I think 8 months is a little too old to be biting ankles, so I feel your husband's frustration. I also rough-house with our boy, but he knows that body parts are off-limits. So, I'm not sure that it's the style of play that's bringing this on... I think it's more that the behavior has been deemed acceptable, so Gunther continues to do it.
That being said, I don't think him yelling at Gunther is the most effective remedy. That is giving Gunther exactly what he wants--attention. At his age, he is old enough to know better. Any teeth making impact on a body part would result in an immediate 'time out.' Play stops right now, and your husband walks away and ignores him completely (on the flip side, Gunther could also be led to a different room for the time out. Whichever works easiest at the time.)
I would also try to get your husband involved in some of the training. It doesn't have to be anything difficult. But I think training would forge a better bond and show that your husband is something more than a chew toy.