Mucor koreanus Hyang B. Lee, S.J. Jeon & T.T.T. Nguyen, sp. nov.
MycoBank number: MB 814424, Facesoffungi number: FoF 02066, Fig. 3
Etymology – koreanus. Referring to the country which from the species was first isolated (Korea).
Holotype – EML-QT1, deposited at the Environmental Microbiology Laboratory Fungarium, Chonnam National University, Gwangju, Korea. Living culture CNUFC-EMLFQT1, in Chonnam National University Fungal Collection, Gwangju, Korea.

Colonies growing fast on PDA, dark brown in the center, with a lighter margin, grayish-white in reverse, reaching 70 – 72 mm diam. at 23 °C after 2 days of incubation. Sporangiophores 21 – 44 μm wide, erect, unbranched or branched sympodially. Sporangia globose, subglobose, yellow to golden brown, multi-spored, reaching 129 – 159 × 137 – 165 μm; at maturity the sporangial wall fully deliquesces, leaving a small collar. Columellae globose, cylindrical-ellipsoidal, reniform or pyriform, 67 – 82 × 71 – 87 μm. Sporangiospores of diverse shape, ellipsoidal, globose, sometimes asymmetrically globose or bean-shaped, 9 – 14 × 6.5 – 11.5μm. Zygospores not observed.

Notes – Mucor koreanus was similar in morphology and closely related to M. piriformis A. Fisch., but differs by larger sporangiospores, their different shapes, and colour of sporangia. Columellae are diverse in shape. Sometimes, the collar is not seen below the columellae. The sporangiospores have thick walls.

Material examined – REPUBLIC OF KOREA, Division of Food Technology, Biotechnology & Agrochemistry, College of Agriculture & Life Sciences, Chonnam National University, Gwangju 61186, Korea, from a tangerine fruit purchased from the grocery store in Korea; EML-QT1 (extype) at Culture Collection of National Institute of Biological Resources (NIBR), Incheon, Korea, 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:012181).

The isolate was observed to grow over a wide range of temperatures with varying growth rates on PDA, MEA (malt extract agar), and CDA (czapek dox agar) of 35 mm, 17 mm and 28 mm per 24 h, respectively. Optimal growth was observed around 20 – 23 °C, slow growth was observed at 5 °C, and no growth at 27 °C. Mucor koreanus appears to be phylogenetically related to M. piriformis, both clustering in the same clade together with M. mucedo which is the type of the genus Mucor (Figs. 1, and 2).

Fig. 1 Phylogenetic tree for Mucor koreanus EML-QT1 and EMLQT2 based on Maximum likelihood analysis of ITS rDNA sequence. Sequence of Syncephalastrum racemosum 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 ex-type strains in bold.

Fig. 2 Phylogenetic tree for Mucor koreanus sp. nov. EML-QT1 and EML-QT2 and related species based on Maximum likelihood analysis of multi-genes of 18S and 28S rDNA, actin (Actin-1) and translation elongation factor (EF-1α). Sequences of Umbelopsis nana and U. isabellina were used as outgroups. Numbers at the nodes indicate the bootstrap values (>50 %) from 1000 replications. The bar indicates the number of substitutions per position.

Fig. 3 Mucor koreanus (holotype) a Colony on potato dextrose agar b – d Young sporangia e Mature sporangium f – k Columellae with clear collar present at the apex of the sporangiophore l Sporangiospores. Scale bars: b, c = 50 μm, d – l = 20 μm.