Longiostiolum 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-

Longiostiolum coffeae L. Lu & Tibpromma sp. nov.

Fig. 10

Etymology.

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

Diagnosis.

Differs from L. tectonae by the presence of sheath in ascospores.

Holotype.

HKAS 137602 .

Description.

Saprobic on decaying branch of C. arabica . Teleomorph: Ascomata 160–280 µm high × 180–280 µm diam. (x- = 212 × 238 µm, n = 15), black spots on the substrate, solitary to scattered, immersed to semi-immersed, when cut horizontally, locules visible as white contents, unilocular, globose to subglobose, with central and short ostioles. Peridium 20–30 µm thick (x- = 23 µm, n = 15), outer layer consists of 2–4 layers of textura angularis, brown and thick-walled cells, inner layer consists of multi-layers of textura angularis, hyaline and thin-walled cells. Hamathecium 2–3 µm wide (x- = 2.5 µm, n = 20), numerous, hypha-like, filiform, septate, branched, cellular, pseudoparaphyses, embedded in a gelatinous matrix. Asci 90–140 × 20–28 µm (x- = 115 × 23 µm, n = 20), bitunicate, 8 - spored, cylindrical to clavate, with a short pedicellate, apically rounded, with an ocular chamber. Ascospores 45–55 × 8–11 µm (x- = 47 × 9 µm, n = 20), overlapping uniseriate to 3 - seriate, hyaline, fusoid, often enlarged at the fourth cell, with one transverse septum when young, 7–8 transverse septa when mature, constricted at the centre septa, slightly constricted at other septa, smooth-walled, sheath present. Anamorph: Not observed.

Culture characteristics.

Ascospores germinating on PDA within 24 h, colonies reached 4 cm in diameter after one month at 25 ° C, circular, with filiform margin, aerial, medium spare, flat or effuse, from above, hyaline, from below, hyaline to light brown at the centre, hyaline at the edge.

Materials examined.

China, Yunnan Province, Lincang , on a decaying branch of Coffea arabica ( Rubiaceae ) (22°8'N, 99°4'E, 870 m alt.), 28 July 2022, LiLu, LC 3 - C 3 ( HKAS 137602 , holotype), isotype MHZU 23-0059 , ex-type living culture KUNCC 24-18345 = KUNCC 24-18346 , ex-isotype living culture ZHKUCC 23-0628 = ZHKUCC 23-0629 .

Notes.

In the concatenated phylogenetic analysis, Longiostiolum coffeae formed a sister branch with L. tectonae ( MFLU 15-3532 ) (Fig. 11 ). Based on nucleotide comparisons, L. coffeae ( HKAS 137602 ) is different from L. tectonae ( MFLU 15-3532 ) by 70 / 480 bp (14 %, without gaps) of the ITS, 13 / 863 bp (1.5 %, without gaps) of the LSU, 4 / 665 bp (0.6 %, without gaps) of the SSU and 75 / 920 bp (8 %, without gaps) of the TEF 1 - α. Based on morphology, our novel taxon is similar to L. tectonae in the hyaline and fusoid ascospores, but differs in the sheath of ascospores, as L. tectonae lacks a sheath. Besides, our species has 1–8 transverse septa, while L. tectonae has 7–10 transverse septa (Fig. 10 ; Li et al. (2016); Phukhamsakda et al. (2020)). In addition, the PHI test results (Fig. 22 e ) revealed no significant recombination relationships between L. coffeae and its phylogenetically related taxa. The morphological differences and phylogenetic analyses support the discovery of L. coffeae as a new species.

Figures

Figure 10. Longiostiolum coffeae (HKAS 137602, holotype). A, B ascomata on a decaying branch of C. arabica; C, D longitudinal section of ascomata; E peridium wall; F pseudoparaphyses; G – K asci; L – O ascospores; P an ascospore stained with Indian ink; Q culture on PDA from obverse and reverse. Scale bars: 100 μm (C, D); 20 μm (E – P).

Figure 11. Phylogram generated from the best scoring RAxML tree, based on a combined ITS LSU, SSU, RPB 2 and TEF 1 - α sequence dataset. Diatrype disciformis (Hoffm.) Fr., (AFTOL-ID 927), Graphostroma platystoma (Schwein.) Piroz. (CBS 270.87) and Sordaria fimicola (Roberge ex Desm.) Ces. & De Not., (AFTOL-ID 216) 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.