Rhytidhysteron hongheense Wanas

Xu, Xiu-Lan, Xiao, Qian-Gang, Yang, Chun-Lin, Jeewon, Rajesh & Liu, Ying-Gao, 2022, Multigene phylogenetic support for novel Rhytidhysteron Speg. species (Hysteriaceae) from Sichuan Province, China, Cryptogamie, Mycologie 20 (3), pp. 63-79 : 67-70

Rhytidhysteron hongheense Wanas

( Fig. 2 )

SPECIMEN EXAMINED. — China. Sichuan Province, Chongzhou city, 30°33’11.89”N, 103°39’25.55”E, alt. 485 m, on dead twigs of Juglans regia L. (Juglandaceae) , 20.VI.2019, collected by C.-L. Yang, YCL201906005 (holo-, SICAU 19-0006), living culture (SICAUCC 19-0007).

ADDITIONAL GENBANK NUMBER. — tub 2, MT075594 ; rpb 2, MT027610 .

DESCRIPTION

Saprobic on decaying twigs of trees of Juglans regia L.

Sexual morphology

Ascomata 1350-2390 µm long × 620-1870 µm wide × 570- 1070 µm high (x = 1899 × 1068 × 718 µm, n = 25), apothecioid, coriaceous, scattered to gregarious, black, elliptic or irregular in shape, perpendicularly striate along the long axis, reddish brown or brown to black on the disc. Exciple 76-131 µm wide (x = 94, n = 15), two-layerd, outer layer comprising of dark brown to brown cells of textura angularis and textura globulosa, inner layer of hyaline cells of textura angularis and textura prismatica. Hamathecium composed of 1.1 to 2.3 µm wide at the base, 2.8 to 4.9 µm wide at swollen tips (n = 20), dense, hyaline, septate pseudoparaphyses, branched and forming a reddish brown epithecium above the asci, swollen with dense septa at the apex. Hymenium turns blue in Melzer’s reagent, J+. Asci 169-220 × 10-15 µm (x = 194 × 12 µm, n = 40), 6-(7-)8-spored, bitunicate, cylindrical, short pedicellate and apically rounded with an ocular chamber, J- in Melzer’s reagent. Ascospores 23-32 × 8-13 µm (x = 27 × 11 µm, n = 40), uniseriate, partially overlapping, 1-2-3-septate, occasionally 1-septate, frequently 3-septate, ellipsoid or fusoid, straight or slightly curved, constricted septum, light brown to dark brown, without a mucilaginous sheath.

Asexual morphology

Undetermined.

Culture characteristics

Ascospores germinating on PDA within 24 hours and germ tubes produced from any cell. Colonies growing on PDA reach 5 cm diam after four days at 25°C, thinaerial hyphae, flat, circular, initially white, becoming gray to deep gray.

NOTES

The type strain of Rhytidhysteron hongheense Wanas was recently known on Dodonaea Mill. from Yunnan, China ( Wanasinghe et al. 2021). The similar morphological characteristics and multigene phylogenetic analysis based on combined LSU, SSU, ITS, and tef- 1 α sequence data showed our collection is a new host record of R. hongheense on Juglans regia . But compared with the type description of R. hongheense , our collection has larger ascomata (1590 × 410 × 840 µm vs 1899 × 718 × 1068 µm) and longer asci (169-220 vs 140-180 µm). The asci in R. hongheense are mainly 6- or 8-spored, but 7-spored observed in this paper, and this feature has only been observed in R. chromolaenae ( Mapook et al. 2020) .

Rhytidhysteron ligustrum X.-L. Xu & C.-L. Yang, sp. nov.

( Fig. 3 )

HOLOTYPE. — China. Sichuan Province, Chengdu City, Wenjiang District , 30°42’19.41”N, 103°51’27.6”E, alt. 526 m, on dead twigs of Ligustrum quihoui Carr. ( Oleaceae ), 26.XII.2019, collected by X.-L. Xu, XXL201912001 (holo-, SICAU 20-0004), ex-type living culture (SICAUCC 20-0004).

ETYMOLOGY. — The epithet refers to the host genus Ligustrum L.

INDEX FUNGORUM. — IF558047.

ADDITIONAL GENBANK NUMBER. — tub 2, MT075589 ; rpb 2, MT075605 .

DESCRIPTION

Saprobic on decaying twigs of Ligustrum quihoui Carr.

Sexual morphology

Ascomata 849-2345 µm long × 508-1490 wide × 452-711 high (x = 1390 × 747 × 565 µm, n = 30), apothecioid, carbonaceous, scattered to gregarious, black, labiates and elliptic or irregular in shape, perpendicularly striate along the long axis, reddish brown to dark brown on the disc. Exciple 50-120 µm wide (x = 78, n = 15), two-layered, outer layer is composed of several layers of thick-walled, brown to dark brown cells of textura angularis, inner layer is composed several layers of narrow, long, thin-walled, hyaline to brown cells of textura prismatica. Hamathecium composed of 1.7-2.7 µm wide at the base, 3.2-6.9 µm wide at swollen tips (n = 20), dense, septate, pseudoparaphyses, branched and forming yellowishbrown to reddish brown epithecium above the asci, obviously swollen at the apex, hymenium turns blue in Melzer’s reagent, J +. Asci 134-196 × 10-18 µm (x = 166 × 13 µm, n = 25), 6-8-spored, bitunicate, clavate to cylindrical, with short pedicel and apically rounded with an ocular chamber, J- in Melzer’s reagent. Ascospores 18-32 × 8.9-13 µm (x = 27 × 11 µm, n = 30), ellipsoidal or fusiform, straight or slightly curved, slightly pointed at both ends, partially overlapping, uniseriate, 1-2-3-septate, and both frequently, constricted septum, hyaline to brown, without a mucilaginous sheath.

Asexual morphology

Undetermined.

Culture characteristics

Ascospores germinating on PDA within 24 hours and germ tubes produced from any cell. Colonies growing on PDA reach 5 cm diam after five days at 25°C, flat, circular, initially white, gradually becoming to brown.

NOTES

The new species Rhytidhysteron ligustrum X.-L. Xu & C.-L. Yang, sp. nov. is morphologically similar to our collection of R. hongheense , but they are different in having coriaceous rim and longer asci (194 µm vs 166 µm) in R. hongheense . In the comparison of ITS, tef- 1 α, rpb 2 and tub 2 sequences, our new strain shows 8.68 %, 1.16 %, 1.44 %, 2.57 % differences to our collection of R. hongheense , respectively. Our strain is phylogenetically close to R. camporesii and R. chromolaenae . Furthermore, a pairwise comparison of tef- 1 α sequence data showed 1.52 % differences between R. ligustrum X.-L. Xu & C.-L. Yang, sp. nov. and R. camporesii , as well as 1.86% differences between R. ligustrum X.-L. Xu & C.-L. Yang, sp. nov. and R. chromolaenae . R. ligustrum X.-L. Xu & C.-L. Yang, sp. nov. has longer ascomata (1390 µm vs 1002 µm vs 780 µm), 6-8-spored asci, and 1-2-3-septate ascospores when mature, while R. camporesii and R. chromolaenae have 8-spored and 7-8-spored asci, respectively, and both 3-septate ascospores at maturity ( Hyde et al. 2020b; Mapook et al. 2020).

Figures

FIG. 2. — Rhytidhysteron hongheense Wanas (SICAU 19-0006): A, appearance of apothecia on host; B, C, ascomata; D, vertical section of hysteriothecium; E, F, exciple; G, pseudoparaphyses;H-K, asci; L, M, ocular chamber;N-P, ascospores;Q, germinated ascospores; R, colonies on PDA for four days. Scale bars: A, B, 1 mm; C, 0.5 mm; D, 200 μm; E-K, 20 μm; L-Q, 10 μm.

FIG. 3. — Rhytidhysteron ligustrum X.-L. Xu & C.-L. Yang, sp. nov. (holo-, SICAU 20-0004): A, appearance of apothecia on host; B, C, ascomata; D, vertical section of hysteriothecium; E, exciple; F, pseudoparaphyses; G-K, asci; L, ocular chamber; M, germinated ascospores; N-Q, ascospores; R, colonies on PDA for five days. Scale bars: A, 1 mm; B, C, 0.5 mm; D, 100 μm; E-K, 20 μm; L-Q, 10 μm.