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

The multicellular discoid convex teliospore heads represent a prominent generic feature of the genus <i>Ravenelia</i>. 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 Ce<i>nostigma macrophyllum</i> (= <i>C. gardnerianum</i>) was described as <i>Ravenelia cenostigmatis</i>. 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 <i>Rav. cenostigmatis</i> and <i>Rav. spiralis</i> on <i>C. macrophyllum</i>, our phylogenetic analyses based on the nuc 28S, nuc 18S, and mt CO3 (cytochrome <i>c</i> oxidase subunit 3) gene sequences demonstrated that these two rust fungi belong in a lineage within the Raveneliineae that is distinct from <i>Ravenelia</i> s. str. Besides proposing their recombination into the new genus <i>Raveneliopsis</i> (type species <i>R. cenostigmatis</i>) and briefly discussing their potentially close phylogenetic affiliations, we suggest that five other <i>Ravenelia</i> species that are morphologically and ecologically close to the type species of <i>Raveneliopsis</i>, i.e., <i>Rav. corbula, Rav. corbuloides, Rav. parahybana, Rav. pileolarioides</i>, and <i>Rav. Striatiformis</i>, may be recombined pending new collections and confirmation through molecular phylogenetic analyses.