Waltergamsia xishuangbannaensis R.F. Xu & Tibpromma, 2025

Liu, Rui-Meng, Xu, Rui-Fang, Elgorban, Abdallah M., Xu, Jianchu, Dai, Dong-Qin, Suwannarach, Nakarin, Karunarathna, Samantha C. & Tibpromma, Saowaluck, 2025, Morphology and multigene phylogeny unveil Waltergamsia xishuangbannaensis sp. nov. (Bionectriaceae, Hypocreales), associated with Pará rubber (Hevea brasiliensis) from Yunnan Province, China, Phytotaxa 682 (2), pp. 138-150 : 144-145

Waltergamsia xishuangbannaensis R.F. Xu & Tibpromma sp. nov ( FIGURE 2 )

Index Fungorum number: IF 903152; Facesofungi number: FoF 17213

Holotype: ZHKU 22-0154

Etymology: Refers to the location “Xishuangbanna in Yunnan Province,” from where the holotype was collected.

Fungi isolated from old rubber latex of Hevea brasiliensis ( Euphorbiaceae ). Sexual morph: Undetermined. Asexual morph: Colonies on old rubber latex, effuse, white or yellowish-brown, flossy, velvety. Mycelium 3–6.5 μm wide (x = 4.9, n = 20), branched, septate, hyaline, smooth-walled hyphae. Conidiophores 15–30 × 1.5–2μm (x = 23 × 1.9 μm, n = 5), erect, solitary, straight, arising directly from hyphae, smooth, thin-walled, hyaline, usually reduced to single phialides emerging from vegetative hyphae, unbranched, wide at base, hyaline, smooth-walled, 1- septate at base, with cell walls usually thicker than those of vegetative hyphae. Phialides 53–90 × 4.5–6 μm (x = 73 × 5.3 μm, n = 10) terminal, cylindrical, hyaline, thin and smooth-walled, aseptate, unbranched, presenting a slender tip, and producing unicellular conidia. Conidia 2–12 × 2–3 μm (x = 4 × 2 μm, n = 30), oval or ellipsoid, aseptate, hyaline, some with truncate base, some both ends rounded, smooth, thin-walled, not arranged long conidial chains. Chlamydospores: not observed.

Culture characteristics: Conidia germinated on PDA within 12 hours, mycelium septa, hyaline. Colonies produced yellowish water drops from above, white, wrinkled from below, entire edge, the culture medium changed from white to yellowish-brown.

Material examined: China, Yunnan Province, Xishuangbanna Tropical Botanical Garden, on old rubber latex of Hevea brasiliensis , 24 November 2020, Rui-Fang Xu , XSBNR-05 ( ZHKU 22-0154 , holotype) ; ex-type culture ZHKUCC 22-0286), other living culture ZHKUCC 22-0287.

Notes: In this study, multi-gene phylogenetic analysis based on LSU, ITS, tef 1-α, and rpb 2 gene regions reveals our novel taxon belong to Waltergamsia and form an independent branch sister to W. citrina with 100% MLBP and 1.00 BYPP support ( FIGURE 1 ). The pairwise nucleotide comparison of LSU, ITS, tef 1-α, and rpb 2 showed that W. xishuangbannaensis differs from W. citrina by 1/776 bp (0.12%), 10/479 bp (2.1%), 9/810 bp (1.1%) and 24/755 bp (3.2%), respectively ( Jeewon & Hyde 2016). Morphologically, our collection ( ZHKU 22-0154, holotype) can be distinguished from W. citrina ( CBS 384.96, holotype) by its shorter conidiophores (15–30 × 1.5–2 μm vs. 18– 50 × 1–2 μm), larger conidia (2–12 × 2–3 μm vs. 3–5 × 1–1.5 μm) and not arranged in chains. Furthermore, the colony characteristics of our isolates on PDA show a yellowish-brown coloration, which differs from the light-yellow coloration of W. citrina ( Giraldo et al. 2014) . In addition, W. citrina was isolated from decaying fruit in Madang, Papua New Guinea ( Giraldo et al. 2014), and our taxon was isolated from old rubber latex in Yunnan Province, Southwestern China. Therefore, we introduce our taxon ( W. xishuangbannaensis ) as a novel species based on molecular and morphological data.

Figures

FIGURE 1. RAxML tree based on a combined dataset of LSU, ITS, tef1-α, and rpb2 partial sequences. Bootstrap support values for MLBP equal to or greater than 60% and BYPP equal to or greater than 0.95 are given above the nodes. Hyphen (-) means a value equal to or lower than 60% (MLBP) or 0.95 (BYPP). The newly generated strains are indicated in bold red. The ex-type strains are noted with “T”.

FIGURE 2. Waltergamsia xishuangbannaensis (ZHKU 22-0154, holotype), a, b Colonies on substrate. c–e Conidiophores with conidia. f Conidiophores and conidia. g, h Conidia. i Germinated conidium. j, k Culture on PDA. Scale bars: c–h = 10 μm, i = 20 μm.