Aquastroma magniostiolatum Kaz. Tanaka & K. Hiray. [as 'magniostiolata']
Holotype: KT 2485 = HHUF 30122
Etymology: from the Latin mangi-, meaning large, and ostiolatus, meaning ostiolate.
Sexual morph: Ascomata scattered to 3–4 grouped, immersed to erumpent, globose in surface view, depressed globose in section, 180–250 μm high, 260–340 μm diam. Ostiolar neck central, compressed, 60–750 μm long, 75–130 μm wide, composed of thick-walled, heavily melanised, subglobose cells (2–3 μm diam), with a wide ostiole. Ascomatal wall in longitudinal section 25–30 μm thick at sides, composed of 5–7 layers of polygonal, thin-walled, 6–17 × 2.5–7.5 μm, pale brown cells; wall at the base 10–18 μm thick or poorly developed, composed of thinwalled flattened cells. Pseudoparaphyses septate, branched and anastomosed, 2–3 μm wide. Asci fissitunicate, clavate, 112.5–137.5 × 25–29.5 μm, with a stipe of 22–28 μm long, with 8 biseriate to triseriate ascospores. Ascospores clavate to fusiform, slightly curved, 30–44 × 9–13.5 μm ( = 36.5 × 10.3 μm, n = 39), l/w 2.8–4.5 ( = 3.6, n = 39), with a supramedian primary septum (0.40–0.47; = 0.43, n = 39), 6–8-septate (2+1+3, 2+1+4, 3+1+3, 3+1+4), slightly constricted at septa, hyaline, smooth, with an entire sheath; sheath delimited and 2–3 μm wide at first, diffuse and up to 10 μm wide at a later. Sexual morph: Undetermined. (Descriptions from Tanaka et al. 2015)
Material examined: JAPAN, Mie, Tsu, Kamihama, Hyourtan pond, on submerged twigs of woody plant, 1 Jun. 2008, K. Tanaka & H. Yonezawa (holotype KT 2485 = HHUF 30122, culture ex-type CBS 139680 = JCM 19429 = MAFF 243824).
Freshwater distribution: Japan (Tanaka et al. 2015), Thailand (Dong et al. 2020)
Fig. 1. Aquastroma magniostiolatum. A, B. Ascomata on the natural host surface; C. Ascoma in longitudinal section; D. Ascomatal wall; E. Pseudoparaphyses; F, G. Asci; H–M. Ascospores (arrowheads indicate gelatinous sheath; J. in Black-Blue ink; K–M. in India ink); N. Germinating ascospore. A–E, G–J, N from KT 2485; F, K–M from culture KT 2485. Scale bars: A = 1 mm; B = 500 μm; C = 100 μm; D–N = 10 μm. (Tanaka et al. 2015; https://www.sciencedirect.com/science/article/pii/S0166061615000160; Revision of the Massarineae (Pleosporales, Dothideomycetes)
Dong W, Wang B, Hyde KD, McKenzie EHC, Raja HA, Tanaka K, Abdel-Wahab MA, Abdel-Aziz FA, Doilom M, Phookamsak R, Hongsanan S, Wanasinghe DN, Yu X-D, Wang G-N, Yang H, Yang J, Thambugala KM, Tian Q, Luo Z-L, Yang J-B, Miller AN, Fournier J, Boonmee S, Hu D-M, Nalumpang S, Zhang H (2020) Freshwater Dothideomycetes. Fungal Diversity 105:319–575
Tanaka K, Hirayama K, Yonezawa H, Sato G, Toriyabe A, Kudo H, Hashimoto A, Matsumura M, Harada Y, Kurihara Y (2015) Revision of the Massarineae (Pleosporales, Dothideomycetes). Studies in Mycology 82:75–136