Arxiella longispora Yue Xu, T. Qiu, S. Gao, W. Meng & L.J. Xu., 2023

Xu, Yue, Du, Tingting, Liu, Yao, Qiu, Tianyi, Gao, Siyu, Meng, Wei & Xu, Lijian, 2023, Arxiella longispora (Muyocopronaceae), a new fungal species from forest litters in Northeast China, Phytotaxa 616 (2), pp. 160-168 : 164-166

Arxiella longispora Yue Xu, T. Qiu, S. Gao, W. Meng & L.J. Xu. sp. nov. ( FIGURE 3 )

Mycobank No.: MB838820

Type: — CHINA. HEILONGJIANG: Greater Hinggan Mountains, 52.33°N, 124.7°E, alt. Ex leaves ( Populus davidiana ., Betula platyphylla , Larix gmelinii . and Pinus Sylvestris ) litter ( MEFL706 ), 10 Oct, 2017, J. Liang, B. Liu, W. Meng, Q. Wang & L. Xu, HMPHU 1245 (holotype) . Ex-type living culture CCTCC M 2021101 ( SGSF 303). GenBank: ITS = MT 921658; LSU = MW 519910; rpb2 = MW 717995; tef1 = MW 883564.

Colonies on PDA, and MEA, reaching 22.00– 22.33 mm after 12 d, smooth, velvet, firstly off-white hyphae, becoming grayish-brown on PDA or grayish-green on MEA after 1 wk; reverse amber, with off-white, smooth, even margin; exudate clear. Colonies on OA reaching 22.00 mm after 12 d, smooth with white hyphae, light yellow to light brown plaques; aerial hyphae sparse, with wavy edge after 3 wk; reverse milk white ( Fig. S1 ). Colonies on CMA reaching 16 mm after 12 d; aerial hyphae dense, becoming grayish towards the outside with black secretions; reverse dark gray ( FIGURE S1 ).

Hyphae septate, branched, hyaline to brown, 1.5–5 μm diam. Conidiophores filamentous, smooth, unbranched, or dichotomously branched, ovoid, clavate, cylindrical or irregular. Conidia (13–)14–22(–24) × 3–4 μm (x̄ = 17.8 × 3.5 μm, n = 100), reniform or cylindrical, hyaline, smooth, guttulate, solitary or occasionally interconnected, medianly 1-septate or no septate, inner plane with apical and basal horn-like appendages, with or without a slightly raised hilum near the base of one of the appendages. Chlamydospores absent. Sexual morph absent.

The optimal temperatures for the colony growth of SGSF 303 on PDA were in the range of 20 ℃ to 25 ℃ where the colony reached around 22 mm diam. in 12 d ( FIGURE S2 ). Growth rates were similar between pH 5 and 10 on PDA for 12 d, but at the pH 4 the fungus had significantly reduced growth speed (5.67 mm, FIGURE S2 ).

Diagnosis: — Colonies grayish brown on surface; conidiophore hyaline, dichotomously branched; conidia up to more than 20 μm long, hyaline, reniform or cylindrical, inner plane with apical and basal horn-like appendages, medianly 1-septate.

Etymology: —Referring to its long spores.

Habitat: —Forest litters.

Known Distribution: —Greater Hinggan mountains, Heilongjiang province, China.

Additional isolates examined: — CHINA, Heilongjiang province, Maoershan, leaves ( Populus davidiana , Betula platyphylla ) litter and soil, September 2018, Siyu Gao SGSF411, ibid. SGSF573.

Notes: — Arxiella longispora is distinct from three asexual morphs in Arxiella , A. dolichandrae , A. lunata , and A. terrestris , by having longer conidia (up to 24 μm long) with a larger length-to-width ratio (>5) ( TABLE 2 ). The closest taxa of A. longispora is A. terrestris based on the similarity of different DNA sequences. The ITS, rpb2 and tef1 sequences of A. longispora showed 97.73%, 94.42%, and 98.61% similarity to A. terrestris , respectively ( TABLE S2 ). Morphologically, A. longispora is closer to A. terrestris and A. dolichandrae due to shape of the conidia which have a straight inner side. In comparison, A. lunata has conidia with a curved inner side. The black-brown colonies of A. longispora on PDA was different with A. terrestris , which shows black-green colonies on PDA. In addition, A. longispora produces unique conidia as mentioned above, but A. celtidis as the only sexual morph do not produce any asexual morph in the culture.

Figures

FIGURE 1. Maximum likelihood phylogeny analysis of the isolates SGSF303 and others based on ITS sequences. The numbers shown in the branches represent ML bootstrap support (BS) values ≥50% and Bayesian posterior probability (PP) scores ≥0.95 and show with “BS / PP”. (*) indicates type sequences.

FIGURE 2. Multi-gene phylogenetic analysis of the isolates SGSF303 and others based on ITS, LSU, rpb2, and tef1 sequences. The numbers shown in the branches represent ML bootstrap support (BS) values ≥50% and Bayesian posterior probability (PP) scores ≥0.95 and show with “BS / PP”.

FIGURE 3. Arxiella longispora. A. The front of colony in PDA. B. The reverse of colony in PDA. C. The front of colony in MEA. D. The reverse of colony in MEA. E–G. Hyphae, conidiogenous cells, and conidia. H. Conidia. Bars = 20 μm.