Fremitomyces punctatus

Lesions hardly differentiated, composed of a narrow band of chlorotic tissue 300‒700 µm wide encircling individual stromata.

Stromata 1‒4 x 2‒6 mm diam., hologenous, irregularly shaped but usually roughly circular, the included leaf tissue at first orange-brown and slightly hypertrophied, ± flat, eventually becoming dark brown or black due to fungal growth and melanin deposition in the epidermal cells. Also present on shoots. In section : the whole of the included leaf tissue is filled with frequently branching hyaline hyphae with thick and somewhat refractive walls, many of the plant cells in the outer regions of the stroma filled with irregular crystalline ? starch deposits.

Anamorph: conidiomata 70‒90 µm diam., globose to ellipsoidal, very inconspicuous, ostiolate.  Conidiomatal wall very poorly developed, composed of perhaps 1‒2 layers of hyaline thin-walled cells, their shapes obscure, with a small amount of melanization of the epidermal cells immediately surrounding the ostiole. Conidiophores not observed. Conidiogenous cells 7‒10 x ca 1.5 µm, cylindrical or tapering, ? proliferating percurrently, collarette and periclinal thickening not observed. Conidia 6.5‒8.5 x 1‒1.5 µm, ± cylindrical but rather irregular, hyaline, thin-walled, aseptate, apparently smooth, without a gelatinous sheath or appendages.

Teleomorph: ascomata hypogenous, visible from the surface only as minute slightly sunken dark brown spots ca 80 µm diam., even these becoming inconspicuous as the melanization of the epidermal cells develops, the ostioles inconspicuous. In section : ascomata occupying the mesophyll, 300‒380 µm diam., 240‒300 µm tall, oblate-conical. Ascomatal wall hyaline, rather variable in thickness, 11‒18 µm thick in the basal region, the lateral walls slightly thinner, but increasing to ca
30 µm in the vicinity of the ostiole where it becomes strongly melanized; composed of 6-7 layers of rather thick-walled refractive strongly flattened cells to 8 µm diam. Paraphyses to 3.5 µm diam, somewhat shorter than the asci, thin-walled, slightly tapered, branching not seen. Periphyses well-developed, ca 2.5 µm diam., to 20 µm long, intergrading with the paraphyses, somewhat melanized in the apical region. Asci 106‒142 x 7‒8.5 µm, cylindrical, with a fairly long tapering stalk to 30 µm in length, fairly thin-walled at all stages, the apex rounded, with an apical ring 2‒2.5 µm diam and ca 1 µm thick, 8-spored. Ascospores 10.5‒13 x 5.5‒6 µm, cylindrical to cylindric-ellipsoidal, rarely very slightly ovoid, thin-walled, hyaline, aseptate, smooth, often with one or two large guttules, without a gelatinous sheath or appendages.

Description published in Mycological Research 103: 577-590 (1999).