Nigrospora platycladiensis Z. X. Bi & C. M. Tian, 2025

Nigrospora platycladiensis Z. X. Bi & C. M. Tian sp. nov.

Fig. 9 View Figure 9

Etymology.

Named after the host genus, Platycladus .

Specimens examined.

China • Beijing City, Changping District, Ming Tombs Reservoir , 40°14'57"N, 116°15'54"E, on the discolored scale leaves of Platycladus orientalis , 23 February 2025, Z. X. Bi, holotype BJFC -S 2578 , ex-type strain CFCC 72632 GoogleMaps .

Description.

Sexual morph: Not observed. Asexual morph: Hyphae Intertwined, hyaline to pale brownish, slightly thick-walled, smooth-surfaced, septate, branched, 1.6–5.1 µm in diam. Conidiophores reduced to conidiogenous cells. Conidiogenous cells Initially hyaline, becoming pale brown with age, solitary or aggregated in clusters, ampulliform to subcylindrical, 5.5–8.9 × 3.9–6.9 µm (av. ± S. D. = 7.3 ± 0.9 × 5.3 ± 0.8; n = 30). Conidia mostly solitary and sparse, but capable of forming clusters under pine needle induction, initially hyaline, turning black to brown at maturity, smooth-walled, aseptate, subglobose, 10.4–17.5 × 9.7–17.3 µm (av. ± S. D. = 14.68 ± 1.75 × 13.6 ± 2.0; n = 50).

Culture characteristics.

When cultured on PDA at 25 ° C under dark conditions for 7 days, the colony diameter reaches 60 mm. The colony appears fluffy with well-developed aerial hyphae. These hyphae later intertwine to form small aggregates. Initially white, the colony begins to produce light yellow hyphae after 10 days. The reverse side of the colony is pale brownish. After 20 days, brownish block-like spots start to develop on the reverse. By 30 days, deep black, irregular patches form near the bottom of the medium.

Notes.

Phylogenetic analysis based on ITS, tub 2, and tef 1 - α loci revealed that strains CFCC 72630 and CFCC 72632 (ex-type strain) formed a distinct clade with strong statistical support of 100 / 1 ( ML / BI) and clustered as a sister clade to Nigrospora guangdongensis (ex-type strain CFCC 53917 ) with bootstrap support values of 98 / 1 ( ML / BI) (Fig. 2 View Figure 2 ). However, this species can be distinguished from N. guangdongensis by nucleotide differences at the ITS, tef 1, and tub 2 loci (1 / 534 bp with 4 gaps in ITS, 7 / 408 bp with 7 gaps in tub 2, 36 / 495 bp with 10 gaps in tef 1). Morphologically, the newly discovered species N. platycladiensis from Platycladus orientalis showed partial overlap in conidial size with its closely related species N. guangdongensis (10.4–17.5 μm vs. 13.6–20.9 μm). However, the average conidial length of N. platycladiensis was significantly smaller than that of N. guangdongensis (av. ± S. D. = 14.6 ± 1.7 μm vs. av. ± S. D. = 16.8 ± 1.9 μm). Additionally, the conidiogenous cells of N. platycladiensis were markedly narrower than those of N. guangdongensis (3.9–6.9 μm vs. 7.1–9.9 μm) ( Tian et al. 2020). Based on integrated phylogenetic and morphological data, Nigrospora platycladiensis is proposed as a novel species.