Pleosporales » Acrocalymmaceae » Acrocalymma

Acrocalymma medicaginis

Acrocalymma medicaginis Alcorn & J.A.G. Irwin, Trans. Br. mycol. Soc. 88(2): 163 (1987)



Caulicolous, corticolous on Medicago saliva (Fabaceae). Sexual morph: undetermined. Asexual morph: Conidiomata dark brown to black, solitary to gregarious or confluent, immersed to semi-immersed, stromatic, pycnidial, globose to subglobose, pyriform or irregular in shape, multilocular or unilocular, with locule 125–390 µm diam., 225–475 µm high, often convoluted and irregularly divided, glabrous, thick-walled, with rounded or cylindrical, sinuate neck, ostiolate. Ostiole 95–280 × 65–120 µm, circular, cylindrical, straight or curved, centrally or laterally located. Conidiomatal wall 23–60 µm wide, composed two cell types; a) outer layers of textura globosa to textura angularis, with dark brown to brown, thick-walled cells; b) inner and middle layers of textura angularis to textura prismatica with pale brown to hyaline, thick-walled cells. Conidiophores reduced to conidiogenous cells arising all around the cavity of conidiomata. Conidiogenous cells 4–9 × 3–6 µm, hyaline, enteroblastic, phialidic, determinate, ampulliform to subcylindrical or lageniform, with a moderate periclinal thickening in collarette zone. Conidia 13–19 × 4–6 µm (mean = 17 × 5 µm; n = 30), hyaline, cylindrical to fusiform, with a rounded or obtuse apex and a narrow truncate base, straight, aseptate or 1–2-septate, not constricted at septa, thick and smooth-walled, bearing helmet-shaped, mucoid appendage at both ends.


Material examined: Australia, Queensland, Hermitage, on PDA, 21 March 1972 – 17 April 1972, J.A.G. Irwin (IMI 165613, ex-isotype).

Acrocalymma medicaginis (IMI 165613, ex-isotype) a, b Herbarium package and specimen. c, d Appearance of dark brown to black conidiomata on dried cultures. e–g Vertical sections of conidiomata. h–j Section of peridium. k Ostiole note k is examined in lactic acid. l–o Conidiogenous cells and developing conidia. p–s Conidia with mucoid appendages (arrows). Scale bars c = 1000 µm, d = 200 µm, e–f = 200 µm, g = 100 µm, h–j = 25 µm, k = 100 µm, l–s = 5 µm.




Li WJ, McKenZie EHC, Liu JK, Bhat DJ, Dai DQ, Caporesi E, Tian Q, Maharachcikumbura SSN, Luo ZL, Shang QJ, Zhang JF, Tangthirasunun N, Karunarathna SC, Xu JC, Hyde KD (2020) Taxonomy and phylogeny of hyaline-spored coelomycetes. Fungal Diversity 100: pages279–80.



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