Myrmecridium hydei Asghari, Phukhams. & E.B.G. Jones, 2023

Asghari, Raheleh, Phukhamsakda, Chayanard, Karimi, Omid, Apurillo, Carlo Chris S. & Jones, E. B. Gareth, 2023, Myrmecridium hydei, a novel marine species from Thailand, Phytotaxa 625 (3), pp. 265-279 : 269

Myrmecridium hydei Asghari, Phukhams. & E.B.G. Jones sp. nov.

Index Fungorum number: IF 901177, Facesoffungi number: FoF 14964

Etymology:— Named in honor of Prof. Kevin D. Hyde for his excellent contribution to mycology.

Holotype:— MFLU 23-0364

Saprobic on decaying branch of Areca species. Sexual morph: Undetermined. Asexual morph: Hyphomycetous (in vivo, Fig. 2 ). Colonies on natural substrate hairy, black, with white conidial masses. Conidiophores 115–250 × 2.5–4 µm (x̄ = 185 × 3 μm, n = 15), solitary or in small groups, macronematous, mononematous, straight or flexuous, unbranched, thick-walled, pale brown, gradually becoming paler towards the apex, later turning dark brown at base and brown toward apex with slightly thickened scars, septate. Conidiogenous cells 50–205 × 1.5–2.5 µm (x̄ = 123 × 2.2 μm, n = 15) with scattered, pimple-shaped denticles bearing conidia. Conidia 4.3−6.5 × 2.5−3.5 µm (x̄ = 5 × 3 μm, n = 25), solitary, ellipsoidal to obovoid to subglobose in mature conidia, with protuberant unpigmented hilum, thick-walled, smooth or finely verrucose to granular, subhyaline, aseptate, without wing-like sheath. Hyphomycetous (in vitro, Fig. 3 ). Colonies on PDA. Submerged hyphae 0.6–2 µm wide (x̄ = 1.5 μm, n = 15), hyaline, thin-walled. Aerial hyphae hyaline to medium brown, septate. Conidiophores 35–275 × 2–4 µm (x̄ = 170 × 3 μm, n = 15), unbranched, straight or flexuous to geniculate-sinuous, sympodial, arising from creeping aerial hyphae, pale brown to medium brown, paler at the apex, thick-walled, smooth, with up to 20 septa, sometimes constricted at septa, basal cell often inflated, 3–7 μm wide (x̄ = 4.5 μm, n = 15). Conidiogenous cells 30–210 × 2–3 µm (x̄ = 133 × 2.5 μm, n = 15), integrated, elongating sympodial, cylindrical, flexuous, polyblastic, pale brown to medium brown at the base, subhyaline in the upper part, septate, thick-walled near the base, thin-walled toward the apex, with scattered pimple-shaped, unpigmented denticles 0.5–1.2 × 0.5–1 µm (x̄ = 0.7 × 0.7 μm, n = 25). Conidia 3–8 × 2–4.5 µm (x̄ = 6 × 3.5 μm, n = 35), solitary, ellipsoid to obovoid to irregular, subhyaline, thick-walled, finely verrucose, containing two large guttules without wing like sheath, with one hilum. Hilum 0.5–1 μm wide (x̄ = 0.7 μm, n = 15), prominent, unpigmented.

Culture characteristics:— Conidia germinating on PDA within 24 hours. Colonies on PDA and MEA reaching up to 2 cm diameter after 2 weeks and 5 cm after 4 months at 24 °C. Mycelium submerged at the edge, flat, white to pale yellow, later becoming powdery to velvety and greyish light brown due to sporulation, with fertile bundles of hyphae and entire margin; reverse yellow with orange at the center.

Material examined:— THAILAND. Prachuap Khiri Khan Province: Pranburi ,on decaying Areca wood submerged in seawater, 25 October 2022, K.D. Hyde, R6B ( MFLU 23-0364 , holotype); ex - type living culture MFLUCC 23-0217 , additional living culture MFLUCC 23-0218 .

GenBank numbers:— MFLUCC 23-0217 (ex - type): ITS = OR500543, LSU = OR500545, rpb2 = OR515019, tef1-α = OR515020 ; MFLUCC 23-0218 : ITS = OR500544, LSU = OR500546 .

Notes:— The reconstruction of phylogenies from ITS and LSU sequences showed that Myrmecridium hydei formed a distinct clade with M. phragmitigenum , M. phragmiticola and M. sambuci in both maximum likelihood and Bayesian analyses with 80 SH-aLRT/77 UFB/0.83 BPP statistical support. In a BLAST search in GenBank, the closest match of the ITS sequence of M. hydei ( MFLUCC 23-0217) was 99.63% similar across 99% of the query sequence to M. schulzeri ( NTOU 4421), which translates into 98.63% similarity. In a BLAST search in GenBank, the closest match of the LSU sequence of M. hydei ( MFLUCC 23-0217) was 100% similar across 98% of the query sequence to M. schulzeri ( CBS 188.96), which translates into 98% similarity. Myrmecridium hydei differs from M. schulzeri in having flexuous conidiophores and lacking a wing-like sheath to the conidia ( Arzanlou et al. 2007). Myrmecridium hydei ( MFLUCC 23-0217) has similar characters to M. flexuosum , but M. flexuosum is distinguishable by having shorter conidiophores without strongly constricted, shorter pimple-like denticles, and it has conidia with a sheath ( Arzanlou et al. 2007). Therefore, Myrmecridium hydei is introduced as a novel species based on its distinct morphology and phylogenetic evidence.

Figures

FIGURE 2. Myrmecridium hydei (MFLU 23-0364, holotype).a. Colonies on the host substrate.b. Close up of colonies.c–g.Conidiophores and conidiogenous cells. h. Conidia. i. Germinated conidium. j. Colony on PDA (above). k. Colony on PDA (below). Scale bars: b = 100 µm, c–d = 50 µm, e = 20 µm, f–i = 10 µm.

FIGURE 3. Myrmecridium hydei (MFLUCC 23-0217, ex-type living culture). a. Colonies on PDA after two weeks (above). b. Colonies on PDA after two weeks (below). c. Colonies on MEA after two weeks (above). d. Colonies on MEA after two weeks (below). e. Close up of colony on PDA after four months. f. Bundle of hyphae. g–j. Conidiophores. k–m. Conidiogenous cells. n. Conidia. o. Conidia mounted in black ink. Scale bars: e = 200 µm, f = 100 µm, g = 20 µm, h–k = 50 µm, l–m = 20 µm, n–o = 5 µm.