Pseudoconiocessia xishuangbannaensis L. Lu & Tibpromma

Lu, Li, Karunarathna, Samantha C., Liu, Yina, Elgorban, Abdallah M., Tibpromma, Saowaluck & Jayawardena, Ruvishika S., 2024, Pseudoconiocessia xishuangbannaensis gen. et sp. nov. in Coniocessiaceae, Xylariales from Coffea liberica in China, Phytotaxa 641 (2), pp. 125-137 : 130-132

Pseudoconiocessia xishuangbannaensis L. Lu & Tibpromma , sp. nov. ( Fig. 2 )

Index Fungorum number: IF 901344, Facesoffungi number: FoF 15058

Holotype:— MHZU 23-0069

Etymology:— The specific epithet refers to the location, Xishuangbanna, from where the holotype was collected.

Saprobic on decaying twigs of Liberian coffee. Sexual morph: Ascomata 130–300 µm, 150–300 µm (x̅ = 200 × 230 µm, n = 10), carbonaceous, some erumpent above the host surface, solitary or scattered, semi-immersed to immersed beneath the clypeus, visible as black patches, sub-globose to globose in shape, uni-loculate, cone-shaped, with short ostiole at central, shiny black, periphasate ostiolar canal. Peridium 10–20 µm (x̅ = 15 µm, n = 20), hard in upper regions, outer layer blackish brown and thick-walled, inner layer hyaline and thin-walled, both composed of cells of textura angularis. Hamathecium 1.5–3 µm wide (x̅ = 2 µm, n = 20), composed of numerous, asepate, branched, flexuous, long, hyaline, paraphyses. Asci 50–75 × 4–5 µm (x̅ = 66 × 4.5 µm, n = 20), 4–8-spored, unitunicate, cylindrical, hyaline, with a short furcate pedicel, with a thin flat apical ring, J+ in Melzer’s reagent. Ascospores 7–9 × 2.5–3.5 µm (x̅ = 7.8 × 3 µm, n = 30), uniseriate, yellowish to brown, fusiform or ellipsoid, straight, guttulate, sometimes conical at the lower end, aseptate, germ slit present when mature, without a sheath. Asexual morph: Not observed.

Culture characteristics:— Ascospores germinated within 12 hours on PDA. Colonies grow on PDA at room temperature (20–25 °C), reaching around 35 mm diam after one month. Colonies on PDA circular, white, surface smooth with aerial mycelium, entire margin. Yellowish on the reverse. No pigment produced in PDA media. Colonies grow on MEA very slowly, reaching around 10 mm diam after one month, circular, white, surface rough with floccose aerial mycelium, convex, undulated margin, and white to brown on the reverse. Colonies grow on OA reaching around 25 mm diam after one month, circular, white, surface smooth with fluffy aerial mycelium, flat, filiform margin. Yellowish on the reverse ( Fig. 3 ).

Material examined:— Xishuangbanna , Yunnan Province, China, on decaying twigs of Liberian coffee ( Rubiaceae ), 24 November 2020, Li Lu, XTBG-C5 ( MHZU 23-0069 , holotype) ; ex-type ZHKUCC 23-0648 ; ibid., 12 July 2022, Li Lu , XSBN-C7 ( ZHKU 23-0095 , paratype) ; ex-paratype ZHKUCC 23-0649 .

Notes:— The phylogenetic analyses showed that Pseudoconiocessia xishuangbannaensis forms a monophyletic branch with 73% ML, and 0.92 PP statistical support ( Fig. 1 ). In morphology, P. xishuangbannaensis is similar to Coniocessia and Paraxylaria , but is distinguished from the two genera by aseptate hamathecium, 4–8-spored asci with a flat apical ring, and fusiform ascospores, conical at lower end ( Asgari & Zare 2011, Samarakoon et al. 2022, Fig. 2 ). Herein we introduce P. xishuangbannaensis as a new species based on both morphological comparison and phylogenetic analyses.

Based on the BLASTn results of ITS sequences of our strain ( ZHKUCC 23-0648, ex-type) is 96.9% similar with Xylariomycetidae sp. ( JQ 761899), LSU and RPB 2 results are similar to Lopadostoma polynesium (LAG) with 95% ( KC 774600) and 88% ( KC 774553), respectively. Lopadostoma polynesium was introduced in Lopadostomataceae by Rappaz (1995), but the species had initially been described as Sphaeria polynesia by Berkeley (1874). In our phylogenetic analysis, L. polynesium was placed outside Lopadostomaceae and appears as a sister group with our new species in Coniocessiaceae (Supplementary Fig. 1 ) and our results showed the same placement of L. polynesium , which was also observed by Wanasinghe et al. (2018). Based on nucleotide comparisons, P. xishuangbannaensis ( ZHKUCC 23-0648) differs from L. polynesium (LAG) by 96/564 bp (17%, 39 gaps) in ITS, 60/957 bp (6%, without gaps) in LSU and 119/1085 bp (10%, without gaps) in RPB 2. In morphology, P. xishuangbannaensis is similar to L. polynesium by having cylindrical asci and apical ring J + in Melzer’s reagent, with uniseriate and ellipsoid ascospores ( Rappaz 1995, Jaklitsch et al. 2014), while P. xishuangbannaensis has a flat apical ring in the asci that differs from apical rings in the plug and pendant of L. polynesium ( Rappaz 1995) . However, the morphology of L. polynesium fits well with Lopadostoma by having cylindrical asci, brown and ellipsoid ascospores with rounded or sometimes weakly pointed ends ( Rappaz 1995), and also similar to the new genus Pseudoconiocessia by having brown and ellipsoid ascospores. While L. polynesium also showed a big difference with the type species L. turgidum (LT) ( ITS-LSU 95/1916 bp, 5%) ( Jaklitsch et al. 2014). Besides, Jaklitsch et al. (2014) revised the phylogeny and taxonomy of Lopadostoma based on both morphology and molecular phylogeny using LSU, ITS, and RPB 2 sequences, and they also showed L. polynesium is phylogenetically distinct from Lopadostoma . Thus, it is advised that L. polynesium needs more fresh collections to resolve the taxonomic problems and also to provide a better understanding of their phylogeny and evolution.

Figures

FIGURE 1. RAxML tree based on a combined dataset of ITS, LSU, and RPB2 gene sequences. 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. Strains of the newly described species are in red, while all the type strains are in bold.

FIGURE 2. Pseudoconiocessia xishuangbannaensis (MHZU 23-0069, holotype). a, b. Ascomata on Liberian coffee twig surface. c. A vertical section of an ascoma. d. Peridium of an ascoma. e. Hamathecium. f. A germinating ascospore. g–k. Asci (arrows indicate the thin apical ring J+ in Melzer’s reagent). l–q. Ascospores (arrows indicate the germ slit). Scale bars: c = 50 µm, d, e = 20 µm, f–q = 10 µm.

FIGURE 3. Colonies of Pseudoconiocessia xishuangbannaensis (ZHKUCC 23-0648, ex-type) grown for 30 days at 25 ºC. a, b. Forward and reverse colony on PDA. c, d. Forward and reverse colony on MEA. e, f. Forward and reverse colony on OA.