Pleosporales » Acrocalymmaceae


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


Saprobic on submerged wood, leaf litter or other plants. Sexual morph: (from culture) Ascomata scattered, erumpent becoming superficial, uniloculate, globose, covered with light gray, gnarled, warted hairs, black, coriaceous, with ostiolate papilla. Neck central, terete, composed of 2–5 lay- ers of brown, polygonal cells around ostiole with hyaline periphyses. Peridium thin, composed of polygonal, brown, pseudoparenchyma cells. Pseudoparaphyses numerous, septate, anastomosing. Asci bitunicate, 8-spored, cylindrical, short pedicellate, apically rounded, with an distinct ocular chamber. Ascospores uni- to bi-seriate, narrowly fusiform, straight or slightly curved, hyaline first, pale reddish brown with lighter coloured end cells, 1–3-septate, constricted at first submedian septum, basically symmetrical, smooth to rough-walled, thin-walled, with 4 guttules, with a thin sheath (Shoemaker et al. 1991). Asexual morph: Coelomycetous. Pycnidia scattered or aggregated, semi-immersed to superficial, unilocular, globose, brown to black, with ostiolate papilla or rostrate. Conidiophores reduced. Conidiogenous cells holoblastic, determinate, discrete, cylindrical, lageniform to ampulliform, hyaline, smooth. Conidia cylindrical to fusoid with subobtuse apex, straight, hyaline at first, becoming pigmented with age, 0–3-septate, not constricted at septa, smooth, thin-walled, with or without helmet-shaped appendages (Zhang et al. 2012a). (Description from Dong et al. 2020)


Type species: Acrocalymma medicaginis Alcorn & J.A.G. Irwin


Notes: Acrocalymma is well-studied because all species have sequences in GenBank. Acrocalymma species are easy to produce pycnidia in culture (Trakunyingcharoen et al. 2014). The sexual morph was linked to Massarina walkeri Shoemaker et al. which formed in the pure culture of Acrocalymma medicaginis (Shoemaker et al. 1991). However, these two species are phylogenetically distinct (Trakunyingcharoen et al. 2014). Therefore, Trakunyingcharoen et al. (2014) transferred M. walkeri to Acrocalymma and treated A. medicaginis and A. walkeri as distinct species. The type material of A. medicaginis was re-examined and described by Li et al. (2020). Acrocalymma aquatica is the first species reported from freshwater habitats, and it is characterized by cylindrical to fusoid, 0(–1)-septate conidia with an apical, mucilaginous, helmet-shaped appendage (Zhang et al. 2012). In this study, we report a new freshwater species A. bipolare, which is collected from Egypt. (Notes from Dong et al. 2020)


List of freshwater Acrocalymma species

*Acrocalymma aquatica H. Zhang & K.D. Hyde, Cryptog. Mycol. 33(3): 337 (2012)

*Acrocalymma bipolare Abdel-Aziz & Abdel-Wahab


Key to freshwater Acrocalymma species

1. Conidia 12–17 × 3–4 μm, with a single, helmet-shaped appendage….......... A. aquatica

1. Conidia 9–12 × 3–5 μm, with bipolar appendages filled with oil droplets, appendages elongate in water to form filaments...... A. bipolare



Li WJ, McKenzie EHC, Liu JK, Bhat DJ, Dai DQ, Camporesi E, Tian Q, Maharachchikumbura SSN, Luo ZL, Shang QJ, Zhang FJ, Tangthirasunun N, Karunarathna SC, Xu JC, Hyde KD (2020) Taxonomy and phylogeny of hyaline-spored coelomycetes. Fungal Divers 100:279–801

Dong W, Wang B, Hyde KD, et al (2020) Freshwater Dothideomycetes. Fungal Divers 105:319–575

Shoemaker RA, Babcock CE, Irwin JAG (1991) Massarina walkeri n. sp., the teleomorph of Acrocalymma medicaginis from Medicago sativa contrasted with Leptosphaeria pratensis, L. weimeri n. sp., and L. viridella. Can J Bot 69:569–573

Trakunyingcharoen T, Lombard L, Groenewald JZ, Cheewangkoon R, To-anun C, Alfenas AC, Crous PW (2014) Mycoparasitic species of Sphaerellopsis, and allied lichenicolous and other genera. IMA Fungus 5:391–414

Zhang H, Hyde KD, Mckenzie EHC, Bahkali AH, Zhou DQ (2012a) Sequence data reveals phylogenetic affinities of Acrocalymma aquatica sp. nov., Aquasubmersa mircensis gen. et sp. nov. and Clohesyomyces aquaticus (freshwater coelomycetes). Cryptogam Mycol 33:333–346


About Freshwater Fungi

The webpage Freshwater Fungi provides an up-to-date classification and account of all genera of freshwater fungi.


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