Phaeoisaria sparsa B. Sutton, Mycol. Pap.

Phaeoisaria sparsa B. Sutton, Mycol. Pap. 132: 87. 1973. Fig. 10. Description on the natural substrate: See Sutton (1973) and Hughes (1978). Culture characteristics: On CMD colonies 27–29 mm diam., circular, raised with a flat margin, margin entire, funiculose, cobwebby to mucoid towards the periphery, white-beige, margin isabelline, reverse isabelline. On MLA colonies 20–21 mm diam., circular, slightly convex, margin finely undulate, velvety, furrowed, grey, margin olivaceous grey, reverse dark olivaceous grey. On OA colonies 31–33 mm diam., circular, flat, margin entire, cobwebby to mucoid, farinose with sparse funiculose ropes of hyphae at the margin, olivaceous brown, beige towards the periphery, reverse olivaceous brown. On PCA colonies 28–30 mm diam., circular, raised with a flat margin, margin entire, velvety, funiculose at the inoculation block, white-beige, creamy at the margin, reverse pale brown. Sporulation was abundant on CMD, MLA and PCA, moderate on OA. Description in culture: Colonies on CMD effuse. Mycelium composed of hyaline, subhyaline to brown, septate hyphae, 1.5–2.5 μm wide. Synnemata absent. Conidiophores macronematous, semi-macronematous or reduced to a single conidiogenous cell. Conidiogenous cells 5–18 × 2–3.5 µm, integrated, terminal and intercalary, polyblastic, sympodially extending, oval, cylindrical to subulate, hyaline, smooth, with several denticles, 1.5 × 0.5 µm; conidiogenesis holoblastic-denticulate. Conidia solitary, dry, hyaline, aseptate, smooth, with one or two large guttules, with a truncate basal scar, secession schizolytic, of two types (formed on all media): 5.5–8 × 2–2.5 µm (mean ± SD = 7.2 ± 0.7 × 2.2 ± 0.2 μm), on MLA 4.5–7.5 × 2–3 µm (mean ± SD = 6.1 ± 0.8 × 2.6 ± 0.3 μm), oblong to elongate clavate, straight or slightly curved, rounded at the apex, hyaline, aseptate; 3–3.5 × 1.5–2 µm (mean ± SD = 3.4 ± 0.3 × 1.7 ± 0.2 μm), on MLA 3.5–4.5 × 1.5–3 µm (mean ± SD = 3.8 ± 0.4 × 2.2 ± 0.4 μm), guttuliform to dacryoid; sporulation associated with the aerial part of the colony. Sexual morph not observed. Material examined: Spain, Aragón, Ordesa y Monte Perdido National Park, Torla, on dead twig, 23 Mar. 2011, M. Hernández-Restrepo & J. Gené, culture FMR 11939. Habitat and geographical distribution: Saprobe, originally described from decaying bark of Acer spicatum, with additional reports from decaying wood of various deciduous trees, e.g. Alnus sp., Betula papyrifera, Corylus sp., Populus tremuloides, Populus balsamifera, Salix sp. in Canada, New Zealand, and Spain (Sutton 1973, MyCoPortal, this study). According to GlobalFungi database, this species was the second most abundant within the genus, detected in 66 samples. Most records originated from forests and woodlands (83 %), followed by anthropogenic habitats (10 %), croplands (5.7 %), and to a lesser extent, grasslands and desert biomes (1.3 %). The majority of samples were soil-related (66 %), with additional occurrences from dead organic matter (17 %), air (9 %), and roots or shoots (7 %). The samples predominantly originated from temperate zones across three continents: North America (USA), Europe (Czech Republic, Belgium, Germany, Latvia, Estonia, Italy, Spain, Sweden), and East Asia (China, South Korea). Two exceptions included records from Mediterranean climates (Seville, Spain) and a single occurrence in the Antarctic polar zone. Notes: In our phylogenetic analyses, P. sparsa is represented by strain FMR 11939, isolated from a dead twig in Spain (Hernández-Restrepo et al. 2017). Our material corresponds well with the protologue (Sutton 1973) based on observations on natural substrate: synnemata 220–250 × 17–28 µm, conidiogenous cells 15–20.5 × 3–3.5 µm with denticles 1.5–2 × 0.5 µm, and conidia 12–17 × 2.5–3.5 µm. It is well defined by its 0–3-septate, fusiform to oblong-clavate conidia and subulate conidiogenous cells, which are mostly confined to the apices of the synnemata, giving them a somewhat penicillate appearance. In culture, the synnemata were absent and the fungus produced two types of conidia differing in shape and size (oblong to elongate clavate and guttuliform to dacryoid), a feature also observed in P. parallela. In culture, the conidia were consistently aseptate. Furthermore, in culture, the size and shape of both conidial types were comparable across all media, although on MLA, the oblong to elongate conidia were slightly shorter, while the guttuliform to dacryoid conidia were slightly longer (see description). The longer conidia, although comparable in shape to those on the natural substrate, were shorter in culture (5.5–8 × 2–2.5 µm on CMD, 4.5–7.5 × 2–3 µm on MLA). Phaeoisaria sparsa is similar to P. parallela in conidial characteristics; however, both species are morphologically well differentiated. As only ITS and LSU sequences of the strain FMR 11939 were available in GenBank, we generated sequences from other gene regions to complete its molecular dataset. The combined morphological and molecular differences support the recognition of P. parallela and P. sparsa as distinct species. For a detailed morphological comparison of both species, see the notes under the description of P. parallela.

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