Marie-Agnès Letrouit-Galinou (née Galinou; born 1931) is a French botanist, mycologist, and lichenologist, known for her contribution to revolutionizing the scientific understanding of ascomycete development and classification.
David L. Hawksworth refers her as one of Chadefaud's "gang of four" — consisting of her with André Bellèmere, Marie-Claude Janex-Favre, and Agnès Jarguey-Leduc.
[2] In the early part of her career she worked at Rennes with Henry Nicollon des Abbayes and was strongly influenced by him in her study of lichen systematics and ecology.
In 1993 she worked closely with David L. Hawksworth in planning NATO's Advanced Research Workshop on "Ascomycete Systematics" held in Paris.
At the "Ascomycete Systematics" Workshop the lichenological "gang of four" presented a summary of their now famous results and the concepts introduced by Chadefaud.