Hypoderma paralinderae J.F. Zhang & Z.Y. Liu, 2020

Zhang, Jin-Feng, Liu, Jian-Kui, Hyde, Kevin D., Ekanayaka, Anusha H. & Liu, Zuo-Yi, 2020, Morpho-phylogenetic evidence reveals new species in Rhytismataceae (Rhytismatales, Leotiomycetes, Ascomycota) from Guizhou Province, China, MycoKeys 76, pp. 81-106 : 81

Hypoderma paralinderae J.F. Zhang & Z.Y. Liu sp. nov. Figure 2

Etymology.

Referring to the morphological similarity with Hypoderma linderae .

Holotype.

GZAAS 19-1769.

Description.

Apothecia developing on dead stems, scattered, dark brown to black, shiny, long elliptical to slightly fusiform, straight or somewhat curved, ends rounded or obtuse, rising above the surface of the substrate, opening by a single longitudinal split. Lips moderately developed, pale brown (Fig. 2a, b ). In median vertical section (Fig. 2c ), apothecia subcuticular, 200-280 µm deep. Covering stroma (Fig. 2e ) up to 38-45 µm thick near the opening, becoming to 12-18 µm thick towards the edges, extending to the basal stroma, consisting of an outer layer of host cuticle and several layers of dark brown, thick-walled cells of textura angularis. Lip cells (Fig. 2d ) clavate to cylindrical, 11-23 × 2-3 µm, thin-walled, hyaline to pale brown, 0-1-septate. Basal stroma (Fig. 2f ) 10-16 µm thick, consisting of several layers of brown, thick-walled cells, arranged in textura angularis, becoming colourless, thin-walled cells of textura prismatica towards the subhymenium. Subhymenium 19-27 µm thick, composed of several layers of hyaline, thin-walled cells of textura angularis. Paraphyses 1.5-2 µm, filiform, aseptate, unbranched, often curved, but not swollen at the apex, anastomosing at the base. Asci (81.5-)110-120(-129) × 10-14 µm (x ¯ = 108 × 12 µm, n = 25), 8-spored, unitunicate, cylindrical-clavate, round to subtruncate at the apex, with a 38-49 µm long stalk, thin-walled, J-, apical ring, without circumapical thickening. Ascospores 26-32.5 × 2.5-4.5 µm (x ¯ = 30.5 × 3.5 µm, n = 35, measured without the gelatinous sheath), multi-seriate and mostly arranged in the upper half of ascus, fusiform to slightly cylindrical, straight or lightly curved, apex rounded and tapering slightly to an acute base, aseptate, hyaline, guttulate, surrounded by a 0.5-1.5 µm thick gelatinous sheath (extending to 2.5 µm at the poles). Asexual morph: Not observed.

Material examined.

CHINA, Guizhou Province, Leishan County, dead stems of unidentified herbaceous plants, 2 November 2017, J.F. Zhang, LS-21 (GZAAS 19-1769, holotype).

Notes.

Our phylogenetic analysis shows that Hypoderma paralinderae is placed in Hypoderma D clade (Fig. 1 ) and clustered with H. cordylines , H. hederae and H. rubi . Both H. paralinderae and H. codylines have similar sized asci (110-122.5 × 5.5-7 µm vs. 90-140 × 11-16 µm); however, they can be distinguished by the different shape and size of ascospores (fusiform to slightly cylindrical, 26-32.5 × 2.5-4.5 µm in H. paralinderae vs. elliptic, 14-21 × 4.5-6 µm in H. cordylines ) ( Johnston 1990). Hypoderma paralinderae shares similar-sized asci with H. hederae ; however, it is differentiated from the latter by larger ascospores (26-32.5 × 2.5-4.5 µm vs. 18-22 × 3.5-4 µm) ( Powell 1974). Moreover, H. hederae was described with oblong-cylindrical ascospores that are bluntly round on both ends; however, the ascospores in H. paralinderae are fusiform to cylindrical, but rounded at the apex and tapering slightly to an acute base ( Powell 1974), while H. paralinderae differs from H. rubi by having obviously larger asci (110-122.5 × 5.5-7 µm vs. 60-100 × 10-12.5 µm) and ascospores (26-32.5 × 2.5-4.5 µm vs. 14-18 × 3.5-4.5 µm) ( Hou et al. 2007). Besides, the recommendations of delineation taxa from Jeewon and Hyde (2016) are followed and comparisons of the ITS gene region between H. paralinderae and H. cordylines (ICMP 17344), as well as H. paralinderae and H. rubi (ICMP 17339) are processed. The results showed that there are 9/468 bp (1.9%) and 9/467 (1.9%) bp differences (including gaps) between them, respectively. According to the above evidence, H. paralinderae is introduced herein as new to science.

Figures

Figure 1. Phylogram of Rhytismataceae is presented as the best tree revealed by MP analysis, based on the concatenated LSU-ITS-mtSSU sequence dataset. MP bootstrap support values (MPBP ≥ 50 %) and Bayesian inference posterior probabilities (BYPP ≥ 0.95) are shown near the nodes. The tree is rooted to Marthamyces emarginatus (ICMP 22854), the scale bar showing 10 changes. Type strains are indicated in bold and new sequences, generated in this study, are given in red.

Figure 2. Hypoderma paralinderae a, b apothecia observed under a dissecting microscope in face view c vertical section through an apothecium d lips adjacent to the top of covering stroma e section of covering stroma f section of basal stroma g paraphyses and asci in various states of maturity h immature ascus i, j ascospores. Note: c-j mounted in water. Scale bar: 1 mm (a), 500 µm (b), 200 µm (c), 20 µm (d, g, h), 10 µm (e, i, j), 5 µm (f).