juvenile North of Ampá INPA 128 M clf North of Ampá INPA 141 F dult North of Ampá INPA 129 M dult North of Ampá INPA 142 F dult North of Ampá INPA 130 F juvenile North of Ampá INPA 143 F dult North of Ampá INPA 131 F clf Amzons Estury MPEG I dult Mrjó Islnd INPA 132 F clf Amzons Estury MPEG F juvenile Mrjó Islnd Tle 3. List of Sotli guinensis nlysed from the Northest region (Cerá stte, Brzil), deposited t AQUASIS s collection. F - femle, M - mle, I - indeterminte gender. N = 41. Collection Sex Age Loclity Collection Sex Age Loclity Aq 002 M dult Cuci Aq 210 F dult Prcuru Aq 004 I juvenile Fortlez Aq 212 F dult Fortlez Aq 012 I dult Fortlez Aq 213 M clf Fortlez Aq 013 M dult Fortlez Aq 214 F juvenile Cuci Aq 023 M dult Cuci Aq 215 I dult São G. Amrnte Aq 026 I dult Cuci Aq 218 M juvenile São G. Amrnte Aq 036 F dult Fortlez Aq 222 F dult Fortlez Aq 038 M dult Cuci Aq 231 M dult Cuci Aq 039 I dult São G. Amrnte Aq 232 M dult Fortlez Aq 040 I clf São G. Amrnte Aq 234 M dult Cuci Aq 041 I immture Fortlez Aq 236 I dult São G. Amrnte Aq 042 M dult Fortlez Aq 239 M dult Fortlez Aq 058 F dult Fortlez Aq 240 I immture Prip Aq 071 I dult Cscvel Aq 241 I dult Cuci Aq 084 M dult Fortlez Aq 247 F dult Fortlez Aq 132 M juvenile São G. Amrnte Aq 250 M clf Prip Aq 134 M dult Fortlez Aq 251 I dult Triré Aq 139 I dult Itpipoc Aq 253 M dult Fortlez Aq 159 I dult Fortlez Aq 259 M dult Fortlez Aq 184 F dult Fortlez Aq 262 I dult Bitupitá Aq 196 I immture São G. Amrnte turine specimens (S. guinensis) from Prá Stte (PA). The other collections only possess mrine specimens from their respective loclities. Forty-four specimens of S. fluvitilis nd 105 specimens of S. guinensis were nlyzed (AP = 24; PA = 02; CE = 41; SC = 38). The mrine specimens were divided into 3 lrge res: NOR (including specimens from AP nd PA), for the specimens from the cost of Ampá nd Prá Sttes, CE for Brz. J. Biol., 69(3): ,

4 Fettucci, DC. d Silv, VMF. nd Simões-Lopes, PC. Tle 4. List of Sotli guinensis nlysed from the Southern region (Snt Ctrin stte, Brzil), deposited t LAMAq s collection (UFSC). F - femle, M - mle, I - indeterminte gender. N = 38. Collection Sex Age Loclity Collection Sex Age Loclity UFSC1010 I juvenile Dniel Bech UFSC1222 M immture Estreito UFSC1073 I dult Biguçu UFSC1223 M clf Anhtomirim Islnd UFSC1079 F dult Beir Mr Norte UFSC1226 M dult G. Celso Rmos UFSC1082 I dult Beir Mr Norte UFSC1236 F clf Smqui UFSC1083 M dult Beir Mr Norte UFSC1245 I juvenile São F. do Sul UFSC1104 F immture Beir Mr Norte UFSC1247 I dult Ccupé UFSC1108 M dult Beir Mr Norte UFSC1253 M juvenile Beir Mr Norte UFSC1117 I dult Biguçu UFSC1266 M immture Biguçu UFSC1130 F dult G. Celso Rmos UFSC1268 F dult Biguçu UFSC1174 M clf Smqui UFSC1289 F dult G. Celso Rmos UFSC1175 M dult São F. do Sul UFSC1291 M dult G. Celso Rmos UFSC1176 I dult Costeir UFSC1296 M juvenile Anhtomirim UFSC1178 M juvenile Smqui UFSC1297 M dult G. Celso Rmos UFSC1179 M juvenile Beir Mr Norte UFSC1302 I dult Itpoá UFSC1180 F dult Ccupé UFSC1307 M juvenile Dniel Bech UFSC1203 F dult Anhtomirim UFSC1311 I immture São F. do Sul UFSC1208 F dult Estreito UFSC1312 M dult Estreito UFSC1218 F dult Curtume Bech UFSC1321 F dult Itguçu Bech UFSC1219 F dult Costeir UFSC1327 M clf Beir Mr Norte c f e d g e c Figure 1. Scheme of Delphinide skull in dorsl view, showing non-metric chrcters: ) Asymmetry of position of the two nterior most lrge mxillry formin; ) Numer of smll formin in the mxillry; c) Numer of formin in the mxillry ehind line t the level of the nterior edge of the externl nres; d) Contct etween mxillry nd occipitl; e) Contct etween premxillry nd nsl, on right side; f) Asymmetry of position of the two premxillry formin; nd g) Development of dorsl mesethmoid spine t the nterior mrgin of externl nres. Adpted from Perrin et l. (1982). m d Figure 3. Scheme of Delphinide skull in posterior view, showing non-metric chrcters: ) Medil occipitl ridge, projecting ove level of the occipitl swellings t midheigh; ) Accessory formen ove formen mgnum; c) Cler notch in upper mrgin of formen mgnum; d) Numer of fenestrtions in occipitl, ner formen mgnum nd in exoccipitl region; e) Numer of fenestrtions in occipitl swellings region. Adpted from Perrin et l. (1982). l 1 fr 2 3 Figure 2. Composition of the nteoritl process, in lterl view, of the left side: 1) formed y lcriml; 2) formed y lcriml nd frontl; 3)formed y lcriml nd mxillry. l: lcriml; m: mxilr; fr: frontl. Adpted from Perrin et l. (1982). the specimens off the Cerá cost nd SC for specimens from the Snt Ctrin cost. The skulls were compred using non-metric chrcters, in ccordnce with Perrin et l. (1982) nd two newly proposed chrcters (Tle 5; Figures 1-4). The 4 Brz. J. Biol., 69(3): , 2009

5 Non-metric chrcters in Sotli Tle 5. List of non-metric chrcters nlysed in skulls nd cervicl vertere from specimens of the genus Sotli. Adpted from Perrin et l. (1982) nd two new proposed chrcters (4 e 4g). NI: not illustrted. Figure chrcter nd chrcter condition 1. Asymmetry of position of the two nterior most lrge mxillry formin: 1- symmetricl; 2- left formen more nteriorly plced; right formen more nterior.. Numer of smll formin in the mxillry nterior to the nterior-most of the three lrge formin. c. Numer of formin in the mxillry ehind line t the level of the nterior edge of the externl nres nd perpendiculr to the long xis of the skull. d. Contct etween mxillry nd occipitl, t point where occipitl crest intersects mrgin of temporl foss: 1- contct (or spce of <1 mm); 2- no contct. e. Contct etween premxillry nd nsl, on right side: 1- contct (or spce of <1 mm); 2- no contct. f. Asymmetry of position of the two premxillry formin: 1- symmetricl; 2- left formen more nteriorly plced; right formen more nterior g. Development of dorsl mesethmoid spine t the nterior mrgin of externl nres, etween ngles of premxillries: 1- elevtion of the ossified portion of the mesethmoid to, or ner to the level of the dorsl surfces of the premxillries; 2- no such elevtion. 2 Composition of the nteoritl process, in lterl view, of the left side: 1- formed y lcriml; 2- formed y lcriml nd frontl; 3- formed lcriml nd mxillry. 3. Medil occipitl ridge, projecting ove level of the occipitl swellings t mid-height: 1- present; 2- sent, or not projecting ove swellings.. Accessory formen ove formen mgnum: 1- present; 2- sent. c. Cler notch in upper mrgin of formen mgnum: 1- present; 2- sent. d. Numer of fenestrtions in occipitl, ner formen mgnum nd in exoccipitl region. e. Numer of fenestrtions in region of occipitl swellings. 4. Shpe of the vomer mong posterior process of the pterygoids: 1- wide; 2- intermedite; 3- nrrow.. Anterior contct etween pterygoid hmuli: 1- open (gp > 1 mm); 2- closed.. Posterior contct etween pterygoid hmuli: 1- open (gp > 1 mm); 2- closed. d. Shpe of posterior projection of left pterygoid hmulus: 1- longer thn wide (y > x); 2- wider thn long, or equl (x > y). e- Vomer s posterior lignment in reltion to pterygoids s lmellr process: 1- nterior; 2- ligned; 3- posterior. f- Numer of fenestrtions in region of soccipitl. g- Shpe of the nterior lcerte formen (right): 1- open; 2- with projection spine form; 3- nrrow. h- Visiility, in ventro-occipitl view of mesilly directed hypogossl formen etween soccipitl nd exoccipitl process (jugulr notch): 1- visile; 2- not visile. NI Cervicl ri: 1- present; 2- sent. cervicl vertere were nlyzed ccording to the presence or sence of cervicl ris. In order to oserve ontogenetic vrition, the chrcters were evluted y ge es (clf, juvenile, immture nd dult) (dpted from Dwin et l., 1970). Vritions etween the sexes were not nlysed in this study due to the smll smple size. The terminology used for skeletl ones followed Flower (1885), Krglievich (1937), Lessertieur nd Sn (1967), Rommel (1990) nd Simões-Lopes (2006). 3. Results Of the 22 non-metric chrcters nlysed, only six were informtive for the distinction etween the two species Fenestre A high frequency of fenestre in the occipitl region ws oserved, ner the formen mgnum in S. fluvitilis (66%; n = 44). In S. guinensis the percentge of occurrence of fenestre vried etween 31% (specimens from NOR, n = 26), 10 % (CE, n = 41) nd 13% (SC, n = 39). The of fenestre ner the condyle ws lso lrger in the riverine species, vrying from one to four per individul. In oth species, these structures were found in ll ge es. In the mrine species, the specimens from CE nd NOR exhiited one to three fenestre, while those from SC exhiited only one to two. Fenestre cn occur only on one side (more common in the mrine species) or on Brz. J. Biol., 69(3): ,

6 Fettucci, DC. d Silv, VMF. nd Simões-Lopes, PC. g' e' d' ' c' ' oth sides of the occipitl condyle (more common in the riverine species). In neworn nd young specimens, other openings in the occipitl region (locted ove the fenestre) were oserved, corresponding to the fontnelles, formed y the union of the exoccipitl, prietl nd suproccipitl ones (Figure 5). In the region of occipitl protuernce, in generl, the occurrence of fenestre ws less frequent: 4.5% in S. fluvitilis (n = 44), 10% for S. guinensis of CE (n = 41), 5% for specimens from SC (n = 38) nd no occurrence for mrine specimens from NOR (n = 26). In some specimens of the two species, smll fenestre of irregulr contour in the sioccipitl were oserved. In the mrine species, such fenestre occurred in 2% (n = 41) nd 8% (n = 39) of the specimens from CE nd SC, h' f' c x y x y d Figure 4. ) Skull of Sotli fluvitilis in ventrl view, showing non-metric chrcters (dpted from Perrin et l., 1982): ) shpe of the vomer mong posterior process of the pterygoids: 1) wide; 2) intermedite; 3) nrrow; ) nterior contct etween pterygoid hmuli; c ) posterior contct etween pterygoid hmuli; d ) shpe of posterior projection of left pterygoid hmulus: 1) longer thn wide (y > x); 2) wider thn long, or equl (x > y); e ) vomer s posterior lignment in reltion to pterygoids s lmellr process: 1) nterior; 2) ligned; 3) posterior; f ) of fenestrtions in soccipitl region; g ) Shpe of the nterior lcerte formen (right); h ) visiility, in ventro-occipitl view of mesilly directed hypogossl formen etween soccipitl nd exoccipitl process (jugulr notch). ) Detil of vomer shpe (chrcter ); c) Detil of hmulr process shpe from left pterygoide (chrcter d ); d) Detil of lignment from posterior order of vomer (chrcter e ). Skull design from Izeni P. Fris. 10 cm Figure 5. Skull of Sotli in posterior view. ) Clf of S. guinensis (SC), indicting the sutures (lck rrows) nd fontnelles (white rrow) in occipitl re. ) Adult of S. fluvitilis (AM), indicting the fenestrs next from condile occipitl (lck rrows). In the clf skull the fenestrs re locted elow the sutures of occipitl re. 6 Brz. J. Biol., 69(3): , 2009

7 Non-metric chrcters in Sotli c pt pt pt vo vo vo Figure 6. Shpes of the vomer oserved in the genus Sotli: ) wide; ) intermedite; nd c) nrrow. vo: vomer, pt: posterior process of pterygoide. (%) AM NOR CE Figure 7. Vrition of the vomer shpes in the genus Sotli: 1- wide; 2- intermedite; 3- nrrow. AM- Amzons, CE- Cerá, NOR (smples from AP nd PA together). fo respectively. In the riverine species, these fenestre occurred in 9% (n = 43) of the specimens. These openings were not oserved in the mrine specimens from NOR Vomer There ws prevlence of one form of vomer for the mrine species, nd nother form for the riverine species (Figure 6). The wide form (wider in the posterior region) ws more frequent in the riverine species, occurring in 57% (n = 37) of specimens, followed y the intermedite form (32%) nd the nrrow form (11%) (Figure 7). In the mrine species, the nrrow form ws most frequent, occurring in 76% (n = 21) of the specimens from NOR nd in 66% (n = 38) of the specimens from CE. The intermedite form of the vomer occurred in 9.5% (n = 21) of the specimens from NOR nd in 31.5% (n = 38) of the specimens from CE. This chrcteristic ws dded lter to the nlysis, thus the specimens from SC were not included in the nlyses. This chrcteristic seems to e relted with individul vrition nd not with development Pterygoids The contct, nterior nd posterior, etween pterygoids exhiited no vrition, eing seprte (gp >1 mm) in 100% of specimens of oth species (except for INPA fo Figure 8. Shpe of the nterior lcerte formen (fo) oserved in the genus Sotli: ) open; nd ) with spine form projection (lck rrow). specimen 130 from AP, whose pterygoides hd medil contct). In riverine species it ws oserved tht generlly there ws greter distnce etween pterygoids in the posterior portion, forming n inverted v. Young individuls of mrine species seems to present this sme greter distnce in the posterior portion. This could in- Brz. J. Biol., 69(3): ,

8 Fettucci, DC. d Silv, VMF. nd Simões-Lopes, PC. dicte neoteny in the riverine species, ut in order to e le to interpret this vrition more thorough morphometric study is needed Anterior lcerte formen The predominnt form of nterior lcerte formen ws distinct in the two species (Figures 8 nd 9). In S. fluvitilis, the mjority of specimens (88%, n = 43) exhiited open/elongted nterior lcerte formen. In S. guinensis, the mjority of the specimens nlysed exhiited formen divided y projection in the form of spine: 72% (NOR, n = 25), 77.5% (CE, n = 40) nd 98%, (SC, n = 38). This spine projection, which rrely develops in dults of the riverine species, seems to e ssocited with ontogenetic development in the mrine species, leding to the ssumption tht it is relted to neoteny. A more detiled study with lrger of young nd juveniles of oth species could provide n nswer to this question. In the three mrine smples nlysed, it ws oserved tht some individul dults exhiited formtion of fusion points etween the projection nd one side of the lcerte formen Hypoglossl formen The loction of hypoglossl formen next to the jugulr notch ws considerly higher in S. guinensis: 88% (NOR, n = 25), 95% (CE, n = 41) nd 98% (SC, n = 39). In this species, this formen is generlly visile in the ventrl view, externlly displced to the jugulr notch. Conversely, in the riverine species, the mjority of specimens (87%, n = 45) exhiited this formen internlly displced to the jugulr notch, not esily oserved in the ventrl view (Figures 10 nd 11). It is worth noting, however, tht vrition exists in the proximity of this formen to the jugulr notch in oth species, where some individuls exhiit displced formen, eing either seprted or together with the notch. This chrcteristic doesn t seem to e relted with development Cervicl vertere In the cervicl vertere, projections on the seventh cervicl vertere (Ce 7 ) ssocited with the trnsversl cnl (= verterrteril cnls), re clled pleuropophisel pltes or cervicl ris (Figures 12). The occurrence of these structures ws higher in S. fluvitilis (87%; n = 31) thn in S. guinensis from CE (9%, n = 23) nd from SC (19%, n = 32). Furthermore, the size of the (%) AM NOR CE SC Figure 9. Vrition of the nterior lcerte formen shpes (fo) oserved in the specimens of genus Sotli: 1- open; 2- with projection spine form; 3- nrrow or prtilly closed. AM- Amzons, CE- Cerá, NOR (smples of AP nd PA together), SC- Snt Ctrin. Figure 10. Locliztion of hipoglossl formen in specimens of the genus Sotli. ) Sotli fluvitilis, the formen cnnot e oserved in ventrl view; ) Sotli guinensis (SC), the formen is dislocted externlly to jugulr notch nd cn e oserved in ventrl view. Structures indicted y the lck rrows. 8 Brz. J. Biol., 69(3): , 2009

9 Non-metric chrcters in Sotli (%) AM NOR CE SC 1 2 Figure 11. Percentge of the occurrence of hipoglossl formen: 1- Hipoglossl formen visile in ventrl view; 2- Hipoglossl formen not visile in ventrl view. AM- Amzons, CE- Cerá, NOR (smples of AP nd PA together), SC- Snt Ctrin. Figure 12. Cervicl vertere from Sotli. ) Seventh cervicl verter (Ce7) of S. guinensis (norml); ) Ce7 of S. guinensis (CE) with cervicl ri on lef side; c) Ce7 of S. fluvitilis (AM) with cervicl ri in oth sides. Structures indicted from rrows. ris is proportionlly smller in the riverine species thn in the mrine species. In S. guinensis, the cervicl ris were generlly oserved only on one side (right or left), while in S. fluvitilis they were oserved on oth sides. The UFSC specimen 1117 exhiited this structure on the on the right side of the third cervicl verter (Ce 3 ). The cervicl ris were oserved in ll ge es. c 4. Discussion 4.1. Fenestre The presence of fenestre commonly oserved in the occipitl region, ner the condyles of Sotli fluvitilis ws lso recorded in juveniles nd dults of Pontopori linvillei (Gervis nd d Origny, 1844) (Pinedo,1991). However, in Pontopori, the of fenestre ws greter thn tht oserved for the genus Sotli. In the genus Sotli, the occurrence of fenestre next to protuernces of the occipitl region ws low compred with the region next to the condyles. In the sioccipitl, the presence of fenestre ws less frequent in immture specimens thn in mture specimens. In Pontopori linvillei nd in Stenell the occurrence of this structure ws rre nd occsionl, respectively (Pinedo, 1991; Perrin et l., 1982). Considering tht the fenestre oserved next to the condyles in S. fluvitilis do not hve the sme origin s the fontnelles present in neworn individuls, given their different loction, the origin nd function of these fenestre re not cler Vomer The crnil floor is not generlly included in morphologic studies nd reveled interesting results. Simões- Lopes (2006), nlysing specimens of S. guinensis in the southern region, oserved tht the lminr posterior process of the vomer is nrrower thn the lmelr pterygoid processes. In the sme study, the uthor found the converse in S. fluvitilis where the vomer is roder nd the lmelr pterygoid processes nrrower. In the present work we verified tht this chrcteristic descried y Simões-Lopes (2006) ws present in the mjority of the mrine specimens nlysed. However, in the smples from CE nd AP, we oserved tht some specimens lso possessed rod vomer, similr to the riverine species, herein clled the wide form. Apprently, this chrcteristic cn e used to distinguish the two species, ut it is importnt to note tht smll percentge of mrine specimens possess rod vomer just s some riverine specimens possess nrrow vomer. Thus, the use of this chrcteristic should e considered in comintion to others when seprting the species. In reltion to the posterior lignment of the vomer, the rrngement nterior to the lmelrs pterygoid processes ws oserved in 100% of the cses for the mrine species. In the riverine species (n = 39), 18% were oserved with the posterior edge of the vomer ligned with the pterygoids, while in nother 18% the posterior edge of the vomer extended eyond the pterygoides. Dwin et l. (1970) ttriute the lignment of the vomer in reltion to the posterior pterygoid processes to ge. For these uthors, in su-dults Peponocephl electr (Gry, 1846) the vomer extends to the level of the sutures etween the pterygoides nd sioccipitl nd in dults, the vomer extends eyond the djcent pterygoides. This Brz. J. Biol., 69(3): ,

10 Fettucci, DC. d Silv, VMF. nd Simões-Lopes, PC. pttern ws not oserved in the current study, since ll dults of S. guinensis were oserved with the posterior suture of the vomer nterior to the pterygoides. Moreover, the vrition oserved in the riverine species does not pper to e relted to ontogenetic development, ut rther to individul vrition Pterygoides The pterygoides were found to e medilly seprted y projection in the tip of the pltines in ll specimens, corroorting the dt found in the literture (vn Bénéden, 1875; Flower, 1885; Mirnd-Rieiro, 1936, d Silv nd Best, 1994; 1996; Avil et l., 2002; Simões- Lopes, 2006). The vrition in the form of the posterior projection of the left pterygoide ws very sutle etween the two species Anterior lcerte formen The nterior lcerte formen is formed y two formens (the optic formen nd the oritorotundum formen). These two structures re divided y wll (Ymgiw, et l., 1999) here clled spike-shped projection. In S. guinensis, the mjority of the dult specimens (etween 72 nd 98%) exhiited this projection etween the optic nd the oritorotundum formen. On the other hnd, the nrrow form ws only oserved in dults, suggesting tht with time, this spiny projection fused with one side of the lcerted formen (s oserved in some mrine specimens). In S. fluvitilis, in contrst, the sence of this projection ws more common (88%), nd could indicte neoteny Hypoglossl formen The loction of the hypoglossl formen vried etween the two species. In S. guinensis the hypoglossl formen generlly meets etween the crest of the sioccipitl nd the proccipitl process, more precisely in the jugulr notch s it occurs in other species of mrine Delphinide, for exmple, Grmpus griseus (Cuvier, 1812) (Ymgiw et l., 1999) nd Tursiops trunctus (Montgu, 1821) (Rommel, 1990). In contrst, the hypoglossl formen in S. fluvitilis, in the mjority of cses, ws found to e internlly displced Cervicl vertere The occurrence of cervicl ris ws higher (87%) in the riverine species. The presence of pleuropophisel pltes ws initilly suggested for some groups of mmmls, especilly monotremes nd mrsupils (Lessertisseur nd Sn, 1967). Unilterl or ilterl processes in the cervicl vertere re common in some groups of mmmls (including Homo), nd the costl rudiments re ssocited with the verterl or verterrteril formens (Lessertisseur nd Sn, 1967). These uthors lso mention their presence in mrine mmmls s Orcinus orc (Linneus, 1758), Tursiops trunctus nd Blenopter sp. Such processes hve een considered serilly homologous to the cervicl ris, lso ppering in the literture s costl pltes or pleuropophisel pltes (Flower nd Lyddeker, 1891). The presence of cervicl ris is n intriguing chrcteristic in comprtive ntomy, s these structures re typiclly oserved in reptiles (Pul Couto, 1979; Ferigolo, 1987). In S. guinensis, these structures hve lredy een reported in out 22.5 % (n = 31) of the specimens of the southern region (Fettucci nd Simões-Lopes, 2004). In this work, considering lrger smple, the oserved frequency of cervicl ris in the specimens from SC ws 19% (n = 33), nd of 9% (n = 23) from CE. Cervicl ris in mmmls re exmples of tvism (reppernce of n extinct chrcter, common to ncestrl lineges tht rrely occur in current popultions). Other cses of tvism re descried in the literture s the occurrence of vestigil posterior memers in whles nd extr-numeric teeth in ts nd se lions (Bejder nd Hll, 2002; Rui nd Drehmer, 2004 nd Drehmer et l., 2004). According to Hll (1984), there re four sic criteri for the recognition of n tvism: 1) persistence of the chrcteristic in dult life; 2) sence of this chrcteristic in the prents or recent ncestors; 3) occurrence in one or few individuls within popultion; nd 4) similrity or identity with the sme chrcter exhiited y ll the memers of the ncestrl popultion. Moreover, if the incidence of the chrcter is still reltively high in popultion, it is considered polymorphism (Hll, 1984). Thus, considering the high occurrence of cervicl ris in specimens of the riverine species, these structures do not pper to e tvistic, suggesting the need for more detiled study with more representtive smple for more consistent conclusion. Acknowledgements The uthors would like to thnk Angel Enzo Crovetto, Césr Drehmer, Fernndo Ross, Len Geise nd two nonymous referees for their helpful suggestions on improving the mnuscript. We would lso like to thnk Nin Best for the English review. Specil thnks to the Museu Prense Emilio Goeldi (MPEG) nd Associção de Pesquis e Preservção de Ecossistems Aquáticos (AQUASIS). This work ws supported y grnts from CNPq nd IEB. References ALVES-JÚNIOR, TT. nd MONTEIRO-NETO, C., Crcterizção morfológic e morfométric crnin do otocinz, Sotli fluvitilis Gervis, 1953, d Cost do Cerá, Brsil. Arq. Ciên. Mr, vol. 32, p ÁVILA, FJC., ALVES-JÚNIOR, TT., PARENTE, CL., VAZ, LAL. nd MONTEIRO-NETO, C., Osteologi do otocinz, Sotli fluvitilis Gervis, 1853, d Cost do Estdo do Cerá, Brsil. Arq. Ciên. Mr, vol. 35, p BEJDER, L. nd HALL, BK., Lims in whles nd limlessness in other vertertes: mechnisms of evolutionry nd developmentl trnsformtion nd loss. Evol. Dev., vol. 4, no. 6, p VAN BÉNÉDEN, E., Mémoire sur un duphin nouveu de l Bie de Rio de Jneiro, désigné sous le nom de Sotli rsiliensis. Mem. Acd. Sc. Royl, vol. 41, p Brz. J. Biol., 69(3): , 2009

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