Kees
Bramwell & Bramwell has an useful key.
"3. Plants glabrous or subglabrous
9. Leaf-margins with purple crenulations..............A. punctatum
9. Leaf-margins without purple crenulations.........A. pachycaulon"
Bramwell advises that the only Aichryson species found on La Gomera are A. laxum, A. parlatori, A. punctatum and A. pachycaulon subsp. gonzalez-hernandezii.
I can provide more text if required.
Frazer