Caryospora quercus Jayasiri, E.B.G. Jones & K.D. Hyde
Index Fungorum number: IF555535; Facesoffungi number: FoF05236
Saprobic on decaying wood submerged in freshwater. Sexual morph: Ascomata 400–450 μm high, 410–460 μm diam., black, scattered, semi-immersed to superficial, conical, flattened at the base, carbonaceous, ostiolate, 70 μm diam., often covered with mass of black, glistening ascospores. Peridium 60–70 μm at the sides, poorly developed at the base, easily cracked, two-layered, outer layer strongly carbonized, composed of several layers of black cells that cannot be differentiated and often occluded, inner layer composed of 8–10 layers of hyaline, compressed cells of textura angularis. Pseudoparaphyses 2 μm diam., numerous, trabeculate, filiform, hyaline, distantly septate. Asci (165–)205–270(–305) × (58–)65–80 μm (x̄ = 235 × 70 μm, n = 10), 8-spored, bitunicate, narrowly to broadly clavate, indistinctly pedicellate which become tapered and disappeared with age, 30–60 μm long, apically rounded. Ascospores 47–60 × 19–33 μm (x̄ = 54 × 27 μm, n = 30), overlapping bi- to tri-seriate, straight, broadly fusiform to ellipsoidal, hyaline to pale brown, 1-septate when young, becoming irregularly diamond-shaped, dark brown to black, 3-septate when mature, with acute ends, constricted and darker at the median septum, not constricted and inconspicuous at two terminal septa, asymmetric, with two large central cells and two small end cells, thick-walled, smooth,
sometimes with polar germ pores at each end, surrounded by a large, ellipsoidal, gelatinous, mucilaginous sheath, 3–37 μm thick, sheath two-layered and large when young, becoming one-layered and smaller after mature. Asexual morph: Undetermined. (Dong et al. 2020)
Culture characteristics: On PDA, colony circular, reaching 5 mm diam. in 20 days at 25 °C, grey from above and brown from below, surface rough, dry, raised, edge entire.
Material examined: THAILAND, Chiang Mai Province, on submerged wood in a stream, 1 September 2017, X.D. Yu, 1A (MFLU 17-1705, holotype), ex-type living culture MFLUCC 17-2342; ibid., G.N. Wang, 4.2 (MFLU 17-1668), living culture MFLUCC 17-2323.
Notes: Dong et al. (2020) collections MFLUCC 17–2342 and MFLUCC 17–2323 cluster with Caryospora quercus with strong bootstrap support. They have identical LSU sequence data and there are two nucleotide differences in SSU sequence data between MFLUCC 17–2342 and MFLU 18–2151 (type). No other genes can be compared. Collections of Dong et al. (2020) have overlapping ascospore size (47–60 × 19–33 μm vs. 41–54 × 18–28 μm) and similar morphological characters with C. quercus, i.e. broadly fusiform to ellipsoidal and hyaline to pale brown when young, becoming irregularly diamond-shaped and dark brown to black when mature, with acute ends, with one primary median septum and two inconspicuous septa near both ends, asymmetric, and with a sheath (Jayasiri et al. 2019). However, the ascospore sheaths in our collections are up to 37 μm thick, while they are 5.5 μm thick in the holotype of C. quercus. This might be a result of only measuring the mature ascospores in Jayasiri et al. (2019), because they are 37 μm thick in young ascospores and 3 μm thick in mature ascospores in our collections. Additionally, our col- lections have longer and wider asci ((165–)205–270(–305) × (58–)65–80 μm vs. (69–)110–147 × 30–35 μm) than the holotype of C. quercus. It is very likely that Jayasiri et al. (2019) only measured the immature asci as shown in their photo plate. Dong et al. (2020) identify the collections to be C. quercus based on current phylogenetic analysis, single gene comparison and morphology. (Notes from Dong et al. 2020)
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 Divers 105:319–575
Jayasiri SC, Hyde KD, Jones EBG, McKenzie EHC, Jeewon R, Phillips AJL, Bhat JD, Wanasinghe DN, Liu JK, Lu YZ, Kang JC, Xu J, Karunarathna SC (2019) Diversity, morphology and molecular phylogeny of Dothideomycetes on decaying wild seed pods and fruits. Mycosphere 10:1–186 . https://doi.org/10.5943/mycosphere/10/1/1