Pleosporales » Phaeosphaeriaceae » Phaeosphaeria

Phaeosphaeria cycadis

Phaeosphaeria cycadis Wanas., Phookamsak & K.D. Hyde, in Phookamsak et al., Fungal Diversity: 10.1007/s13225-019-00421-w, [58] (2019)

Index Fungorum number: IF556169         Facesoffungi number: FoF05703

 

 

Sexual morph: Undetermined. Asexual morph: Coelomycetous. Conidiomata (60–)100–160 μm high, (60–) 135–200 μm diam., pycnidial, visible as black dot on host surface, scattered to clustered, solitary to gregarious, semiimmersed to erumpent, uni-loculate, subglobose to ampulliform, or irregular in shape, ostiolate, with minute papilla. Conidiomata walls 10–20(–30) μm wide, composed of 4–5 cell layers, of brown to dark brown pseudoparenchymatous cells, of textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells (3.5–)4.5–8 × 4–8 (–10) μm ( = 6.4 × 5.7 μm, n = 30), ampulliform to broadly conical, gradually tapering toward the apex, holoblastic, phialidic, hyaline, smooth-walled, with periclinal wall thickening, arising from the inner cavity of the conidioma wall. Conidia (10–)12–14(– 16) × 3–5 μm ( = 12.9 × 3.9 μm, n = 50), pale brown to light yellowish, oblong to ellipsoidal, or subcylindrical, (0–)1–2-septate, truncate to obtuse base, with obtuse apex, not constricted at the septa, smooth-walled.

 

Culture characteristics: Colonies on PDA reaching 50–52 mm diam. after 3 weeks at room temperature (20–30 ºC). Colony dense, irregular in shape, flattened, surface slightly smooth, edge undulate, with entire margin, cottony to floccose, slightly sparse near the margin; from above, white to cream, slightly radiated outwards colony; from below, slightly radiating, cream at the margin, pale brown to yellowish-brown at the centre, sectering with golden brown; not producing pigmentation on agar medium.

 

Habitat: -

 

Known hosts: -

 

Known distribution: -

 

Material examined: CHINA, Yunnan Province, Kunming City, Kunming Institute of Botany, associated with leaf spots on Cycas sp. (Cycadaceae), 5 April 2017, R. Phookamsak, KIB022 (KUN-HKAS 102235, holotype), ex-type living culture, KUMCC 18-0161 (KIB022A), KUMCC 18-0162 (KIB022B).

 

GenBank Accession No: ITS: MK356378, LSU: MK356352, SSU: MK356366, TEF1-a: MK359069

(KUMCC 18-0161); ITS: MK356379, LSU: MK356353, SSU: MK356367, TEF1-a: MK359070 (KUMCC 18-0162).

 

Notes: In the NCBI BLASTn search of ITS sequences, Phaeosphaeria cycadis most closely matches P. acaciae Tennakoon et al. with 99% similarity. Multigene phylogenetic analyses based on a combined LSU, SSU, TEF1-a and ITS sequence dataset show that P. cycadis forms a sister lineage with P. acaciae with high support (100% ML and 1.00 BYPP). The ITS gene could not clarify the novelty of P. cycadis in this study as the species is not significantly different from P. acaciae in a comparison of ITS sequences (5/452 bp). Phookamsak et al. (2014b) mentioned that Phaeosphaeria contains species complexes that cannot be resolved based only on the ITS gene and that a combination of protein coding genes, such as TEF1-a and RPB2, is necessary to clarify species in this genus. Based on morphological characteristics, P. cycadis differs from P. acaciae in having larger conidia (P. cycadis, (10–)12–14 (– 16) × 3–5 μm versus 8–12 × 2.4–3.5 μm, P. acaciae; Hyde et al. 2017), with (0–)1–2 conidial septa and is associated with leaf spots on Cycas sp. Phaeosphaeria acaciae has 1–3 conidial septa and occurs on dead stems of Acacia sp. as a saprobe (Hyde et al. 2017). Furthermore, P. acaciae produced a pink pigment on PDA, but this is absent in P. cycadis. We therefore, introduce P. cycadis as a new species in this study based on its morphological distinctiveness.

 

Figure X. Phaeosphaeria cycadis (KUN-HKAS 102235, holotype).a Appearance of conidiomata on host. b, c Section through conidiomata. d Section through conidioma wall. e, f Conidiogenous cells. g–k Conidia. Scale bars a = 100 µm, b = 50 µm, c, d = 20 µm, e, g = 10 µm, f, h–k = 5 µm.

 

Reference:

Phookamsak R, Hyde KD, Jeewon R, Bhat DJ, et al. (2019) Fungal diversity notes 929–1035: taxonomic and phylogenetic contributions on genera and species of fungi. Fungal Diversity (2019) 95:1–273

 

 

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