Pleosporales » Leptosphaeriaceae

Leptosphaeria

Leptosphaeria Ces. & De Not., Comm. Soc. crittog. Ital. 1(fasc. 4): 234 (1863).

Index Fungorum number: IF 2800; Facesoffungi number: FoF 02297, 605 morphological species (Species Fungorum 2022), 15 species with molecular data.

Saprobic or pathogenic on stems and leaves of herbaceous or woody plants in terrestrial habitats. Sexual morph: Ascomata solitary, scattered or in small groups, erumpent to superficial, globose to subglobose, broadly conical, small- to medium-sized, smooth, easily removed from the host substrate, with a flattened base, black, coriaceous, ostiolate. Ostiole apex with a well-developed, conical, shiny, papilla, ostiolar canal filled with periphyses, dark brown to black. Peridium composed of two strata, outer stratum composed of small, thick-walled, scleroplectenchymatous cells of textura angularis, surface heavily pigmented, thinner at the apex, wide at the sides, inner layer composed of subhyaline or light brown, scleroplectenchymatous cells of textura angularis, cells near the base comparatively larger. Hamathecium comprising dense, long, septate, cellular pseudoparaphyses, branching and anastomosing above the asci, embedded in a gelatinous matrix. Asci 8-spored, bitunicate, fissitunicate, cylindrical, pedicel furcate, rounded at the apex, with an ocular chamber. Ascospores uni- or bi-seriate, partially overlapping, reddish to yellowish brown, narrowly fusoid with sharp to narrowly rounded ends, 3-septate, constricted at each septum, cell above central septum widest, smooth-walled, lacking a mucilaginous sheath. Asexual morph: Coelomycetous. Conidiomata depressed globose with a flattened base and cylindrical neck, wall scleroplectenchymatous. Conidia ellipsoidal to subcylindrical (adapted from Ariyawansa et al. 2015).

 Type species: Leptosphaeria doliolum (Pers.) Ces. & De Not.

Notes: Leptosphaeria was introduced by Cesati and de Notaris (1863) with L. doliolum as the lectotype (Shearer et al. 1990). Leptosphaeria is characterised by solitary, scattered, erumpent to superficial ascomata, with a conical, shiny, papilla ostiole, and reddish to yellowish brown, narrowly fusoid 3-septate ascospores. Persoon (1800) observed several specimens of Sphaeria doliolum from National Herbarium Netherlands, Leiden University (L) and provided a lectotype for S. doliolum hence, L. doliolum. Höhnel (1909) separated Leptosphaeria based on centrum morphology with Leptosphaeria, Scleropleella and Nodulosphaeria. Müller (1950) subdivided Leptosphaeria into four sections (Eu-Leptosphaeria, ParaLeptosphaeria, Scleropleella and Nodulosphaeria) based on ascospores, pseudothecium and centrum features. Barr (1987) and Eriksson and Hawksworth (1991) included Leptosphaeria in Leptosphaeriaceae while Eriksson and Hawksworth (1986) transferred Leptosphaeria to Phaeosphaeriaceae. Leptosphaeria resembles several genera such as Amarenomyces, Bricookea, Diapleella, Entodesmium, Melanomma, Nodulosphaeria, Paraphaeosphaeria, Passeriniella, Phaeosphaeria and Trematosphaeria but differs in forming ascomata on dicotyledonous substrate, in having cylindrical asci with short bulbous pedicels and smooth-walled, fusoid, multiseptateascospores. In the phylogenetic analyses of Schoch et al. (2009), Zhang et al. (2012) and Hyde et al. (2013), Leptosphaeria formed a paraphyletic clade in Leptosphaeriaceae based on multi-gene analysis with moderate statistical support. Ariyawansa et al. (2015) did a phylogenetic analysis for the Leptosphaeria doliolum species complex and showed the placement of their fresh collections of L. doliolum in Leptosphaeria. Ariyawansa et al. (2015) also reported several species such as L. veronicae, L. sydowii, L. errabunda, L. macrocapsa, L. italiensis, L. slovacica, L. pedicularis, L. conoidea, L. sclerotioides, and L. cichorium are closely related to L. doliolum species complex, and placed them in Leptosphaeria s. str. Several authors added new species to Leptosphaeria based on morphology and molecular data (Dayarathne et al. 2015, Liu et al. 2015, Hyde et al. 2016, Phookamsak et al. 2019, Pem et al. 2020, Lestari et al. 2021). Leptosphaeria is morphologically and phylogenetically a distinct genus in Leptosphaeriaceae. Molecular markers available for Leptosphaeria include LSU, SSU, ITS, Actin, Histone, TEF1 and RPB2.

 

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