Spartans at Adrianople in 378 AD?

[qcarr]

Several sites on the Web claim that a Spartan phalanx fought for the Romans at Adrianople in 378 AD. Here is an example from Wikipedia (the first place I noticed this):

"Purportedly, following the disaster that befell the Roman Imperial Army at the Battle of Adrianople (378 AD), a Spartan phalanx met and defeated a force of raiding Visigoths in battle. There is, however, no genuine evidence of this occurring."

Does anyone know where this statement comes from? Is there primary source evidence? I have not read Marcellinus' account of the battle - does he mention the Spartans?

Thanks for any help anyone can provide!