Sudovian word for "Ossetian"

From: wtsdv
Message: 13959
Date: 2002-07-02

An online Sûdovian (Yatvingian) dictionary
at http://www.suduva.com/virdainas/ gives
"(en) spaliskai" with the meaning "(in)
Ossetian". This word doesn't contain
the usual 'os(s)-', or '(j)as-' element.
Can anybody explain the 'spal-' here?

David