Rostriconidium aquaticum Z.L. Luo, K.D. Hyde & H.Y. Su
Index Fungorum number: IF 823173; Facesoffungi number: FoF 03765
Etymology: Referring to aquatic habitat.
Holotype: MFLU 17–1415
Saprobic on submerged decaying wood. Sexual morph: Undetermined. Asexual morph: Colonies effuse on natural substrate, scattered, hairy, brown. Mycelium immersed in the substrate, composed of pale brown to brown, septate, unbranched hyphae. Conidiophores macronematous mononematous, single, erect, septate, smooth, straight or slightly flexuous, dark brown to black, pale pigment at apex, 370–590 μm (x̄ = 485 μm, SD = 105, n = 10) long, 13–17 μm (x̄ = 15 μm, SD = 2, n = 10) wide. Conidiogenous cells monotretic or polytretic, sympodial, integrated, terminal, cylindrical, dark brown. Conidia solitary, dry, fusiform to pyriform, rostrate at maturity, dark brown to black, with guttulate cells, thickly cicatrized at narrow, with a thick, black truncate scar at base and pale pigment cell above the scar, wide in the middle, narrowly cylindrical, obtuse, and subhyaline at apex, 8–9-septate, slightly constricted at some septa, smooth, 134–180 μm (x̄ = 157 μm, SD = 23, n = 20) long, 22–26 μm (x̄ = 24 μm, SD = 2, n = 20) wide. (Description from Su et al. 2018)
Material examined: CHINA, Yunnan Province, submerged decaying wood in Nujiang River, May 2016, Z.L. Luo, S-336 (MFLU 17–1415, holotype), ex-type living culture, MFLUCC 16–1113, KUMCC 15–0491; submerged decaying wood in Dulong River, May 2016, Z.L. Luo, S-514 (MFLU 17–1416, paratype), living culture, KUMCC 15–0297.
Notes: Rostriconidium, described herein as a monotypic genus and typified by R. aquaticum, is characterized by solitary, erect, septate, straight to flexuous, dark brown to black conidiophores, monotretic or polytretic conidiogenous cells and solitary, dry, rostrate, septate conidia with a subhyaline apex. Rostriconidium aquaticum superficially resembles Phaeotrichoconis aquaticus in having macronematous, single, erect, septate, straight conidiophores, polytretic conidiogenous cells and rostrate, septate conidia with a small scar at the base (Arambarri et al. 1987). However, Rostriconidium aquaticum differs by its longer and wider conidiophores (370–590 × 13–17 vs − 150 × 4–4.5 μm) and comparatively larger conidia (134–180 × 22–26 vs 110–150 × 10–11 μm). Besides, the two strains of Rostriconidium aquaticum form a separate clade between Sporidesmioides and Neotorula based on analysis of combined ITS, LSU, RPB2, and TEF1α sequence data. (Notes from Su et al. 2018)
Freshwater distribution: China (Su et al. 2018)
Arambarri A, Cabello M, Mengascini A (1987) New hyphomycetes from Santiago River (Buenos Aires Province, Argentina). Mycotaxon 29:29–32
Su XJ, Luo ZL, Jeewon R, Bhat DJ, Bao DF, Li WL, Hao YE, Su HY, Hyde KD (2018) Morphology and multigene phylogeny reveal new genus and species of Torulaceae from freshwater habitats in northwestern Yunnan, China. Mycol Prog 17:531–545
Fig 1. Rostriconidium aquaticum (MFLU 17–1415, holotype). A. Colonies on wood. b. Conidiophore. c, d, f. Conidiophores with conidia. e. Conidiogenous cells. g–l. Conidia. m. Germinating conidium. n, o. Colonies on PDA from surface and reverse. Scale bars at d 150 μm, b, c, f. 100 μm, e, i–m. 40 μm, and g, h. 25 μm. (Su et al. 2018)