Sclerencoelia fraxinicola
Sclerencoelia fraxinicola Baral & Pärtel, IF: 815441
Etymology: The name refers to the host that this species is restricted to.
Diagnosis: This species is characterized by its growing on Fraxinus, unlike the two other known Sclerencoelia species, which grow on Populus. It differs from S. fascicularis by its solitary to gregarious apothecia, which usually do not form roundish fascicles. Holotype TAAM 198511, isotype M-0,281,055/H.B.9358. Sclerotia-like aggregations developing within or beneath the bark, discoid-shaped or with one side elongated, in association of flat, reticulate dark brown strands >10 mm long, 0.4–0.8 mm wide, 0.25–0.3 mm thick, composed of branched blackish brown-walled hyphae. Apothecia erumpent, scattered or densely aggregated in small groups of 2–3 apothecia, sessile to substipitate, hydrated cupulate, slightly tough, 2–8 mm in diam., 300–500 μm thick at lower flanks, 200 μm near margin; disc brownish grey to brownish black, margin finely rough to crenulate, outside blackish-grey, ± strongly white-pruinose, especially near margin; dry greyishblack. Ectal excipulum 25–50(−70) μm thick at flanks, inner part of vertically oriented t. globulosa-angularis-prismatica, cells *11–18(−21) × 7–10(−11.5) μm, slightly gelatinized,ncortical cells broadly ellipsoid to globose, *thin-walled, †thick-walled, 6–10 μm in diam., with scattered grey-brown (in KOH olivaceous) exudate especially towards the cortex; marginal cells cylindric-clavate, forming free protruding elements, covered by brown exudate. Medullary excipulum 200–300 μm thick, less towards the margin, of rather dense t. intricata, non-gelatinized, hyaline or with brownish hue,
cells 60–85 × 2–8 μm, slightly rough, forming a 15–20 μm thick pale grey-brown (in KOH black-brown) layer towards the ectal excipulum. Subhymenium light olivaceous-brown, small-celled. Asci cylindric-clavate, apex medium truncate to rounded with †1–2(−3.5) μm thick apical wall (mature 0.5–1.5 μm), inamyloid {2} or faintly blue {1} in upper part of wall in MLZ or IKI (without KOH-pretreatment), *(79–)85–120(−142) × (9–)10–12(−13) μm {4}, †85–90 × 6.8–8 μm {1}, *equal with or finally 15–25 μm longer than paraphyses, † shorter than paraphyses, pars sporifera *31–40 μm, arising from croziers {4}. Ascospores cylindric-allantoid, slightly to strongly curved, *(11–)12–15(−18) × (2.9–)3.2–3.5(−4) μm {6}, †11–15(−16) × 2.8–3.4(−3.8) μm {1}, aseptate but when overmature 1(−3)-septate, rarely forming globose to ellipsoid
conidia at one or both ends. Paraphyses apically uninflated to slightly clavate-capitate or moniliform, partly flexuous or with outgrowths, *2.5–5.3 μm wide, upper 10–20(−38) μm densely covered by light to dark olivaceous-brown granules, surrounded by brown exudate, sometimes apices tipped by fasciculate hyaline phialides forming subglobose conidia {2}. Crystals 4–10 μm in diam., abundant on exterior of excipulum, also some in inner parts and over hymenium, abundant in sclerotia.
Habitat: on dead wood or bark of corticated, 4–8 mm thick, attached or fallen twigs, or 10–15 cm thick, recently felled trunks of Fraxinus excelsior, 0–2 m above ground.
Phenology: nearly year round. Distribution: known only from temperate humid Central Europe.
Comments: The present concept of S. fraxinicola is based mainly on the available molecular data (two strains from Germany). Tissue cells survive for at least 6 weeks in dry specimens. Seaver (1951) discussed the ash-inhabiting populations of E. fascicularis but concluded that these all represent one species, because the ascospore measurements are the same as in poplar inhabiting specimens. Gremmen (1952) described E. fascicularis in culture, isolated from apothecia growing on Fraxinus. The mycelia produced crystals on agar. Mature apothecia developed after pieces of a Fraxinus branch were added to the agar medium. Gremmen compared cultures derived from apothecia on Populus and found them to be similar.
Based on rDNA ITS BLAST search in GenBank, a sequence originating from Fraxinus shoots with advanced necrosis symptoms (Bakys et al. 2009) was found to be identical to our apothecia-derived sequences of S. fraxinicola. In the ITS phylogeny (Fig. 2), all three sequences formed a strongly supported group, distinguished from S. fascicularis by 15 synapomorphies.
Type specimens examined: GERMANY, Baden-Württemberg, 5 km NE of Tübingen, Pfrondorf, Blaihofstraße, 48.552°N 9.109°E, alt. 435 m, attached dead twigs & branches of Fraxinus excelsior, on bark, 11 Jul 2010, H.O. Baral (TAAM 198511 holotype, M-0281055 isotype, INSD accession number KT876983); ibid., 24 Aug 2010, H.O. Baral (H.B. 9421, topotype). Specimens examined: GERMANY, Sachsen-Anhalt, 9.5 km SW of Merseburg, 2 km E of Braunsbedra, Kleinkayna, forest in old lignite mine, 51.283°N, 11.916°E, alt. 150 m, F. excelsior, on branch lying on pile, 10 Feb. 1997, U. Richter (M-0,281,054/ H.B. 5714, KL156). Baden-Württemberg, 7.5 km W of Karlsruhe, 2.5 km W of Daxlanden, Großgrund, 49.005°N 8.30°E, alt. 115 m, branch of F. excelsior, on bark, 1 Jan. 1994, S. Philippi (H.B. 5020);
6.5 km SE of Nürtingen, 2.5 kmWNWof Owen, Moosbacher Wald, 48.592°N 9.418°E, alt. 380 m, trunk of F. excelsior, on bark, 24 Sep. 1992, U. Richter, H.O. Baral & E. Weber (H.B.4756); Bayern, Schwaben, Wof Leipheim, E of Weißlingen, 48.445°N 10.19°E, alt. 450 m, branch & trunk of F. excelsior, 19 Apr 1980, M. Enderle (H.B. 2841);Oberbayern, 8.5 km SE of München, 1 km ESE of Neuperlach, Kieswerk, Putzbrunner Str., 48.09°N 11.665°E, alt. 550 m, branch of F. excelsior, on bark, 4 May 2015, B. Fellmann (d.v.). SWITZERLAND, Thurgau, 3.5 km NNE of Frauenfeld, Ochsenfurt, 47.585°N 8.92°E, alt. 400 m, branch of F. excelsior, on bark, 14 Mar 1986, P. Blank (H.B. 3005).
Sclerencoelia fraxinicola. a–d Apothecia (a, d rehydrated, b–c dry). e, g Cross-section of apothecium, e in KOH. f, h Ectal excipulum with crystals on outer part. i Outer ectal excipulum in KOH. j–k Medullary excipulum, k in KOH. l–m Asci*. n Ascus apex† in IKI. o Croziers in KOH. p Ascospores*. q–s Paraphyses in KOH. Scale bars: a– b = 1 mm; c–d = 5 mm; e = 100 μm; g = 50 μm; f, h–m, p–s = 10 μm; n–o = 5 μm. Sources: a–e, g, h, j–n, p, q TAAM 198511/H.B. 9358 holo/isotype; f, i, o, r, s M-0,281,054/ H.B. 5714
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