Periconia pseudodigitata Kaz. Tanaka & K. Hiray.
Index Fungorum number: IF811329
Etymology: after its morphological and phylogenetic similarity to Periconia digitata.
Holotype: KT 1395
Saprobic on submerged stems of herbaceous plant. Sexual morph: Ascomata numerous, scattered or 2–3 grouped, immersed to erumpent, globose, 160–200 μm high, 130–250 μm diam. Ostiolar neck central, papillate, 45–55 μm long, 45–65 μm wide, with hyaline periphyses, surrounded by clypeus-like structure composed of subglobose to polygonal, slightly thickened, 5–7 × 3–4 μm, dark brown cells. Ascomatal wall in longitudinal section 8–13 μm thick at side, 5–8 μm thick at the base, composed of 3–5 layers of thin-walled, 6–13 × 2–5 μm, brown cells. Pseudoparaphyses cellular, numerous, 2–2.5 μm wide at the apex, 4–6 μm wide at the base, septate, branched, anastomosed, guttulate, associated with gelatinous material. Asci fissitunicate, cylindrical, 70–110 × 10.5–15.5 μm (av. 88.4 × 12.2 μm, n = 33), rounded at the apex and with an apical chamber, short-stalked (5–15 μm long), with 8 irregularly biseriate ascospores. Ascospores broadly fusiform with rounded ends, straight or slightly curved, 19.5–27(–32) × 5–7 μm (av. 22.5 × 6.1 μm, n = 134), l/w 2.9–4.5 (av. 3.7, n = 134), with almost median septum (0.48–0.55, av. 5.1, n = 36), slightly constricted at the septum, hyaline, with or without guttules, smooth, with an entire sheath; sheath gelatinous, 1–2 μm wide at side and 2–4 μm wide at both ends in fresh, becoming delimited sheath in dry condition. Senescent spores brown, echinulate, 1-septate. Ascospores germinating from one or both ends. Asexual morph: Colonies on PDA (after 4 wk) attaining a diam of 3.2–4.6 cm, straw to amber with white margin; reverse pale luteous; no pigment produced. In culture conidial and spermatial morphs formed. Conidiophores macronematous, mononematous, single or rarely 2–3 together on stromata, 250–450 μm long, mostly 8.5–15 μm wide (16–24 μm wide at basal stromatic portion), 4–7-septate at 35–90 μm long intervals, with several branches. Branches 10–50 μm long, septate, pale brown to brown, slightly echinulate. Conidial heads spherical, ca. 60–120(–150) μm diam. Conidiogenous cells monoblastic, discrete on stipe and branches. Conidia catenate, globose, brown, verruculose to shortly echinulate, 7–9.5 μm (av. 8.3 μm, n = 90). Spermogonia globose to subglobose, single to gregarious, uniloculate to multiloculate, 140–340 μm diam. Spermatia subglobose, hyaline, smooth, 3–5 × 1.5–2 μm (av. 3.7 × 1.7 μm, n = 30). (Descriptions from Tanaka et al. 2015)
Material examined: JAPAN, Aomori, Hirakawa, Hirakawa-river, riverbank, on dead culms of Phragmites australis, 5 Aug. 2001, K. Tanaka, KT 644 = HHUF 27569, culture JCM 13164 = MAFF 239674; Aomori, Hirosaki, Kawai, Hirakawariver, riverbank, 18 Aug. 2001, K. Tanaka, KT 680 = HHUF 27570; Aomori, Hirosaki, Shimizumori, Oowasawa-river, riverbank, 14 Aug 2001, K. Tanaka, KT 673 = HHUF 27571; Hokkaido, Akkeshi, Toraibetsu-river, on submerged stems of herbaceous plant, 3 Jun. 2003, K. Tanaka & S. Hatakeyama, KT 1195A = HHUF 29368, culture JCM 13165 = MAFF 239675; ibid., on dead culms of Phragmites australis, 7 Sep. 2003, K. Tanaka & S. Hatakeyama (holotype KT 1395 = HHUF 29370, culture ex-type CBS 139699 = JCM 13166 = MAFF 239676); ibid., KT 1396–1398 = HHUF 29371–29373.
Notes: Periconia pseudodigitata is phylogenetically and morphologically closest to P. digitata, but the conidial dimensions of P. pseudodigitata (7–9.5 μm) are slightly smaller than those reported for P. digitata by Ellis (1971) (7–11 μm). Sequence similarity between these two taxa in the ITS region was 95.8 % (503/525) with 0.8 % (4/525) gaps. Periconia pseudodigitata superficially resembles P. igniaria (= Massarina igniaria), which also has an ascomatal morph. The sexual morph of P. pseudodigitata, however, differs from that of P. igniaria (Booth 1968) by its narrower ascospores (5–7 μm vs. 8–9 μm) surrounded by a mucilaginous sheath, and shorter but wider asci (70–110 × 10.5–15.5 μm vs. 150–165 × 8–12 μm) with biseriate ascospores. The asexual morph of P. pseudodigitata has verruculose to shortly echinulate conidia, while that of P. igniaria has conidia with conspicuous spines about 1 μm long (Mason & Ellis 1953, Ellis 1971, Matsushima 1971, Bunning & Griffiths 1984). (Notes from Tanaka et al. 2015)
Fig. 1 Periconia pseudodigitata. A, B. Ascomata on the natural host surface; C. Ascomata in longitudinal section (in lactophenol cotton blue); D. Ascomatal wall; E. Pseudoparaphyses; F. Ascus; G–I. Ascospores (arrowheads indicate gelatinous sheath; H. in Black-Blue ink); J. Germinating ascospore; K. Conidiomata in culture (on rice straw); L–O. Conidial heads and conidiophores; P, Q. Conidia. A, B, E, G–J from KT 1395; C, D, F from KT 644; K–M from culture KT 1195; N from culture KT 644; O–Q from culture KT 1395. Scale bars: A = 1 mm; B, K = 500 μm; C = 100 μm; D–J, P, Q = 10 μm; L–O = 20 μm. (Tanaka et al. 2015)
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