Pseudodidymosphaeria Thambugala & K.D. Hyde, 2015

Thambugala, Kasun M., Chunfang, Yu, Camporesi, Erio, Bahkali, Ali H., Liu, Zuo-Yi & Hyde, Kevin D., 2015, Pseudodidymosphaeria gen. nov. in Massarinaceae, Phytotaxa 231 (3), pp. 271-282 : 273-278

Pseudodidymosphaeria Thambugala & K.D. Hyde , gen. nov.

Etymology: Referring to its similarity with Didymosphaeria

Index Fungorum number: IF550959; Facesoffungi number: FoF00465

Saprobic on Spartium junceum L. and possibly grasses in terrestrial habitats. Sexual morph: Ascomata scattered, or in small groups, immersed, globose to subglobose, ostiolate. Peridium thin-walled, 1-layered, composed of hyaline to brown compressed cells of textura angularis and textura prismatica, cells towards the inside lighter and somewhat flattened, at the outside, darker, fusing and indistinguishable from the host tissues. Hamathecium of dense, long, branched, septate, cellular pseudoparaphyses, anastomosing mostly above the asci, embedded in mucilage. Asci 8- spored, bitunicate, fissitunicate, cylindro-clavate, pedicellate, rounded at the apex and with an ocular chamber. Ascospores uniseriate to obliquely uniseriate, ellipsoid with broadly obtuse ends, brown to reddish brown, 1-septate, constricted at the septum, verrucose, surrounded by mucilaginous sheath. Asexual morph: Conidiomata solitary or in groups, scattered, globose to subglobose, dark brown to black, semi-immersed on PDA, pulvinate, unilocular. Conidiomatal wall comprising several cell layers; outer layers composed of brown to lightly pigmented cells of textura angularis to globosa, becoming thin-walled and hyaline towards the inner region. Conidiophores reduced to conidiogenous cells. Conidiogenous cells formed from the cells lining the inner walls of the conidiomata, phialidic, fusiform to cylindrical, determinate, hyaline. Conidia solitary, ovoid, straight, oval to ellipsoidal, producing conidia at their tips, smooth, hyaline, aseptate.

Type species:— Pseudodidymosphaeria spartii (Fabre) Thambugala, E. Camporesi & K.D. Hyde , comb. nov.

Basionym: Didymosphaeria spartii Fabre, Annls Sci. Nat., Bot. , sér. 6 9: 83 (1879) [1878]

≡ Didymosphaerella spartii (Fabre) Chleb., Mycotaxon 110: 444 (2009)

≡ Microthelia spartii (Fabre) Kuntze, Revis. gen. pl. (Leipzig) 3(2): 498 (1898)

≡ Montagnula spartii (Fabre) Aptroot , Nova Hedwigia 60(3–4): 342 (1995)

≡ Sphaeria spartii Castagne, Cat. Pl. Mars. : 169 (1845)

Index Fungorum number: IF550960; Facesoffungi number: FoF 00466

Description from isotype

Saprobic on Spartium junceum L. Sexual morph: Ascomata 215–360 × 180–310 μm (x = 308 × 262 μm, n = 10), scattered, or in small groups, immersed, globose to subglobose, ostiolate. Peridium 10–20 (x = 14.1 μm, n = 10) μm

wide, 1-layered, composed of hyaline to brown compressed cells of textura angularis and prismatica, cells towards the inside lighter and somewhat flattened, at the outside, darker, fusing and indistinguishable from the host tissues.

Hamathecium of dense, 1–2.4 μm wide, long, branched, septate, cellular pseudoparaphyses, anastomosing mostly above the asci, embedded in mucilage. Asci 105–150 × 15–20 μm (x = 142.8 × 17 μm, n = 15), 8-spored, bitunicate, fissitunicate, cylindro-clavate, pedicellate, apex rounded with an ocular chamber. Ascospores 18–24 × 9–11 μm (x = 22

× 10 μm, n = 25), uniseriate to obliquely uniseriate, slightly overlapping, ellipsoid, with broadly obtuse ends,yellowish when immature, becoming brown to reddish-brown when mature, 1-septate, upper cell slightly broader than the lower one, constricted at the septum, verrucose, surrounded by mucilaginous sheath. Asexual morph: Not observed.

Material examined:— FRANCE, Bouches-du-Rhône, Montaud-les-miramas, on Spartium junceum L., Castagne,

J. L. Martin, G 345707/1, Isotype of Sphaeria spartii ).

Description from reference specimen (MFLU 14–0578)

Saprobic on Spartium junceum . Sexual morph: Ascomata 200–420 × 195–330 μm (x = 300 × 252 μm, n = 10), scattered, or in small groups, immersed, globose to subglobose, ostiolate. Peridium 9–20 (x = 14.2 μm, n = 10) μm wide, 1-layered, composed of hyaline to brown compressed cells of textura angularis and textura prismatica, cells towards the inside lighter and somewhat flattened, at the outside, darker, fusing and indistinguishable from the host tissues. Hamathecium of dense, 1–2.5 μm wide, long, branched, septate, cellular pseudoparaphyses, anastomosing mostly above the asci, embedded in mucilage. Asci 100–175 × 14–20 μm (x = 142.8 × 17 μm, n = 15), 8-spored, bitunicate, fissitunicate, cylindro-clavate, pedicellate, apex rounded with an ocular chamber. Ascospores 18.4–22 × 9–11.5 μm (x = 20.4 × 10.2 μm, n = 30), uniseriate to obliquely uniseriate, slightly overlapping, ellipsoid, with broadly obtuse ends, yellowish when immature, becoming brown to reddish-brown when mature, 1-septate, upper cell slightly broader than the lower one, constricted at the septum, verrucose, surrounded by mucilaginous sheath. Asexual morph: Conidiomata up to 300 μm diam, solitary or in groups, scattered, globose to subglobose, dark brown to black, semi-immersed on PDA, pulvinate, unilocular. Conidiomatal wall 45 μm thick, comprising several cell layers; outer layers composed of brown to lightly pigmented cells of textura angularis to globosa, becoming thin-walled and hyaline towards the inner region. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 9.1–18.2 × 1–2.2 μm (x = 14.5 × 1.6 μm, n = 25), formed from the cells lining the inner walls of the conidiomata, phialidic, fusiform to cylindrical, determinate, hyaline. Conidia 4.5–6.2 × 1.6–2.2 μm (x = 5.2 × 1.9 μm, n = 50), solitary, ovoid, straight, oval to ellipsoidal, producing conidia at their tips, smooth-walled, hyaline, aseptate.

Culture characteristics:—Ascospores germinating on PDA within 12–18 h. Germ tubes produced from both ends of the ascospore. Colonies growing on PDA 18 mm diam after 10 days at 16 °C, slow growing; flattened, fairly dense, white, smooth, surface with crenate edge, after a 2–3 weeks conidiomata produced on PDA at 16°C.

Material examined:— ITALY. Province of Forlì-Cesena [FC], Lago di Corniolo, on Spartium junceum L. ( Fabaceae ), 13 October 2012, Erio Camporesi, IT 802 ( MFLU 14–0578, PDD 105282, reference specimen), living culture, MFLUCC 13–0273, CBS); ITALY. Province of Forlì-Cesena [FC], Cusercoli—Civitella di Romagna, on Spartium junceum , 11 September 2014, Erio Camporesi, IT 802–2 ( MFLU 14–0928), living culture, MFLUCC 14– 1212.

Notes:—We re-examined the isotype of Didymosphaeria spartii and compared it with other collections by various authors including our specimen ( Table 2). There are not significant differences among these specimens. In the phylogenetic analysis two new strains ( MFLUCC 13–0273 and MFLUCC 14–1212) and a putatively named strain of Montagnula spartii ( CBS 183.58) form a well-supported clade in Massarinaceae . We believe that the new specimen is identical to Didymosphaeria spartii and therefore, propose a new genus Pseudodidymosphaeria for Didymosphaeria spartii . A species of Dendrophoma ( Scheinpflug, 1958) and a species of Diplodia ( Moreau 1956) have been reported as the asexual morphs of M. spartii , but neither of these reports have yet been verified ( Aptroot, 1995a).

Pseudodidymosphaeria shares common morphological characters with Didymosphaeria but it is distinct from other Didymosphaeria species mainly in having a peridium with brown to hyaline cells of textura angularis and textura prismatica, cellular pseudoparaphyses and a mucilaginous sheath around the ascospores ( Hyde et al. 2013; Ariyawansa et al. 2014a). Pseudodidymosphaeria is distinct from Massarina , the generic type of Massarinaceae in having 1-layered peridium composed of hyaline to brown compressed cells of textura angularis and prismatica and brown, 1-septate, verrucose ascospores ( Zhang et al. 2012; Hyde et al. 2013).