Abstract:[Background] Dictyostelids cellular slime molds are model organisms for biology, cytology and developmental biology. Although more than one hundred species of dictyostelids have been reported up to now, the developmental process of each species is still unclear. [Objective] To understand the ontogenetic characteristics of this group. [Methods] Dictyostelids were isolated and identified from soil samples collected from Cang Mountain in Yunnan Province. The ontogeny of isolated dictyostelid species were investigated. The 18S sequences of this species were sequenced. The morphological features and 18S sequence were used to identify the taxonomic status. Furthermore, the development from spore to spore including characteristics of spore, myxamoeba, aggregation, pseudoplasmodia, ascent, and sorocarp were microbiologically observed on bi-concavity slide and water agar in this paper. [Results] Dictyostelium macrocephalum was obtained and identified. It adapt a wide range of temperatures, which suggested that this dictyostelid species is common species distributing in subtropical and tropical area. The whole life cycle of D. macrocephalum extends of a period of less than 3 d (71 h). The spores germinated and released myxomoebae 20 h after inoculation. The aggregations formed 50 h after the inoculation, whereas the pseudoplasmodia formation needed 56 h. After that, the sorogen formed needed 56 h, and finally form fruiting sorocarps after 71 h. [Conclusion] This new record of Yunnan Province, D. macrocephalum, extented our understanding on the distribution of this species in subtropical areas of China. The developmental process of D. macrocephalum was clarified.
