Rachicladosporium pennatum X. Yu. Zhang, Q. Y. Zhang & B. Fan, 2025

Zhang, Xiu-Yu, Zhang, Qiu-Yue, Li, De-Wei, Sun, Jing-Zu & Fan, Ben, 2025, Novel endophytic fungi from Pinus: introducing three new genera and six new species within Capnodiales (Ascomycota, Dothideomycetes) sensu lato, IMA Fungus 16, pp. e 175931-e 175931 : e175931-

Rachicladosporium pennatum X. Yu. Zhang, Q. Y. Zhang & B. Fan sp. nov.

Fig. 15

Type.

CHINA • Jiangsu Province, Nanjing, Nanjing Forestry University, Baima Campus , endophytes from Pinus thunbergii , May 2023, Ben Fan and Xiuyu Zhang, NF 412 ( holotype HMAS 354160 , culture ex-type CGMCC 3.28959 ) .

Etymology.

Derived from the Latin word “ pennatum ”, the specific epithet refers to the distinctive pinnate arrangement of conidiophores and conidia.

Description.

Mycelium composed of branched, multi-septate, subhyaline to pale brown hyphae, smooth-walled, 1.9–3.3 μm diam. Asexual state consisting of two conidiation modes: Blastic conidiation: Conidiophores arising laterally or terminally from hyphae, subcylindrical to clavate, multi-septate, pale brown, smooth, (41.9 –) 57.6–150.0 (– 166.2) × (2.0 –) 2.5–4.3 (– 4.9) μm. Conidiogenous cells integrated, terminal, mono- to polyblastic, producing conidia sympodially, (6.8 –) 7.8–11.1 (– 11.9) × (1.9 –) 2.3–3.1 (– 3.2) μm. Conidia pale brown to brown, smooth or slightly verrucose, thick-walled, clavate to fusiform, mostly aseptate, occasionally one-septate or with two septa, (4.4 –) 5.1–7.6 (– 8.8) × (3.7 –) 4.3–6.3 (– 7.2) μm (c; Fig. 15 D – F, H ). Thallic conidiation: Vegetative hyphae directly transformed into thick-walled chlamydospores, arranged in short chains, subcircular to elliptical, pale brown to brown, smooth to finely verruculose, (5.4 –) 5.7–7.5 (– 8.3) × (1.6 –) 1.9–2.7 (– 2.8) μm (d; Fig. 15 G ). Sexual state not observed.

Culture characteristics.

Colonies on MEA are slow-growing, wrinkled, with irregularly serrated edges, densely packed, and light olive green. On OA and SNA media, the colonies are black to off-white, with the aerial hyphae on SNA being fluffier. The optimal temperature is 20 ° C, reaching 9–11 mm diam after 10 d. It can grow a little at 5 ° C. No growth at 35 ° C.

Additional materials examined.

CHINA • Jiangsu Province, Nanjing, Nanjing Forestry University, Baima Campus , fungal endophytes from Pinus thunbergii , May 2023, Ben Fan and Xiuyu Zhang, NF 413, NF 416 .

Notes.

The genus Rachicladosporium currently comprises 21 accepted epithets according to Index Fungorum ( https://www.indexfungorum.org), four of which have since been transferred to the genus Cryoendolithus . Although not all species were included in the phylogenetic analyses, a pairwise comparison of ITS sequences showed that strain NF 412 differs from its closest relative, Rachicladosporium alpinum , by 3.28 % (15 nucleotide substitutions across 458 aligned base pairs), supporting its recognition as a distinct species. Species within this genus have been reported from diverse substrates and habitats, including sooty mold communities on leaves and needles of trees and shrubs, as well as on rocks and insects ( Cruywagen et al. 2015). Phylogenetic analysis shows that three new isolates of R. pennatum , obtained as endophytic fungi from resistant Pinus thunbergii , cluster within the main Rachicladosporium clade and are closely related to R. alpinum and R. paucitum . However, both R. alpinum and R. paucitum were isolated from rocks in the Italian Alps and produce only subhyaline to pale brown hyphae ( Egidi et al. 2014; Crous et al. 2019 a). Morphologically, R. pennatum produces both conidia and chlamydospores, whereas in the closely related species R. alpinum , conidia or chlamydospore-like cells have not been observed ( Egidi et al. 2014).

Figures

Figure 15. Morphology of Rachicladosporium pennatum (isolate NF 412). A – C Colonies on MEA (A), OA (B) and SNA (C) at 25 ° C for 10 days. A shown on a 90 mm Petri dish. D – H Conidiophores (a), conidiogenous cells (b), and conidia (c, d) arranged in chains. Letters “ c ” and “ d ” indicate two distinct conidial morphologies. Scale bars: 5 mm (B, C); 10 μm (D – H).