Pseudoplectania mystica Jia Y. Lin, Ling-Han Guo & Kun L. Yang

Lin, Jia Y., Guo, Ling-Han, Li, Guang-Mei, Zhang, Ming, Xie, De-Chun, He, Shu-Xian & Yang, Kun L., 2024, Pseudoplectania mystica (Ascomycota, Pezizales), a new cup fungus with an endophytic habit of a broad range of host plants, Phytotaxa 650 (1), pp. 8-22 : 16-17

Pseudoplectania mystica Jia Y. Lin, Ling-Han Guo & Kun L. Yang , sp. nov. ( Figs 1–4 )

Registration identifier: FN571899

Etymology:— “ mystica ”, mysterious, as this species is currently only found to produce ascomata on senescing to dead rhizomes of bamboo, while previous studies suggested it to have a broad range of host plants and act as an endophyte (see Discussion section for details).

Diagnosis:— This species is closely related to Pseudoplectania africana in the phylogeny, while it produces a stipe up to 1 mm long, hymenial hairs with a straight apex, crystals in the hymenium up to 170 µm long and up to 18.5 µm wide, and external hairs 3.5–7 µm wide, differing from the longer stipe (up to 3 mm long), hymenial hairs with a straight, hooked or bent in right or obtuse angle apex, longer and thicker crystals in the hymenium (sometimes up to over the whole thickness of the hymenium and up to 60 µm wide) and slightly thicker external hairs (5–8 (–10) µm wide) of the latter ( Sochorová et al. 2022).

Type:— CHINA. Zhejiang Province: Ningbo City , Ninghai County, 29°18′ N, 121°27′ E, elevation 60 m, on the senescing to dead rhizomes of bamboo (probably Phyllostachys sp. ) in a bamboo forest, March 5, 2023, Ling-Han Guo, S2302 B ( HKAS133073 , holotype! (nrITS: PP422101; nrLSU: PP422115 ); HTBM1844 , isotype!) .

Description:— Ascomata tiny to small, sessile to shortly stipitate. Apothecium 8–15 mm broad, 1–4 mm high, hemispherical when immature, cupulate to nearly plane, sometimes with a ruptured margin when mature. Hymenial surface smooth, shiny, smoke gray (#BCC6C8), mongoose brown (#B5A284), coffee red (#7B5B4E), flint brown (#736960), coal blue (#40474D) to dull black (#0B0C0E), sometimes with prune violet (#615074) or night blue (#525A88) tinges. External surface dull lavender purple (#75647A) to dull black (#0B0C0E), covered with abundant tomenta. Stipe lacking or short, up to 1 mm long, sharing the same colour with the external surface. Flesh cottonseed gray (#BEC0BB), strong gray (#9D9D9D) to wood-ash brown (#A0968A), flexible when fresh. Odor indistinct. Taste unknown. Anamorph not observed.

Ascospores mostly globose, rarely subglobose, thick-walled, smooth, nearly colorless, {40/4/3} (10.5) 11–13 [11.58 ± 0.63, 11.00] × (10) 10.5–12 (13) [11.29 ± 0.64, 11.00] µm, Q = 1.00–1.09 (1.10) [1.03 ± 0.03, 1.00] including the spore wall, with globose to subglobose contents, encased in a slightly to distinctly eccentric sheath thickened up to 1.5 µm beyond the spore wall. Asci narrowly cylindrical, operculate, 8-spored, nearly colorless, inamyloid, 255–360 µm long, with a sporiferous part 83–95 × 11–14 µm when the 8 ascospores were fully developed, with an obtuse apex, a tapered and flexuous basal part, and a simple septum at base. Paraphyses abundant, subcylindrical, tinged dark thatch yellow (#CDC591) to kelp brown (#ACA47E), becoming lighter to nearly colorless from apex to base, with the apical cell 7–29 × 2–3 µm and the lower cells 1.5–2.5 µm wide, septate, unbranched or branched 1 to 2 times, sometimes anastomosed between each other, with a slightly enlarged, simple to bifurcate, rarely diverticulated apex. Hymenial hairs scarce, cylindrical, 2–3 µm wide, tinged almost the same colour with the paraphyses but overall darker, unbranched, with a straight apex, and a simple septum at base. Crystals in the hymenium abundant, subcylindrical, angular, sometimes cracked, sometimes tapering downwards, mostly thicker (9–18.5 µm wide), rarely thinner (3.5–7 µm wide), up to 170 µm long, tinged oat orange (#DFCE7E), arranged in the same direction with the other elements in hymenium. Subhymenium up to 76 µm thick, nearly colorless, composed of a dense textura intricata. Medullary excipulum up to 435 µm thick, composed of a gelatinized textura intricata, with hyphae thick-walled, nearly colorless, 2.5–7 µm wide. Ectal excipulum up to 265 µm thick, composed of a textura globulosa to angularis-prismatica, with cells slightly to properly thick-walled, not or very slightly encrusted, nearly colorless, 10.5–35.5 × 7–30 µm in the inner layer, thick-walled, slightly encrusted, tinged barleycorn brown (#9D8F59) to chinchilla gray (#7F7E80), 9.5– 24.5 × 7–15 µm in the 2–5 most external layers, containing crystals similar to those in the hymenium but scarcer and shorter. External hairs cylindrical, up to 1 mm long, 3.5–7 µm wide, tinged camel brown (#CDC196), slightly to properly thick-walled, septate, wavy, unbranched, with an obtuse apex. Basal tomenta cylindrical, very long (may be more than 3 mm), 4.5–8 µm wide, tinged straw brown (#C4B179), thick-walled, septate, wavy, unbranched, with an obtuse apex.

Habitat and distribution:— Growing in groups on senescing to dead rhizomes of bamboo (probably Phyllostachys sp. ) in bamboo forests in spring and winter (between December and April). Previous studies suggested it to have a broad range of host plants including Aegiceras , Cinnamomum , Dendrobium and Lindera (see Discussion section for details). Currently known from East Asia ( China: Zhejiang (according to our collections and the reference information of the nrITS sequences KP050642 and JF502436 ( NCBI 2024a; Wu et al. 2012)) and Guangxi (according to the reference information of the nrITS sequence KX065280 ( Li et al. 2016; NCBI 2024a)); Japan (according to the reference information of the nrITS sequence LC646017 ( NCBI 2024a))).

Additional specimens examined:— CHINA. Zhejiang Province: Ningbo City , Ninghai County, 29°18′ N, 121°27′ E, elevation 60 m, on senescing to dead rhizomes of bamboo (probably Phyllostachys sp. ) in a bamboo forest, March 5, 2023, Ling-Han Guo, S2302 A (completely used up (nrITS: PP422100 )) ; same location, March 19, 2023, Ling-Han Guo, S2314 ( HKAS133074 , partly isolated as HTBM0257 (nrITS: PP422102; nrLSU: PP422114 )) ; same location, December 17, 2023, Ling-Han Guo, L24001 ( HTBM1845 (nrITS: PP422103 )), L24002 ( HTBM1846 (nrITS: PP422104; nrLSU: PP422116 )), L24003 ( HTBM1847 (nrITS: PP422105; nrLSU: PP422117 )), L24004 ( HTBM1848 (nrITS: PP422106; nrLSU: PP422118 )), L24005 ( HTBM1849 (nrITS: PP422107; nrLSU: PP422119 )), L24006 ( HTBM1850 (nrITS: PP422108; nrLSU: PP422120 )), L24007 ( HTBM1851 (nrITS: PP422109; nrLSU: PP422121 )), L24008 ( HTBM1852 (nrITS: PP422110; nrLSU: PP422122 )), L24009 ( HTBM1853 (nrITS: PP422111; nrLSU: PP422123 )), L24010 ( HTBM1854 (nrITS: PP422112; nrLSU: PP422124 )), L24011 (completely used up) .

Comments:— Pseudoplectania mystica is close to P. ericae and P. tasmanica on the nrITS and nrLSU sequences, but they have relatively clear morphological differences. Compared with P. ericae that produces an apothecium up to about 10 mm broad and paraphyses with a bifurcate to often trifurcate apex ( Uzun & Kaya 2018, Sochorová et al. 2022), P. mystica can be distinguished by its slightly broader apothecium (8–15 mm broad) and paraphyses with a simple to bifurcate, rarely diverticulated apex. Compared with P. tasmanica that produces a sessile apothecium up to 30 mm broad, paraphyses “very branched just from the lower part” with a mostly bifurcate to trifurcate apex, and external hairs 5–8 μm wide ( Carbone et al. 2014), P. mystica can be distinguished by its sessile to shortly stipitate and smaller apothecium (8–15 mm broad), having paraphyses unbranched or branched 1 to 2 times with a simple to bifurcate, rarely diverticulated apex and slightly thinner (3.5–7 µm wide) external hairs.

Pseudoplectania mystica can be easily distinguished from other Peudoplectania species that have nrITS and nrLSU data by the evident genetic distances among them ( Fig. 1 ). For P. carranzae and P. ryvardenii that lack these data, they can also be distinguished morphologically. Compared with P. carranzae that produces branched paraphyses 3–4 µm wide with a curved apex (note that in the original description ( Calonge & Mata 2002) of this species, only “paraphyses” were mentioned; it means that the “hymenial hairs” of this species are either absent or treated as paraphyses by the authors), medullary excipulum composed of 3–4 μm wide hyphae, ectal excipulum composed of cells 8–10 µm in diameter, external hairs 8–10 µm wide and basal tomenta 8–10 µm wide ( Calonge & Mata 2002), P. mystica can be distinguished by its unbranched or branched, thinner (up to 3 µm wide) paraphyses with a straight apex, also unbranched and thinner (up to 3 µm wide) hymenial hairs with a straight apex, medullary excipulum composed of thicker (up to 7 µm wide) hyphae, larger (10.5–35.5 × 7–30 µm in the inner layer, 9.5–24.5 × 7–15 µm in the 2–5 most external layers) cells in the ectal excipulum, thinner external hairs (3.5–7 µm wide) and thinner (4.5–8 µm) basal tomenta. Compared with P. ryvardenii that produces a stipitate apothecium 5–7 mm broad, 5–8 mm high without hymenial hair ( Iturriaga et al. 2012), P. mystica can be distinguished by its sessile to shortly stipitate, broader (8–15 mm broad) and shorter (1–4 mm) apothecium with hymenial hairs presented.

Additionally, the above-mentioned species also show a clear distribution pattern, see Discussion section for details.

Figures

FIGURE 1. Phylogenetic tree of Pseudoplectania inferred from concatenated nrITS-nrLSU alignment. Nodes are annotated if supported by ≥50% MLB or ≥0.9 BPP. The clades and subclades concerned are highlighted with background colours and coded. The specimens that we collected are highlighted in bold. (HT), (PT) and (NT) represent holotype, paratype and neotype, respectively. The sites diverging from the majority rule consensus within subclade a that represent the new species are shown with highlights on the left of the tree. The results of species delimitation generated from the ABGD and ASAP programs, and the host of each specimen (according to the references in Table 1) are shown on the right of the tree.

FIGURE 2. The fresh ascomata and habitat of Pseudoplectania mystica (photos by Ling-Han Guo). a–c. Habitat of the specimens—a bamboo forest dominated by a single bamboo species (probably Phyllostachys sp.); the yellow arrows indicate where the ascomata grew. d. Immature ascomata with a blackish hymenial surface growing on dead rhizome roots of bamboo (HTBM1851). e. Immature ascomata with a brownish hymenial surface growing on dead rhizome roots of bamboo (HTBM1853). f. Immature ascoma with a greyish hymenial surface growing on the mossy dead rhizome roots of bamboo (HTBM1854). g. Longitudinal sections of an immature ascoma (L24011). h. Mature ascomata growing on senescing to dead rhizome joints and internodes of bamboo (HKAS133073, holotype). i. Mature ascomata growing on mossy dead rhizome roots of bamboo (HKAS133074). The scale in i is valid for d–i.

FIGURE 3. Microscopic structures of Pseudoplectania mystica (drawings by Jia Y. Lin, from holotype HKAS133073). a. Ascospores. b. Ascus with 8 developed ascospores and an invisible operculum. c. Hymenium elements, from left to right: the sporiferous part of an ascus with 8 developed ascospores and an invisible operculum, the sporiferous part of an empty ascus with its operculum opened, 2 hymenial hairs, and 5 paraphyses. d. Medullary excipulum. e. Ectal excipulum. f. External hairs. g. Basal tomenta. Bars: a, c–g = 10 µm, b = 50 µm (f and g sharing same bar).

FIGURE 4. Crystals in the hymenium of Pseudoplectania mystica (photos by Jia Y. Lin, from holotype HKAS133073). a. Overview of crystals in the hymenium. b. Thicker crystals. c. Thinner crystals. d. Medium-sized crystals. Bars: a = 100 µm, b–d = 20 µm.