Trichobotrys sinensis Phookamsak, Bhat & Hongsanan, 2024

Phookamsak, Rungtiwa, Hongsanan, Sinang, Bhat, Darbhe Jayarama, Wanasinghe, Dhanushka N., Promputtha, Itthayakorn, Suwannarach, Nakarin, Kumla, Jaturong, Xie, Ning, Dawoud, Turki M., Mortimer, Peter E., Xu, Jianchu & Lumyong, Saisamorn, 2024, Exploring ascomycete diversity in Yunnan II: Introducing three novel species in the suborder Massarineae (Dothideomycetes, Pleosporales) from fern and grasses, MycoKeys 104, pp. 9-50 : 9

Trichobotrys sinensis Phookamsak, Bhat & Hongsanan sp. nov.

Fig. 5

Etymology.

The specific epithet " sinensis " refers to the country, China, where the holotype was collected.

Holotype.

KUN-HKAS 129041.

Description.

Saprobic on dead culm of Brachiaria mutica , submerged in a small stream. Sexual morph: Undetermined. Asexual morph: Colonies dull, black, effuse, visible as hairy fluffy on the host. Mycelia up to 1 mm long, 2-4 µm wide, superficial, composed of brown to dark brown, branched, septate, thick-walled, echinulate hyphae. Conidiophores (9-)15-40(-70) × 2-4 µm (x̄ = 26.9 × 3.3 μm, n = 30), sometimes reduced to conidiogenous cells, macronematous, mononematous, straight or flexuous, brown to dark brown, septate, verruculose or echinulate, bearing short, lateral, unciform, fertile branches, with setiform apex. Conidiogenous cells 1-3.5 × 2.5-5 µm (x̄ = 2.1 × 2.5 μm, n = 30), polyblastic, subhyaline to pale brown, ellipsoidal or hemispherical (2.5-5 × 3.5-6 µm), intercalary or terminal, integrated or discrete, sometimes denticulate on branches. Conidia 7-11 × 8-12 µm (x̄ = 10 × 10 μm, n = 30) simple, solitary, brown to dark brown, spherical, aseptate, verruculose; sometimes in short acropetal chains. In vitro Conidiomata 280-470 µm high, 280-570 µm diam., black, pycnidial, solitary or clustered in a small group (2-4-loculate), scattered to gregarious, globose to subglobose, glabrous, covered by brown to dark brown mycelium, becoming a packed pycnidial wall, ostiolate, with inconspicuous, minute papilla. Pycnidial wall 20-35 µm wide, thick-walled of unequal thickness, thicker at the base, composed of multi-layered, dark brown to black pseudoparenchymatous cells, outer layers composed of textura intricata, inner layers composed of flattened cells of textura angularis to textura prismatica. Conidiophores reduced to conidiogenous cells. Conidiogenous cells (6.5-)10-16(-25) × 2-4.5 µm (x̄ = 13.4 × 3.2 μm, n = 30), holoblastic to phialidic, hyaline, cylindrical to subcylindrical, terminal or intercalary, septate, smooth-walled, with distinct collarette. Conidia 2-3 × 1.5-2.5 µm (x̄ = 2.8 × 2 μm, n = 30) hyaline, ellipsoidal to ovoid, aseptate, smooth-walled, with a guttulate.

Culture characteristics.

Colonies on PDA reaching 25-28 mm diam. after two weeks at room temperature (20-27 °C), medium dense, circular, surface smooth with an entire edge, flattened, slightly raised, fairly fluffy to feathery; from above, initially white, with cream conidial masses, becoming white to cream at the margin, pale yellowish towards the centre with age; from below, white at the margin, dark grey to black towards the centre; pigmentation not produced in PDA. Sporulation in PDA after two weeks, initially visible as cream conidial masses, later forming black conidiomata with hyaline to cream conidial masses on colonies.

Distribution.

China (Yunnan).

Specimen examined.

China. Yunnan Province: Xishuangbanna Dai Autonomous Prefecture, Mengla County, Bubeng, 21°36'30.13"N, 101°35'52.54" E, 664 + 5 m a.s.l., on culms of Brachiaria mutica submerged in a freshwater stream, 27 Apr 2021, R. Phookamsak BB21-007 (KUN-HKAS 129041, holotype), ex-type living culture, RPC 21-007 = KUNCC 23-14554.

Notes.

Based on NCBI nucleotide BLAST search of ITS sequence, the closest hit of Trichobotrys sinensis (RPC 21-007/ KUNCC 23-14554) is Gregarithecium sp. DQD-2016a strain MFLUCC 13-0853 with 99.03% similarity (Identities = 508/513 with 2 gaps) and is similar to Trichobotrys effusus [as ' effusa '] isolate 1179 (93.51% similarity, Identities = 504/539 with 13 gaps), T. effusus [as ' effusa '] strain FS522 (93.35% similarity, Identities = 477/511 with 12 gaps) and T. effusus [as ' effusa '] isolate HNNUZCJ-94 (93.08% similarity, Identities = 471/506 with 16 gaps). In LSU nucleotide BLAST search, the closest hit of T. sinensis (RPC 21-007/ KUNCC 23-14554) is Gregarithecium sp. DQD-2016a strain MFLUCC 13-0853 with 99.88% similarity (Identities = 848/849 with 1 gap) and is similar to Gregarithecium sp. isolate L13E (99.40% similarity, Identities = 830/835 with 3 gaps) and G. curvisporum HHUF 30134 (97.74% similarity, Identities = 822/841 with 5 gaps).

Multigene phylogenetic analyses of a concatenated ITS, LSU, SSU and tef1-α sequence dataset demonstrated that Trichobotrys sinensis (RPC 21-007/ KUNCC 23-14554) shared a branch length with Gregarithecium sp. DQD-2016a strain MFLUCC 13-0853 and Gregarithecium sp. isolate GMB 1217 and clustered with the clade of T. effusus (Fig. 2 ). However, Gregarithecium sp. DQD-2016a strain MFLUCC 13-0853 and Gregarithecium sp. isolate GMB 1217 are unpublished strains. Hence, Trichobotrys sinensis (RPC 21-007/ KUNCC 23-14554) is introduced herein as a new species and Gregarithecium sp. (strains MFLUCC 13-0853 and isolate GMB 1217) is re-identified as T. sinensis to avoid misidentification. Morphologically, T. sinensis (RPC 21-007/ KUNCC 23-14554) is typical of Trichobotrys , but can be distinguished from T. effusus , T. pannosus , T. ramosus and T. trechisporus in having larger conidia (2 µm diam. of T. effusus vs. 4 µm diam. of T. pannosus vs. 3-5 µm diam. of T. ramosus vs. 5 × 3 µm or 4 µm diam. of T. trechisporus ) ( Berkeley and Broome 1873; Penzig and Saccardo 1902; Petch 1917; Ellis 1971; D’Souza and Bhat 2001).

Figures

Figure 2. Phylogram of the best-scoring ML consensus tree of Trichobotrys species in Dictyosporiaceae and closely-related families viz. Didymosphaeriaceae, Lentitheciaceae, Morosphaeriaceae, Sulcatisporaceae and Trematosphaeriaceae. The new isolate is indicated in blue. Isolates from type materials are in bold. The ML ultrafast bootstrap and Bayesian PP values greater than 70 % and 0.95 are shown at the nodes.

Figure 5. Trichobotrys sinensis (KUN-HKAS 129041, holotype) A, B the appearance of colonies on the host surface C mycelium D-H conidiophores bearing conidiogenous cells and conidia I conidia in a short acropetal chain J-N conidia O culture characteristics on PDA P conidioma forming on PDA after eight weeks Q pycnidial wall R-T conidiogenous cells (note: T = stained in Congo red) U conidia. Scale bars: 100 μm (P); 50 μm (C); 10 μm (D-H, Q-U); 5 μm (J-N).