Mortierella irregularispora X. Y. Ji, H. Zhao & X. Y. Liu, 2025

Ji, Xin-Yu, Ding, Zi-Ying, Liu, Wen-Xiu, Li, Fei, Zhao, Heng, Wang, Shi & Liu, Xiao-Yong, 2025, Unveiling species diversity within Mortierellomycota from China X: Three new species in Linnemannia and one in Mortierella, MycoKeys 125, pp. 245-262 : 245-262

Mortierella irregularispora X. Y. Ji, H. Zhao & X. Y. Liu sp. nov.

Fig. 6

Type.

China • Xizang, Shigatse City , Nyalam County, ( 28°17'53"N, 85°58'26"E, altitude 4300 m), from soil, 27 June 2024, X. Y. Ji, holotype HMAS 354074 , ex-holotype living culture CGMCC 3.28893 (= XG 00435-2-1 ) .

Etymology.

The epithet irregularispora (Lat.) refers to irregular sporangiospores.

Description.

Colonies on PDA at 16 ° C for 5 d, reaching 53 mm diameter, slow growing with a rate of 10.6 mm / d, with a wet dog smell, with sparse aerial mycelia. Hyphae hyaline, upright or bent, sometimes swollen. Sporangiophores arising from aerial mycelia, erect or slightly bent, unbranched, 48.6–176.7 µm long (n = 15, x ̄ = 89.5 µm), 4.3–7.3 µm (n = 15, x ̄ = 5.3 µm) wide at the base, and 2.2–3.0 µm (n = 15, x ̄ = 2.8 µm) wide at the top. Sporangia almost spherical, smooth, 7.3–19.6 µm in diameter (n = 15, x ̄ = 15.0). Sporangiospores hyaline, with irregular shape, smooth, 3.3–4.7 µm vertical height (n = 15, x ̄ = 4.0). Chlamydospores absent. Zygospores not observed.

Temperature requirements.

Minimum growth temperature 4 ° C, and maximum growth temperature 28 ° C.

Additional strains examined.

China • Xizang, Shigatse City , Nyalam County ( 28°17'53"N, 85°58'26"E, altitude 4300 m), from soil, 26 June 2024, X. Y. Ji, living culture XG 00435-2-2 .

Notes.

Phylogenetic analysis of five loci (ITS, LSU, SSU, RPB 1, and Act) showed that the new species M. irregularispora is closely related to M. parvispora (Fig. 2 ). The new species is distinguished from M. parvispora by 46 / 629, 117 / 1061, and 27 / 1019 characters in ITS, LSU, and SSU sequences, respectively. Morphologically, compared to M. parvispora , the new species has smaller sporangia (7.3–19.6 µm vs 20.0–35.0 µm), larger sporangiospores (3.3–4.7 µm vs 2.0–3.0 µm), and no chlamydospores.

Figures

Figure 2. The Maximum Likelihood phylogenetic tree for the genus Mortierella based on combined ITS, LSU, SSU, RPB 1, and Act sequences with Umbelopsis autotrophica as an outgroup. Node supports are indicated by two metrics: Maximum Likelihood Bootstrap Values (left, MLBV ≥ 70 %) and Bayesian Inference Posterior Probabilities (right, BIPP ≥ 0.90), separated by a slash (/). Novel species are emphasized in red. Bold entries with asterisks (*) denote ex-type or ex-holotype strains. The scale bar in the lower left represents 0.1 substitutions per site.

Figure 6. Mortierella irregularispora ex-holotype CGMCC 3.28893. a, b. Colonies on PDA (a. obverse; b. reverse); c – e, h. Sporangia; f. Swollen hyphae; g, i. Sporangiospores. Scale bars: 10 µm (c – i).