Aquadictyospora nujiangensis S. Luan, H.W. Shen & Z.L. Luo, 2024

Wang, Wen-Peng, Luan, Sha, Shen, Hong-Wei, Liu, Ning-Guo, Li, Yun-Xia & Luo, Zong- Long, 2024, Two new freshwater dematiaceous hyphomycetes of Pleosporales from Yunnan Province, China, Phytotaxa 676 (1), pp. 63-74 : 66-68

Aquadictyospora nujiangensis S. Luan, H.W. Shen & Z.L. Luo , sp. nov. FIGURE 1

Index Fungorum number: IF900051

Etymology:—Referring to the place ‘Nujiang River’ where this species was collected.

Holotype:—KUN-HKAS 130427

Saprobic on submerged decaying wood in a freshwater river. Asexual morph: Hyphomycetous. Conidiomata on natural substratum sporodochial, superficial, compact, scattered, dark brown, punctiform. Mycelium immersed, consisted of septate, smooth, thin-walled hyphae. Conidiophores 12–31 × 3.3–6.3 µm (x = 21 × 4.1 µm, n = 10), reduced or micronematous, mononematous, hyaline, subcylindrical, septate, thin and smooth-walled, rounded at the apex. Conidiogenous cells monoblastic, integrated, terminal, hyaline. Conidia (41–)52–64 × (20–)26–35 µm (x = 57 × 30 µm, n = 50), acrogenous, cheiroid, ellipsoidal to pyriform, composed of uniformly medium brown, compactly adpressed 3–6 apically curved rows of cells appearing muriform, each row with (6–)9–11 cells, slightly truncate at the apex, sometimes with a broadly ovate to subglobose, hyaline, smooth separating cells, not complanate, guttulate. Secession schizolytic. Sexual morph: Undetermined.

Culture characteristics:—Conidia germinating on PDA within 10 hours and germ tubes produced from both ends. Colonies on PDA reach 3 cm in three weeks at room temperature. Mycelia loose, flocculent, colonies subcircular, with entire edges, white to light yellow at the center, white at the outer ring from above, greyish brown at the center, pale yellow at the outer ring from below.

Material examined:— China, Yunnan Province, Nujiang River (27°15′39.58″N, 98°52′52.65″E, 1303m), on submerged decaying wood, 4 May 2023, Ying Wang, S-4615 (KUN-HKAS 130427, holotype), ex-type culture CGMCC 3.27012 = KUNCC 23–14351.

Notes:—The phylogenetic analysis showed that Aquadictyospora nujiangensis exhibits a close relationship with A. clematidis and A. lignicola with low support ( FIGURE 2 ). Aquadictyospora nujiangensis resembles A. lignicola in having muriform, cheiroid, not complanate conidia. However, Aquadictyospora nujiangensis differs from A. lignicola in having micronematous, mononematous, subcylindrical conidiophores and ellipsoidal to pyriform conidia without broadly rounded at the apex ( Li et al. 2017).The ITS sequences of Aquadictyospora nujiangensis differ from A.clematidis and A. lignicola by 52/524 bp (9.9%) and 24/481 bp (5%), respectively. Phylogenetic analysis and morphology support Aquadictyospora nujiangensis as a new species in Aquadictyospora , which tally with recommendations outlined by Jeewon and Hyde (2016).

Figures

FIGURE 1. Aquadictyospora nujiangensis (KUN-HKAS 130427, holotype). a Colony on the substratum. b, c Conidiophores and conidiogenous cells. d, e Conidiogenous cells with conidia. f–o Conidia. p Germinated conidium. q, r Colonies on PDA from front and reverse. Scale bars: b, c = 10 µm, d–p = 20 µm.

FIGURE 2. RAxML tree generated from combined LSU, ITS, SSU, and tef1-α dataset. The combined analysis included 28 strains with 3221 characters (LSU: 1–818 bp, ITS: 819–1345 bp, SSU: 1346–2318 bp, tef1-α: 2319–3221 bp). The tree is rooted with Periconia igniaria (CBS 845.96 and CBS 379.86). Tree topology of the maximum likelihood analysis and Bayesian analysis are similar. The best RAxML tree with a final likelihood value of –12094.185940 is presented. The matrix had 734 distinct alignment patterns, with 24.16% undetermined characters or gaps. Estimated base frequencies were as follows:A = 0.239714, C = 0.247968, G = 0.268927, T = 0.243392; substitution rates AC = 1.383610, AG = 3.228746, AT = 2.017041, CG = 0.669678, CT = 8.970280, GT = 1.000000, gamma distribution shape parameter α = 0.145270 and tree-length = 0.783748. Bootstrap values for ML ≥ 75% and Bayesian posterior probabilities (PP) ≥ 0.95 are labelled on the nodes. The newly obtained sequence is indicated in red, and ex-type strains are in bold.