Sordaria macrospora Auersw.

Yang, Erfu, Lu, Wenhua, Tibpromma, Saowaluck, Dai, Dongqin, Gao, Ying, Promputtha, Itthayakorn & Karunarathna, Samantha C., 2023, Three interesting fungi from American bullfrog larvae (Rana catesbeiana) in Yunnan, China, Phytotaxa 587 (3), pp. 251-268 : 259-260

Sordaria macrospora Auersw. , Fungi Europaei exsiccati, Klotzschii herbarii vivi mycologici continuatio. Editio nov. Series secunda. Cent. 10: no. 954 (1866) ( Figure 5 )

Index Fungorum number: IF 237763

Isolated from intestinal contents of dead American bullfrog larvae. Sexual morph on PDA: Ascomata 340–420 × 270–380 μm (x̅ = 330 × 380 μm, n=20), semi-immersed to superficial, perithecial, solitary or gregarious, ampulliform or pyriform, globose, coriaceous, brown to black, ostiolate. Neck 140–180 × 85–120 μm (x̅ = 160 × 99 μm, n=10) central, oblong, straight to bent, extended, blunt ends. Peridium consist of dark-brown, thick-walled cells of textura angularis. Hamathecium 6–15 wide (x̅ = 9.5 μm, n=20), numerous, wide, branched, septate, markedly constricted at the septa, hyaline, paraphyses. Asci 130–180 × 17–22 μm (̄x̅ = 155×19 μm, n=20), unitunicate, eight-spored, slenderly cylindrical, with a lobate pedicel and a prominent J- ring. Ascospores 20–30 × 15–20 μm (x̅ =25.5 × 15.5 μm, n=20), one-celled, ellipsoidal to ovoid, uniseriate, hyaline to golden to brown to black when mature, guttulate, with some prominent oil droplets, with a thin gelatinous sheath, acute to round ends, with a basal germ pore. Asexual morph: Undetermined.

Culture characteristics: Colonies growing on PDA reach around 60 mm in diameter after one week at 27 °C, forming dark brown fruiting bodies within one month in PDA. Obverse: flat, white, entire edge, peripheral fertile. Reverse: pale brown. Without pigments produced in PDA.

Known substratum: Pinus sylvestris , Fagus sylvatica ( Petrini & Fisher 1988) ; Salix fragilis , Quercus robur ( Petrini & Fisher 1990) ; Olea europaea ( Fisher et al. 1992) ; Eucalyptus nitens ( Fisher et al. 1993) ; Dactylis glomerata ( Sanchez Marquez et al. 2007) ; Herbivore dung ( Lytvynenko & Hayova 2018); Intestinal contents of dead American bullfrog larvae (this study).

Known Distribution: England (Petrini & Fisher 1998,1990); Balearic Islands ( Fisher et al. 1992); Australia ( Fisher et al. 1993); Spain ( Sanchez Marquez et al. 2007); Ukraine ( Lytvynenko & Hayova 2018); China (This study).

Material examined: China, Yunnan Province, Qujing Normal University, on intestinal contents of dead American bullfrog larvae, GPS: 103°44’35”E, 25°30’46”N, 1856.6 m, Wen-hua Lu, ER3 , (Herb. HKAS 125766 ), living culture 22-12509 .

Notes: Sordaria macrospora is a coprophilic homothallic pyrenomycete, a fungal model organism in biology that was first described in 1866 by Auerswald. Our isolate fits the concept of S. macrospora by having elongated neck, oblong asci with a “J-” apical ring, enwrap eight hyaline to golden to dark brown ascospores, ascospores uniseriate, visible distinct oil droplets when its young, present verruculose surface when it is mature, without gelatinous sheath ( Lord & Read 2011). The BLASTn results of ITS, and LSU showed our isolate (KUNCC22-12509) are highly similar to Sordaria species ( Sordaria macrospora CBS :346.62, S. humana CBS :416.82, S. fimicola CBS :566.67, S. lappae CBS :154.97, S. tamaensis and S. nodulifera NBRC :32551), with 99–100% similarity. However, the tub2 gene is mostly similar to Sordaria macrospora (FGSC 4818) and S. superba (CBS 784.96) with 99% similarity, the tub2 gene of other species is not available ( Table 1). From morphology, Sordaria superba is different, as the ascospores are wrapped by a distinct gelatinous sheath with a single basal germ pore ( Yul et al. 2010), our isolate is more similar to S. macrospora (ascomata: 370–400 (500) × 250–300 µm VS. 340–420 × 270–380 μm; and asci: 160–175 ×20 VS. 20–30 × 15–20 μm) ( Ivanová et al. 2015). The phylogenetic tree indicated that our Sordaria macrospora KUNCC 22-12509 is complex with the other species that have high similarity in ITS, and LSU genes ( Figure 2 ), and this problem may be caused by lacking tub2 genes, therefore, our isolate KUNCC22-12509 is identified based on morphological features (Table 2) coupled with BLASTn results and phylogenetic analyses as Sordaria macrospora which is a new host and country record.

Figures

FIGURE 2. Phylogram of Sordariaceae were constructed based on combined ITS, LSU and tub2 sequences. Related sequences were taken from Phukhamsakda et al. (2020) and Huang et al. (2021). The tree is rooted with Chaetomium globosum (CBS 160.62) and C. microthecia (LC4685). The BI and ML bootstrap support values equal to or above 0.90 BYPP and 60 % are shown at the first and second positions above the nodes. Type strains are in bold, and newly generated strains are in red.

FIGURE 5 Sordaria macrospora (HKAS 125766). a–c Colony on PDA for one month. d Mature ascomata. e Undeveloped ascomata. f, g Close-up of ascomata. h Peridium. i Paraphyses. j “J-” apical ring. k Ascus. l–p Ascospores. Scale bars: d = 200 μm, e, h, i, k = 50 μm, l–q = 20 μm, j = 10 μm.