Chaetosphaeronema misuriniensis Mlčoch, 2024

Mlčoch, Patrik & Matušinsky, Pavel, 2024, Phylogenetic and morphological revision sexual stages of the genus Paraphoma (Phaeosphaeriaceae) and next related species from clade of Ophiobolus-like (Phaeosphaeriaceae), Phytotaxa 663 (4), pp. 184-204 : 198-199

Chaetosphaeronema misuriniensis Mlčoch sp. nov. —Fig. 7.

Holotype. BRNM 840269 .

MycoBank no: 854610

Etymology. Species name ¨misuriniensis¨ is according to type locality, which is located near the Misurina lake in the Italy.

Sexual morph. Ascoma pseudothecial, globose, semiglobose to conical, in numerous groups, 440–550 μm in diam., subepidermal, later semi-immersed to erumpent by ostioles. Ostioles inconspicuous, small or truncate and conical. Ascomal wall composed of several layers of pseudoparenchymatous cells, composed of yellowish brown, isodiametric to polygonate cells of textura angularis, (5)6–10(12) × (5)6.5–9(10) μm, N =20. Asci bitunicate, 8–spored, cylindrical to cylindrical-clavate, short pedicellate, (70)90–100(110) × (8.5)10–11 μm, N =10. Ascospores narrowly fusiform, biseriate in ascus, rare to triseriate, hyaline, 6 to 7-septate, third cell of spore from apex enlarged towards base, third cell constricted to first septum, smooth, without appendages gelatinous sheath or ornamentation, with or without lipid drops, (31)35–41(45) × (4)4.5–6(6.5) μm, Q =6.5–8.3, Q AV =7.5, N =41. Asexual morph. Undetermined.

FIGURE 7. Chaetosphaeronema misuriniensis ( BRNM 840269). A, J: asci; B – I, K – L: ascospores. Scales: A, J: 15 μm; B – I, K – L: 5 μm.

Culture characters. Colony on the PDA in culture grown slow, 12–15 mm in diam. after two weeks at 25 ° C. Colony irregular, whitish to purplish, with raised to convex elevation, margin undulate and purplish white. Conidiomata in culture globose, pycnidial, gregarious, 190–250 μm in diam., 190–250 μm on height, with inconspicuous, small ostiole. Conidiomatal setae hyaline to brownish, septate, unbranched, smooth wall, 57–88 × 3.5–4 μm. Conidiomatal wall composed of several layers of pseudoparenchymatous cells, composed of hyaline to brownish, isodiametric to polygonate cells of textura angularis, (3)3.5–4.5 (5) × 2.5–3.5 (4) μm. Conidiogenous cells are hyaline, enteroblastic, annelidic, cylindrical to lageniform, determinate, smooth-walled, with periclinal thickenings at collarette zone or percurrently proliferating 1–2 times. Conidia hyaline, cylindrical, rounded at apex, straight or slightly curved, aseptate, often guttulate, smooth-walled, 3.5–5(6.5) × (1.3)1.5–2(2.5) μm, Q =2.2–3.1, Q AV =2.6, N =30.

Habitat. Dead stems of various herbs, e. g. Cirsium erisithales ( Asteraceae ), Aconitum lycoctonum subsp. vulparia ( Ranunculaceae ) and Listera ovata ( Orchidaceae ). All collections were found in subalpine high-herbs vegetation on the limestone substrates.

Distribution. Italy (three collections, this study).

Material examined: ITALY: 1. col. P. Mlčoch, Dolomites, Auronzo di Cadore provincy, Misurina, Lago di Misurina lake, subalpine high-herbs vegetation on the dolomitic limestones, 1775 m a. s. l., 21. 7. 2019, on the dead stems of Cirsium erisithales, GPS : 46.5842486N, 12.2565528E ( BRNM 840269, GenBank no. OQ 359107). 2. col. P. Mlčoch, Dolomites, Auronzo di Cadore provincy, Misurina, Lago di Misurina lake, subalpine high-herbs vegetation on the dolomitic limestones, 1775 m a. s. l., 21. 7. 2019, on the dead stems of Cirsium erisithales, GPS : 46.5842486N, 12.2565528E ( BRNM 840268); 3. col. P. Mlčoch, Dolomites, Auronzo di Cadore provincy, Misurina, Lago di Misurina lake, subalpine high-herbs vegetation on the dolomitic limestones, 1775 m a. s. l., 21. 7. 2019, on the dead stems of Aconitum lycoctonum subsp. vulparia, GPS : 46.5841956N, 12.2548444E ( BRNM 840267); 4. col. P. Mlčoch, Dolomites, Auronzo di Cadore provincy, Misurina, Lago di Misurina lake, subalpine high-herbs vegetation on the dolomitic limestones, 1775 m a. s. l., 21. 7. 2019, on the dead stems of Listera ovata, GPS : 46.5841956N, 12.2548444E ( BRNM 840270).

Notes. Isolate reports 99 % identity with the species Chaetosphaeronema achilleae and 98.5 % identity with the species Ophiobolus cirsii . Morphologically, this collection is similar to the phylogenetically related species Chaetosphaeronema barriae , which is grown on the other substrate and has the largest ascospores.Taxa of Leptosphaeria ogilviensis and Leptosphaeria planiuscula has the similar characteristics of ascospores, but they are only 5-septate, and both species have terminal appendages, which is not present in this example ( Mlčoch 2021; Shoemaker 1984). Leptosphaeria nanae descripted by Shoemaker (1984), has the largest asci (100–120 × 12–15 μm) and wider ascospores (6–7 μm), which has also terminal appendages. Ch. misuriniensis is very similar its morphological appearance some taxa from the genus Plenodomus ( De Gruyter et al 2013). However, they are descripted from the other substrates and phylogenetically belong to another phylogenetic clade ( Leptosphaeriaceae ) ( De Gruyter et al. 2013). Visual similarity is here more likely random homoplasy of characters.