Thyridium lauri Voglmayr, D. Aiello & G. R. Leonardi, 2024

Leonardi, Giuseppa Rosaria, Aiello, Dalia, Di Pietro, Chiara, Gugliuzzo, Antonio, Tropea Garzia, Giovanna, Polizzi, Giancarlo & Voglmayr, Hermann, 2024, Thyridium lauri sp. nov. (Thyridiaceae, Thyridiales): a new pathogenic fungal species of bay laurel from Italy, MycoKeys 110, pp. 211-236 : 211-236

Thyridium lauri Voglmayr, D. Aiello & G. R. Leonardi sp. nov.

Figs 6 , 7

Etymology.

Referring to its host, Laurus nobilis .

Type.

Italy • Sicily, Catania province, plant nursery located in Mascali , 37°44.85'N, 15°12.25'E, isolated from diseased corticated twigs of Laurus nobilis , 23 June 2021, G. Polizzi (holotype WU-MYC 0052725 dried culture; ex-holotype culture ALF 11 = CBS 151898 ) .

Description.

On PDA reaching 54–56 mm diameter after 21 days, first pale creamy to yellowish, cottony in the centre, with dense whitish aerial mycelium after 14 days, after 1 month colonies ochraceous to umber brown in the centre, with distinct concentric lighter and darker zones, aerial mycelium white or grayish in the centre, sparse or lacking towards the margins, forming dry effused patches of branched aerial conidiophores interspersed with spot-like to effused patches of densely branched conidiophores immersed in white to cream slimy conidial masses; reverse dark umber brown in the centre, with lighter and darker brown concentric zones towards the margins. On CMD reaching 59–62 mm diameter after 21 days, colonies first whitish, from the centre becoming greenish brown with age, finally blackish brown in the centre, aerial mycelium sparse to absent, with scant erect branched conidiophores and strands of aggregated radial hyphae on the agar surface. Sporodochia and pycnidia not observed. Conidiation of three types, all of (sub) hyaline, thin-walled cells: (1) on tufts of aerial, several times loosely branched conidiophores, with straight elongate hyphal conidiophore cells and cylindrical to narrowly-ampulliform terminal or lateral conidiogenous cells (phialides) of variable length up to 50 µm long, producing conidia terminally; (2) on densely branched, interwoven-aggregated conidiophores, with knobby to sinuous conidiophore cells and terminal or lateral conidiogenous cells (polyphialides) of variable, irregular flexuous-knobby shape, 4–18 × 1.2–3.6 µm (n = 155), forming conidia terminally and / or laterally; and (3) on straight to bent adelophialides formed singly on hyphae at more or less right angles, 1–13 × 0.7–1.8 μm (n = 56), with a tiny pericline apical thickening, but without visible collarettes. Conidia hyaline to subhyaline, thin-walled, of two types: (1) subglobose to broadly ellipsoid, uni- to irregularly multiguttulate, commonly aggregated in spot-like to effuse slimy masses, produced on the branched conidiophore type (2), (2.2 –) 3.0–3.8 (– 4.8) × (2.0 –) 2.3–3.0 (– 3.7) μm, l / w = (1.0 –) 1.2–1.5 (– 1.9) (n = 211); (2) elongate, ellipsoid to allantoid, mostly biguttulate with a guttule near each end, mainly borne from adelophialides but also on conidiophore type (1), (2.3 –) 3.0–4.0 (– 4.9) × (1 –) 1.3–2.0 (– 2.8) μm, l / w = (1.2 –) 1.8–2.8 (– 4.0) (n = 169). Subglobose to broadly ellipsoid conidia mainly produced in masses on PDA in older parts of the colony; elongate to allantoid conidia commonly observed on CMD, more rarely on PDA, produced within 3–4 days mainly in the actively growing younger parts of the colony. On inoculation plugs of PDA cultures placed on CMD yeast-like cells observed 3 to 4 days after inoculation, developing by budding at one or two ends from swollen subglobose conidia. Sexual morph unknown.

Additional specimens examined.

Italy • Sicily, Catania province, plant nursery located in Giarre , 37°41.81'N, 15°11.52'E, isolated from twig necrosis of Laurus nobilis , 10 June 2021, G. Polizzi ( WU-MYC 0052726 , dried culture ALF 2 ; CBS 151896 ) ; • Catania province, plant nursery located in Giarre , 37°41.81'N, 15°11.52'E, isolated from twig necrosis of Laurus nobilis , 10 June 2021, G. Polizzi ( WU-MYC 0052727 , dried culture ALF 6 ; CBS 151897 ) .

Based on the results of molecular phylogenies (Fig. 3 ) and the synonymy of Phialemoniopsis with Thyridium two recently described Phialemoniopsis species are here combined in Thyridium .

Figures

Figure 3. Phylogram of the best ML tree (- lnL = 13574.613578) revealed by RAxML from an analysis of the combined ITS- LSU - act 1 - rpb 2 - tef 1 - tub 2 matrix of Thyridium, showing the phylogenetic position of the new species from diseased Laurus nobilis (bold), with Annulusmagnus triseptatus, Ascitendus austriacus and Myrmecridium montsegurinum selected as outgroup to root the tree. Maximum Likelihood (ML) and Maximum Parsimony (MP) bootstrap support above 70 % are given at first and second position, respectively, above or below the branches. ET = epitype; HT = holotype.

Figure 6. Colonies of Thyridium lauri (ALF 11, ex-holotype culture) A on PDA (1 month, 22 ° C) B on PDA (1 month, 22 ° C), reverse C on ½ PDA (21 days, 22 ° C) D on CMD (21 days, 22 ° C).

Figure 7. Morphology of Thyridium lauri (a – c, e – h, t. ALF 6; d, i, j, k, m – o, r, s. ALF 11; l, p, q. ALF 2) a tufts of aerial conidiophore type 1 interspersed with patches of conidiophore type 2 submerged in slimy conidal masses (PDA, 1 month) b inoculation plug of PDA culture on CMD showing branched aerial conidiophore type 1 (11 days) c densely branched conidiophore type 2, showing flexuous-knobby conidiophore cells and irregular terminal and lateral conidiogenous cells (PDA, 1 month) d – f loosely branched conidiophore type 1 showing straight terminal and lateral conidiophore and conidiogenous cells (PDA, 1 month) g, h irregular conidiogenous cells from conidiophore type 2, showing terminal and lateral conidiation (PDA, 1 month) i ampulliform conidiogenous cell from conidiophore type 1 (CMD, 11 days) j surface mycelium with hyphal strand and adelophialides with ellipsoid-allantoid conidia (CMD, 11 days) k – r adelophialides on hyphae with ellipsoid-allantoid conidia (k, l, p – r CMD, 11 days; m – o PDA, 3 days) s swollen conidia showing yeast-like budding (arrows; PDA plug on CMD, 3 days) t subglobose conidia from conidiophore type 2 (PDA, 1 month). All from pure cultures grown at 22 ° C. Scale bars: 100 μm (a, b); 10 μm (c – f, j); 5 μm (g – i, k, l, s, t); 3 μm (m – r).