Musicillium theobromae (Turconi) Zare & W. Gams

Asghari, Raheleh, Phukhamsakda, Chayanard, Jones, E. B. Gareth, Bahkali, Ali, Apurillo, Carlo Chris S., Karimi, Omid, Kakumyan, Pattana & Hyde, Kevin D., 2025, Morphology and phylogeny reveal two new species and host records of hyphomycetous fungi on Areca species from marine habitats in Thailand, MycoKeys 118, pp. 179-206 : 179-206

Musicillium theobromae (Turconi) Zare & W. Gams

Description.

Saprobic on decaying branches of Areca sp. Sexual morph: Undetermined. Asexual morph: Hyphomycetous (in vivo, Fig. 7 ). Colonies on natural substrates hairy, black, with glistering white conidial masses. Conidiophores 108–503 × 3–7 µm (x – = 252 × 4.5 μm, n = 15), solitary or in groups, macronematous, mononematous, mostly straight or slightly flexuous or bent, wider at the base, unbranched or branched, septate, thick-walled, smooth-walled or slightly asperulate, brown, pale brown to subhyaline or hyaline near the apex, bearing whorls of 3–6 (– 7) phialides. Conidiogenous cells 13.5–27 × 2–3 µm (x – = 19 × 2.5 μm, n = 20), monophialidic, subhyaline to hyaline, cylindrical, wider at the base and tapering towards the tips, sometimes with an inconspicuous collarette, asperulate. Conidia 3.1-4.8 × 1.4-2.1 µm (x – = 3.9 × 1.8 μm, n = 40), forming in slimy heads, hyaline, cylindrical, obovoid or ellipsoidal, thick-walled, guttulate, verrucose to granular. Hyphomycetous (in vitro, Fig. 8 ). Colonies on PDA. Vegetative hyphae subhyaline, pale brown to brown, sometimes aggregating into microsclerotium-like structures, moniliform hyphae are present. Conidiophores 178–375 × 2.5–4 µm (x – = 255 × 3 μm, n = 15), arising from vegetative hyphae, mostly straight or slightly flexuous or bent, slightly tapering toward the upper part, unbranched or branched, thick-walled, septate, smooth-walled, sometimes slightly asperulate, brown to pale brown, subhyaline or hyaline at upper part, bearing phialides. Conidiogenous cells 21–35 (– 43) × 2–4 µm (x – = 29 × 2 μm, n = 20), phialidic, in whorls of 1–6 phialides, smooth-walled, sometimes slightly asperulate, subhyaline to hyaline, cylindrical, wider at the base and tapering towards the tips. Conidia 3-6 (- 7.5) × 2-4 µm (x – = 4.8 × 2.8 μm, n = 40), forming in slimy heads, hyaline, obovoid or ellipsoidal to cylindrical, thick-walled, guttulate, smooth-walled.

Culture characteristics.

Conidia germinating on PDA within 12 h. Colonies on PDA reaching 2 cm diam. after two weeks and 4 cm diam. after two months at 25 ± 2 ° C, finely floccose, round, entire margin to finely rhizoid, white and gray brown at the center, becoming raised and brown with age. Reverse white with gray brown at the center, becoming darker with age.

Material examined.

Thailand, Prachuap Khiri Khan Province, Pranburi , on decaying Areca wood submerged in seawater and trapped between rocks, 25 October 2022, K. D. Hyde, R 6 a ( MFLU 24-0454 ), living culture ( MFLUCC 24-0563 ) .

GenBank numbers.

Musicillium theobromae MFLUCC 24-0563 : ITS = PQ 778936, LSU = PQ 778931, rpb 2 = PQ 885480, tef 1 - α = PQ 885481.

Notes.

The reconstruction of phylogenies from LSU - ITS - tef 1 - α- rpb 2 sequences showed that Musicillium theobromae ( MFLUCC 24-0563 ) formed a sister clade with M. theobromae ( CBS 968.72 ) in both maximum likelihood and Bayesian analyses with 100 % ML / 1.00 BPP statistical support (Fig. 3 ). In a BLAST search in GenBank, the closest match of the ITS sequence of M. theobromae ( MFLUCC 24-0563 ) was 99.33 % similar across 99 % of the query sequence to M. theobromae ( NZ 62). In a BLAST search in GenBank, the closest match of the LSU sequence of M. theobromae ( MFLUCC 24-0563 ) was 99.89 % similar across 98 % of the query sequence to M. theobromae ( CBS 243.74 ). Musicillium theobromae ( MFLUCC 24-0563 ) has similar morphology to the neotype species of M. theobromae ( CBS 968.72 ), in having slightly asperulate brown septate conidiophores bearing whorls of up to six phialides, almost the same length (21–35 (– 43) µm vs. 17-35 µm) of phialide, which are tapering towards the tips, hyaline smooth-walled conidia forming in a slimy head ( Zare et al. 2007). Therefore, M. theobromae ( MFLUCC 24-0563 ) is introduced as a new host record on Areca based on morphology and phylogenetic evidence.

Figures

Figure 3. Phylogram generated from maximum likelihood analysis based on combined LSU, ITS, tef 1 - α and rpb 2 sequence data of Plectosphaerellaceae. Maximum likelihood bootstrap support ≥ 65 % and Bayesian posterior probabilities (BPP) ≥ 0.90 are given near the nodes, respectively. The tree is rooted to Cylindrotrichum clavatum (CBS 125296, CBS 125297). The newly generated sequence is highlighted in yellow and the type strains are indicated in bold.

Figure 7. Musicillium theobromae (MFLU 24-0454, a new host record) a appearance of colony on the host b, c a close appearance of colony on the host d, e conidiophores f conidiogenous cells and developing conidia g close up of the phialide with an inconspicuous collarette h, i conidia j germinated conidium k colony on PDA after two months. Scale bars: 100 µm (b, e); 200 µm (c); 50 µm (d); 20 µm (f); 5 µm (g – i); 10 µm (j).

Figure 8. Musicillium theobromae (MFLUCC 24-0563, a new host record) a colony on PDA after two weeks (above) b colony on PDA after two weeks (below) c, d appearance of conidiophores and conidia on the culture e conidiophore and conidia f conidiogenous cells bearing conidia g conidia h moniliform hyphae. Scale bars: 200 µm (c); 100 µm (d, e); 50 µm (f, h); 10 µm (g).