Caenoplana sp. (undescribed species);
Volusia county, Florida (26 October 2013).
Learn more about this taxa at iNaturalist.org.
I solicited identification help for this species on Twitter and received this reply from Jean-Lou Justine (https://twitter.com/Plathelminthe4):
“After consulting Leigh Winsor, who is a real flatworm maestro, this is an undescribed species of the genus Caenoplana. Known from various localities such as Queensland (Australia), Florida, Guadeloupe. Country of origin unknown.”