Acrogenospora alangii H.Z. Du & Cheewangkoon, 2024

Li, Lu, Du, Hong-Zhi, Thiyagaraja, Vinodhini, Bhat, Darbhe Jayarama, Phookamsak, Rungtiwa & Cheewangkoon, Ratchadawan, 2024, Two novel freshwater hyphomycetes, in Acrogenospora (Minutisphaerales, Dothideomycetes) and Conioscypha (Conioscyphales, Sordariomycetes) from Southwestern China, MycoKeys 101, pp. 249-273 : 249

Acrogenospora alangii H.Z. Du & Cheewangkoon sp. nov.

Fig. 3

Etymology.

The epithet ' alangii ' refers to the host genus Alangium on which the holotype was collected.

Holotype.

KUN-HKAS 130312.

Description.

Saprobic on submerged decaying branches of Alangium chinense ( Alangiaceae ). Asexual morph: Hyphomycetous. Colonies on natural substrate, effuse, hairy, black, glistening. Mycelium partly semi-immersed, composed of septate, brown to dark brown, branched, smooth hyphae. Conidiophores 179-687 × 2.7-5.5 µm (x - = 485 × 4.2 µm, n = 20), mononematous, macronematous, solitary, erect, straight or slightly flexuous, cylindrical, unbranched, brown to dark brown, paler toward apex, septate, proliferating percurrently, smooth. Conidiogenous cells monoblastic, integrated, initially terminal, later becoming intercalary, cylindrical, smooth, pale brown. Conidia 15-22 × 15-23 µm (x - = 19.5 × 19 µm, n = 30) acrogenous, solitary, spherical or subspherical, truncate at base, aseptate, with apical appendages, hyaline and pale gray when young, pale to dark brown when mature, smooth. Sexual morph: Undetermined.

Culture characteristics.

Conidia germinating on PDA within 24 h and germ tubes produced from the conidial base. Colonies reaching 16 mm diam at the room temperature in natural light for one month. Colonies on PDA medium dense, irregular in shape, slightly raised to umbonate or convex, surface rough, radially striated with lobate edge, fairy fluffy to floccose, white at the center, white-gray to gray sparse towards the margin; in reverse, white to white-gray at the center, with dark gray to brown-gray in the middle, white to pale yellowish at the edge, radiating outwards with irregular ring; no pigmentation on PDA.

Material examined.

China, Guizhou Province, Guiyang City, Wudang District, Xiangzhigou scenic spot, (26°46'7"N, 106°54′55"E), on dead branches of medicinal plant Alangium chinense ( Alangiaceae ) from freshwater stream, 25 February 2022, H.Z. Du, S136 (KUN-HKAS 130312, holotype), ex-holotype living culture = KUNCC 23-14553 ; ibid., S136A (HUEST 23.0140, isotype), ex-isotype living culture = UESTCC 23.0140 .

Notes.

In the combined multi-locus phylogenetic analyses, Acrogenospora alangii formed a distinct clade with A. terricola and A. thailandica with significant support (71% MLBS/ 0.95 BPP; Fig. 1 ). The nucleotide base pair comparison between A. alangii (KUNCC 23-14553) and A. terricola (PS 3610) revealed the differences as 25/829 bp (3.0%) of LSU and 5/1006 bp (0.50%) of SSU. While the differences between A. alangii (KUNCC 23-14553) and A. thailandica (MFLUCC 17-2396) showed 30/834 bp (3.6%) of LSU and 2/1029 bp (0.2%) of SSU and 131/1045 bp (12.5%) of RPB2. Acrogenospora alangii can be distinguished from A. terricola in having conidia that are hyaline to pale gray when young, becoming pale brown to dark brown when mature, while A. terricola has olive green to dark brown conidia. Additionally, A. thailandica differs from A. alangii in having deep brown to black conidia ( Hyde et al. 2019; Harrington et al. 2022). Furthermore, A. alangii also differs from the type species A. sphaerocephala in conidial color which is dark reddish brown, or pale to mid brown in A. sphaerocephala ( Hughes 1978). Both A. alangii and A. guizhouensis were collected from Guizhou Province. However, morphological comparison of A. alangii with A. guizhouensis shows their differences in conidial color (hyaline, to pale gray, becoming pale brown to dark brown vs. brown) and position of conidial development (acropleurogenous vs. acrogenous) ( Hyde et al. 2023).

Figures

Figure 1. Phylogenetic tree constructed from RAxML analysis of LSU, SSU, ITS, RPB 2 and TEF 1 - α sequences data. Bootstrap support values for ML equal or greater than 50 % and Bayesian posterior probabilities greater than 0.95 BPP are indicated at the nodes. The tree is rooted to Minutisphaera aspera (DSM 29478) and Minutisphaera japonica (HHUF 30098). The new isolates are in red bold.

Figure 3. Acrogenospora alangii (KUN-HKAS 130312, holotype) a hostplant growing near water body b, c colonies on host substrate d-h conidiophores, conidiogenous cells and conidia i germinating conidium j, k colony on PDA (up-front, down-reverse) l, n conidia with apical appendages l-p conidia. Scale bars: 100 µm (d, e), 40 µm (f-i), 20 µm (l-p).