Marginipes is the smaller of the two. I call it yellow foot. And ciliata I call white foot. This is for obvious reasons. Displaying or fighting males in flight hold their legs forward, a striking feature. Fresh specimens have all white abdomens, a cause of confusion for the unwary. And immature specimens of P. ciliata have reddish legs, another cause of confusion.
|Pseudocopera ciliata, male, with striking white legs and blackish knees|
|Female Pseudocopera ciliata, with reddish legs|
|Copera marginipes, male, with striking yellow legs|
|Still immature male with whitish abdominal segments, but thorax and legs already of mature coloration|