Loculosulcatispora juglans F.H. Wang & C.L. Yang, 2023

Wang, Fei-Hu, Wang, Yan-Lin, Zeng, Qian, Xu, Xiu-Lan, Liu, Ying-Gao & Yang, Chun-Lin, 2023, A novel species of Loculosulcatispora (Sulcatisporaceae, Pleosporales) on Juglans regia from Sichuan, China, Phytotaxa 620 (4), pp. 264-272 : 268-269

Loculosulcatispora juglans F.H. Wang & C.L. Yang , sp. nov. ( FIG. 2 )

Index Fungorum: IF 558308

Etymology:— Referring to the host genus Juglans on which the fungus was collected.

Type:— China, Sichuan Province, Neijiang City, 29°48′30′′N, 105°6′36′′E, 340 m, on dead twigs of Juglans regia ( Juglandaceae ), 17 May 2021, F. H. Wang, WFH202105006, ( SICAU 22-0078 , holotype), ex-type culture SICAUCC 22-0079 .

Saprobic on dead twigs of Juglans regia. Sexual morph: Ascomata 370–470 × 410–520 µm (x = 380 × 430 µm, n = 10), solitary, scattered, or sometimes gregarious, immersed, erumpent at maturity, dome-shaped to ellipsoid or irregular, black, uni-loculate, glabrous, with a central ostiole. Ostioles 60–90 × 80–140 μm (x = 75 × 110 μm, n = 40), single, black, short papillate. Peridium 10–13 μm, thick, unequal thickness, outer layer comprising brown to black cells of textura angularis, internal wall thin and hyaline. Pseudoparaphyses 1–2.5 μm wide, dense, filamentous, septate, unbranched, hyaline, arising around inner wall of locules. Asci (46–)78–112(–135) × (7–)9–21 μm (x = 90 × 14 μm, n = 40), 4-spored, bitunicate, fissitunicate, clavate, pedicellate, apically rounded with well-developed ocular chamber. Ascospores (20–)26–36(–34) × (8–)9–12(–14) μm (x = 31 × 10 μm, n = 50), overlapping, uni- to bi-seriate, hyaline, fusiform, broad fusiform with oval ends, 1-septate, distinctly constricted at septum, smooth-walled, with two large droplets in each cell, surrounded by inapparent, thin, sheath at ends. Asexual morph: Undetermined.

Culture characteristics:— Ascospores germinated in sterilized water within 24 h and producing germ tubes from both ends. The colonies on PDA exhibited slow growth, achieving a diameter of approximately 2.8 cm after 25 days at 25ºC under a 12-hour light/12-hour dark cycle, featuring circular, white-grey centers with white margins, floccose texture, slight elevation, smooth edges, white granular surface spots, circular cracks, and a red-brown ring on the reverse side.

Notes:— Loculosulcatispora juglans forms a sister clade to L. hongheensis , L. thailandica , and Parasulcatispora clematidis with high statistical support ( FIG. 1 ). Morphologically, L. juglans differs from the sexual descriptions of L. hongheensis and P. clematidis . A morphometric analysis revealed that the ascomata, asci, and ascospores of P. clematidis were comparatively smaller than those of L. hongheensis and L. juglans . Notably, P. clematidis ( MFLUCC 17-2082) exhibited the unique trait of oil droplet production in culture, a characteristic not observed in L. hongheensis and L. juglans . A morphological comparison of L. juglans , L. hongheensis , and P. clematidis is presented in TABLE 2 . Nucleotide comparisons of ITS, LSU, SSU, tef 1-α, and rpb 2 sequences from our isolate showed discrepancies with sequences from L. hongheensis ( HKAS 122920, holotype), with similarities of 91% (697/762, 23 gaps), 98.98% (877/886, 3 gaps), 99.3% (996/1003, 1 gap), 96.8% (877/906, 36 gaps), and 89.5% (936/1046, 39 gaps), respectively. Comparisons with L. thailandica ( MFLUCC 20-0108, holotype) revealed similarities of 97.4% (742/762, 12 gaps), 96.3% (853/886, 2 gaps), 88.4% (887/1003, 1 gaps), 99.9% (877/878, 38 gaps), and 71.9% (752/1046, 22 gaps), respectively. Furthermore, comparisons with P. clematidis ( MFLUCC 17-2082, holotype) indicated similarities of ITS 66.9% (510/762, 53 gap), LSU 97.5% (864/886, 5 gaps) and tef 1-α 98.3% (877/892, 39 gaps), respectively. Therefore, considering the observed morphological distinctions and strong phylogenetic support, we hereby propose the introduction of L. juglans sp. nov.

Figures

FIGURE 1. Maximum likelihood (RAxML) tree based on a combined dataset of SSU, LSU, ITS, rpb2, and tef1-α sequences. Bootstrap support values for ML (MLBP) equal to or greater than 75% and Bayesian posterior probabilities (BYPP) equal to or greater than 0.95 are shown as ML/BYPP above the nodes. The holotype materials are symbolized with T. The new isolate is in bold. The scale bar represents the expected number of nucleotide substitutions per site.

FIGURE 2. Loculosulcatispora juglans (SICAU 22-0078, holotype). a, b Appearance of ascomata on dead host. c, d Vertical section of ascomata. e Ostiole. f Peridium. g Hamathecium interwoven with asci and pseudoparaphyses. h–j Asci. k Asci stained by Melzer’s reagent. l–o Ascospores. p Germinating ascospores in sterilized water. q, r Culture characters on PDA. Scale bars: b = 1 mm, c = 500 µm, d = 100 µm, e = 50 µm, f–k = 20 µm, p = 10 µm, l–o = 5 µm.