Comoclathris lanata Clem.

[as ‘Comochlatris’], Gen. fung. (Minneapolis): 1-227 (1909).

Saprobic on dead stem. Sexual morph: Ascomata175–245 × 142–197 µm ( =205 × 159 µm, n = 20), scattered or aggregated on the host stem, subglobose or nearly globose, superficial, coriaceous, covered with a pale membrane, brown to blackish brown, with a central ostiole. Peridium 10–22 µm wide, comprising 3–4 layers of brown, relatively thick-walled cells of textura angularis, inner cells flattened, thin-walled and lighter. Hamathecium composed of dense 2–4 µm wide, septate, hyaline, filiform, pseudoparaphyses longer than the asci. Asci 108–149 × 20–30 µm ( =24 × 125 µm, n= 20), 8-spored, bitunicate, fissitunicate, thick-walled, cylindrical to cylindro-clavate, with a short knob-like pedicel, and indistinct shallow ocular chamber. Ascospores 20–32 × 8–13 µm ( = 12 × 28 µm, n = 20 ), 1–2 overlapping seriate, fusiform, with 4–5-transverse septa and 1–2-longitudinal septa, not constricted at the septa, applanate, muriform, brown to reddish-brown, surrounded by a distinct, hyaline, mucilaginous 3–8 µm wide sheath. Asexual morph: not observed.

Material examined: USA, Colorado, on stem of Leptotaenia multifida Nutt (Umbelliferae), 8 July 1907, F.E. & E.S. Clements (COLO 62872, holotype).

Notes: Comoclathris, typified by Comoclathris lanata, was introduced by Clements (1909). The genus is characterized by ascomata with circular lid-like openings and applanate reddish-brown to dark reddish-brown, muriform ascospores, with single longitudinal septa (Ariyawansa et al. 2014a). Zhang et al. (2012) tentatively placed Comoclathris in the Pleosporaceae based on Alternaria-like asexual morphs and this was followed by Woudenberg et al. (2013). Comoclathris shares common characters with Pleospora herbarum, the type of Pleospora, in having cylindrical to cylindro-clavate asci with an ocular chamber and muriform, brown or pale brown, with or without sheath ascospores. Comoclathris and Pleospora differ in the opening of ascomata (opening via a large circular aperture or lid versus opening by a central pore and applanate ascospores). Comoclathris and Pleoseptum share similar characters in having globose, black, ascomata and cylindrical to cylindro-clavate asci with muriform, yellowish to dark brown ascospores. Comoclathris differs from Pleoseptum in having superficial ascomata with circular lid-like openings composed of comparatively thin peridium and applanate and fusiform ascospores surrounded by a distinct hyaline, mucilaginous thick sheath (Ariyawansa et al. 2014a). In Pleoseptum ascomata are immersed, usually with a papillate apex, with a relatively broad peridium and ovoid to fusoid ascospores (Ariyawansa et al. 2014a). Comoclathris was considered to differ from Clathrospora as in the latter genus species has two or more rows of longitudinal septa as compared with a single row in Comoclathris (Ariyawansa et al. 2014a). Shoemaker and Babcock (1992) provided a key to 21 species of Comoclathris. Presently 32 epithets are listed for Comoclathris in Index Fungorum (2014).

Molecular data for Comoclathris lanata, the type species of Comoclathris, is not available. Two putative strains of Comoclathris compressa (CBS 157.53 and CBS 156.53) however, cluster together in a well-supported clade within the family Pleosporaceae (Ariyawansa et al. 2014a). Based on the phylogenetic result, coupled with the morphological characters (Alternaria-like asexual morph), we agreed with Ariyawansa et al. (2014a), Zhang et al. (2012) and Woudenberg et al. (2013) to the placement of Comoclathris in Pleosporaceae. But re-collection of the type species and epitypification or a reference specimen (Ariyawansa et al. 2014a) with molecular data is essential to establish the correct placement of the genus.

During this study we have proposed several new combinations in order to resolve the paraphyletic nature of Pleospora and to make a stable taxonomy for the family Pleosporaceae. Pleospora incompta (Sacc. & Martelli) Gruyter & Verkley) (CBS 467.76) was introduced by de Gruyter et al. (2013) in order to accommodate Phoma incompta Sacc. & Martelli. In the same study Pleospora typhicola was proposed by de Gruyter et al. (2013) to accommodate Phoma typhina (Sacc. & Malbr.) van der Aa & Vanev in the family Pleosporaceae but during our study Pleospora typhicola (Cooke) Sacc. 1875) (CBS 132.69) and Pleospora incompta (CBS 467.76) form separate clades within the genus Comoclathris. Therefore we provide two new combinations namely Comoclathris incompta and C. typhicola to accommodate Pleospora incompta and P. typhicola in Comoclathris, family Pleosporaceae.

Fig 1. Comoclathris lanata (holotype). a. Herbarium material showing habit of fungus on host stem. b. Erumpent ascomata. c. Section through ascoma. Note the arrangement of asci and external setae. d. Section showing peridial cells of ascoma. e. Hyaline, filform, pseudoparaphyses. f. Asci with short knob-like pedicels and shallow ocular chamber. g-i. Muriform, applanate ascospores with a thick sheath. Scale Bars: b =200µm, c = 40 µm, d-e = 10 µm, f =20 µm, g-i = 10 µm.