It's interesting to me that you say they were sold as rhabdotus, because one of the rhabdotus group/complex would have been my runner up choice, if pressed.
They are very similar to Gymno australis, Gymo sp. cuna piru, or Gymno sp. verna.
To me, many in the G braziliensus and Gymno rhabdotus are easy to confuse with each other.