Amauromyza labiatarum

I initially misidentified this as Amauromyza morionella as I wrongly interpreted the narrowness of the initial gallery. Photos of labiatarum mines that I had looked at seemed to all show the gallery narrow all the way to where it formed a blotch whereas mine clearly broadened out for most of its pre-blotch length, but the mistake was mine because the very start of the gallery on mine was indeed narrower than it would have been on morionella. Thanks to Barry (I assume?) at the Agromyzidae Recording Scheme for putting me right.

The adult mine finished developing pretty quickly after I found it and the larva had pupated within 4 days (possibly less), and the adult emerged within another 4 weeks. I keyed the adult out using the keys at the Agromyzidae Recording Scheme and whilst the undarkened yellow halters and the apparent absence of presutural dorso-central bristles had me question the genus, the genus key worked pretty well considering it was a female. The only point I really hesitated at was the frons colour - darker than I thought was implied by the key's "pale brown or slightly darker" - on a cursory look I thought it was black, though a more careful look did reveal a hint of dark brownish yellow.

Amauromyza labiatarum leaf-mine and larva in Hedge Woundort, North Elmham railway (Norfolk, UK), 16th October 2021

same Amauromyza labiatarum leaf-mine having developed the blotch-end, 17th October 2021

pupa from the same Amauromyza labiatarum leaf-mine, 20th October 2021

adult Amauromyza labiatarum emerged from the above leaf-mine and pupa, 17th November 2021

I think this leaf-mine in White Dead Nettle is also this spcecies, though always welcome confirmation or correction.

Amauromyza labiatarum leaf-mine in White Dead Nettle, St Mary's churchyard, North Elmahm, 5th November 2021