Splanchnonema Corda, Deutschl. Fl., 3 Abt. (Pilze Deutschl.) 2: 115 (1829).
Saprobic on host. Sexual morph: Ascomata medium to large, solitary or scattered, immersed in cortex with a pseudostromal covering, with a small ostiole appearing on the host surface, flattened subglobose. Peridium thin. Hamathecium of dense, cellular pseudoparaphyses, embedded in mucilage, anastomosing and branching. Asci bitunicate, fissitunicate, clavate to broadly cylindrical, with a short, narrowed, furcate pedicel. Ascospores clavate with a rounded apex and acute base, reddish brown, constricted at the septa. Asexual morph: Myxocyclus, Steganosporium (Adapted from Zhang et al., 2012).
Type species: Splanchnonema pustulatum Corda
Notes: Splanchnonema was introduced by Corda (1829) with S. pustulatum as type species. Splanchnonema is characterized by medium to large, solitary or scattered ascomata, dense, cellular pseudoparaphyses, clavate to broadly cylindrical asci and reddish brown, clavate with a rounded apex ascospores. Shoemaker and LeClair (1975) provided an account of Splanchnonema but this was confusing. Eriksson (1981) and Sivanesan (1984) mentioned the lectotype of Splanchnonema as S. pupula but according to Index fungorum and Mycobank (2022), the type species of Splanchnonema is S. pustulatum. It seems that Eriksson (1981) followed the treatment of Shoemaker and LeClair (1973), who considered S. pustulatum as the synonym of S. pupula. Barr (1993a) provided a key to 27 North American species but included species with a range of ascospores types and immersed to superficial ascomata which indicate that Splanchnonema is polyphyletic. Tanaka et al. (2005) suggested that Splanchnonema might include species that belong to Pleomassaria, hence this genus needs revision. Zhang et al. (2012) provided illustration of a specimen of Splanchnonema pustulatum collected by CE Broome in United Kingdom ans accepted Splanchnonema in Pleomassariaceae based on morphology. Splanchnonema differs from similar genera such as Pleomassaria or Splanchospora in having depressed ascomata, and obovoid and asymmetrical ascospores (Barr, 1982; Zhang et al., 2012). Splanchnonema pustulatum is characterized by immersed ascomata and unique ascospores and these characters suggest that Splanchnonema sensu stricto should be restrained to a few similar species. Splanchnonema is currently a distinct genus in Pleomassariaceae but fresh collections with DNA sequence data is needed to confirm the taxonomic placement of the genus. The type species need to be recollected and the genus needs epitypification. Molecular data available for Splanchnonema include LSU, SSU, ITS, RPB2 and TEF1.