Spathulospora A.R. Caval. & T.W. Johnson, Mycologia 57(6): 927 (1965)
Sordariomycetes order incertae sedis, Spathulosporales, Spathulosporaceae, Spathulospora
Index Fungorum number: IF5071; Facesoffungi number: FoF 02133; 5 morphological species; 2 species with sequence data.
Parasitic on marine algae. Sexual morph: Ascomata superficial to immersed, globose to subglobose, carbonaceous or subcarbonaceous, brown or black, ostiolate. Ostiole conical, papillate. Peridium comprising numerous cell layers of scleroplectenchymatous cells. Paraphyses lacking. Asci 8-spored, unitunicate, lacking an apical ring, deliquescent. Ascospores overlapping multi-seriate, elongate, straight or curved, aseptate, hyaline, with an equatorial, cytoplasmic band, ends spatulate, with a gelatinous, lateral, appressed appendage. Reproductive structures: Antheridial. Spermatia ellipsoidal to fusiform, without appendages. Trichogynes simple or branched, septate, arising from the margin of young ascoma (adapted from Maharachchikumbura et al. 2016b & Hyde et al. 2020).
Type species: Spathulospora phycophila A.R. Caval. & T.W. Johnson, Mycologia 57(6): 927 (1965)
Notes: Spathulospora was introduced by Cavaliere & Johnson (1965) and referred to the Spathulosporomycetes, Spathulosporomycetidae (Locquin 1984), Spathulosporales (Kohlmeyer 1973), Spathulosporaceae (Kohlmeyer 1973). However, two Spathulospora species (S. antarctica, S. adelpha) have shown a relationship to Lulworthiales, but with low support (Inderbitzin et al. 2004, Campbell et al. 2005, Jones et al. 2009, 2019). There are no sequences for the type of this genus, hence, new collections, isolations and sequencing are required to determine its phylogenetic placement.
Spathulospora species are parasitic on algae, potentially leading to malformations. They proliferate in the host cells without penetrating the plasma membrane, and only afterwards form the stroma and sexual structures on the surface, presumably using nutrients acquired from the host. In some cases, the interaction of Spathulospora species and host triggers a reaction analogous to witches’ broom in vascular plants: the alga produces long hairs, which surround the stromata and ascomata of the fungus (Inderbitzin et al. 2004).