The Cylindrocladium candelabrum species complex includes four distinct mating populations
Cylindrocladium candelabrum-like isolates were collected from a wide variety of geographic locations and compared based on their morphology, sexual compatibility and the nucleotide sequences of their rDNA ITS regions. All isolates included in this study mated to produce Calonectria teleomorphs with viable progeny. Four distinct mating populations were identified, each representing a genetically isolated, biallelic, heterothallic population. Several representative isolates of each mating population, reflecting geographic diversity, were chosen for sequence comparisons. The internal transcribed spacer (ITS) regions 1 and 2 that flank the 5.8S rDNA gene, as well as the gene itself, were sequenced and compared. All isolates representing the same group yielded similar sequences, but small, consistent differences were found between the groups. Based on these results we recognise Calonectria scoparia (anamorph Cylindrocladium candelabrum), and describe three new species, namely Calonectria pauciramosa (anamorph Cylindrocladium pauciramosum), Calonectria insularis (anamorph Cylindrocladium insularae) and Calonectria mexicana (anamorph Cylindrocladium mexicanum).