Diachea mitchellii: A new myxomycete species from high elevation forests in the tropical Andes of Peru.

A new species of the genus Diachea (order Physarales, Myxomycetes, Amoebozoa) is described from Peru. Relevant details on spore germination, as well as morphological and phylogenetic data, are provided. At first glance, the new species shares some morphological similarities with both D. leucopodia, type of the genus, and D. koazei, but it strikingly differs from all other species of its genus by combining a short dark stalk, with a reticulate columella, and clustered spores. Moreover, it seems to be the only species of Diachea exclusively associated with Polylepis tropical forests at elevations above 3500 m. Apart from a comprehensive morphological study of 31 specimens, we here provide phylogenetic evidence to confirm the inclusion of this species in the genus Diachea. Specifically, our phylogenetic analyses of the nuclear 18S rDNA (18S), mitochondrial 17S rDNA (17S), and elongation factor-1 alpha (EF-1α) genes show that the new species is related to D. leucopodia and D. bulbillosa. The remarkably different morphological characters distinguishing the new Diachea from all other species of its genus, along with its particular ecological preferences and geographic distribution, indicate that it is a distinct entity deserving recognition as an independent species.

Didymium azorellae, a new myxomycete from cushion plants of cold arid areas of South America.

A new species of Didymium (Myxomycetes), D. azorellae, isolated from plant debris in a moist chamber, collected during studies of cold arid areas of Argentina and Peru, is described. It can be distinguished by its small size, the tightly packed layer of lime crystals on the peridium, the very scant, or absent, capillitium, and the unique spore ornamentation, especially by scanning electron microscopy. The species developed on dead leaves of cushion plants growing in the extremely harsh environments of the central Andean puna at almost 5000 m elevation and the Andino-Patagonian steppe. Morphology was examined with scanning electron microscopy and light microscopy, and micrographs of relevant details are included here. In order to confirm the identity of the new species described in this paper, a molecular study was conducted based on partial sequences of both the 18S rRNA and the elongation factor 1-alpha gene. Phylogenetic analysis including two specimens from different countries of the newly described species, Didymium azorellae, strongly supports the grouping of these specimens as a separate clade from the rest of the analyzed species.