Julella buxi Fabre, Annls Sci. Nat., Bot., sér. 6 9: 113 (1878)

Index Fungorum number: IF 167562; MycoBank number: MB 167562; Facesoffungi number: FoF 00039

Saprobic on woody substrates. Sexual state: Ascomata 200–350 × 190–250 µm (x̄ = 300 × 230 µm, n = 10), immersed becoming erumpent to nearly superficial, sphaeroid, black, coriaceous, ostiolate, formed under a clypeus. Ostiole usually widely porate, with a short neck, ostiolar canal filled with periphyses. Peridium two-layered, outer wall composed of small, dark brown to black, heavily pigmented, thick-walled cells of textura angularis and fusing with the host to the outside, inner wall comprising broad yellowish-brown cells of textura angularis, thick at the apex and thinner at the base. Hamathecium of dense, 2–4 µm broad, septate, pseudoparaphyses anastomosing and branching above the asci and embedded in mucilage. Asci 90–130 × 25–35 µm (x̄ = 110 × 30 µm, n = 10), two-spored, bitunicate, fissitunicate, clavate to cylindrical, with a short, broad, furcated or knob-like pedicel, rounded at apex and without a distinct ocular chamber. Ascospores 30–35 × 10–15 µm (x̄ = 32 × 30 µm, n = 13), biseriate or partially uniseriate, asymmetric or nearly symmetric, hyaline, obovoid, fusoid, or elongate, multi-septate, muriform, verruculose, thin-walled, surrounded by a mucilaginous sheath, guttulate, constricted at the septa. Asexual state: unknown.

 Material examined – FRANCE, Serignan, on Buxus sempervirensL.(Buxaceae), H. Fabre (S-F5992, holotype).

Fig. 1 Julella buxi (S-F5992, holotype). a–b Surface view of ascomata on host substrate (bark). c Longitudinal section of ascoma with clypeus. d Close-up of the peridium. e Cellular pseudoparaphyses. f–g Two spored asci lacking an ocular chamber. h–j Muriform ascospores. m Ascospore mounted in Indian ink to show mucilaginous sheath. Scale bars: c = 80 µm, d = 10 µm, e = 5 µm, f–g = 25 µm, h–j = 15 µm.

Notes – Julella has been confused, with some species being saprotrophic on bark, while others are lichenized, and the delineation of the genus is poorly defined. Currently, 46 epithets are listed in Index Fungorum (2014). Many of the species assigned to the genus are facultatively lichenized with the alga Trentepohlia as the photobiont (Purvis et al. 1992). Julella shares many common features with Peltosphaeria but differs in having bisporous asci (Barr 1985). Barr (1985) proposed Peltosphaeria as a synonym of Julella. Treatments of Julella are by Barr (1985) who lists three species and one variety and Aptroot and van den Boom (1995) who considered Julella a predominantly tropical group of bark saprotrophs, and recognized the species: J. lactea (A. Massal.) M.E. Barr, J. sericea (A. Massal.) Coppins(= J. fallcaiosa (Stizenb. ex Arnold) R.C. Harris) and J. vitrispora (Cooke & Harkn.) M.E. Barr (=J. sublactea), and regarded other species as synonyms or assigned them to other genera. After examine the generic type of Julella, Ariyawansa et al. (2013a) introduced Halojulellaceae and Halojullela to accommodate J. avicenniae, a marine species in the suborder Pleosporineae, order Pleosporales, Dothideomycetes. Justification for the new family was based on combined gene analysis of the large and small subunits of the nuclear ribosomal RNA genes (LSU, SSU) and two protein-coding genes RPB2 and TEF1, as well as morphological characters (Ariyawansa et al. 2013a). Combined gene analysis of nuSSU, nuLSU, mtSSU and TEF1 has shown that the putative strains of Julella fallaciosa (MPN141 and MPN547) form a separate clade in Trypetheliales (Nelsen et al. 2011) and are therefore excluded from our analysis. Zhang et al. (2012) suggested that with the exception of hyaline ascospores, most of the characters of Julella are compatible with Montagnulaceae. Julella is compatible with Didymosphaeriaceae in having immersed ascomata formed under a clypeus, short neck, 2-layered peridium composed of cells of textura angularis and cylindric or oblong, pedicellate, often with an ocular chamber and oblong to narrowly oblong muriform ascospores but differing in having hyaline ascospores. We add Julella to Didymosphaeriaceae but this has to be confirmed by molecular data.