Neptunomyces soli Yasanthika & K.D. Hyde, 2024

Yasanthika, W. A. E., Chethana, K. W. T., Wanasinghe, D. N., Tennakoon, D. S., Otibi, F. Al- & Hyde, K. D., 2024, Taxonomic novelties of soil-inhabiting pleosporalean fungi in Thailand using baiting method, Phytotaxa 676 (1), pp. 1-24 : 13-15

Neptunomyces soli Yasanthika & K.D. Hyde , sp. nov.

Index Fungorum number: IF902620, Faces of Fungi number: FoF 16493, ( Fig. 3 )

Etymology:— soli , soil in Latin, substrate from which the holotype was collected.

Holotype:— MFLU24-0379

Sexual morph: Undetermined. Asexual morph: Conidiomata scattered throughout the media, globose to subglobose, brown to dark brown, superficial to semi-immersed, pseudoparenchymatous walled. Conidiogenous cells 7–3 × 7–2.5 μm (x̅ = 5 × 4.5 μm, n = 10), hyaline to subhyaline, doliiform to obovoid, smooth. Conidia 5–6.5 × 3–5 μm (x̅ = 5.8 × 3.8 μm, n = 25), initially hyaline, becoming golden yellow, ellipsoidal to fusiform, 0.5–1.5 μm (x̅ = 1 μm) thick-walled, slightly pointed apex and rounded base.

Culture characteristics:— Colonies on PDA at 25 ℃, become 3–4 cm diam., appear white after seven days, become yellowish-white when mature, reverse whitish-orange to yellow, cottony flat surface with filiform margin. Mycelium immersed to semi-immersed, hyaline, smooth-walled hyphae, aseptate when immature, become septate at maturity, 2–4 μm (x̅ = 2.3 μm) wide, sporulated after two weeks.

Material examined:— THAILAND. Chiang Rai: tropical forest soil, on woody baits, 20°4'35"N, 100°5'43"E, 450 m, 7 January 2020, W. A. Erandi Yasanthika ( MFLU 24-0379 , holotype) ; ex-type, MFLUCC 24-0272 ( CRL5- 120 ) ; ibid., ( MFLU 24-0380 ) ; MFLUCC 24-0279 ( CRL5 b-120b) .

Notes:— According to the multi-gene phylogenetic analyses, our isolates ( MFLUCC 24-0272 and MFLUCC 24-0279) formed an independent lineage sister to Neptunomyces juncicola ( CPC 45436) with 94% ML and 0.93 BYPP bootstrap support. A comparison of the 557 nucleotides of the ITS (+ 5.8S) gene region of N. soli revealed 39/378 bp (10%) differences (including gaps) with N. aureus ( CMG 12), 20/545 bp (3.6%) differences (including gaps) with N. juncicola ( CPC 45436) and 18/534 bp (3%) (including gaps) differences with N. litoralis ( BRIP 75555a). Morphologically, our isolate MFLUCC 24-0272 is characterized by doliiform to obovoid conidiogenous cells and ellipsoidal to fusiform conidia with slightly pointed apex and rounded base. N. aureus has ampulliform to subcylindrical conidiogenous cells and subcylindrical conidia with rounded apices ( Gonçalves et al. 2019), while N. juncicola has ampulliform conidiogenous cells and subcylindrical to fusoid-ellipsoid conidia with subobtuse apices ( Crous et al. 2024). Conidial sizes of our species are relatively shorter and broader (5–6.5 × 3–5 μm) compared to N. aureus (7.0 × 2.7 µm) and N. juncicola (7–8× 2–2.5 µm) ( Gonçalves et al. 2019, Crous et al. 2024). However, we were not able to compare the morphology of N. litoralis , as its data was unavailable. We used a polyphasic approach based on morphology and multigene phylogeny ( Maharachchikumbura et al. 2021) to introduce Neptunomyces soli as a new species isolated from forest soil in Thailand. This is the first record of the genus from Thailand. We isolated this species from wood pieces using the baiting technique. Thus, we suggest that this species has an affinity to ligno-cellulosic substrates and introduce it as a cellulophilic species. However, future biochemical analyses are required to confirm this and define its contribution to lignocellulose degradation in soil.

Curvularia dactylocteniicola Y. Marín, Senwanna & Crous [as ' dactyloctenicola '], Mycosphere 8(9): 1567 (2017) Index Fungorum number: IF 822083, Faces of Fungi number: FoF 16494, ( Fig. 4 )

Sexual morph: Undetermined. Asexual morph: Conidiophores 150–200 × 6.5–3 μm (x̅ = 172.5 × 5 μm, n = 10), single or often in groups, mononematous, macronematous, subhyaline, becoming hyaline towards apices, septate, straight or flexuous, geniculate in the upper part, size of cells not decreasing towards apex, sometimes branched, thick-walled. Conidiogenous cells 4–11 × 3–7.5 μm (x̅ = 7.2 × 5 μm, n = 10), hyaline to subhyaline, smooth-walled, terminal or intercalary, sympodially proliferating, subcylindrical to swollen. Conidia 14–20 × 6.5–12 μm (x̅ = 17 × 9.5 μm, n = 25), thick-walled, verrucose, straight to slightly curved, middle cells sometimes unequally enlarged, ellipsoidal to obovoid or sometimes subglobose, pale brown, 2–3-distoseptate, hila inconspicuous to slightly conspicuous.

Culture characteristics:— Colonies 4–5 cm diam. after seven days at 25 °C on PDA, brownish-orange to blackbrown, cottony, with moderate aerial mycelium, irregularly margin, reverse black. Mycelium hyaline to subhyaline to pale brown, branched, smooth-walled to verrucose, thick-walled, septate, 2–7 μm (x̅ = 3.6 μm) µm wide.

Material examined:— THAILAND. Chiang Mai: Omkoi District, Yang Piang , tropical forest soil, on hair baits, 17.7145N, 98.4286E, 935 m, 16 October 2019, W. A. Erandi Yasanthika ( MFLU 24-0381 ) ; living culture, MFLUCC 24-0280 ( CM21-1 ) .

Notes:— Soil-inhabiting Curvularia species have previously been isolated from forests (Yassanthika et al. 2023) and rice fields in Thailand ( Leewijit et al. 2016, Marin-Felix et al. 2017b). In the multi-gene (ITS-GAPDH- tef1-α) phylogenetic analyses of Curvularia species ( Fig. 2 ), our strain ( MFLUCC 24-0280) grouped with C. dactylocteniicola ( CPC 28810, USJCC-0094) with 100% ML and 1.00 BYPP statistical support. Curvularia dactylocteniicola was introduced by Marin-Felix et al. (2017b) associated with a leaf spot of Dactyloctenium aegyptium in Doi Saket, Chiang Mai, Thailand. Curvularia dactylocteniicola has been reported from Saccharum officinarum , Sorghum sp. and Zea mays in China, Indonesia and Sri Lanka ( Ferdinandez et al. 2024, Hidayat & Ramadhani 2019, Raza et al. 2019). It has also been isolated from the phylloplane of xerophytic plants ( Bhanot et al. 2024). Our isolate is morphologically similar to the type species ( CPC 28810) in having straight or flexuous, occasionally branched, mononematous, semito macronematous conidiophores that are sometimes geniculate in the upper part, terminal or intercalary, sympodial proliferating, subcylindrical to swollen conidiogenous cells and verruculose, mostly curved, occasionally unequally enlarged middle-celled, ellipsoidal to obovoid conidia ( Marin-Felix et al. 2017b). Our isolate ( MFLUCC 24-0280) differs from the type species ( CPC 28810) in having thick-walled, verrucose, straight to slightly curved, ellipsoidal to obovoid or sometimes subglobose, pale brown, 2–3-distoseptate conidia and inconspicuous to slightly conspicuous hila, in contrast to the smooth- to slightly verruculose-walled, mostly curved, ellipsoidal to obovoid, 3-distoseptate with flat to slightly protruding, darkened conidia with thickened hila of the latter ( Marin-Felix et al. 2017b).Based on the morphology and phylogeny, we confirmed our collection as C. dactylocteniicola isolated from forest soils in Thailand; this is the first time this species has been reported from soil. Curvularia dactylocteniicola was isolated using the hair-baiting technique, and we suggest that it is a keratinophilic species. Further biochemical analyses are necessary to confirm and identify its contribution to the hair degradation process.

Figures

FIGURE 2. Maximum likelihood phylogenetic tree generated based on the combined ITS-GAPDH- tef1-α sequence data for Curvularia taxa. Bootstrap support values of maximum likelihood greater than 60% and Bayesian posterior probabilities (BYPP) greater than 0.90 are indicated above the nodes. Newly added strains are in blue and ex-type strains are in bold. The tree is rooted to Bipolaris maydis (CBS136.29) and B. panici-miliacei (CBS 199.29).

FIGURE 3. Neptunomyces soli (MFLU24-0379, holotype). a, b. Colony on PDA (top and reverse). c. Pycnidia forming on culture. d Immature aseptate hyphae. e. Mature septate hyphae. f. Pycnidia. g. Pycnidial matrix. h–j. Conidiogenous cells with developing conidia. k–o. Conidia. Scale bars: d, e, g = 20 μm, f = 75 μm, h–o = 5 μm.

FIGURE 4. Curvularia dactylocteniicola (MFLU24-0381). a. Colony from above on PDA. b. Colony from below on PDA. c. Sporulating colony with conidial attachmentson the mycelium.d. Immature hypha.e. Mature melanizedhypha.f–j.Conidiogenesis on the conidiophore. k–p. Conidia. Scale bars d–h, k–p = 20 μm, i, j =10 μm.