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Thanks again, John!

I found some perfect photos of both species, but I am not sure what black spot we are talking about to separate the two species.

https://diptera.info/photogallery.php?photo_id=10565
https://www.discoverlife.org/mp/20p?act=zoom&img=/DL/IM/I_HHGA/0002/640/Nephrotoma_ferruginea_m,I_HHGA277.jpg?449,208

And I include cropped photo of my specimen. Not perfect because I couldn't get any nearer.