Environmental factors influencing the diversity and distribution of dictyostelid cellular slime molds in forest and farmland soils of western China

ABSTRACT Dictyostelid cellular slime molds (dictyostelids) are one of the major groups of eukaryotic amoeboid protists occurring in the soil microhabitat. The past few decades have witnessed an unprecedented interest in the ecology of dictyostelids, stimulated in part by the hidden soil protist diversity that has long been overlooked. However, a better understanding of the impact of various environmental factors on the biodiversity of dictyostelids is needed to understand the critical functional role of these organisms in the soil ecosystem. Species diversity of dictyostelids has been surveyed in some provinces of China, but little data exist for Gansu and Guizhou Provinces in western China. In this paper, we report data on the distribution and occurrence of dictyostelids in the soils of these two provinces. Samples were collected from 13 localities in central Gansu and the southeastern and southcentral portions of Guizhou Province. Eleven species of dictyostelids were recovered from 99 samples of soil. Six new records of dictyostelids are reported from Gansu Province and six species from Guizhou Province, respectively. Polysphondylium violaceum is a common species in both regions, while Dictyostelium sphaerocephalum and Dictyostelium mucoroides are widely distributed in Lanzhou, Gansu Province. The total number of species (seven) and the number of endemic species (three) of dictyostelids in mixed forests were higher than those in other forest types. Redundancy analysis indicated that soil pH, temperature, and elevation were the primary factors that affected dictyostelid occurrence. Nonmetric multidimensional scaling and principal component analysis indicated that the dictyostelid communities were significantly different between Gansu and Guizhou Provinces. IMPORTANCE Soil protists are an essential yet seriously understudied component of the soil microbiome. In this study, 11 new records of dictyostelids belonging to 2 orders, 3 families, and 4 genera were identified from 99 soil samples collected from different elevations and habitats in central Gansu and the southeastern and southcentral portions of Guizhou Province, China. We found that dictyostelid communities were significantly different between Gansu and Guizhou Provinces, apparently in response to different environmental factors. Moreover, dictyostelids were found to have the highest species diversity in mixed forests. Soil pH, temperature, and elevation were determined to be the primary factors that affect the distribution and occurrence of dictyostelids in Guizhou and Gansu Provinces. This work supplements the survey data available for dictyostelids elsewhere in China. These new findings have significant implications for our understanding of the diversity of soil microorganisms.