Acaulospora galapaguensis, a new fungal species in the Glomeromycetes detected at Santa Cruz Island, Galapagos-Ecuador

Background/Question/Methods

Arbuscular mycorrhizal fungi (AMF) are soil symbionts associated with the majority of vascular plants and are considered to be obligated biotrophs as they can only complete their life cycle in association with a living root. The symbiosis contributes to ecosystem functions at different scales ranging from influencing plant individual performance, plant community responses resulting in changes to ecosystem functions and global process. Therefore, the knowledge of the local biodiversity of AMF is relevant for the preservation of ecosystem health particularly in vulnerable ecosystems such as island. In this context, the characterization of the island AMF is fundamental to improve our capacity to predict ecological change. We detected spores isolated from field samples taken from the highlands of Santa Cruz Island, Galapagos Archipelago, Ecuador in December 2010, with morphological characters that indicated membership in Acaulosporaceae family. These spores seemed to be from undescribed species. Subsequent detailed morphological studies of these fungi and molecular phylogenetic analyses were used to confirm our observation. 

Results/Conclusions

A. galapaguensis have exterior walls ornamented by minute spines and have wall structures typical of Acaulosporaceae. The morphological characters distinguishing this species as a new species from other ornamented Acaulopora species. The size range of A. galapaguensis is 30 - 80 µm in diameter and ornamented with spines 1 µm high. The phylogenic trees reconstructed from partial nrLSU gene sequences placed A. galapaguensis within the Acaulospora clade. Maximum-Likelyhood tree and Neighbor-Joining tree are presented to show phylogenetical relationships among other Acaulospora species.