Septocystis minor F.C. Huang, 2025

Huang, Fu-Chang & Lin, Jian-Tian, 2025, Septocystis (Polyporales, Basidiomycota), a new genus of Polyporaceae from Southern China, Phytotaxa 710 (3), pp. 231-248 : 234-237

Septocystis minor F.C. Huang sp. nov., Figs. 1 , 2 , 3 , 4 , 5 and 6 .

MycoBank no.:—MB 859843

Diagnosis:—Basidiomata resupinate, cork to hard leathery, 6–7 pores per mm. Hyphal system dimitic; generative hyphae bearing clamp connection, skeletal hyphae from trama dominant, frequently branched, most skeletal hyphae with a well differentiated basal stalk. Cystidia fusoid, long clavate and flask shaped, usually with 1–3 septa at tip, and some turn to be a thin membrane, some short or long irregular linear object. Cystidioles, crystals and hyphal pegs present; basidiospores cylindrical, thin-walled, smooth, many with visible inclusion, IKI−, CB+.

Holotype:— China, Guangxi Autonomous Region, Chongzuo , Longzhou County, Nonggang Nature Reserve (106°42′28″– 107°04′54″E, 22°13′56″– 22°39′09″N), on rotten angiosperm wood, July 26, 2022, Fu-Chang Huang, GXU 12865 (Holotype), GenBank accession numbers OR634847 ( ITS), OR634848 (nLSU), PQ304574 (RPB2).

Etymology:— “ minor ” refers to the small pores.

Description:—Basidiomata annual, resupinate, cork to hard leathery, up to 26.7 cm long, 5.5 cm wide and 3 mm thick at center. Sterile margin absent, or up to 1.5 mm wide with finely velutinous, white (N, 9.5/) when fresh, become brown (7.5YR, 5/4) when bruised, pale yellow (2.5Y, 8/4) to olive brown (2.5Y, 4/3) when dry. Pore surface white (2.5Y, 8/1), gray (2.5Y, 5/1) to dark gray (2.5Y, 4/1) when fresh, gray (2.5Y, 6/1) to dark grayish brown (2.5Y, 4/2) when dry, pores angular, circular, irregular, 6–7 pores per mm, dissepiments thin to thick, entire to lacerate; tubes concolorous with pore surface, cork to hard leathery, up to 2.5 mm long; context corky, yellow (2.5Y, 8/6) to olive brown (2.5Y, 4/3).

Hyphal system dimitic. Tissues negative reaction in Melzer reagent, becoming brown in 5% KOH, and positive reaction in Cotton Blue. Generative hyphae bearing clamp connections.

Generative hyphae from context hyaline, thin-walled, moderately branched, 1.9–5.9 µm diam; skeletal hyphae dominant, thick-walled, broad to narrow lumen, even subsolid, frequently branched, 1.3–4 µm diam. Generative hyphae from trama hyaline, thin-walled, usually branched, 1.3–4.6 µm diam. Skeletal hyphae from trama dominant, thick-walled with broad to narrow lumen, even subsolid, frequently branched, most skeletal hyphae with a well differentiated basal stalk, 3.9–8.1 µm wide, the branches 1.2–4 µm wide. Cystidia fusoid, long clavate or flask shaped, usually with 1–3 septa at tip, and some turn to be a thin membrane, some a short or long irregular linear object, hyaline, thin-walled, 11.5–59.4 × 3.1–7.2 µm, L = 23.36 µm, W = 5.21 µm. Cystidioles fusoid, long clavate or flask shape, hyaline, thin-walled, 11.5–43.9 × 3.2–6.4 µm, L = 24.91 µm, W = 4.79 µm. Crystals abundant or few in subhymenium and hymenium, square, rectangular to irregular. Hyphal pegs occasionally present in the hymenium. Basidia barrel-shaped to cylindrical, 12.2–37.9 × 4.7–11.3 µm, with four sterigmata and a basal clamp connection; basidioles in shape similar to basidia, 10.1–19.4 × 5.6–9.2 µm. Basidiospores cylindrical, hyaline, thin-walled, smooth, and many with visible inclusion, IKI−, CB+, (5.8−) 6.9−11 (−11.2) × (3−) 3.1−4 (−4.5) µm, L = 9.42 µm, W = 3.55 µm, Q = 2.65 (n = 65/3).

Additional specimens examined:— China, Guangxi Autonomous Region, Chongzuo , Longzhou County, Nonggang Nature Reserve (106°42′28″– 107°04′54″E, 22°13′56″– 22°39′09″N), on rotten angiosperm wood, July 26, 2022, Fu-Chang Huang, GXU 12859, GenBank accession numbers OR634845 ( ITS), OR634846 (nLSU), PQ304573 (RPB2) ; on rotten angiosperm wood, June 23, 2022, Jian-Tian Lin, GXU 12295, GenBank accession numbers OR634849 ( ITS), OR634850 (nLSU), PQ304571 (RPB2) ; on dead angiosperm branches, June 24, 2022, Jian-Tian Lin, GXU 12319, GenBank accession numbers OR634851 ( ITS), OR634852 (nLSU), PQ304572 (RPB2) .

Figures

FIGURE 1. Phylogenetic tree inferred from MP analysis based on combined ITS+nLSU+RPB2 sequences. Branches are labeled with MP bootstrap>50% (before the/), Bayesian posterior probabilities>0.50 (after the/). New species are indicated in bold.

FIGURE 2. Microscopic structures of Septocystis minor A: basidiomata; B, C: Basidioles (arrow pointed); D, E and F: Basidia (arrow pointed); G: Basidiospores (two of them pointed by arrow were observed in Cotton Blue). A, Bars: 1 cm; B, C, D, E, F and G, Bars: 10 μm.

FIGURE 3. Microscopic structures of Septocystis minor A, B, C (arrow pointed and these three photographed from tubes), D (arrow pointed), E, F and G (arrow pointed): Cystidia; H (arrow pointed) and I: Cystidioles. Bars: 10 μm.

FIGURE 4. Microscopic structures of Septocystis minor A: Skeletal hyphae (arrow pointed) from trama; B: Generative hyphae with clamp connections (arrow pointed) from trama; C: Hyphal peg; D: Skeletal hyphae (arrow pointed) from context; E: Generative hyphae with clamp connections (arrow pointed) from context; F: Crystals (arrow pointed). Bars: 10 μm.

FIGURE 5. Microscopic structures of Septocystis minor shown by line drawings. A: Basidia (including arrow pointed); B: Basidioles (arrow pointed); C: Basidiospores; D: Cystidia; E: Cystidioles. Bars: 10 μm.

FIGURE 6. Microscopic structures of Septocystis minor shown by line drawings. A: Skeletal hyphae from trama; B: Generative hyphae with clamp connections from trama; C: Skeletal hyphae from context; D: Generative hyphae with clamp connections from context; E: Crystals; F: Hyphal peg. Bars: 10 μm.