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

Index Fungorum Number: IF 306062; MycoBank number: MB 306062; Facesoffungi number: FoF 07238; Fig. 1

Saprobic on palm stem. Asexual morph: Hyphomycetous. Sporodochia powder-like, dark, dense, dry, 1–3.5 mm in diameter. Conidiophores 65–120 × 1–3 μm (x̅=93.5 × 2.4 μm, n=15), macronematous, micronematous, narrow, subspherical to doliiform, flexuous or erect, unbranched, hyaline to pale brown, verruculose. Conidiogenous cells 10–20 × 2–4 μm (x̅=15.8 × 3 μm, n=15), basauxic, terminal, erect, unbranched, hyaline to pale brown, verruculose, each producing a single, holoblastic conidium at the conidiophore apex. Conidia two types, disc-like and stellate; disc-like conidia 20–28×17–19 μm (x̅=25.2×18.1 μm, n=20), usually 8-celled, solitary, hyaline when immature, pale to dark brown on maturity, crossseptate, slightly constricted at the septa, with short and blunt spines at the periphery, frequently accompanied by attached conidiogenous cells post splitting from the conidiophores; stellate conidia 18–27 × 16–29 μm (x̅= 22.6 × 24.3 μm, n = 20), globose or variously shaped, frequently 4- to 6-celled, solitary, septate, deeply constricted at the septa, pale to dark brown, comprising spines 4–5 μm long. Sexual morph: Not observed.

Culture characteristics – Conidia germinating on PDA within 16–18 h. Colonies growing on PDA, reaching a diameter of 55 mm after 14 days at 25 °C, aerial, moderately dense, undulate margine, middle grey, periphery olive green at immature stage and brownish gray at maturity; reverse greyish white to white.

Material examined – Thailand, Chiang Rai, on dead stem of palm (Arecaceae), 20 December 2019, Binu C. Samarakoon, E003 MFLU 22-0277), living culture MFLUCC 22-0180.

Hosts – Spegazzinia deightonii has been reported from several hosts, including, Andropogon glomeratus (Arnold 1986), Areca catechu (Tianyu 2009; Matsushima 1980), Arundo donax (Tanaka et al. 2011), Bambusa vulgaris (Camino-Vilaro et al. 2019), Calathea makoyana (Tianyu 2009), Cocos nucifera (Tianyu 2009), Imperata cylindrical (Thaung 2008), Musa sp. (Samarakoon et al. 2018), Panicum maximum (Lu et al. 2000; Wong and Hyde 2003), Phoenix hanceana (Tianyu 2009), Quercus xalapensis (Heredia et al. 1995), Saccharum spontaneum (Mel’nik et al. 2000), Thysanolaena latifolia (Mel’nik et al. 2000) and Tillandsia sp. (Delgado-Rodriguez et al. 2002).

Distribution – China (Tianyu 2009), Cuba (Arnold 1986; Delgado-Rodriguez et al. 2002; Camino-Vilaro et al. 2019), Hong Kong (Lu et al. 2000; Wong and Hyde 2003), Japan (Tanaka et al. 2011), Mexico (Heredia et al. 1995), Myanmar (Thaung 2008), Philippines (Whitton et al. 2012), Taiwan (Matsushima 1980), Thailand (Samarakoon et al. 2020), United States (Delgado 2008), Vietnam (Mel’nik et al. 2000).

GenBank numbers – ON885254 (SSU); ON873996(LSU); ON873998(ITS); ON885741 (tef1)

Notes – Our isolate (MFLUCC 22-0180) clusters with other strains of Spegazzinia deightonii with 95% ML, statistical support in the multi-loci phylogenetic tree (Fig. 2). Pairwise comparison of DNA sequence data shows insignificant differences among our strain (MFLUCC 22-0180) and the other strains of S. deightonii, following which our isolate is considered as S. deightonii. Furthermore, the isolate in the present study shares similar features with other strains of S. deightonii, including two types of pale to dark brown conidia which are multi-cellular, constricted at the septa and comprise either long (stellate conidia) or short (disc-like conidia) spines (Ellis 1961; Tanaka et al. 2011; Samarakoon et al. 2018). Small differences in sizes may be accounted for by host variations. Spegazzinia deightonii has been reported on a palm substrate in China, Taiwan and the United States
(Matsushima 1980; Delgado 2008; Tianyu 2009). We recovered the species from Thailand and thus report it as a new record on Palm from Thailand. Recently this species was also reported to occur in Thailand, in the same Province and area, on Musa sp. (Samarakoon et al. 2020).

Figure 1 – Spegazzinia deightonii (MFLU 22-0277, new host record) a Host. b Close-up of conidia on host. c Mass of conidia. d Conidiogenous cell of stellate conidia. e Stellate conidium on a conidiophore. f Stellated conidium. g Disk-liked conidium. h Disk-like conidium with attached conidiogenous cell. Scale bars: c–h=10 μm

Figure 2 – Phylogram generated from maximum likelihood analysis based on combined LSU, SSU, ITS and tef sequence data of selected taxa in Didymosphaeriaceae. Bootstrap support values for ML≥65% and BYPP≥0.95 are indicated above or below the branches. Ex-type strains are in bold. The new isolate is in blue. The tree is rooted with Laburnicola zaaminensis (TASM 6152) and L. murtfirmis (MFLUCC
16-0290).