Cryptocoryneum polyramosum X.D. Liang. & Jian K. Liu, 2025

Liang, Xiang-Dong & Liu, Jian-Kui, 2025, Cryptocoryneum polyramosum sp. nov., associated with Camellia sinensis in Sichuan Province, China, Phytotaxa 681 (1), pp. 11-19 : 14

Cryptocoryneum polyramosum X.D. Liang. & Jian K. Liu , sp. nov. ( Fig. 2 )

MycoBank number MB 856774

Etymology: —Named for having numerous conidial arms.

Holotype:— HKAS 135162

Saprobic on dead twigs of Camellia sinensis . Sexual morph: Undetermined. Asexual morph: Sporodochia pulvinate, often confluent, dark brown to black. Conidiophores arising from stromatic cells, simple, straight, septate, hyaline to pale brown, smooth. Conidiogenous cells 7.0–13.0 × 4.0–8.0 µm (x̄ = 9 × 6.5 µm, n = 20), monoblastic, cylindrical, terminal, determinate, hyaline to pale brown. Conidia 33.5–58.5 × 20–51.5 µm (x̄ = 46.0 × 28.0 µm, n = 50), solitary, acrogenous, branched, cheiroid, with dark brown to black cap cells firmly uniting the branches together, multi-armed. Basal cells 3.0–7.0 × 3.0–6.5 µm (x̄ = 5.0 × 5.0 µm, n = 30), dark brown to black, cuneiform, smooth, thin-walled. Arms 17.0–44.5 × 3.5–6.0 µm (x̄ = 33.5 × 4.5 µm, n = 50), 7–24 armed, cylindrical, branched at base, pale brown, smooth, 3–9-septate, slightly constricted at the septa, guttulate in each cell, cells 3.0–6.0 × 3.0–4.5 µm (x̄ = 4.5 × 3.5 µm, n = 50).

Culture characteristics:— Conidia germinating on PDA within 24 h and germ tubes arising from cells of the arms. Colonies growing on PDA reaching a diam. of 3 cm after 4 weeks at 25 ° C. Velvety, grey olivaceous to olivaceous black, reverse almost black with white edges, without sporulation.

Material examined:— CHINA. Sichuan Province: Le Shan City, Mabian Yi Antonomous County, Fu Lai Village , 28°55’52’’N, 103°33’15’’E, 1100 m, on dead twigs of Camellia sinensis , 22 October 2023, X.D. Liang, M5 ( HKAS 135162 , holotype; ex-type living culture, CGMCC 3.27592 ) ; ibid., M5-2 ( HUEST 24.0151 , isotype; ex-isotype living culture, UESTCC 24.0134 ) .

Notes:— In the multi-gene phylogenetic tree ( Fig. 1 ), two isolates of Cryptocoryneum polyramosum form a distinct clade basal to other species within the genus Cryptocoryneum ( Cryptocoryneaceae ). Morphologically, C. polyramosum resembles Cryptocoryneum species by appearing as pulvinate sporodochia, with cheiroid conidia, and occasionally branched conidial arms that irregularly developed downward from the cap cells. However, asexual morph of adjacent family Lophiotremataceae species, which are characterized by pycnidial colonies, globose to subglobose, scattered, semi-immersed ostiolates, differ distinctly from C. polyramosum ( Hashimoto et al. 2017) . Comparison with the morphological key to Cryptocoryneum ( Hashimoto et al. 2016) and ten other species lacking molecular data reveals that C. polyramosum shares similarities with C. rilstonei in conidial size ( Hashimoto et al. 2016). However, C. polyramosum has slightly longer and wider conidia than C. rilstonei (33.5–58.5 × 20.0–51.5 µm vs. 21–40 × 17–32.5 μm) and more arms (7–24, x = 13 arms vs. 5–9, x = 7 arms). Further morphological comparison with nine species for which molecular data are available indicates that C. polyramosum closely resembles C. rosae ( Boonmee et al. 2021) in conidial morphology. Nevertheless, C. polyramosum has slightly longer and wider conidia (33.5–58.5 × 20.0–51.5 µm vs. 30–50 × 20–30 μm), fewer septa (3–9, x = 6 septa vs. 8–12, x =9 septa) and more arms (7–24, x = 13 arms vs. 4–12, x = 9 arms). This combination of unique morphological features and robust phylogenetic evidence supports the recognition of C. polyramosum as a novel species. The morphological distinctions and basal phylogenetic position underscore its evolutionary significance and contribute to a more comprehensive understanding of species diversity within the Cryptocoryneaceae .

Figures

FIGURE 1. Phylogenetic tree generated from RAxML analysis of combined LSU, SSU, ITS, tef1-α and rpb2 dataset. ML bootstrap values equal to or greater than 75% are shown above the nodes. Branches in bold indicate BI posterior probabilities (PP) equal to or greater than 0.95. Newly generated isolates are indicated in red and ex-type strains are in bold. The tree is rooted with Aquasubmersa japonica (KT 2862) and A. mircensis (MFLUCC 11-0401).

FIGURE 2. Cryptocoryneum polyramosum (HKAS 135162 holotype). a–c. Appearance of sporodochia on host surface. d, e. Cheiroid conidia. f, g. Conidia with exfoliated cap cells. h, i. Conidia with brown basal cells. j. Germinating conidium. k, l. Culture on PDA from above and below. Scale bars: d–i = 10 μm, j = 20 um.