Ophiostoma pehueninum M. Zapata, M. A. Palma & E. Piontelli 2018, sp. nov.
Creators: name: Zapata, Mario
name: Palma, Maria Antonieta
name: Piontelli, Eduardo
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Fungi
Ascomycota
Sordariomycetes
Ophiostomatales
Ophiostomataceae
Ophiostoma
Ophiostoma pehueninum

description: Ophiostoma pehueninum M. Zapata, M.A. Palma & E. Piontelli sp. nov. (Fig. 3–4)   
MycoBank no.: MB822101  
 Etymology. The epithet pehueninum refers to the host tree name in Mapudungun (Mapuche language), Pehuén.   
 Sexual morph: Ascomata developing after 30 days on WA with autoclaved araucaria twigs, superficial, mostly embedded on media, only in crosses done between isolates RGM 2388 and RGM 2389. Ascomatal bases dark brown to black (10 YR 3/1), globose to subglobose, bases (105–)145–200(–210) μm in diameter, ornamented with brown, short and long twiggy hyphal hairs in the peridia and basal perithecia, 40–150 μm, up to 200 μm long. Ascomatal necks dark brown to black (10 YR 3/1), straight or curved without annuli, (105–)145–350(–800) μm long, (27–)30– 42.5(–50) wide at the base, (12–)17.5–27.5(–30) μm wide at the apex. Ostiolar hyphae divergent, tapering towards the apex, subhyaline, without septa and rounded end, (15–)30–40 × 1.5–2(–2.2) μm, 8–13 in number. Asci not observed. Ascospores accumulating in a clear white mucilaginous mass at the ascomatal apex, turning light yellow with age, hyaline, 1-celled, allantoid in side view, surrounded by a narrow gelatinous sheath, (3.8–)4.5–5.6(–6) × (1–)1.3–1.7(– 2) μm (average = 5 × 1.5 μm).   
 Asexual morph: After 14 days on MEA, hyalorhinocladiella-like micronematal state present. Conidiogenous cells arising directly from narrow undifferentiated hyphae or as distinct unbranched or branched conidiophores, revealing in the main axis low-profile scars on the extending conidiophore, (25–)35–50(–60) × 1.5–2.5 μm. Conidia hyaline at first, light brown in time, smooth, ellipsoidal, obovoid to round, base truncate, narrow or wide (more notable on OA), without denticles, (3.1–)3.6–5.2(–9.0) × (2.9–)3.0–4.2(–4.7) μm, often giving rise to secondary conidia. In some wide hyphae, apparent synchronic development of blastic conidia formed in small groups (3–5) by repeated percurrent proliferation at the apex of sessile conidiogenous cell. Mycelium aerial, superficial, embedded in the agar.   
 Colonies growing: Cultures on MEA reaching 40.3 ± 1.7 mm in diameter at 7 days, 69.0 ± 2.3 mm at 14 days and 76.8 ± 1.1 mm at 21 days, granular in appearance, brown-colored after 21 days (5 Y 6/3). Growing on PDA reaching 23.7 ± 0.7 mm in diameter at 7 days, 46.0 ± 2.0 mm at 14 days and 59.2 ± 3.7 mm at 21 days, color variable from white (5 Y 8/1) to light brown (5 Y 6/3) after 21 days. Growing on OA reaching 32.7 ± 1.7 mm in diameter at 7 days, 58.8 ± 3.7 mm at 14 days and 76.1 ± 1.9 mm at 21 days, color white forming brown fluffy masses (2.5 Y 6/4) after 21 days. No growth at 35° C.   
 Typification:— CHILE, Alto Bío Bío, Ralco Forest Reserve (37°56’41’’ S, 71°20’12’’ W), from Araucaria araucana, June 2016, collected by Viviana Sepúlveda, holotype RGM 2389, ex-type culture CBS 142995.   
 Additional specimens examined:— CHILE, Alto Bío Bío, Ralco Forest Reserve (37°56’04’’ S, 71°21’48’’ W), from Araucaria araucana, March 2017, Rodrigo Kiger, living culture RGM 2387, CBS 142996. Alto Bío Bío, Ralco Forest Reserve (37°56’02’’ S, 71°21’54’’ W), from Araucaria araucana, March 2017, Rodrigo Kiger, living culture RGM 2388, CBS 142997.   
 Notes: Ophiostoma species are pleomorphic and several types of asexual reproduction can be found in a single culture. In our specimen a continuum of conidial ontogeny was observed not including two of the common asexual morphs of Ophiostoma such as pesotum-like and sporothrix-like.This species has a special conidiogenesis in appearance similar to Hyalorhinocladiella because of its micronematous development and mycelial form in nature (Upadhyay & Kendrick 1975), but differs from this group by the shape and brown color of its conidia. The conidiogenous cell also resembles Pesotum because of its conidium dehiscence, but differs from this group by the color of conidia at maturity and lacks synnematous character. The conidia observed in a percurrent proliferation of the conidiogenous cell under the light microscope (or interdiferencial contrast) is a situation that could be easily misinterpreted as arising from a sympodial proliferation by the effect of repeated incomplete dehiscence (Benade et al. 1995).   
 Known hosts and substrate:— Araucaria araucana, stem and branches.   
 Known insect vector:—Unknown.   
 Known distribution:— Chile, Bío Bío Region.
description: Published as part of Zapata, Mario, Palma, Maria Antonieta & Piontelli, Eduardo, 2018, Ophiostoma pehueninum, a new species associated with Araucaria araucana in Chile, pp. 93-103 in Phytotaxa 346 (1) on pages 98-100, DOI: 10.11646/phytotaxa.346.1.5, http://zenodo.org/record/13708199