Boeremia parva S.Y. Lee, L.N. Ten & H.Y. Jung, 2021

Das, Kallol, Ten, Leonid N., Ban, Jae-Ho, Lee, Seung-Yeol & Jung, Hee-Young, 2021, Boeremia parva sp. nov., a novel species of the family Didymellaceae isolated from soil, Phytotaxa 518 (1), pp. 25-35 : 28-31

Boeremia parva S.Y. Lee, L.N. Ten & H.Y. Jung sp. nov. ( FIGURE 1 )

MycoBank: MB835936

Etymology: The specific epithet is derived from the Latin word parva (“small”), and refers to the small colony size.

Typus: The culture was isolated from soil taken in Miryang , Korea (35°31’43.7’’N, 128°46’07.6’’E) in 2019. The stock culture (NREFFGC000000237) was deposited in the National Institute of Biological Resources ( NIBR), metabolically inactive culture .

Habitat: The species was found in soil. The soil was yellowish-brown, fine gravelly clay loam, lower moisture capacity.

Description: Colonies on PDA reached 30–35 mm after 7 days of cultivation at 25 °C, dark greenish olivaceous with irregular light gray margin, reverse dark brown with irregular light brown margin. Colonies on MEA 52-58 mm in diameter after 7 days of incubation, light gray with irregular white margin, reverse brown, with white to slightly brownish margin, black irregular spots around center. Colonies on OA reached 39–43 mm after 7 days of cultivation, brownish gray to pale beige with white aerial mycelium, reverse slightly pale beige, light dark in center with fuzzy margin ( FIGURE 1 ). Application of NaOH did not result in any color change in cultures. Conidiomata pycnidial, scattered to aggregated, globose to subglobose, dark brown to black, irregular, 102.6–237.0 μm (average 169.8 μm) in diameter. Conidia on OA hyaline, smooth, pyriform, aseptate, straight, irregular, with 1–2 small guttules or eguttulate, 3.6–8.4 × 1.8–4.2 μm (average 5.4 × 2.9 μm) ( FIGURE 1 ).

Notes: Boeremia parva is similar to the B. exigua , the type species of the genus, in having mostly globose to subglobose, pycnidial conidiomata, oblong conidia with guttules ( de Gruyter & Boerema 2002, Aveskamp et al. 2010). The new strain shows close phylogenetic affinities to Boeremia rhapontica (Berner, Woudenb. & Tunali) Jayawardena, Jayasiri, K.D. Hyde ( Jayawardena et al. 2019) and Boeremia coffeae (Henn.) Jayasiri, Jayaward. & K.D. Hyde ( Jayawardena et al. 2019) ( FIGURE 2 ). Boeremia parva can be distinguished from B. rhapontica by the colony color on OA and MEA and by the measurements of conidiomata and conidia (102.6–237.0 μm vs 50.3–199.1 μm and 3.6–8.4 ×1.8–4.2 μm vs 3.6–7.1 × 1.7–3.9 μm ( Berner et al. 2015). Similarly, Boeremia parva can be differentiated from B. coffeae by the colony color on OA and MEA, the absence of colony color change under NaOH treatment, by the aseptate conidia and color of conidiomata, and the measurements of conidiomata and conidia (102.6–237.0 μm vs 120–255 μm and 3.6–8.4 x 1.8 ~ 4.2 μm vs 4–7 × 2–3 μm) ( de Gruyter et al. 2002).

rhapontica .

Boeremia coffeae (= Boeremia exigua var. coffeae = Ascochyta coffeae = Ascochyta tarda ) was originally described by Stewart (1957) as Ascochyta tarda , the causal agent of coffee leaf blight and stem dieback and Boeremia exigua var. rhapontica was introduced by Berner et al. (2015) to accommodate the pathogen on Rhaponticum repens . There are no previous records of Boeremia species from any soil-based habitats. Boeremia parva is the first species of the genus isolated from a soil.

Figures

FIGURE 1. Cultural and morphological characteristics of Boeremia parva KNU-NL4. Cultures were grown at 25 °C for 7 days in darkness. A and B, front and reverse view of colony on potato dextrose agar; C and D, front and reverse view of colony on malt extract agar; E and F, front and reverse view of colony on oatmeal agar; G, conidia; H, conidiomata. Scale bars: G, H = 10 µm

FIGURE 2. Maximum-likelihood phylogenetic tree based on the concatenated sequences (ITS +ACT+CAL+TEF1-α + β-TUB) showing the phylogenetic position of novel strains KNU-NL4 and KNU-OL2 among the closest Boeremia species. Bootstrap values greater than 50% (percentage of 1000 replications) are shown at branching points. Filled circles indicate that the corresponding nodes were also recovered in trees generated using the neighbor-joining and maximum-parsimony algorithms. Open circles indicate that the corresponding nodes were also recovered in the tree generated using the neighbor-joining or maximum-parsimony algorithm. The isolated strains are shown in boldface. The tree was rooted using Phoma herbarum CBS 615.75 as an outgroup. Bar, 0.02 substitutions per nucleotide position.