Geotrichum xishuangbannaensis E.F. Yang, 2025

Yang, Erfu, Karunarathna, Samantha C., Shao, Shicheng, Han, Lisu, Samarakoon, Milan C., Elgorban, Abdallah M., Chiu, Chuni, Tibpromma, Saowaluck & Promputtha, Itthayakorn, 2025, Additions to Termitomyces aurantiacus growing termite comb-associated fungi, Phytotaxa 690 (2), pp. 212-230 : 216-217

Geotrichum xishuangbannaensis E.F. Yang sp. nov.

Fungal Names number: FN571980

Etymology: The specific epithet is derived from the location "Xishuangbanna" from where the holotype was collected.

Harboured in termite fungus gardens. Hyphae 3–5 μm (x = 3.7 μm, n = 20) wide, with rounded apices, straight, septate, laterally branched, hyaline, thin-walled, smooth, with cells with or without oil droplets. Asexual morph: Conidiophores 4–8 × 2.5–4 μm (x = 6 × 3.2 μm, n = 20), hyaline, usually simple, cylindrical, oblong, branched to unbranched, sometimes with septa. Conidiogeneses arthric, on terminal hyphae or on branches by quickly disarticulating and producing arthroconidia. Arthroconidia 6–10 × 3.5–5 μm (x = 8 × 4.5 μm, n = 20), one-celled, thick-walled, catenated, globose to subglobose at the young age, cylindrical to rectangular when mature, hyaline, often with one or two distinct oil droplets. Sexual morph: Undetermined.

Culture characteristics: Colonies sporulated on PDA within one month, reaching around 50 mm diam after one month. Obverse: circular, flat, smooth, whitish to creamy, slightly moist, floccose aerial mycelium, with a well-defined margin; reverse: whitish to cream-colored, odour fruity. In PDA, no pigments were observed.

Material examined: China, Yunnan Province, Xishuangbanna Tropical Botanical Garden, isolated from active termite fungus gardens, 20 July 2022, E.F. Yang, P, P-1 ( HKAS 129047, holotype), ex-type, KUNCC 22-12514. GenBank numbers, KUNCC 22-12514 = LSU: PP915829, ITS: PP915822. ZHKUCC22-0291 = LSU: PP915830, ITS: PP915823.

Notes: Based on morphological comparisons, our isolate resembles the genus Geotrichum ( Figure 3 ), producing cylindrical to rectangular and catenate arthroconidia ( Zhu et al. 2024). The results of BLASTn searches of LSU (D1/D2) show around 99% similarity to that of Geotrichum europaeum ( JX 17A04, ZJ02A01, CBS 866.68) and Ge. pseudocandidum ( CBS 11392, 398R-4); while ITS only shows 93–94% similarity to that of Geotrichum candidum ( HNNU 0034, FJAT-32266), Ge. geotrichum (UBOCC-A-101170), Ge. pseudocandidum ( CBS 626.83, MVGY-37- 2) and Geotrichum sp. (UFMG-CM-Y2816). Moreover, the combined D1/D2 and ITS multi-gene phylogenetic tree shows that our Geotrichum isolates ( KUNCC 22-12514 = ZHKUCC22-0291) are sister to Ge. pseudocandidum ( CBS 10073, CBS 626.83, CBS 820.71, 398R-4), with 86% ( ML) and 1.00 (BI) at neighboring branches ( Figure 2 ). Here we introduce Geotrichum xishuangbannaensis sp. nov., the first known species in this genus Geotrichum associated with the fungus gardens of fungus-growing termites.

Figures

FIGURE 2. Phylogram of Geotrichum constructed using maximum likelihood analysis, based on a combined LSU and ITS sequence dataset. The analysis encompassed 54 strains and encompassed a total of 1054 characters (LSU: 1–599 bp, ITS: 600–1054 bp). Newly introduced species are highlighted in red, and the type strains are indicated in bold. Bootstrap values equal to or higher than 60% (ML, left) and Bayesian posterior probabilities equal to or higher than 0.95 (BI, right) are indicated at the nodes, while hyphens (-) denote values below these thresholds for ML/BI.

FIGURE 3. Geotrichum xishuangbannaensis (HKAS129047): (a) Colony on PDA, (b) Branched mycelia, (c–g) Conidiophores with arthroconidia, (d) Conidiophores with arthroconidia stained with congo red dye.