Spegazzinia deightonii (S. Hughes) Subram., J. Indian bot. Soc. 35: 78 (1956)

Samarakoon, Binu C., Phookamsak, Rungtiwa, Wanasinghe, Dhanushka N., Chomnunti, Putarak, Hyde, Kevin D., McKenzie, Eric H. C., Promputtha, Itthayakorn, Xu, Jian-Chu & Li, Yun-Ju, 2020, Taxonomy and phylogenetic appraisal of Spegazzinia musae sp. nov. and S. deightonii (Didymosphaeriaceae, Pleosporales) on Musaceae from Thailand, MycoKeys 70, pp. 19-37 : 19

Spegazzinia deightonii (S. Hughes) Subram., J. Indian bot. Soc. 35: 78 (1956) Figure 2

Description.

Saprobic on dead leaves of Musa sp. Sexual morph Undetermined. Asexual morph Hyphomycetous. Sporodochia powder like, dark, dense, dry, 1-3 mm diameter. Conidiophore mother cells 3.5-6.8 × 2.5-5.0 μm (x̄ = 5.59 × 4.15 μm, n = 6), hyaline to light brown, subspherical or doliiform. Conidiophores long or short and give rise to two types of conidia referred here as α and β. Conidiophores of α conidia up to 48-120 × 1-2 μm (x̄ = 95.3 × 1.6 μm, n = 20) long, erect or flexuous, narrow, verruculose, unbranched, hyaline to golden-brown. Conidiophores of β conidia initially hyaline, light brown to brown at maturity, very short and slightly bent, 1.6-2 × 2.5-3 μm (x̄ = 1.8 × 2.6 μm, n =10). Conidiogenous cell development basauxic, forming a single, terminal holoblastic conidium at the apex of conidiophore. Conidial development holoblastic. Conidia two types: α conidia stellate, 18-28 × 17-29 μm (x̄ = 25.1 × 23.3 μm, n = 25), solitary, globose to variously shaped, with spines 4-6 μm long, 4-8-celled, frequently 4- to 6-celled, deeply constricted at the septa. β conidia disc-shaped, initially hyaline, light brown to dark brown at maturity, 8-celled, 16-21 × 11-14 μm (x̄ = 19.2 × 14.6 μm, n = 25), flat from both sides with short and blunt spines, frequently with attached conidiogenous cells when splitting from the conidiophores.

Culture characteristics.

Conidia germinating on PDA within 13-14 h. Colonies growing on PDA, reaching a diameter of 55 mm after 14 d at 25 °C, raised, moderately dense, undulate margin, middle grey, periphery brownish grey and olive green at immature stage; reverse white to greyish white.

Material examined.

Thailand, Chiang Rai Province, Doi Thun, on a dead leaf of Musa sp. ( Musaceae ), 7 December 2018, M.C. Samarakoon, BNS 072 (MFLU 19-2908), living culture MFLUCC 20-0002.

Notes.

Spegazzinia deightonii MFLUCC 20-0002 clustered with S. deightonii (yone 66, yone 212) with significant statistical support (Figure 1 ). All the strains of S. deightonii described in Ellis (1971) and Tanaka et al. (2015) have similar morphological features with our strain such as dark brown, 8-celled, disked-shaped, spiny conidia. With morphological and multigene phylogenetic support, we report a new host record of S. deightonii from Musa sp.

Figures

Figure 1. Maximum likelihood tree revealed by RAxML from an analysis of SSU, LSU and ITS and TEF 1 - α sequence data of selected genera of family Didymosphaeriaceae, showing the phylogenetic position of Spegazzinia musae (MFLUCC 20 - 0001) and S. deightonii (MFLUCC 20 - 0002). ML bootstrap supports (≥ 60 %) and Bayesian posterior probabilities (≥ 0.95 BYPP) are given above in the branches, respectively. The tree was rooted with Pleospora herbarum and Stemphylium botryosum (Pleosporaceae). Strains generated in this study are indicated in red-bold. Ex-type species are indicated in bold. The scale bar represents the expected number of nucleotide substitutions per site. A best scoring RAxML tree is shown with a final ML optimization likelihood value of - 13516.66. The matrix had 795 distinct alignment patterns, with 33.60 % of undetermined characters or gaps. Estimated base frequencies were: A = 0.239862, C = 0.245185, G = 0.277025, T = 0.237927; substitution rates AC = 1.626982, AG = 2.468452, AT = 1.211822, CG = 1.092437, CT = 6.295657, GT = 1.000000; proportion of invariable sites I = 0.484119; gamma distribution shape parameter α = 0.445929.

Figure 2. Spegazzinia deightonii (MFLU 19 - 2908) a-c fungal colonies on host surface d conidiophore mother cell of α conidia e-g α conidia i a developmental stage of β conidia h, k conidia l colonies on PDA after 28 days showing sporulation j, m-p β conidia. Scale bars: 500 μm (a), 200 μm (b), 50 μm (c), 20 μm (e-h), 10 μm (d, k, m-p), 5 μm (i, j).