Rhizopus koreanus Hyang B. Lee & T.T.T. Nguyen, sp. nov.
MycoBank number: MB 814406, Facesoffungi number: FoF 02067, Fig. 3
Etymology – koreanus. Referring to the country which from the species was first isolated (Korea).
Holotype – EML-HO95-1, deposited at the Environmental Microbiology Laboratory Fungarium, Chonnam National University, Gwangju, Korea, as dried fungal mass from culture (PDA), isolated from persimmon fruit, August 2014, by H.B. Lee. Living culture CNUFC-EML-HO95-1, in Chonnam National University Fungal Collection, Gwangju, Korea.

Colonies growing fast on PDA, reaching 73 – 77 mm diam. at 23 °C after 1 day of incubation, initially white, later grayishblack, reverse white, irregularly zonate. Sporangia globose to oval, reaching 88 – 215 × 84 – 193 (mean 123 × 126) μm in diam. Columellae 20 – 62 × 26 – 80 μm, conical, hemispherical or globose. Sporangiospores globose to ellipsoidal, sometimes asymmetrically ovoid, 12.5 – 17 × 14 – 19 (mean 14.6 × 15.4) μm. Zygospores are seldom observed in the artificial media.

Notes – Rhizopus koreanus is similar in morphology and closely related to R. stolonifer (Ehrenb.) Vuill., however the columellae were smaller, diverse in shape, reaching 20 – 61 × 26 – 79 μm, forming a separate clade as a new species in a phylogenetic tree.

Material examined – REPUBLIC OF KOREA, Division of Food Technology, Biotechnology & Agrochemistry, College of Agriculture & Life Sciences, Chonnam National University, Gwangju 61186, Korea, from a persimmon fruit purchased from the grocery store in Korea; EML-HO95-1 (ex-type) at Culture Collection of National Institute of Biological Resources (NIBR), Incheon, and preserved as glycerol stock at -80 °C in the CNUFC; living culture (ex-type) deposited at Jena Microbial Resource Collection (University of Jena and Leibniz Institute for Natural Product Research and Infection Biology, Jena, Germany) (JMRC:SF:012182).

The isolate was observed to grow over a wide range of temperatures with varying growth rates on PDA, MEA (malt extract agar), and OA (oatmeal agar) of 74 mm, 52 mm, and 47 mm per 24 h, respectively. Optimal growth was observed around 20 – 25 °C, slow growth was observed at 5 °C, and no growth at 35 °C. Rhizopus koreanus appears to be phylogenetically related to R. stolonifer which is the type of the genus Rhizopus (Figs. 1, and 2).

Fig. 1 Phylogenetic tree for Rhizopus koreanus EML-HO95-1 and EML-HO95-2 based on Maximum likelihood analysis of ITS rDNA sequence. Sequence of Phycomyces blakesleeanus was used as outgroup. Bootstrap support values >50% are indicated at the nodes. The bar indicates the number of substitutions per position. New taxa are in blue and extype strains in bold.

Fig. 2 Phylogenetic tree for Rhizopus koreanus EML-HO95-1 and EML-HO95-2 and related species based on Maximumlikelihood analysis of multi-genes including 18S and 28S rDNA, actin (Actin-1) and elongation factor (EF-1α). Sequences of Umbelopsis nana and U. isabellina were used as outgroups. Bootstrap support values >50 % are indicated at the nodes. The bar indicates the number of substitutions per position.

Fig. 3 Rhizopus koreanus (holotype) a Colony in potato dextrose agar b Rhizoids (white arrow) c – e Young sporangia f, g Mature sporangia h – k Different shapes of columella l, m Sporangiospores with asymmetrically oval to globose shapes. Scale bars: b = 200 μm, c – g = 50 μm, d, e = 50μm, h – k = 20 μm, l = 30 μm, m = 5 μm.