Dictyosporium duliujiangense L.L. Liu & Z.Y. Liu, 2023

Liu, Ling-Ling, Song, Lian-Chai, Gu, Xiao-Feng, Wei, Quan-Quan, Zhang, Meng, Liu, Zuo- Yi & Gou, Jiu-Lan, 2023, Dictyosporium duliujiangense sp. nov. (Dictyosporiaceae, Pleosporales) from freshwater habitat in Guizhou Province, China, Phytotaxa 606 (4), pp. 259-272 : 266-267

Dictyosporium duliujiangense L.L. Liu & Z.Y. Liu , sp. nov. Figure 3 .

Index Fungorum number: IF 900403, Facesoffungi number: FoF 14119

Etymology: referring to the collecting site of Duliu River.

Saprobic on decaying plant substrates. Asexual morph: Colonies punctiform, sporodochial, scattered, dark brown to black, glistening. Mycelium mostly immersed, composed of smooth, septate, branched, hyaline to pale brown hyphae. Conidiophores macronematous, mononematous, septate, cylindrical, hyaline to pale yellow, smooth-walled, 4–17 × 2–5 μm, sometimes reduced to conidiogenous cells. Conidiogenous cells monoblastic, integrated, terminal, determinate, pale yellow to yellow. Conidia acrogenous, solitary, cheiroid, smooth-walled, complanate, yellowishbrown to pale brown, (17–) 31–36 ×17–22 μm (x = 33 × 20 μm, n = 30), mostly consisting of five arms closely compact with side arms lower than middle arms, rarely with four arms, 4–8-euseptate in each arm, constricted at septa, one or two or more, hyaline, tubular, elongated appendages which are 16–38 × 3.5–10 μm (x = 27 × 6 μm, n = 20) and mostly attached at the apical part of two or more outer arms. Sexual morph: Undetermined.

Cultural characteristics: Conidia germinating on PDA within 24 h and germ tubes produced from the basal cell. Colonies on PDA reaching 17–23 mm diam. in 2 weeks at 25 °C, in natural light, circular, divide into two layers on the surface, with fluffy, dense, white mycelium on the center layer and with sparse, yellow, entire margin, in reverse pale brown in the middle and white at the margin.

Material examined: China, Guizhou Province, Dushan County, Duliu river Deep ditch scenic spot, 25°55′ N, 107°37′ E, at an altitude of 1205 m, on decaying branch submerged in a freshwater River, 5 July 2018, L.L. Liu, 18D-69 ( HKAS 129172 , holotype, GZAAS 20–0321 , isotype), ex-type culture GZCC 19–0426 .

Notes: Dictyosporium duliujiangense ( GZCC 19–0426) has sporodochial colonies, macronematous conidiophores, and cheiroid, digitate conidia with numerous parallel rows of cells, which are typical of Dictyosporium ( Goh et al. 1999) . Dictyosporium duliujiangense shows a close phylogenetic affinity to D. marinum ( MFLU 19–1229) which was isolated from buried wood in sand from UK, Carmarthenshire ( Dayarathne et al. 2020) ( FIGURE 1 ). A comparison of LSU sequence bases between Dictyosporium duliujiangense and D. marinum is 2.48% (785/805) difference. Furthermore, the two species are morphologically distinct, especially in their conidial morphology. Conidia of Dictyosporium duliujiangense are smaller ((17–) 31–36 × 17–22 μm) and comprise outer rows with one or two or more hyaline appendage, whereas D. marinum has relatively larger conidia (34–50 × 22–28 µm) that lacks appendages ( Dayarathne et al. 2020). Dictyosporium duliujiangense shares similar size of the conidia with D. tubulatum ( MFLU 15–1166) and D. zhejiangense ( MW –2009a). In addition, Dictyosporium duliujiangense can be distinguished from D. tubulatum in the cells of former are usually arranged in 5 rows while the cells of D. tubulatum are mostly in 4 rows, well distinguishable from D. zhejiangense by smaller appendages (16–38 × 3.5–10 μm vs. 29–54 × 5.5–8 µm), and inconspicuous septum, while D. zhejiangense constricts at the septa ( Wongsawas et al. 2009, Yang et al. 2018).The PHI analysis further confirms that Dictyosporium duliujiangense has no significant genetic recombination with closely related species (Fw> 0.05, FIGURE 4 ). We thus introduced D. duliujiangense as a new species.

Figures

FIGURE 1. Maximum likelihood majority rule consensus tree for Dictyosporiaceae using ITS, LSU and tef1-α sequence data. Bootstrap support values for maximum likelihood (ML) greater than 75% and Bayesian posterior probabilities greater than 0.95 are indicated near branches as ML BS/PP. The scale bar represents the expected number of changes per site. The tree is rooted with Periconia igniaria (CBS 379.86 and CBS 845.96).The new taxa are in red bold. Genera are indicated with colored blocks. The ex-type strains are marked as T after the strain number. Branches with 100% ML BS and 1.0 PP are marked with black dots.

FIGURE 3. Dictyosporium duliujiangense (GZAAS 20–0321, holotype). a, b Colonies on woody substrate. c, d Squash mount of a sporodochium and conidia with appendages. e–g Conidiophores with conidia. h, i Conidia with appendages. j Germinated conidium. k, l Cultures (k from above, l from reverse). Scale bars: c–j = 25 μm.

FIGURE 4. Split graphs showing the results of PHI test of D. duliujiangense with their most closely related species (Fw = 0.9999). The new taxa are shown in red bold.