Paracremonium laticis R. F. Xu, K. D. Hyde & Tibpromma sp. nov.

Fig. 11

Etymology.

Refers to the isolated source “rubber latex.”

Holotype.

GMB-W 1264.

Description.

Associated with contaminated rubber latex. Sexual morph: Undetermined. Asexual morph: Fruiting bodies observed on the PDA plate covered with a natural rubber disc. Mycelium 3–7 μm wide, hyaline, septate, granulate. Conidiophores borne on aerial mycelium, slightly tapering upward, micronematous, mononematous, erect, simple, straight or slightly flexuous, smooth-walled, thin-walled, hyaline, sometimes reduced to conidiogenous cells. Conidiogenous cells formed singly or integrated within hyphae, mostly enteroblastic, phialidic, arising laterally or terminally from hyphae, hyaline, smooth-walled, cylindrical to subcylindrical, occasionally slightly swollen at the base, tapering towards the apex, producing conidia successively. Conidiogenous loci are inconspicuous, without conspicuous collarettes. Conidia 5–10 × 3–6 μm (x – = 7.2 × 4.5, n = 50), solitary, hyaline, ellipsoidal to ovoid, sometimes slightly oblong, straight, smooth-walled, aseptate, typically rounded at both ends, slightly broader at the center with granular or guttulate.

Culture characteristics.

Colonies on PDA at room temperature (20–25 ° C), covering the whole plate within one week (6 cm diameter Petri dish), white, circular, rough, raised, entire margin; reverse white. Sporulation occurred after prolonged incubation on PDA covered with natural rubber discs.

Material examined.

China, • Yunnan Province, Lincang City, contaminated rubber latex, 28 July 2022, Rui-Fang Xu, L-25 (GMB-W 1264), living culture GMBCC 2520.

Notes.

In this study, a multi-gene phylogenetic analysis based on the ITS, LSU, and TUB 2 gene regions revealed that strain GMBCC 2520 belongs to Paracremonium and forms an independent branch sister to P. binnewijzendii (Fig. 7). Pairwise nucleotide comparison of ITS, LSU, and TUB 2 showed that P. laticis (GMBCC 2520) differs from P. binnewijzendii (CBS 143277, ex-type) by 45 / 531 bp (8.47 %, 9 gaps), 15 / 774 bp (1.94 %, 0 gaps), and 33 / 338 bp (9.76 %, 9 gaps), respectively (Jeewon and Hyde 2016). Morphologically, this collection (GMB-W 1264) can be distinguished from P. binnewijzendii (CBS H-23246, holotype) by its shorter and mostly integrated conidiogenous cells, which are cylindrical to subcylindrical, occasionally swollen at the base, and lack conspicuous collarettes, whereas P. binnewijzendii (CBS H-23246, holotype) possesses erect, unbranched, slightly tapering phialides with a visible collarette. Moreover, P. laticis (GMB-W 1264) produces broader conidia (3–6 μm vs. (1.5 –) 2.5–3.5 (– 4.5) μm) that are ellipsoidal to ovoid, smooth-walled, and typically formed singly, while P. binnewijzendii forms narrower, ellipsoidal to fusoid conidia in slimy heads at the phialide apices (Crous et al. 2017). Therefore, strain GMBCC 2520 (P. laticis) is introduced as a new species based on molecular and morphological analyses. The species was isolated from deteriorated rubber latex collected from a container near a rubber tree in Yunnan Province, China, and was associated with detectable surface alterations and oxidative modification signals on natural rubber during laboratory incubation.