Johnalcornia
Johnalcornia Y.P. Tan & R.G. Shivas, in Tan et al., Australas. Pl. Path. 43(6): 592 (2014).
Index Fungorum number: IF 807731; Facesoffungi number: FoF 00524, 1 morphological species (Species Fungorum 2022), 1 species with molecular data.
Saprobic on host. Sexual morph: Ascomata globose with a short neck. Asci cylindrical to fusoid, straight or curved. Ascospores hyaline, filiform, tightly coiled. Asexual morph: Conidiophores solitary or in fascicles, simple or branched, straight to flexuous, apically geniculate, cylindrical, smooth. Conidiogenous cells integrated, cylindrical, proliferating sympodially, smooth to verruculose, with thickened and conspicuous scars. Conidia solitary, straight to curved, smooth, hilum inconspicuous, distoseptate, germinating from both polar cells, first conidial septum median or submedian, second conidial septum delimiting the apical cell, third septum basal (adapted from Tan et al. 2014).
Type species: Johnalcornia aberrans (Alcorn) Y.P. Tan & R.G. Shivas
Notes: Johnalcornia is characterised by solitary or fasciculate, simple or branched conidiophores, cylindrical conidiogenous cells proliferating sympodially and solitary, straight to curved conidia. The sexual morph is characterised by globose ascomata, cylindrical to fusoid asci and hyaline, filiform ascospores tightly coiled. Johnalcornia aberrans was previously known as Bipolaris aberrans but was not congeneric with the type species of Bipolaris (Alcorn 1990). Alcorn (1990) described the sexual morph of the genus as Cochliobolus aberrans and described B. aberrans as producing holoblastic conidia that did not split from the conidiophores. Tan et al. (2014) re-examined the holotype specimen of B. aberrans (BRIP 16281) and preferred to use the term chlamydospores to describe these structures. Johnalcornia morphologically resembles Bipolaris, Curvularia and Porocercospora in producing tretic (poroblastic) conidiogenous cells and distoseptate conidia. Johnalcornia differs from Bipolaris and Curvularia in that the second conidial septum forms distally delimiting the apical cell while in Bipolaris and Curvularia the second conidial septum forms proximally to delimit the basal cell (Alcorn 1990). Johnalcornia differs from Exserohilum in having fusoid ascospores while paired cultures of single-spored isolates of ex-holotype culture of B. aberrans produced a sexual morph with filiform ascospores (Alcorn 1990). Johnalcornia also differs from Bipolaris or Curvularia in having hyaline, obovoid to dumbbell-shaped or irregularly moniliform protrusions (Alcorn 1990). Johnalcornia is morphologically and phylogenetically a distinct genus in Pleosporaceae. Molecular markers available for Johnalcornia are ITS, LSU, GAPDH, RPB2 and TEF-1.
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