Raveneliopsis, a new genus of ravenelioid rust fungi on Cenostigma (Caesalpinioideae) from the Brazilian Cerrado and Caatinga

ABSTRACT

The multicellular discoid convex teliospore heads represent a prominent generic feature of the genus Ravenelia. However, recent molecular phylogenetic work has shown that this is a convergent trait, and that this genus does not represent a natural group. In 2000, a rust fungus infecting the Caesalpinioid species Cenostigma macrophyllum (= C. gardnerianum) was described as Ravenelia cenostigmatis. This species shows some rare features, such as an extra layer of sterile cells between the cysts and the fertile teliospores, spirally ornamented urediniospores, as well as strongly incurved paraphyses giving the telia and uredinia a basket-like appearance. Using freshly collected specimens of Rav. cenostigmatis and Rav. spiralis on C. macrophyllum, our phylogenetic analyses based on the nuc 28S, nuc 18S, and mt CO3 (cytochrome c oxidase subunit 3) gene sequences demonstrated that these two rust fungi belong in a lineage within the Raveneliineae that is distinct from Ravenelia s. str. Besides proposing their recombination into the new genus Raveneliopsis (type species R. cenostigmatis) and briefly discussing their potentially close phylogenetic affiliations, we suggest that five other Ravenelia species that are morphologically and ecologically close to the type species of Raveneliopsis, i.e., Rav. corbula, Rav. corbuloides, Rav. parahybana, Rav. pileolarioides, and Rav. Striatiformis, may be recombined pending new collections and confirmation through molecular phylogenetic analyses.

KEYWORDS:

• Brazil
• Cerrado fungi
• molecular phylogeny
• neotropical Pucciniales
• Raveneliaceae
• rust fungi
• 3 new taxa

ACKNOWLEDGMENTS

The authors are grateful to Dr. Christiane Ceriani Aparecido from Instituto Biológico de São Paulo/Brazil for the access to the IBI isotypes of Ravenelia cenostigmatis and R. spiralis, and to Dr. Dagmar Triebel from the Botanische Staatssammlung München for the access to the holotype of R. cenostigmatis. The authors also thank Dr. David Rabern Simmons, herbarium curator at The Arthur Fungarium (Purdue University), for helping with remote access to type materials, illustrations, and photos.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author(s).

SUPPLEMENTARY MATERIAL

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00275514.2023.2177048

Additional information

Funding

This work was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ) (P2 Research Fellowship), Fundação de Apoio à Pesquisa do Distrito Federal (FAPDF) (00193-077/2019-41; to Prof. Dirceu Macagnan) and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 447382260.