Xenodidymella coffeae L. Lu & Tibpromma, 2025

Lu, Li, Karunarathna, Samantha C., Rajeshkumar, Kunhiraman C., Elgorban, Abdallah M., Jayawardena, Ruvishika S., Hongsanan, Sinang, Suwannarach, Nakarin, Kumla, Jaturong, Xiong, Yin-Ru, Hyde, Kevin D., Han, Mei-Yan, Zheng, De-Ge, Li, Qiang, Dai, Dong-Qin & Tibpromma, Saowaluck, 2025, Unveiling fungal diversity associated with coffee trees in China using a polyphasic approach and a global review of coffee saprobic fungi, IMA Fungus 16, pp. e 144874-e 144874 : e144874-

Xenodidymella coffeae L. Lu & Tibpromma sp. nov.

Fig. 6

Etymology.

The species epithet “ coffeae ” refers to the host plant genus “ Coffea ” from which the fungus was isolated.

Diagnosis.

Differs from X. clematidis Phukhams., Camporesi & K. D. Hyde , by shorter ostioles and cylindrical conidia.

Holotype.

HKAS 137610 .

Description.

Saprobic on decaying branch of C. arabica . Teleomorph: Not observed. Anamorph: Conidiomata 50–80 µm high × 50–90 µm diam. (x- = 62 × 70 µm, n = 20), separate or scattered, semi-immersed, black, globose to subglobose or pyriform, pycnidial, with short ostioles. Conidiomatal wall 6–12 µm wide (x- = 9 µm, n = 30), composed of 1–3 layers of light brown to brown cells of textura angularis, heavily pigmented at the outer layers, lined with a hyaline layer bearing conidiogenous cells. Conidiophores inconspicuous or micronematous, often reduced to conidiogenous cells. Conidiogenous cells lining inner cavity, 4–6 × 4–7 µm (x- = 5.3 × 5.4 µm, n = 30), hyaline, globose to ampulliform, enteroblastic, phialidic. Conidia 10–15 × 3–4 µm (x- = 12 × 3.3 µm, n = 30), solitary, hyaline, oblong to cylindrical with rounded ends, aseptate, mostly straight, surface smooth or rough.

Culture characteristics.

Conidia germinating on PDA within 24 h, colonies reached 6 cm in diameter after two months at 25 ° C, filamentous, filiform margin, smooth, flat, with aerial mycelium, from above, brown at the centre, dark brown at the edge, from below, dark brown to black.

Materials examined.

China • Yunnan Province, Dali , on a decaying branch of Coffea arabica ( Rubiaceae ) (26°09'N, 101°91'E, 1415 m alt.), 25 July 2022, LiLu, DL-C 11 ( HKAS 137610 , holotype), isotype MHZU 23-0064 , ex-type living culture KUNCC 24-18339 = KUNCC 24-18340 , ex-isotype living culture ZHKUCC 23-0638 = ZHKUCC 23-0639 .

Notes.

In the concatenated phylogenetic analysis, Xenodidymella coffeae shows a close relationship with X. clematidis and X. camporesii D. Pem, Doilom & K. D. Hyde (Fig. 7 ). Xenodidymella coffeae conforms to the characteristics of Xenodidymella by globose to ampulliform conidiogenous cells and hyaline conidia ( Hyde et al. 2020). Xenodidymella coffeae has short ostioles and cylindrical conidia, while X. clematidis has long ostioles with oblong-elliptical or oval conidia (Fig. 6 ; Phukhamsakda et al. (2020)). Besides, the conidia of our species are larger than those of X. clematidis (10–15 × 3–4 µm vs. 4–8 × 2–5 μm). Xenodidymella camporesii has only been reported based on its teleomorph ( Hyde et al. 2020). Based on nucleotide comparisons, X. coffeae ( ZHKUCC 23-0638 ) is different from X. clematidis ( MFLUCC 16-1365 ) by 8 / 482 bp (1.6 %, without gaps) of the ITS, 11 / 786 bp (1.4 %, without gaps) of the LSU; and different from X. camporesii ( MFLUCC 17-2309 ) by 10 / 518 bp (2 %, with one gap) of the ITS, 16 / 890 bp (1.8 %, without gaps) of the LSU and 26 / 282 bp (9 %, without gaps) of the TUB. In addition, the PHI test results (Fig. 22 c ) revealed no significant recombination relationships between X. coffeae and its phylogenetically related taxa. This fungus is, therefore, introduced as a new species of Xenodidymella , following the guidelines of Chethana et al. (2021) and Pem et al. (2021).

Figures

Figure 6. Xenodidymella coffeae (HKAS 137610, holotype). A, B conidiomata on a decaying branch of C. arabica; C, D longitudinal section of a conidioma and conidioma wall; E conidiogenous cells with conidia; F – K conidia; L germinated conidium; M culture on PDA from obverse and reverse. Scale bars: 20 μm (C, D, K, L); 10 μm (E – J).

Figure 7. Phylogram generated from the best scoring RAxML tree, based on a combined ITS LSU, TUB and RPB 2 sequence dataset. Neodidymelliopsis cannabis (G. Winter) Qian Chen & L. Cai, (CBS 121.75) is selected as the outgroup taxon. Bootstrap support values for ML equal to or greater than 70 % and PP equal to or greater than 0.90 are given above the nodes. All type strains are in bold and newly-generated sequences are in red.

Figure 22. Split graphs showing the results of the pairwise homoplasy index (PHI) test of the new taxa and closely-related taxa using LogDet transformation and splits decomposition. a Leucaenicola coffeae; b Montagnula coffeae; c Xenodidymella coffeae; d Flabellascoma coffeae; e Longiostiolum coffeae; f Helminthosporium puerensis; g Neomassaria coffeae; h Neooccultibambusa coffeae; i Pararoussoella coffeae; j Cycasicola coffeae. PHI test result P-value (Φw) ≤ 0.05 indicates that there is significant recombination between the isolates included in the alignment. The new taxa are in red, “ T ” indicate the type species and each PHI test value and scale bars are given in the bottom right corner.