Ascitendus aquaticus Dayar, Fryar & K.D. Hyde
Index Fungorum number: IF554115; Facesoffungi number: FoF03926
Etymology: name reflects the host habitat aquatic environment.
Holotype: MFLU 18-0143
Saprobic on decaying wood submerged in freshwater. Sexual morph: Ascomata 160–280 μm high, 135–190 μm diameter, solitary to gregarious, semi-immersed to superficial, black, coriaceous, globose to subglobose, ostiolate with a prominent neck, venter 150–230 ´ 195–240 μm. Peridium 25–45 μm wide, comprised of three layers: outer layer of pseudoparenchyma cells incorporated with dark brown amorphous material; middle layer of brown, thin-walled, laterally compressed, elongated cells; inner layer of hyaline, laterally compressed, elongated, hyaline cells. Neck 85–300 ´ 50–140 μm, central, cylindrical, periphysate, black at wall 2-layered, outer layer of dark brown, laterally compressed thin-walled cells incorporated with brown amorphous material, inner layer of laterally compressed thin-walled hyaline cells. Hamathecium paraphysate; paraphyses longer than asci, 160–210 μm long, 4–10 μm broad at base, septate. Asci 150–200 ´ 5–12 μm (x̄ = 175.5 ´ 8 μm, n = 20), 8-spored, unitunicate, cylindrical, long pedicellate, with a prominent cylindrical to flaring apical ring, 2.5–3 ´ 3–3.5 μm wide at apex, 1–3 μm wide at the base, J-. Ascospores 15–25 ´ 4–8 μm (x̄ = 20 ´ 6 μm, n = 20), uniseriate, hyaline when immature, becoming brown, fusoid, straight to curved, 3-septate when mature, each cell with a single large guttule, slightly/not constricted at septa; septa prominent, smooth-walled, without appendages or a sheath. Asexual morph: Undetermined.
Material examined: AUSTRALIA, North Queensland, Mulgrave River, S 17.17724, E 145.72374, on decaying wood submerged in a river, 14 April 2015, Sally Fryar and Ben Cawson, MR150 (MFLU 18-0143, holotype); ibid. (AD279865, isotype).
GenBank numbers: LSU: MG813820, SSU: MG813821
Notes: The new species, Ascitendus aquaticus, best fits the genus Ascitendus in both morphology and receives phylogenetic support. It resembles Ascitendus by having globose to subglobose, ostiolate ascomata with a prominent neck, cylindrical to flaring apical ring and brown ascospores, with 3-prominent septa and each cell having a single large guttule. Our phylogenetic analysis indicates that A. aquaticus is closely related to A. austriacus, but with moderate support (78% ML, 70% MP, 1.00 PP) forming a separate lineage basal to A. austriacus. Ascitendus aquaticus can be clearly distinguished from A. austriacus by having smooth-walled ascospores, where the ascospore wall of A. austriacus are roughened in a striated pattern and ascospore end cells have small refractive dots at the ends. Annulatascus velatisporus, Annulusmagnus triseptatus, and Ascolacicola aquatica are also morphologically similar to Ascitendus aquaticus. However, A. aquaticus can be clearly distinguished from all these species by asci, ascospore nature and measurements. (Hyde et al. 2018)
Distribution: AUSTRALIA, North Queensland, Mulgrave River, on decaying wood submerged in a River (Hyde et al. 2018).
Hyde, KD; Chaiwan, N; Norphanphoun, C; Boonmee, S, et al. 2018. Mycosphere notes 169–224. Mycosphere. 9(2):271-430.
Fig. 1. Ascitendus aquaticus (MFLU 18-0143, holotype). a Ascomata on submerged wood. b, c Sections of ascomata. d Section through neck region. e Section through peridium. f Paraphyses g Part of an immature ascus. h Apical ring. i Apical ring in Melzer’s reagent. J Mature ascus. k–o Ascospores. Scale bars: b, c = 50 μm, c–d, f, g, j, k = 20 μm, e, h, i, l–o = 10 μm.