Boeremia maritima Dayar., E.B.G. Jones & K.D. Hyde, in Dayarathne et al., Mycosphere 11:36. 2020.

Index Fungorum number: IF 556576; Facesoffungi number: FoF 14376; Fig. 1

Associated with leaf spots of Morus alba (Moraceae). Leaf spots irregular, pale brown. Sexual morph: Not observed. Asexual morph: Pycnidia forming on PDA, 0.2 – 0.5 mm diam., semi-immersed in culture, solitary or aggregated, globose to subglobose or irregular. Conidiophores reduced to conidiogenous cells. Conidiogenous cells phialidic, hyaline, ampulliform to doliiform, 4 – 6 × 2.5 – 4.5 μm (x̄ = 5.1 × 3.6 μm, n = 5). Conidia 3 – 8 × 1.5–4 μm (x̄ = 5.2 × 2.5 μm, n = 75), hyaline, guttulate, 0–1-euseptate, smooth-walled, cylindrical or ellipsoidal, with slightly curved or rounded apex and base. Chlamydospores 12 – 23.5 × 8–17.5 μm (x̄ = 16.9 × 12.9 μm, n = 10), hyaline to pale brown, globose to subglobose, ellipsoidal or obovoid, sometimes truncate at the end(s), smooth-walled, formed terminally or intercalary in chains of two to five.

Culture characteristics: Colonies on PDA reaching approximately 40 mm diam. after 7 days incubation at 25 ◦C, irregular, mycelium flat or effuse with an entire margin, surface smooth, floccose, top and reverse colony after 7 days greyish white to pale yellowish white; after 28 days of incubation olivaceous brown, with black spherical patches.

Distribution: Sweden (Dayarathne et al., 2020), Thailand (this study).

Habitat: Marine (on Artemisia maritima, located on the shore line) (Dayarathne et al., 2020) and terrestrial (this study).

Specimen examined: THAILAND, CHIANG MAI: Doi Inthanon National Park, Highland Fisheries Unit, on leaves of Morus alba (Moraceae), 18 Oct 2021, D. Gomdola DGM1-L2C (MFLU 23–0263; BBH 50463). Living culture MFLUCC 23–0087.

GenBank: ITS = OR346925; 28S = OR346892; ACT1 = PP155399; TBB1 = PP150338; RPB2 = PP476209; TEF1 = OR582385.

Notes: Conidial shapes and sizes of our isolate (MFLUCC 23–0087) match the morphological species concept of Boeremia (Aveskamp et al., 2010). It shares similar features with the ex-type of B. maritima in having phialidic, hyaline, and ampulliform to doliiform conidiogenous cells, and ellipsoidal, hyaline, and 0–1-euseptate conidia with guttules. The conidiogenous cell of our isolate overlap in size with those of the ex-type strain of B. maritima (4 – 6 × 2.5 – 4.5 μm vs. 3 – 5.5 × 2 – 3.2 μm). The conidia of our isolate fall within the size range of those of the ex-type strain of B. maritima (3 – 8 × 1.5 – 4 μm vs. 6 – 10.3 × 2 – 4 μm) (Dayarathne et al., 2020).

In the resulting phylogram, MFLUCC 23–0087 clusters with the ex-type of Boeremia maritima (MFLUCC 18–0411) with 84 % ML, 75 % MP and 1.00 PP support. A comparison of the genetic distance between the two strains of B. maritima showed no difference in 28S (860 nucleotides). However, a difference of 0.21 % and 0.86 % was observed in ITS (508 nucleotides) and TBB1 (284 nucleotides), respectively. We were unable to compare the differences in genetic distance in ACT1, RPB2 and TEF1 as the ex-type strain of B. maritima lacks sequence data for these genes. Since there are no significant differences between the two strains, we refer our isolate as B. maritima (Fig. 2).

Based on the morphological description and phylogenetic analyses of the combined dataset, we establish MFLUCC 23–0087 as a new host record for B. maritima. This is the first record of B. maritima from a terrestrial habitat, associated with leaf spots of Morus alba in northern Thailand.

Fig. 1. Symptoms, colony morphology and microscopic characteristics of Boeremia maritima. A. Leaf of Morus alba with spots (MFLU 23–0263/MFLUCC 23–0087). B, C. Top and reverse of colony on PDA after 7- and 28-days of incubation. D – F. Chlamydospores. G. Conidiogenous cells. H. Conidia. Bars = 10 μm.

Fig. 2. Maximum likelihood tree of concatenated ITS, 28S, ACT1, TBB1, RPB2 and TEF1 sequences of representative Boeremia species. Bootstrap support values (ML ≥ 70 %) and maximum parsimony (MP ≥ 70 %), and Bayesian posterior probabilities (PP ≥ 0.80) are given above the branches or near respective nodes as ML/MP/ PP. Hyphens (–) represent support values below 70 % (ML and MP) and below 0.80 (PP). The tree is rooted with Didymella segeticola (NTUCC 18-098), Heterophoma nobilis (CBS 507.91), Heterophoma sylvatica (CBS 874.97) and Phoma herbarum (CBS 127589 and CBS 502.91). Ex-type and reference strains are indicated with T. Isolates obtained in this study are in bold. The scale bar indicates expected changes per site per branch.