Endophytic fungi are expected to be hyperdiverse in tropical forests, and here is an article exploring their diversity, hidden in Rubiaceae leaves, in two old-growth forests of Costa Rica. Humberto Castillo-González et al. not only described their diversity, but also test for the impact of leaf development stage, tissue origin, and site location. They distinguish the different fungal lineages and do identify distinct indicators, showing that specialization of endophytic fungi could be related to other factors in tropical forests.

This article is a great example of fungal ecology in the tropics, interacting at fine and large scale with a diversity of hosts. It also invites to discuss the high specialization observed in the tropics, and the ecology of old-growth forests in Costa Rica.

References

Humberto Castillo-González, Jason C. Slot, Stephanie Yarwood, Priscila Chaverri (2025) Exploring Rubiaceae fungal endophytes across contrasting tropical forests, tree tissues, and developmental stages. bioRxiv, ver.3 peer-reviewed and recommended by PCI Ecology https://doi.org/10.1101/2024.02.13.580172