Pararoussoella 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-

Pararoussoella coffeae L. Lu & Tibpromma sp. nov.

Fig. 18

Etymology.

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

Diagnosis.

Differs from other Pararoussoella species by the subcylindrical to ellipsoid or, sometimes, ovoid conidia.

Holotype.

HKAS 137609 .

Description.

Saprobic on decaying branch of C. arabica . Teleomorph: Not observed. Anamorph: Conidiomata 60–120 µm high × 100–160 µm diam. (x- = 92 × 121 µm, n = 15), pycnidial, immersed, globose to subglobose, brown, with central ostioles. Conidiomatal wall 15–25 µm wide (x- = 19 µm, n = 20), hyaline to light brown, thick, 4–6 layers, outer layer composed of brown cells of textura angularis, lined with a hyaline layer bearing conidiogenous cells. Conidiophores inconspicuous or micronematous, often reduced to conidiogenous cells. Conidiogenous cells lining the inner cavity, hyaline, smooth, oval to obpyriform or doliiform, phialidic with periclinal thickening at apex, 3–5 × 2–5 µm (x- = 4 × 3.5 µm, n = 30). Conidia 3.5–5 × 2–3 µm (x- = 4.4 × 2.4 µm, n = 30), aseptate, solitary, guttulate, subcylindrical to ellipsoid or, sometimes, ovoid, smooth, apex bluntly rounded, base truncate, hyaline when young, becoming light brown when mature.

Culture characteristics.

Conidia germinating on PDA within 24 h, colonies reached 2.5–3 cm in diameter after one month at 25 ° C, filamentous, with entire margin, flat to raised, with many white aerial mycelia, from above, white at the centre, yellowish at the edge, from below, yellowish.

Materials examined.

China, Yunnan Province, Lincang , on a decaying branch of Coffea arabica ( Rubiaceae ) (24°17'N, 99°99'E, 960 m alt.), 28 July 2022, LiLu, LC 1 - C 3 ( HKAS 137609 , holotype), isotype MHZU 23-0061 , ex-type living culture KUNCC 24-18355 = KUNCC 24-18356 , ex-isotype living culture ZHKUCC 23-0632 = ZHKUCC 23-0633 .

Notes.

In the concatenated phylogenetic analysis, Pararoussoella coffeae forms a sister branch basal to P. mangrovei (Phukhams. & K. D. Hyde) Phukhams. & K. D. Hyde (Fig. 19 ). Since P. mangrovei has only been reported as teleomorph, we performed nucleotide comparisons; P. coffeae ( ZHKUCC 23-0632 ) is different from P. mangrovei ( MFLUCC 16-0424 ) by 20 / 434 bp (4.6 %, without gaps) of the ITS, 14 / 805 bp (1.7 %, without gaps) of the LSU, 99 / 796 bp (12 %, without gaps) of the RPB 2 and 28 / 718 bp (3.8 %, without gaps) of the TEF 1 - α. Based on morphology, our novel taxon in Pararoussoella is similar to the species P. juglandicola Crous & R. K. Schumach. in aseptate and brown conidia, but differs in the shape of conidia. The conidia of our new species are subcylindrical to ellipsoid, sometimes ovoid, while the conidia of P. juglandicola are subcylindrical; besides, the characteristics of guttulate in our species are more distinct than P. juglandicola (Fig. 18 ; Crous et al. (2019)). In addition, the PHI test results (Fig. 22 i ) revealed no significant recombination relationships between P. coffeae and its phylogenetically related taxa. Therefore, the morphological differences and phylogenetic analyses support the introduction of P. coffeae as a new species.

Figures

Figure 18. Pararoussoella coffeae (HKAS 137609, holotype). A, B appearance of conidiomata on a decaying branch of C. arabica; C, D longitudinal section of conidiomata; E conidiomata wall; F conidiogenous cells and conidia; G conidia; H germinated conidium; I culture on PDA from the obverse and reverse. Scale bars: 20 μm (C – F); 5 μm (G, H).

Figure 19. Phylogram generated from the best scoring RAxML tree. based on a combined ITS LSU, SSU, RPB 2 and TEF 1 - α sequence dataset. Torula herbarum (Pers.) Link, (CBS 111855) and T. hollandica Crous, (CBS 220.69) are selected as the outgroup taxa. 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.