Fungalpedia – Note 2652, Sclerococcum
Sclerococcum Fr.
Citation when using this data: Meng QF et al. – Fungalpedia.
Index Fungorum, Facesoffungi, MycoBank, GenBank. Fig 1.
Classification: Dactylosporaceae, Sclerococcales, Sclerococcomycetidae, Eurotiomycetes, Pezizomycotina, Ascomycota, Fungi.
Sclerococcum was originally described by Fries (1819, 1825) to accommodate the parasitic fungi S. sphaerale, which was transferred from Spiloma sphaerale. Diederich et al. (2013) conducted a phylogenetic analysis and found that the generic type of Sclerococcum, Sclerococcum sphaerale, form a strongly supported clade basal to the Eurotiomycetes that also includes Dactylospora spp. In additions, Diederich et al. (2018a) considerd Dactylospora and Sclerococcum as a monophyletic group based on the phylogenetic analysis. The genus name Sclerococcum was used, and 46 species of Dactylospora were transferred to Sclerococcum. The family name Dactylosporaceae has been used, and Sclerococcaceae became a synonym.
Fries (1825) gave a short diagnosis about the characteristic of Sclerococcum as spores globose, opaque, tightly adhering to each other and to the thin receptacle, forming a rounded tubercle. Since then, none described this genus in detail until Hawksworth (1975b) described and illustrated the type species, Sclerococcum sphaerale. It is characterized by sporodochia-like, circular and punctiform or hemispherical, convex and wart-like colonies scattered on the surface of the host lichen. The conidiophores are semi-macronematous, sporodochial, subglobose to ellipsoid or polyhedral, hyaline, sometimes becoming pale brown in parts. The conidiogenous cells are monoblastic or polyblastic, integrated, terminal, determinate, subglobose, shortly cylindrical or ellipsoid, hyaline to pale brown. Conidia are irregular but frequently biseriate chains, acropleurogenous, irregularly subglobose to ellipsoid, brown to dark brown, almost black in mass (Hawksworth 1975b). Dong et al. (2020) noted that the terrestrial and marine genus Sclerococcum encompasses saprotrophic species and lichenicolous species. Joshi (2021b) further elaborated that Sclerococcum is characterised by blackish apothecia, cylindrical to clavate asci, amyloid with I– tholus covered by an I+ blue external gelatinous cap, 8-spored, and ascospores that are subglobose to ellipsoid with one to several transverse septa.
In the past five years, 40 new species or new combinations have been described, but mostly are saprotrophic species. Olariaga et al. (2019) combined 14 saprotrophic species under Sclerococcum from Dactylospora based on ascal characters and interpretation of the phylogenetic analyses. Only two species, Sclerococcum arthrobotryinum growing on Arthrobotryum spongiosum, and Sclerococcum inopinum growing on Radula magellanica, are lichenicolous fungi. In the same year, three more species, Sclerococcum ricasoliae growing on Ricasolia, Sclerococcum stigma growing on Lecidea platycarpa and Sclerococcum thelotrematicola growing on Thelotrema, were combined (Flakus et al. 2019b, Fryday 2019, Navarro-Rosinés et al. 2019). From then on, nine new lichenicolous species were introduced (Elix et al. 2019, Spribille et al. 2020, Zhurbenko et al. 2020a, Joshi 2021b, Øvstedal et al. 2021, Zimmermann et al. 2021, Zhurbenko 2022d, Paz-Bermúdez et al. 2023). Diederich et al. (2024) have accepted over 80 species in this genus with 64 lichenicolous species and the remainder being saprotrophs on liverworts, wood and bark in both terrestrial and marine habitats. However, we compiled 74 lichenicolous species according to IndexFungorum and MycoBank (2025). It has 127 sequences of Sclerococcum and 106 sequeces of Dactylospora, mostly belonging to LSU, ITS and mtSSU, with a smaller portion in RPB2 and SSU.
Type species: Sclerococcum sphaerale (Ach.) Fr.
= Spiloma sphaerale Ach.
Other accepted species: Species Fungorum – search Sclerococcum.
Figure 1 – Sclerococcum sphaerale redraw from Hawksworth (1975b), a, b Sporodochia-Iike pustules on thallus of Pertusaria corallina. c conidiophores. d conidia. Scale bars: a = 1 mm; c–d = 10 μm.
References
Diederich P, Ertz D, Braun U 2024 – Flora of lichenicolous fungi, Vol. 2, Hyphomycetes. National Museum of Natural History, Luxembourg, 2, 1–544.
Fries EM. 1819 – Novitiae florae suecicae. Nov. Fl. Suec. 5, 79.
Entry by
Meng QF, Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai, 57100, Thailand and School of Public Health, Zunyi Medical University, Guizhou 563000, China.
Published online 1 July 2026