Here's a couple of episode stills from the Parks and Recreation Season 5 Episode 9 Ron and Diane. Promo images are courtesy of NBC and TV|Line. Photographer: Chris Haston. Unfortunately we don't have a clear shot of Lucy as Diane (except for the one photo where she's partially hidden (Photo #1) and the others it's either the back of her head or blurry.
Is it significant that both "Diane" and "Tammy Two" are both wearing red?
Ron (Nick Offerman), Diane (guest star Lucy Lawless), and Leslie (Amy Poehler) attend a wood working awards dinner, after one of Ron's handcrafted chairs is nominated, but the happy occasion is threatened by the arrival of Tammy II (guest star Megan Mullally).
Source: TV|Line and NBC
For more about Lucy's role as Diane on Parks and Recreation Season 5 visit the AUSXIP Lucy Lawless Parks and Recreation subsite