Amphisphaeriales » Sporocadaceae » Seiridium

Seiridium venetum

Seiridium venetum (Sacc.) Nag Raj, Mycotaxon 35(2): 293 (1989)

Basionym: Pestalotia veneta Sacc., Michelia 1(1): 92. 1877.

Monochaetia veneta (Sacc.) Sacc. & D. Sacc., Syll. fung. (Abellini) 18: 485. 1906.

Pestalotia corni Allesch., Bot. Zbl. 42: 106. 1890.

Seiridium corni (Allesch.) B. Sutton, Can. J. Bot. 47(12): 2091. 1969.

Index Fungorum number: IF 126347; Facesofungi number: FoF 585

Associated with dead twigs of Cornus mas. Sexual morph: Undetermined. Asexual morph: Conidiomata 200–400 μm diam., pycnidial, globose to clavate, solitary or aggregated, semi-immersed, dark brown, exuding globose, dark brown, glistening conidial masses. Conidiophores 60–100 μm long, lining the cavity of conidioma, septate, irregularly branched, colorless, smooth-walled, invested in mucus. Conidiogenous cells 10–20 × 1–2.5 (x̄ = 13 × 1.5) μm, discrete, cylindrical, with minute apical periclinal thickenings, colorless, smooth, proliferating 2–5 times percurrently. Conidia 20–30 × 6.5–8.5 (x̄ = 24.5 × 7.6) μm, fusiform to ellipsoid, straight or somewhat curved, basal cell obconic with a truncate base, hyaline, smooth-walled 3–4 (x̄ = 3.4) μm long; 4 median cells doliiform, unequal, brown, thick-walled, together 13–22 (x̄ = 18) μm long; second cell from base 4–5.5 (x̄ = 5) μm long; third cell 3–5 (x̄ = 4) μm long; fourth cell 2.5–5 (x̄ = 3.5) μm long; fifth cell 3–5 (x̄ = 5.5) μm long; apical cell, conical, hyaline, smoothwalled, 2–4 (x̄ = 3) μm long; apical appendages tubular, attenuated, flexuous single, unbranched or once or twice branched, 10–35 (x̄ = 20) μm long; basal appendage single, unbranched or twice branched, centric, 2–5 μm long

Culture characteristics: Colonies on PDA reaching 30– 40 mm diam. after 7 days at 25 °C, entire at the edge, whitish, with dense aerial mycelium on the surface, and black, gregarious conidiomata; reverse similar in color.

Material examined: Italy, Selva, on Cornus sanguinea, 1873 (PAD, holotype); Italy, Trento Province. Val di Sole, Croviana, from dead twigs of Cornus mas, 29 July 2013, E. Camporesi IT 1393 (MFLU 15–0396, reference material of Seiridium venetum designated here); culture MFLUCC 14– 0265, ICMP

Notes: This species was originally described from dry twigs of Cornus sanguinea in Conegliano, Italy. Nag Raj (1993) noted S. venetum as being distributed on Cornus alba, C. sanguinea, C. stolonifera and Cornus sp. in Canada, Germany and Italy. In Seiridium venetum, the apical appendage is single and may branch at some distance from the point of insertion on the apical cell. Sutton (1969) revised and preferred to regard Pestalotia as a monotypic genus, and many species have been transferred to other genera. In his revision of Pestalotia, Sutton (1969) transferred P. corni to Seiridium. Nag Raj (1993) introduced a new combination of Seiridium venetum, which was originally described by Saccardo in 1877 as Pestalotia veneta. Furthermore, Seiridium corni was synonymized under S. venetum. The first alternative for supplementing poor type material is by means of epitypification (Hyde and Zhang 2008). The holotype of Seiridium venetum (at herbarium PAD) has the same host, morphology and country of origin as our fresh collection. However, “selection of an epitype is not always justifiable under the current provisions of the ICN, and cannot be undertaken simply because no sequence data is obtainable from the name-bearing type” (Ariyawansa et al. 2014). Therefore, in this paper we designate our fresh collection as a reference specimen. In the ITS analysis, S. venetum received low support, with branches resulting in a polytomy with S. ceratosporum (strain J21 and 143331) and Seiridium sp. (strain 51). However, S. venetum is distinct from S. ceratosporum (conidia 29–35×10–12 μm; Nag Raj 1993) by its smaller conidia and presence of longer branched or unbranched apical conidial appendage. Based on a Mega BLAST search of NCBI GenBank nucleotide database, the closest hits using the TUB gene sequence are S. cupressi [GenBank DQ926979; identities = 318/346 (92 %), gaps = 1/346 (0 %)] and Seiridium cardinale [(DQ926973; identities = 329/362 (91 %), gaps = 4/362 (1 %)].

 

 

Figure x.  Seiridium venetum (MFLUCC 14–0265). a Conidiomata on Cornus mas b Conidiomata sporulating on PDA. c–e Conidiogenous cells. f– h Conidia. Scale bars: c–h= 10 μm.

 

References:

 

Ariyawansa HA, Hawksworth DL, Hyde KD et al. 2014 – Epitypification and neotypification: guidelines with appropriate and inappropriate examples. Fungal Divers 69, 57–91.

Hyde KD, Zhang Y 2008 Epitypification: should we epitypify? J Zhejiang Univ Sci B 9, 842–846.

Nag Raj TR 1993 – Coelomycetous anamorphs with appendage bearing conidia. Mycologue publications, Waterloo

Shang QJ, Hyde KD, Camporesi E, Maharachchikumbura SSN et al. 2020 – Additions to the genus Cytospora with sexual morph in Cytosporaceae, Mycosphere 11, 189–224.

Sutton BC 1969 – Forest microfungi. III. The heterogeneity of Pestalotia de Not. section Sexloculatae Klebahn sensu Guba. Can J Bot 48, 2083–2094.

 

Last Update: 08 September 2021

 

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