Suggestion of a Cytotaxonomical Classification

Transcrição

1 CARYOLOGIA Vol. 60, no. 4: , 2007 An update Cytogenetic Review for Species of the Families Pseudopimelodidae, Pimelodidae and Heptapteridae (Pisces, Siluriformes). Suggestion of a Cytotaxonomical Classification Swarça 1 * Ana Cláudia, Alberto Sérgio Fenocchio 2 and Ana Lúcia Dias 1 1 Universidade Estadual de Londrina, CCB, Caixa Postal 6001, Londrina, PR, Brasil. 2 Universidad Nacional de Misiones, Depto. de Genética, Félix de Azara 1552, 3300, Posadas, Misiones, Argentina. Abstract Fifty three species (48 species valid) belonging to the Pimelodidae, Heptapteridae and Pseudopimelodidae families have been studied cytogenetically, and in the present paper the chromosome number, the presence of B chromosomes and other relevant data were examined. The diploid number varies from 2n=42 to 2n=58 and were detected three cases of triploids with 3n=87 in Rhamdia species. The karyotypes show a high fundamental number because there are constituted predominantly by meta/submetacentric chromosomes. Key words: cytogenetic, Heptapteridae, Pimelodidae, Pseudopimelodidae. INTRODUCTION Fifteen Neotropical freshwater families compose the Order Siluriformes: Diplomystidae, Cetopsidae, Aspredinidae, Nematogenydae, Trichomycteridae, Callichtydae, Scoloplacidae, Astroblepidae, Loricariidae, Pimelodidae, Heptapteridae, Auchenipteridae, Pseudopimelodidae, Ariidae, Doradidae (REIS et al. 2003). REIS et al. (2003) proposed that a large part of the traditional Pimelodidae was included in a separate family, the Heptapteridae, and another additional group constitutes actually the Pseudopimelodidae with few genera and species described at now. According to BOCKMANN and GUAZZELI (2003) the family Heptapteridae, closely corresponds to the subfamily Rhamdiinae of LUND- BERG et al. (1991) and Heptapterinae of the PINNA (1998) and includes many catfishes long classified together in the Pimelodidae but now placed in a more restricted version of Pimelodidae (LUND- BERG and LITTMANN 2003) and Pseudopimelodidae (SHIBATTA 2003). A recent checklist of catfishes (Order Siluriformes) presented by FERRARIS (2007) proposed that the Heptapteridae family is composed by 24 * Corresponding author: Rua Vila Lobos, 793; Jardim Tucanos; CEP ; Londrina, Paraná, Brazil; szwarcy@bol.com.br genera and 189 valid species, the Pimelodidae by 29 genera and 93 valid species and Pseudopimelodidae by 5 genera and 29 valid species. The aim of the present paper is update the cytogenetic data for species of the families Pimelodidae, Heptapteridae and Pseudopimelodidae and suggest a cytotaxonomical classification. MATERIALS AND METHODS The data here discussed are available from four distinct hydrographic basins (Upper Paraná, Paraguay, São Francisco and Amazon) found in articles, unpublished thesis and congress abstracts. They take into consideration the diploid, triploid and haploid numbers, the presence of B and sexual chromosomes and other relevant data (Tables 1, 2, 3). The classification of the hydrographic basin was performed as described by VARI (1992). Karyological analyses were performed from cephalic kidney cells, with either of the following protocols: short-term culture cells (FENOCCHIO et al. 1991) or the conventional air-drying method (BERTOLLO et al. 1978) and from lymphocyte culture following the technique of FENOCCHIO and BERTOLLO (1988). The diploid number was determined for each specimen studied (Tables 1, 2, 3). The chromosomes were classified as metacentrics (m), submetacentrics (sm), subtelocentrics (st) and acrocentrics (a) according to their morphology

2 cytogenetic review for species of the families pseudopimelodidae, pimelodidae and heptapteridae 339 Table 1. Cytogenetic data on the Pimelodidae Family Genera, Species Locality HB n 2n Karyotype FN Bs Size B HS References Bergiaria B. westermanni R. São Francisco, MG SF 56 42m,sm + 14st small Dias and Foresti (1993) Calophysus C. macropterus R. Negro; R. Solimões, AM AM 50 22m+18sm+10a (90) Ramirez-Gil et al. (1998) Iheringichthys I. labrosus R. Mogi-Guaçu, SP UP 56 26m+14sm+12st+4a 96* 0-2 micro Dias and Foresti (1990) I. labrosus R. Paraná, PR UP 56 42m,sm+42st,a 98 Garcia et al. (1990) I. labrosus R. Tibagi, PR UP 56 32m+8sm+6st+10a (96) 0-3 micro Carvalho et al. (2004) I. labrosus D. Jurumirim, SP UP 56 22m+18sm+10st+6a acrocentric Vissotto et al. (1999b) Parapimelodus P. valenciennes R. Guaiba, RS PA 56 Costa and Reggi (1986) Pimelodus P. blochii R. Solimões, AM AM 58 Della-Rosa et al. (1980) P. blochii PA 56 36m/sm+20st/a 92* Faria et al. (2000) P. blochii 36m/sm+20st/a 92* PA 56/58 14m+8sm+36a 80* Silva et al. (2004) P. clarias Argentina PA 56 Fenocchio et al. (1994) P. clarias Uruguai PA 26 Gonzales (1994) P. fur 56 30m+14sm+12a 100* Toledo and Ferrari (1976b) P. fur R. São Francisco, MG SF 54 32m+8sm+6st+8a (94) Garcia and Moreira Filho (2005) P. maculatus 56 30m+14sm+12a 100* Toledo and Ferrari (1976b) P. maculatus R. São Francisco, MG; SF; R. Mogi-Guacu, SP UP 56 40m,sm+16st,a 96 Dias and Foresti (1993) P. maculatus R. Guaíba, RS PA 56 Costa and Reggi (1986) P. maculatus R. Tibagi, Pr UP 56 20m+20sm+10st+6a (96) Swarça et al. (2001b) P. maculatus R. Sapucaí; D. Furnas, MG UP 56 40m/sm+16st/a 96 Marques et al. (1998) P. maculatus R. Paranapanema; D. Jurumirim, SP UP 56 20m+20sm+10st+6a 96 Vissotto et al. (1999a) P. maculatus Delta Paranaense, Arg. UP 56 24m+14sm+12st+6a 94* Heras and Mendoza (2002) P. maculatus R. Paraguai, MS PA 56 22m+16sm+10st+8a (94) Souza et al. (2003) P. maculatus R. São Francisco, MG SF 56 32m+12sm+12st (100) Garcia and Moreira Filho (2005) P. maculatus R. Paraná, Porto Rico/PR UP 56 20m+20sm+10st+6a (96) Borin and Martins-Santos (2002) P. cf. maculatus R. Jarí Almerim, PA 58 30m/sm+28st/a 88* Souza et al. (2000) P. maculatus R. Tejuco; R. Araguari, MG UP 56 Moreira et al. (2004) P. ornatus R. Paraná, PR UP 56 18m+22sm+6st+10a 96* Abucarma and Martins-Santos (1996) P argenteus R. Paraguai, MS PA 56 24m+16sm+12st+4a (96) Souza et al. (2003a) P. mysteriosus R. Paraguai, MS PA 56 26m+20sm+2st+8a (102) Souza et al. (2003a) P. heraldoi R. Tibagi, PR UP 56 22m+22sm+6st+6a (100) Souza et al. (2004) P. ortmanni Caxias Reservoir, R, Borin and UP 56 24m+18sm+8st+6a 98* 1-4 small Iguaçu, PR Martins-Santos (2004) P. absconditus R. Paraná, Porto Rico/PR 56 24m+18sm+8st+6a (98) Borin and Martins-Santos (2002) P. ornatus R. Paraná, Porto Rico/PR 56 20m+18sm+8st+10a (94) Borin and Martins-Santos (2002) P. sp 56 30m+14sm+12a 100* Toledo and Ferrari (1976b) P. sp 26 Scheel (1973) P. sp R. São Francisco,MG SF 56 40m/sm+16st/a 96* Dias and Foresti (1993) P. sp R. São Francisco, MG SF 56 32m+12sm+6st+6a (100) Garcia and Moreira Filho (2005) P. sp R. Iguaçu, PR UP 56 24m+26sm+4st+2a (106) Souza et al. (2004) P. sp Caxias Reservoir, R, Iguaçu, PR UP 56 30m+14sm+8st+4a 100* 0-4 small Borin and Martins-Santos (2004) Pinirampus P. pirinampu R. Paraná, PR UP 50 22m+12sm+4st+12a (84) Vasconcelos and Martins-Santos (2000) P. pirinampu R. Tibagi, PR UP 50 26m+12sm+2st+10a (88) Swarça et al. (1999) P. pirinampu R. Paraná, Corrientes, ARG UP 50 18m+14sm+4st+14a (81) Sanchez and Fenocchio (2005) P. pirinampu R. Araguari, MG SF 50 Molina and Morelli (2004) For abbreviations see legend to table III.

3 340 swarça, fenocchio and dias Genera, Species Locality HB n 2n Karyotype FN Bs Size B HS References Luciopimelodus L. pati R. Paraná, Corrientes, ARG UP 50 16m+14sm+8st+12a (80) Sanchez and Fenocchio (2005) Megalonema M. platanum R. Paraná, Corrientes, ARG UP 54 14m+18sm+12st+10a 98 Sanchez and Fenocchio (2005) Hemisorubim H. platyrhynchos R. Paraná, PR UP 56 22m+18sm+6st+10a (96) Martins-Santos et al. (1996) H. platyrhynchos PA 56 20m/sm+8st/a Faria et al. (2000) H. platyrhynchos PA 56 Silva et al. (2004) Pseudoplatystoma P. coruscans R. Paraná, PR UP 56 18m+16sm+10st+12a (90) Martins-Santos et al. (1996) P. coruscans Coxim, MS PA 56 42m/sm+14st/a (98) Souza et al. (1992) P. coruscans R. Mogi-Guaçu,SP UP 56 18m+18sm+10st+10a 92* Bigoni et al (1992) P. coruscans D. Tres Marias, MG SF 56 20m+12sm+12st+12a (88) Fenocchio (1993) P. corruscans R. Paraguai, MS PA 56 20m+16sm+8st+12a (92) Swarça et al. (2005b) P. corruscans R. Paraná, Jupiá/SP; R. Paraná, PR UP 56 26m+10sm+6st+14 a (92) Swarça et al. (2005b) P. fasciatum R. Solimões, AM AM 56 18m+14sm+10st+14a (88) Fenocchio and Bertollo (1992) P. tigrinum R. Solimões, AM AM 56 18m+16sm+8st+14a (90) Fenocchio and Bertollo (1992) Paulicea/Zungaro P. luetkeni R. Paraná,PR UP 56 26m+10sm+6st+14a (92) Martins-Santos et al. (1996) Z. zungaro R. Paraná, Jupiá, SP UP 56 32m+6sm+8st+10a (94) Swarça et al. (2001a) Sorubim Silva et al. (2004) S. lima R. Solimões, AM AM 56 18m+12sm+14st+12a 86 Fenocchio and Bertollo (1992) S. lima R. Paraná,PR UP 56 20m+14sm+10st+12a (90) Martins-Santos et al. (1996) S. lima PA 56 Steindachneridion S. scriptum R. Paranapanema, R. Tibagi, PR UP 56 24m+20sm+4st+8a (100) Swarça et al. (2005a) S. melanodermatum R. Iguaçu,PR UP 56 20m+24sm+2st+10a XX/ 21m+23sm+2st+10a (100) XY Swarça et al. (2006) For abbreviations see legend to table III. Table 2. Cytogenetic data of the Heptapteridae Family Genera, Species Locality HB n 2n 3n Karyotype FN Bs Size B HS References Pimelodella P. kronei Iporanga, SP UP 58 54m/sm+4st (112) 1 micro Almeida-Toledo et al. (1992) P. transitoria Iporanga, SP UP 58 54m/sm+4st (112) Almeida-Toledo et al. (1992) P. sp R. Mogi-Guaçu, SP UP 46 40m/sm+6st/a 86 XX/ XY Dias and Foresti (1993) P. sp R. Mogi-Guaçu, R. Pardo, SP UP 46 28m+10sm+8a 84 Toledo and Ferrari (1976a) P. sp R. Araquá;R. Capivara, SP UP 46 32m,sm+14st/a 78* Braga (1989) P. sp Argentina PA 46 Fenocchio et al. (1994) P. sp R. Tibagi, PR UP 46 34m/sm+12st/a 80* Silva et al. (1996) P. sp1 R. Paraná, PR UP 46 20m+20sm+6st (86) Vasconcelos and Martins-Santos (2000) P. sp2 R. Paraná, PR UP 52 22m+22sm+8st (96) Vasconcelos and Martins-Santos (2000) P. avanhandavae R. Araquá; R. Capivara, SP UP 46 20m+20 sm+6 st 86 Vissotto et al. (1999a) P. avanhandavae R. Machado, MG 58 48m+10st Pereira and Maistro (2002) P. aff. avanhandavae R. Tibagi, PR UP 52 30m+22sm (82) Swarça et al. (2003) For abbreviations see legend to table III.

4 cytogenetic review for species of the families pseudopimelodidae, pimelodidae and heptapteridae 341 Genera, Species Locality HB n 2n 3n Karyotype FN Bs Size B HS References P. meeki R. Tibagi, R. Couro do Boi; R. Gabriel da Cunha, PR UP 46 30m+12sm+4st (88) Vidotto et al. (2004) P. cristata PA 52/46 36m/sm+20st/a 92* Faria et al. (2000) P. gracilis R. Paraguai, MS PA 52 Mazzuchelli et al. (2004) Rhamdella R.sp Itaetê, BA SF 56 26m/sm+30st/a 82* Souza et al. (1994) R. microcephala R. Machado, MG SF 56 18m+30sm+8st 104 Fonseca et al. (2003) Cetopsorhamdia C. iheringi D. Três Marias, MG; SF; R. das Marrecas, SP UP 58 22m+16sm+10st+10a 96* Fenocchio et al. (2003a) C. iheringi R. Capivara, R. Pardo, SP UP 58 28m+24sm+6st 110 Vissotto et al. (1999a) C. sp b. Canta Galo, SP UP 58 22m+16sm+10st+10a 96* Fenocchio et al. (2003a) Rhamdia R. hilarii R. Onça, SP UP Toledo and Ferrari (1976a) R. hilarii D. Monjolinho, SP UP 58 > small Fenocchio and Bertollo (1990) R. hilarii D. Lobo, SP UP 58 > small Fenocchio et al (2000) R. hilarii D. 29, SP UP 58 > small Fenocchio et al. (2000) R. hilarii R. Mogi-Guaçu, SP UP 58 >100 Fenocchio et al. (2000) R. hilarii R. São Francisco, MG SF 58 > small Fenocchio et al. (2000) R. hilarii R. Aguapey, Corrientes, ARG PA 58 26m+16sm+8st+8a (100) Fenocchio et al. (2003a) R. hilarii L. Nova; L. Jataí, SP UP 58 > small Fenocchio (1993) R. hilarii R. Mogi-Guaçu, SP UP 58 58m/sm 116* 0-2 medium Maistro et al. (2002) R. cf. hilarii S. Hortelã, S. Quinta, R. Araquá, b. Jacutingá, R. Pardo, S. Jurumirim, SP UP 58 30m+18sm+10st metacentric Vissotto et al. (1999b) R. sp Sapucaí, D. Furnas, MG SF Andrade et al (1998) R. sp R. Iguaçu, Usina de Salto Segredo, PR UP 58 36m+14sm+4st+4a (108) 0-2 small Abucarma et al. (2001) R. sp S. Grande, SP UP 58 46m/sm+12st 104* 0-4 metacentric Garcia et al. (2003) R. sp S. Grande, SP UP 87 69m/sm+18st 156* Garcia et al. (2003) R. sp R. São João, PR UP 58 26m+10sm+10st+12a 94* Roman et al. (2001) R branneri R. Iguaçu, Usina de Salto Segredo, PR UP 58 36m+14sm+4st+4a (108) 0-4 medium Abucarma et al. (2001) R. branneri R. iguaçu, PR UP 58 30m+10sm+14st+4a 98* 0-4 medium Roman et al. (2002a) R. voulezi R. Iguaçu, Usina de Salto Segredo, PR UP 58 36m+14sm+4st+4a (108) 0-2 medium Abucarma et al. (2001) R. voulezi R. Iguaçu, Quedas do Iguaçu, PR UP 58 30m+10sm+14st+4a 98* Roman et al. (2001) R. quelen R. Iguaçu, PR UP 58 32m+16sm+ 6st+4a (106) 0-1 small Fenocchio et al. (2003b) R. quelen R. Paraná, Posadas, ARG PA 58 26m+16sm+8st+8a (100) Fenocchio et al. (2003a) R quelen L. Nova and Jataí, SP UP small Fenocchio (1993) R. quelen R. Guaíba; Hochberg and Erdtmann PA 58 52m,sm,st+6a small L. dos Quadros, RS (1988) R. quelen R. Iguaçu, Porto União, SC UP Fenocchio et al. (2000) R. quelen R. Tibagi, PR UP Carvalho and Dias (2001) R. quelen R. Taquarussu, SP UP 58 26m+20sm+6st+6a 104* 1-4 medium/ Stivari and large Martins-Santos (2004) R. quelen S. Maringá, PR UP 58 26m+22sm+6st+4a 106* Stivari and 26m+24sm+8st 108* Martins-Santos (2004) R. quelen B. Sarandi, L. Fragata, Canal São Gonçalo, B. Santa Izabel, RS Born (2002) R. quelen S. Lindóia, Londrina, PR UP 58 30m+14sm+10st+4a (102) Tsuda (2005) R. quelen S. Lindóia, Londrina, PR UP 87 45m+21sm+30st+12a 174* Tsuda (2005) R. quelen R. São Francisco, MG SF 58 40m+6sm+8st+4a (104) 0-4 meta/micro Garcia (2005) R. quelen R. Uberabinha, MG SF Guilherme et al. (2004) R. quelen R. Aguas das Pedras, PR UP 58 Mattanó and Dias (2004) R. sapo Buenos Aires, Arg PA 58 44m/sm+14st/a medium Valcarcel et al. (1993) R. sapo Uruguai PA Gonzales (1994) Heptapterus H. longicauda S. Quinta, SP UP 52 22m+26sm+4st 100 Vissotto et al. (1999a) For abbreviations see legend to table 3.

5 342 swarça, fenocchio and dias Genera, Species Locality HB n 2n 3n Karyotype FN Bs Size B HS References Imparfinis I. piperatus R. São João, SP UP 56 56m,sm 112* Vicente et al. (1994) I. cf. piperatus R. Juquiá, SP UP 56 24m+12Ssm+20st (92) Fenocchio et al. (2003a) I. cf. piperatus R. Juquiá, SP UP 56 22m+26sm+4st+4a 104 Vissotto et al. (2001) I. piperatus R. Araras, SP UP 58 32m+26sm 116 Vissotto et al. (2001) I. piperatus R. Grande, SP UP 58 26m+22sm+8st+2a 106 Vissotto et al. (2001) I. aff. schubarti b. Canta Galo, SP UP 58 22m+16sm+10st+10a (96) Fenocchio et al. (2003a) I. aff. schubarti R. Tibagi, PR UP 58 28m+28sm+2st (114) Stolf et al. (2004) I. mirini b. Jacutingá, S. Quinta, SP UP 58 24m+34sm 116 ZZ/ ZW Vissotto et al. (1997) Pariolius P. cf. longicaudus R. Tibagi, PR UP 52 22m+16sm+4st+10a 90* Garcia et al. (2004) P. hollandi R. Iguaçu, PR UP 42 22m+10sm+4st+6a 74* Roman et al. (2002b) For abbreviations see legend to Table 3. Table 3. Cytogenetic data of the Pseudopimelodidae Family Genera, Species Locality HB n 2n Karyotype FN Bs Size B HS References Lophiosilurus L. alexandri D. Três Marias, MG 54 54m/sm/st/a Marques et al. (2002) Microglanis M. garavelloi r. Araquá, R. Capivara, SP UP 54 22m+20sm+12st 96* Vissotto et al. (1999b) Pseudopimelodus P. bufonius R. Capim, Pará 54 18m+22sm+6st+8a 94* Souza et al. (2003b) P. mangurus R. Mogi-Guaçu, SP 54 6m+26sm+12st+10a 86* Martinez et al. (2004) P. zungaru R. São Francisco, MG SF 54 30m+14sm+10a (98) Garcia (2005) HB = Hydrografic basin; n = haploid number; 2n = diploid number; FN = fundamental number; Bs = supernumerary chromosome; HS = heterogametic Sex; m = metacentrics; sm = submetacentrics; st = subtelocentrics; a = acrocentrics; R. = river; b = brook; L. = lagoon; D = Dam; PA = Paraguay; UP = Upper Paraná; SF = São Francisco; AM = Amazon; MG, AM, SP, PR, RS, MS, MT, BA = Brazilian states; () FN recalculated; * FN calculated and arm rates (LEVAN et al. 1964). In order to determine the NF we considered as monoarmed only the acrocentric ones. RESULTS AND DISCUSSION Along the last thirty years, from the first description of the chromosomal number of a Pimelodidae specie, in 1973 by SCHEEL, until 2006, were analyzed cytogenetically twenty four genera and fifty three species (48 species valid) of Pimelodidae, Heptapteridae and Pseudopimelodidae families. These numbers were increased in four genera and seventeen species from the last revision made by SWARÇA et al. (2000) and at now the diploid number varies from 2n=42 to 2n=58, not considering the diploid number of 2n=62 in Rhamdia hilarii described by TOLEDO and FERRARI (1976a). Additionally have been found three cases of triploids with 3n=87 in Rhamdia branneri (RO- MAN et al. 2002) Rhamdia sp (GARCIA et al. 2003) and Rhamdia quelen (TSUDA 2005). In the present study to compare the fundamental number (FN) of all species some of them were recalculated (in parentheses) and the others were calculated for the first time (asterisk), considering M and SM with two arms and ST-A with one arm. The three families have a relatively high FN (from 74 to 116), due to the predominance of biarmed chromosomes and not considering the triploids and supernumerary chromosomes (Tables 1, 2, 3). In the family Pimelodidae 23 of the 27 karyotyped species, have a diploid number of 2n= 56 chromosomes, being exceptions Calophysus macropterus. Luciopimelodus plati and Pinirampus pirinampu with 2n=50 and Megalonema platanum with 2n=54, which seems to be share another characteristics (Table 1). The species with 56 chromosomes could be divided in two groups, the Pimelodus group and the Sorubiminae group (=Sorubinae), according to their particular cytogenetic attributes, i.e., the NORs localized on one single chromosome pair but in the first one in terminal position in long arm, and in the second one in terminal position of short arms (FEN- OCCHIO et al. 2003a) (Fig. 1). Karyotypes with 56 chromosomes represent a conservated character for this family, reinforcing previous observations of LE GRANDE (1981) and

6 cytogenetic review for species of the families pseudopimelodidae, pimelodidae and heptapteridae 343 Fig. 1. Hypothetical phylogenetic tree modified from LUNDBERG et al. (1988; 1991) and FENOCCHIO et al. (2003a); based in new available cytogenetic data. The interrogation signs suggest probable dichotomy ways of branch. Asterisks indicate cytogenetically studied species. KLINKHARDT (1998). OLIVEIRA and GOSZTONYII (2000) reported that in thirteen genera of Siluriformes have been reported 2n=56, suggesting that this could be the basal chromosome number for the Order. However, as in some groups have been few available cytogenetic data, generalizations should be carefully revised. The variability in chromosome number is greater among species of the family Heptapteridae ranging from 2n=42 in Pariolius to 2n=58 in Rhamdia hilarii (Table 2) and this feature suggests that extensive chromosomal rearrangements were involved in speciation within this group. In this family were analyzed twenty-two species, twelve having 2n= 58 (more than 50%). The family Pseudopimelodidae is smaller than Pimelodidae and Heptapteridae with only forty species and cytogenetic data on this group of fish are scarce and relatively hard to collect, where only three genera and five species were analysed all of them with 2n=54 chromosomes (Table 3). Mistakes and changes in specific names are a frequent trouble in this group, i. e. in a recent taxonomic revision of the genus Steindachneridion was described Steindachneridion melanodermatum (GARAVELLO 2005), endemic from the Iguaçu river (Paraná State, Brazil), this specie was cytogenetically characterized by SWARÇA et al. (2006), being named by the authors as Steindachneridion sp. Another case is Microglanis garavelloi from upper Paraná river, identified as new species by SHIBATTA and BENINE (2005) but that had been katyotypically studied as M. cottoides by VISSOTO et al. (1999). The genus Rhamdia also shows cases of synonymy, being reported cytogenetic studies about R. voulezzi and R. branneri, that are considered synonymous of R. quelen (SILFVERGRIP 1996). Have been reported cases with two diploid numbers Pimelodus blochii of Solimões River and Araguaia River with 2n=58 and 56 respectively, and Pimelodus fur with 2n=54 and 56 chromosomes (Table 1), but the taxonomic identification of these species as well as the numbers should be revised. In the Pimelodidae family, B chromosomes have been identified in Bergiaria westermanni, Iheringichthys labrosus, Pimelodus ortmanni, Pimelodus sp (Table 1), and in the Heptapteridae family in Pimelodella kronei, Rhamdia hilarii, Rhamdia sp, R. branneri, R. voulezi, R. quelen, R. sapo (Table 2). This extra chromosome is highly

7 344 swarça, fenocchio and dias conserved in the genus Rhamdia being found in several populations of these species along a wide geographic area. Systems of sexual chromosomes have been reported only in Steindachneridion melanodermatum (Pimelodidae) (Table 1) and Pimelodella sp (Heptapteridae) (Table 2) where the male is the heterogametic sex, possessing a system of the type XX/XY. VISSOTTO et al. (1997) described in Imparfinis mirini a ZZ/ZW system, but later the same authors rectified the first information (VIS- SOTTO 2000). At now the only confirmed sex chromosome system in Pimelodidae corresponds to S. melanodermatum (SWARÇA et al. 2006). Among all the species analyzed (Tables 1 and 2), Pimelodus maculatus, Rhamdia hilarii and Rhamdia quelen, are the most studied until now, demonstrating, a very wide geographic distribution of these species along the South American river basins associated with a very high facility of capture. According to REIS et al. (2003) the Heptapteridae family is composed by 238 species (valid and undescribed), the Pimelodidae by 128 and Pseudopimelodidae by 40, but were analyzed citogenetically only around fifty species in these three families of Siluriformes, this fact demonstrates that more species must be studied to increase the number of cytogenetic data for a better understanding of the species relationships and karyotypic evolution in this fish group. In spite of this, could be suggested a preliminary version of a phylogenetic tree, on the basis of available phylogenetic data and the chromosome features summarized in the present paper (Fig. 1). REFERENCES ABUCARMA M. and MARTINS-SANTOS I.C., 1996 Caracterização cromossômica de duas espécies da família Pimelodidae (Pisces, Siluriformes). In: Proceedings of VI Simpósio de Citogenética Evolutiva Aplicada a Peixes Neotropicais, São Carlos SP. pp. 73., 2001 Karyotype and B Chromosome of Rhamdia species (Pisces, Pimelodidae) Endemic in the River Iguaçu Basin. Cytologia, 66: ALMEIDA-TOLEDO L.F., FORESTI F., TRAJANO E. and TO- LEDO FILHO S.A., 1992 Cytogenetic analysis of the Brazilian blind catfish Pimelodella kronei and of its presumed ancestor Pimelodella transitoria. Caryologia, 45: ANDRADE S.F., MAISTRO E.L., OLIVEIRA C. and FAUSTO F., 1998 Caracterização cromossômica da espécie Rhamdia sp. (Pisces, Pimelodidae), proveniente do Rio Sapucaí, Represa de Furnas, MG. In: Proceedings of 44º Congresso Brasileiro de Genética, Águas de Lindóia, SP. pp. 66. BIGONI A.P.V., ALMEIDA-TOLEDO L.F. and TOLEDO FIL- HO S.A., 1992 Estudos citogenéticos em Pseudoplatystoma corruscans (Pimelodidae, Sorubiminae) do rio Mogi-Guaçu, SP. In: Proceedings of IX Simpósio de Citogenética Peixes Neotropicais pp. 32. BOCKMANN F.A. and GUAZZELI G.M., 2003 Family Heptapteridae (Heptapterids). Pp In: R.E. REIS, S.O. KULLANDER and C.J. FERRARIS JR (eds). Check list of the freshwater fishes of South and Central America. Edipucrs, Porto Alegre. BORIN L.A. and MARTINS-SANTOS I.C., 2002 Cytogenetic aspects in species of the genus Pimelodus (Pisces, Siluriformes, Pimelodidae) of the river Paraná Basin. Cytologia, 67: , 2004 Study on karyotype and occurrence of B chromosomes in two endemic species of the genus Pimelodus (Siluriformes, Pimelodidae) from the River Iguaçu. Hereditas, 140: BORN G.G., 2002 Análise citogenética de Rhamdia quelen (Pisces, Rhamdiidae) da região sul do Rio Grande do Sul. In: Proceedings of IX Simpósio de Citogenética e Genética de Peixes, Maringá, PR pp. 79. BRAGA M.A., 1989 Estudos citogenéticos em Pimelodella sp. (Pisces, Siluriformes). Monografia de Bacharelado, Instituto de Biociências, UNESP Botucatu, SP. CARVALHO R.A. AND DIAS A.L., 2001 Caracterização citogenética de Rhamdia quelen (Pisces, Rhamdiidae) proveniente da bacia do Rio Tibagi/PR. In: Proceedings of Congresso Nacional de Ictiologia, p. 73. CARVALHO R.A., GIULIANO-CAETANO L., DIAS A.L., 2004 Cytogenetic Analysis of A- and B- Chromosomes of Iheringichthys labrosus (Pisces, Pimelodidae) from the Tibagi River, Paraná, Brazil. Cytologia, 69(4): COSTA L.J. and REGGI R., 1986 Estudos preliminares de duas espécies da família Pimelodidae: Pimelodus maculatus e Parapimelodus valenciennes do rio Guaiba, RS. In: Proceedings of I Simpósio de Citogenética Evolutiva Aplicada em Peixes Neotropicais, São Carlos, SP. pp. 34. DELLA-ROSA V.A., BERTOLLO L.A.C., FERRARI I., TAKA- HASHI C.S., MOREIRA FILHO O. and FORESTI F., 1980 Estudos citogenéticos de peixes da Amazônia. II. Ordem Siluriformes. Ciênc. Cult. 32:735 (proceedings). DIAS A.L. and FORESTI F., 1990 Algumas considerações a respeito do cariótipo de Iheringichthys labrosus (Siluriformes, Pimelodidae) do rio Mogi-Guaçu. In: Proceedings of III Simpósio de Citogenética Evolutiva Aplicada em Peixes Neotropicais., Botucatu, SP. pp. 32., 1993 Cytogenetic studies on fishes of the family Pimelodidae (Siluroidei). Rev. Bras. Genet., 16: FARIA A.A., BRITO J.G. and VENERE P.C., 2000 Citogenética de Pimelodidae: Caracterização cromo-

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