Gongronella koreana H.B. Lee & T.T.T. Nguyen, sp. nov.
MycoBank number: MB 811445; Faces of fungi number: FoF 01015; Fig. 1
Etymology: koreana. Referring to the country which from the species was first isolated (Korea, Jeonnam Province).
Holotype: EML-TS2Bp was maintained permanently in a metabolically inactive state at the Environmental Microbiology Laboratory Herbarium, Chonnam National University Gwangju, Korea. CNUFC- EML-TS2Bp, as dried fungal mass from culture (PDA), August 2013, by H. B. Lee, in the Chonnam National University Fungal Collection (CNUFC), Gwangju, Korea.
Colonies exhibit slow growth on SMA, attaining 21 – 25 mm in diam. after 7 days at 25 °C. All colonies are cotton white in color. The colony reverse is also white with an irregular margin. Although the growth of mycelia on SMA is sparse, the sporulation observed is extensive. Sporangiophores grow to a width of 2.5 – 2.8 μm and a variable length surfacing directly from the aerial mycelia, erect, many-branched, and always displaying a septum clearly below the apophysis, separating the sporangium from the sporangiophore (Fig. 1g). Sporangia measure 12.3 – 15.5 × 12.4 – 15.6 μm in diam., and are globose, light yellow to chestnut yellow, and are multispored. The sporangial wall is thin and purple. Sporangiospores are released after the sporangial wall is deliquesced at maturity. The sporangiospores measure 1.7 – 2.1 × 2.1 – 2.8 μm, and are mostly bean-shaped. Columellae 1.2 – 2.3 × 2.6 – 3.3 μm in size, hemispherical with a collarette. Apophyses are 5.4 – 6.5 × 5.9 – 7.1 μm in size, and typically pyriform (Fig. 1g). Chlamydospores are present on the aerial mycelia. Zygospores are not observed. Rhizoids are not well developed.
On PDA, colonies grow more rapidly than on SMA, reaching 31.5 – 33 mm in diam. after 7 days at 25 °C. The initial color of the colonies at 25 °C is light white, which later turned to cotton white. The color of the colony reverse is lightcolored to white. The center of the colony appeared moist. Sporangiophores are 2.8 – 3.0 μm wide, erect, but slightly curved inwardly, and arising from the aerial mycelia, either singly or with up to six branches. Sporangia measure 17.5 – 20.6 × 17.0 – 21.0 μm in diam., and are mostly globose and multispored. Sporangiospores are subglobose to ellipsoidal or bean-shaped, became hollow inwardly and measure 1.3 – 1.6 × 2.7 – 3.2 μm. Apophyses measure 8.7 – 10.0 × 5.7 – 8.2 μm, and display a subglobose to pyriform shape. Columellae are hemispherical and globose and measure 2.7 – 3.3 × 3.9 – 5 μm, and a large collarette is usually present. Mycelial development and chlamydospore formation is well defined on PDA medium. Zygospores are not observed on this medium.
Colonies on MEA attain a diameter of 27.0 – 28.5 mm. after 7 days at 25 °C. The color of the colonies is creamy – white. The colony reverse color is milky – white. Sporangiophores are 2.4 – 2.7 μm wide, erect, displaying either a single branch or 2 – 4 branches. Sporangia measure 13.2 – 15.6 × 13.7 – 16.0 μm indiam., and are typically globose. Sporangiospores measure 1.4 – 1.6 × 2.6 – 3.2 μm, and are subglobose to ellipsoidal, or bean – shaped. Apophyses are pyriform, and measure 4.4 – 7.5 × 5.4 – 8.1 μm. Zygospores are not observed on this medium. Mycelial development is notably better than that on SMA medium; however, a smaller number of sporangia are produced on MEA medium.
Material examined: REPUBLIC OF KOREA, Division of Food Technology, Biotechnology & Agrochemistry, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 500 – 757, Korea, from forest soil in the Jeonnam Province in Korea; KOSPFGC 1268 (ex-type) at the Culture Collection of National Institute of Biological Resources (NIBR), Incheon,, Korea, and also additional ex-types EML-TS2Bp-1 to −3 preserved as glycerol stock at −80 °C in the CNUFC.
The isolate was observed to grow in a wide range of temperatures with varying growth rates on PDA, SMA, and MEA media. The average growth rates of the EML-TS2Bp isolate on PDA, SMA, and MEAwere 5.5 mm, 3.5 mm, and 4.5 mm per day, respectively. The optimal growth temperature was found to be 27 °C, and slow growth was observed at 18 °C. No growth was observed at 37 °C.
Fig. 1 Morphology of Gongronella koreana. a, d colony in potato dextrose agar. b, e colony in synthetic mucor agar c, f colony in malt extract agar after 7 days at 25 °C. a – c colony representing the obverse plate view. d – f colony representing the reverse plate view. g sporangiophore with short columella, apophysis, and collarette (yellow arrow). h, I simple sporangiophore with young sporangium. j development of sporangia and sporangial septum (red arrow). k mature sporangia and sporangiospores. Scale bars: g – j = 20 μm, k = 10 μm.