Three new phylogenetic and biological Neurospora species: N. hispaniola, N. metzenbergii and N. perkinsii.

The recent recognition of provisional Neurospora phylogenetic species (PS) 1-3 gave us the opportunity to compare genetic isolation, which underlies phylogenetic species recognition (PSR), with reproductive isolation as criteria for recognizing new species. This investigation involved first finding new individuals of PS 1-3 from a search of the Perkins culture collection, then assessing genetic isolation by PSR for old and new members of PS 1-3 and finally comparing species recognition by genetic isolation as determined by PSR to species recognition by reproductive isolation as determined by biological species recognition (BSR) and geographic distribution. To aid the search for additional members of the PS we used the genetic variation originally used to discover Neurospora PS 1-3 to easily distinguish members of Neurospora PS 1-3 from the closely related species N. crassa and N. intermedia. To increase our chance of success the analysis was performed on N. crassa and N. intermedia isolates that were either not clearly assignable to species by BSR using tester strains or were from the same geographic locations as the known members of PS1-3. Eleven new members of Neurospora PS 1-3 were identified: one new PS1, nine new PS2 and one new PS3. To complement PSR we investigated reproductive isolation with BSR in PS1-3 and the two other most closely related species, N. intermedia and N. crassa, with intraspecific and interspecific crosses. PS1 and PS2 appear reproductively isolated because they successfully mated intraspecifically and not interspecifically. PS3 isolates successfully crossed with other PS3 isolates, however they also successfully crossed with N. crassa, as previously reported, indicating that genetic isolation can precede reproductive isolation. We compared phylogenetic, mating and geographical data to challenge the use of PSR as the main criterion in the formal description of species and, having failed to discredit the approach, describe the new species, N. hispaniola (PS1), N. metzenbergii (PS2) and N. perkinsii (PS3).