INTRODUCTION

Zygomycetous fungi, such as Mortierellomycota and Mucoromycota, are classified based on their reproductive characteristics. They produce zygospores for sexual reproduction, and conduct asexual reproduction via sporangia [1]. In yesteryears, the two phyla were grouped in a same phylum, Zygomycota; however, recently, they have been classified as two separate phyla [2]. Several species belonging to Mortierellomycota and Mucoromycota have been isolated from the soil, plant roots, decaying plant materials, endophytic plant litter, insect guts, mosses, animal dung, and freshwater environments [3,4].

Fungal species belonging to Mortierellomycota generally possess anastomosing hyphae and thalli with dichotomously branching multispored spherical sporangia [2]. They are found worldwide in various habitats including aquatic and terrestrial environments [2]. As stated in Mycobank, 21 genera have been reported as of 2022 [5].

The genus Dissophora of Mortierellaceae contained three species as of 2021 [6]. Using low-coverage genome sequences, this genus forms a clade distinct from Mortierella species [3]. Dissophora fungi are known to be found in forest litter and soil, unlike common Mortierella species [3]. Fungal species of this genus have fertile, septate aerial stolons that are differentiated from vegetative hyphae [3].

In the genus Linnemannia of family Mortierellacae, 26 species have been reported as of 2022 [7]. Numerous fungal species of this genus have been isolated from soils, and are associated with the plant rhizosphere or litter [3]. This genus is classified according to the sporangia characteristics and sporangiospore morphology [3].

In the genus Mortierella of family Mortierellacae, 173 species were reported in 2023 [5]. Many Mortierella species grow well at cooler temperatures and few species have been reported to be mycoparasites [3]. Various Mortierella species have been found in a wide range of habitats, including soil, water, living plant roots, and plant debris [3]. In South Korea, four Mortierella species have been isolated from freshwater sources [8,9].

Several fungal species belonging to Mucoromycota have been reported to be plant-associated fungi (e.g., plant symbionts, plant debris decomposers, or pathogens) [10]. They generally produce globose, smooth, or ornamented zygospores and exhibit rapid mycelial growth [10].

The genus Umbelopsis belongs to the family Umbelopsidaceae, order Umbelosidales, class Umbelopsidomycetes, and phylum Mucoromycota [2]. To date, 22 species of this genus have been reported [11]. Several species have been isolated from the soil, plant debris, roots, and human skin [11,12]. This genus is classified according to characteristics such as the morphology of the sporangia, sporangiospores, and colonies [12].

This is the first report of four fungal species (namely Dissophora globulifera, Linnemannia exigua, Mortierella rishikesha, and Umbelopsis autotrophica) found in South Korea from environmental samples such as freshwater, plant litter, and sediment in streams. The molecular, phylogenetic, and morphological characteristics of these species were also investigated.

MATERIALS AND METHODS

RESULTS AND DISCUSSION

TAXONOMY