During a survey of Phytophthora diversity in Panama, fast-growing oomycete isolates were obtained from naturally fallen leaves of an unidentified tree species in a tropical cloud forest. Phylogenetic analyses of sequences from the nuclear ITS, LSU and ß–tubulin loci and the mitochondrial cox1 and cox2 genes revealed they belong to a new species of a new genus, officially described here as Synchrospora gen. nov., which resided as a basal genus within the Peronosporaceae. The type species S. medusiformis has unique morphological characters. The sporangiophores show determinate growth, multifurcating at the end forming a stunted, candelabra-like apex from which multiple (8 to >100) long, curved pedicels are growing simultaneously in a medusa-like way. The caducous papillate sporangia mature and are shed synchronously. The breeding system is homothallic, hence more inbreeding than outcrossing, with smooth-walled oogonia, plerotic oospores and paragynous antheridia. Optimum and maximum temperatures for growth are 22.5 and 25–27.5 °C, consistent with its natural cloud forest habitat. It is concluded that S. medusiformis is adapted to a lifestyle as canopy-dwelling leaf pathogen in tropical cloud forests. More oomycete surveys in the canopies of tropical rainforests and cloud forests are needed to elucidate the diversity and role of oomycetes and, in particular, S. medusiformis and possibly other Synchrospora taxa in this as yet under-explored habitat.

For phylogenetic analyses, the sequences obtained in this study were complemented with publicly available sequences of Oomycetes sourced from the GenBank Nucleotide Collection and GenBank Whole-Genome Shotgun contigs.

To study the phylogenetic position of the potentially new genus among other oomycete genera, a 5–partition (LSU - ITS - Btub - cox1 - cox2) dataset of representative species from all genera of the Peronosporaceae and Pythiaceae together with five isolates from the new species were analysed with Saprolegnia parasitica (CBS 223.65) and Aphanomyces euteiches (ATCC 201684) as outgroups (dataset: 60 isolates and 4,954 characters). Maximum likelihood (ML) and Bayesian (BI) analyses were carried out. Detailed methodology can be found in the official publication "Synchrospora gen. nov., a new Peronosporaceae genus with aerial lifestyle from a natural cloud forest in Panama".

Data supplied:

• Table for identification of species, isolates and sequences used on the phylogenetic analyses;
• Sequence alignments (fasta files, used as input files in ML and BI analyses).
• Trees obtained from BI and ML analyses (50% majority-rule consensus trees).