Sarcopodium tibetense Z.Q. Zeng & W.Y. Zhuang, 2021

Zeng, Zhao-Qing & Zhuang, Wen-Ying, 2021, A new species of Sarcopodium (Hypocreales, Nectriaceae) from China, Phytotaxa 491 (1), pp. 65-71 : 67-70

Sarcopodium tibetense Z.Q. Zeng & W.Y. Zhuang , sp. nov. FIGURES 2 & 3

Fungal Names: FN570743

Etymology:—Referring to the type locality of the fungus.

Holotype: — CHINA. Tibet Autonomous Region, Motuo, Dexing , on rotten stem base of maize straw, 20 Sept 2016, Z.Q. Zeng, Z.H. Yu, H.D. Zheng, X.C. Wang, K. Chen & Y.B. Zhang 11073 ( HMAS 255809 ).

Paratype: — CHINA. Tibet Autonomous Region, Motuo, Dexing , on rotten base of maize straw, 20 Sept 2016, Z.Q. Zeng, Z.H. Yu, H.D. Zheng, X.C. Wang, K. Chen & Y.B. Zhang 11074 ( HMAS 255810 ) .

Description: —Ascomata superficial, non-stromatic or with a minute basal stroma, perithecial, mycelium usually visible around host, solitary to gregarious, globose to subglobose or pyriform, with an acute papilla, surface smooth to slightly roughen, not becoming cupulate upon drying, bright reddish brown, becoming dark red in KOH and yellow in LA, 176–235 × 118–235 μm (n = 14). Hairs arising from perithecial surface, hyaline to yellowish, straight or hooked, unbranched, septate, 27–83 μm long, 4–6 μm wide. Perithecial wall of two layers, 15–25 μm thick; outer layer of textura angularis, 10–20 μm thick, cells pale brown to subhyaline, 5–10 × 2–5 μm, walls 1–1.2 μm thick; inner layer of textura prismatica, 4–6 μm thick, cells hyaline, 6–10 × 2–3 μm, walls 0.6–0.8 μm thick. Asci unitunicate, 8-spored, cylindrical to clavate, without an apical ring, 30–58 × 5–8 μm. Ascospores fusoid to elliptic-fusoid, hyaline, striate, 1-septate, not constricted at septum, irregularly biseriate, 9–12 × 2.5–4 μm (n = 27).

Colony on PDA reaching 38 mm at diameter after 14 d under daylight at 25 °C, surface cottony, with concentric rings and white aerial mycelium. Colony on SNA reaching 33 mm at diameter after 14 d under daylight at 25 °C, surface velvet, with white aerial mycelium. Conidiophores penicillate, septate, with 2–3 whorls and with the terminal one of 3–15 phialides. Phialides subulate, tapering towards apex, slender, hyaline, smooth, compactly arranged, 40–65 μm long, 1.5–3 μm at the widest part. Conidia mostly ellipsoidal to rod-shaped, aseptate, smooth, hyaline, aggregated in a slimy mass, 2.5–6(–8) × 2–3 μm.

Notes: Morphologically, the combination of perithecia bright red, KOH+, LA+, not collapsing when dry, covered with septate, unbranched, curved hairs on the surface; striate ascospores; penicillate conidiophores and ellipsoidal conidia aggregated in a slimy mass indicates the Tibetan fungus belongs to Sarcopodium . Among the known species of the genus, S. tibetense is most similar to S. circinosetiferum in white, sessile sporodochia, simple setae and aseptate conidia ( Matsushima 1971, Watanab 1993). However, S. circinosetiferum known only by the asexual state differs in somewhat wider conidiophores (2–3.5 μm vs. 1.5–3 μm wide) ( Matsushima 1971) and the presence of 50 bp and 9 bp sequence divergences in the ITS and LSU regions ( Jeewon & Hyde 2016). We treat the above distinctions at species level.

Phylogenetically, the combined analyses of act, ITS, LSU and tub sequences resulted in a similar tree topology to that showed by Chaiwan et al. (2019). The result indicated that the Chinese collection grouped with other members of Sarcopodium , which confirmed its taxonomic placement. Sarcopodium tibetense is closely related to S. circinosetiferum and S. flocculentum . Sarcopodium flocculentum can be differentiated morphologically by thicker perithecial wall (30– 35 μm vs. 15–25 μm thick), wider asci (6.5–12 μm vs. 5–8 μm wide), larger ascospores (10–17 × 2.5–6 μm vs. 9–12 × 2.5–4 μm) and conidia (6–14 × 2.5–4.5 μm vs. 2.5–8 × 2–3 μm) with 1 septum ( Samuels et al. 1990, Rossman et al. 1999). The two Tibetan collections represent a new species based on morphological and DNA sequence data.

Since the establishment of Sarcopodium ( Ehrenberg 1818) , the following genera were treated as its synonyms including Actinostilbe Petch , Kutilakesa Subram. , Kutilakesopsis Agnihothr. & G.C.S. Barua , Periolopsis Maire and Tricholeconium Corda ( Sutton 1981) . Considering the type species of Actinostilbe ( A. vanillae Petch ), Lanatonectria Samuels & Rossman ( L. flocculenta ) and Sarcopodium ( S. circinatum ) formed a monophyletic clade and they were considered as congeneric ( Rossman et al. 1999; Lombard et al. 2015). Following the current nomenclatural code ( McNeill et al. 2012), one fungus—one name, the widely used and oldest Sarcopodium has the priority and is the correct name for the group ( Rossman et al. 2016), which is followed in this study.

Figures

FIGURE 2. Sarcopodium tibetense sexual state (holotype).a–c. Ascomata and conidiomata on natural substratum.d–g. Ascomata covered with hyaline to yellowish hairs. h. Median section through perithecium. i. Lateral perithecial wall with a hair. j–l. Asci with ascospores. m–p. Ascospore. Scale bars: a–c = 1 mm, d–g = 0.5 mm, h, i = 50 μm, j–p =10 μm.

FIGURE 3. Sarcopodium tibetense asexual state (ex-type culture). a. Colony after 2 wk at 25 °C on PDA. b. Colony after 2 wk at 25 °C on SNA. c–h, k. Conidiophores, phialides and conidia. i. Phialides and conidia. j, l, m. Conidia. Scale bars: c–m = 10 μm.