Cordyceps unilateralis in Thailand: An example of hidden species
2002
Tasanatai, K.(National Science and Technology Development Agency, Bangkok (Thailand). National Center for Genetic Engineering and Biotechnology)
Genus Cordyceps contains ca. 300 described species plus at least the same number again of synonyms. Many more species await description. In surveys of natural forest in Thailand a species was identified from ants attached to the underside of leaves as Cordyceps unilateralis. However, our re-assessment of the collections (especially recent collections) indicates that Cordyceps unilateralis in Thailand consists of three related species. Previously, only one other species on ants had been reported with overall morephology similar to Cordyceps unilateralis-namely Cordyceps formicivora. This was rejected for much of the twentieth century as a synonym of Cordyceps unilateralis and was treated so in our original identifications. Comparison of descriptions of Cordyceps unilateralis from around the world suggest that other workers have also described as Cordyceps unilateralis specimens that might be better named as Cordyceps formicivora. Material from Thailand clearly separates into species with hyaline ascospores (comparable with typical Cordyceps formicivora). Significantly, the ascospore sizes reported for Thai material and from published records cover a broad range (90-160+ micro m) suggesting more than one species. These species are especially significant to understanding the phylogenetic relationships of the genus Cordyceps. Petch erected the genus Ophiocordyceps (based on Cordyceps blattae but including Cordyceps unilateralis) to accommodate species that produce whole, stout ascospores. This was later reduced to the level of a sub-genus. Now we have evidence suggesting that Cordyceps unilateralis is a whole-ascospored ancestor of the problematic Neocordyceps clade (which have ascospores that typically separate into 64 part-spores).
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