Nivicolous myxomycetes in the French Pyrenees – A biodiversity study aided by two molecular markers

We report a systematic survey for nivicolous myxomycetes (Amoebozoa, Myxomycetes) carried out between April 30 and May 6 in the French Pyrenees (Hautes-Pyrénées, 900-2000 m). The 738 specimens were barcoded for the nuclear small subunit ribosomal gene (nucSSU, 652, 88.3 % successful). Trichia alpina, the only bright-spored species found, was not sequenced. Additionally, a section of the translation elongation factor 1-alpha gene (EF1A) was successfully sequenced for 496 specimens (67.2 %). The nucSSU phylogeny showed 31 dark-spored species as genetically distinct, yet not always monophyletic lineages. Two species, Polyschismium fallax and P. peyerimhoffii, were grouped in one clade, although differing in barcode sequences. These separations were confirmed by EF1A in all cases except Didymium pseudodecipiens, where EF1A sequences could not be obtained. The resolution for the species pair P. fallax and P. peyerimhoffii increased, and for Polyschismium chailletii two distinct clades were found, indicating a cryptic species complex. Based on the molecular clades, we describe in detail the corresponding morphological differences in four taxa (Didymium dubium and Didymium pseudodecipiens; Polyschismium chailletii groups a and C). The study confirms the reliability of barcoding via nucSSU with an independent second marker and delivers a barcoded, quality-checked comprehensive data set for the Pyrenees.