TY  - JOUR 
T1  - Karyotype description and evidence of multiple sex chromosome system X1X1X2X2/X1X2Y in Potamotrygon aff. motoro and P. falkneri (Chondrichthyes: Potamotrygonidae) in the upper Paraná River basin, Brazil
JO  - Neotropical Ichthyology
A1  - Cruz, Vanessa Paes da
A1  - Shimabukuro-Dias, Cristiane Kioko
A1  - Oliveira, Claudio
A1  - Foresti, Fausto
SN  - 1679-6225
UL  - 10.1590/S1679-62252011000100020
VL  - 9 
Y1  - 2011
PB  - Brasil 
ER  -