In an example from a book I'm reading, they talk about a loss of a conditioning environment creating a new phoneme.

Old Irish "man": wyiryi > wyiry

The reasoning is that the word final front vowel "i" which triggered the palatalization was lost, but the palatalization of r (ry) remained. They claim that this makes ry a new phoneme.

Is this true? I thought you needed a minimal or near-minimal pair to support the existence of a phoneme in a language.