Calyptronectria Speg., Anal. Mus. nac. B. Aires, Ser. 3 12: 412 (1909)
Saprobic on host. Sexual morph: Ascomata small- to medium sized, basally immersed, sub globose to lenticular, ostiole surrounded by a small, white disk, sparse golden hyphae on ascomata and substratum becoming red in KOH. Ascomatal wall black, KOH+ reddish brown. Asci bitunicate, clavate, sessile, apex with a fluorescent ring. Pseudoparaphyses abundant, trabeculate, branching, anastomosing, embedded in mucilage. Ascospores fusiform, muriform, constricted in the middle, hyaline, smooth-walled (Adapted from Spegazzini 1909 and Zhang et al. 2012).
Type species: Calyptronectria platensis Speg.
Notes: Calyptronectria was introduced by Spegazzini (1909) with C. platensis as type species. Calyptronectria is characterized by its immersed ascomata, trabeculate pseudoparaphyses and hyaline, muriform ascospores as well as its peridium that turns reddish brown in KOH. Calyptronectria is a morphologically well-defined genus. Tian et al. (2015) retained Calyptronectria in Melanommataceae based on the character of trabeculate pseudoparaphyses. Sequence data is required to confirm the correct taxonomic position of Calyptronectria.