The genus Alwisia (Myxomycetes) revalidated, with two species new to science

Abstract

Based on morphological investigations and a phylogeny constructed with partial sequences of the SSU rDNA gene, we revalidate the genus Alwisia and propose the combination Alwisia bombarda Berk. & Broome to be used against Tubifera bombarda (Berk. & Broome) G.W. Martin. Two new species, Alwisia morula and A. repens, are described based on material collected respectively in Costa Rica and Australia. Both new species lack a capillitium and possess individually stalked subspherical sporothecae. Alwisia repens differs from A. morula by its procumbent stalks and iridescent peridium. A comparison of 83 sequences of species in the genera Lycogala, Reticularia and Tubifera with a recent two-gene phylogeny of the bright-spored myxomycetes resulted in a similar topology of both Bayesian and maximum likelihood trees and placed A. bombarda, A. morula and A. repens in one well delimited clade within Reticulariaceae.

Perichaena longipes, a new myxomycete from the Neotropics

“…We could not carry out these calculations in the present study because most of the species are represented only by one specimen. We, however, can compare our data with the natural threshold values proposed by Leontyev et al (2015) to distinguish among species within the bright-spored myxomycetes. The value proposed for distinguishing species within the bright-spored myxomycetes is p = 0.11-0.15, indicating that if the difference between two partial 18S genotypes is lower than 0.11 then they both belong to the same species whereas if the calculated p value is higher than 0.15 they belong to different species (Leontyev et al 2015).…”

“…We, however, can compare our data with the natural threshold values proposed by Leontyev et al (2015) to distinguish among species within the bright-spored myxomycetes. The value proposed for distinguishing species within the bright-spored myxomycetes is p = 0.11-0.15, indicating that if the difference between two partial 18S genotypes is lower than 0.11 then they both belong to the same species whereas if the calculated p value is higher than 0.15 they belong to different species (Leontyev et al 2015). Therefore the value p = 0.08 obtained by comparing sequences of Perichaena longipes from Panama and Costa Rica corresponds to only intraspecies genetic diversity and does not suggest the separation into separate species.…”

“…Gmel.) by Leontyev et al (2014) were used as outgroup. An alignment of the 29 sequences was generated in MEGA 5.1 (Hall 2011, Tamura et al 2011) with the automatic procedure implemented in multiple sequence comparison by log-expectation (MUSCLE).…”

“…This brings us to question whether these two 18S genotypes represent one or two different species. To answer similar questions in another group of Lucosporideans, Leontyev et al (2015) proposed an approach for calculating the p distances between all 18S genotypes. This distance index is calculated as the proportion (p) of nucleotide sites at which two sequences are different and varies from 0 (sequences are identical) to 1 (sequences share no common nucleotides) (Hall 2011, Tamura et al 2011.…”

“…This distance index is calculated as the proportion (p) of nucleotide sites at which two sequences are different and varies from 0 (sequences are identical) to 1 (sequences share no common nucleotides) (Hall 2011, Tamura et al 2011. It was shown that there exists a natural gap between p values when comparing specimens of the same species (low p values) to those of different species (high p values) (Leontyev et al 2015). We could not carry out these calculations in the present study because most of the species are represented only by one specimen.…”