Canonically? Do you have a reference? The writeup I have of them is credited to Greg Videll and is labeled as non-canon. Hans
"Darmine: Cultural region in the Zarushagar sector. Darmine had a separate but submerged cultural identity within the First Imperium and happily threw off that dominion when the First Imperium fell. Allowed to flourish by the Rule of Man, the community of worlds survived the Long Night with little harm." MT IE p 22.
Per MT RM p102 Mega Traveller 'Cultural Regions' of the Imperium are 'Regions which historically developed independent cultures and which have retained their cultural identity under the Imperium.'
The list includes Antares (just a culture), Sylea (human minor race), Vland (major human race), Vega (non-human minor race) and the Darmine. Thus Darmines inclusion on the list does not prove that they are a minor human race.
The older online Traveller library data says:
Darmine Cultural Region
Cultural region in Zarushagar sector. Darmine had a separate but submerged cultural identity within the First Imperium and happily threw off that domination when the it fell. Allowed to flourish by the Rule of Man, the community of worlds survived the Long Night with little harm.
The first Darmine Corporate, an economic consortium, existed from -1643 to 100 and covered about five subsectors. This interstellar common market came to an end during the Ilelish Pacification Campaign (76 to 120); indeed, the Darmine Corporate was the major focus of that campaign.
The main world of the Darmine region is Ishag ( Lias / Zarushagar 1323). A peculiarity of that world is that the natives do not use an "ian" or "er" suffix.
UWP (1120): B525986-A N Hi In 515DCs.
http://web.archive.org/web/20091027...et.au/~davidjw/libdata/alphabet/d/darmine.htm
The Darmine are mentioned in articles Greg did for Challenge magazine, but they were later (TNE era) articles. I'll leave it to you to decide their canonicity. Greg says that the Darmine language is known as 'Kadli'.
If you accept the Darmine homeworld data below than they couldn't be merely a culture, since it would take a minor human race or a non-human race to breathe the air:
Ishag 1323 Zarushagar. Second Survey Statistics
Ishag 1323 B525966-A N Hi In 515 Im G1 V
I wrote my own non-cannonical version of the Darmine in the 1990's. Basically they're delusional numerological obsessed, nymphomanical, borderline OCD, green-haired (due to the chelation of the heavy metals, especially copper, that taint Ishags air), bisexual, merchants. My motto was 'If they're not annoying, you're not playing them right.'