Endococcus Nyl., Mém. Soc. Sci. Nat. Cherbourg 3: 193 (1855).
Lichenicolous, parasymbiotic or parasitic on the thalli of lichen-forming fungi. Sexual morph: Ascomata arising singly, perithecioid, black, subglobose, immersed to erumpent, ostiolate, ostiole internally lined with distinct periphyses. Peridium carbonaceous, comprising 3–6 layers of radially compressed, thick-walled, dark brown pseudoparenchymatous cells. Hamathecium lacking paraphysoids and pseudoparaphyses, asci originating in a gelatinized matrix. Asci 4–8 spored, bitunicate, elongate-clavate to sub-cylindrical, with short furcate, broad pedicel, thickened and rounded at apex, with an ocular chamber. Ascospores uniseriate or 2-seriate, dark brown, ellipsoidal, with rounded or somewhat pointed apices, l-septate, sometimes markedly constricted at the septum, smooth-walled. Lacking a sheath or appendages. Asexual morph: Undetermined (Adapted from Jayasiri et al. 2016).
Type species: Endococcus rugulosus Nyl.
Notes: Endococcus was introduced by Nylander (1855) with E. rugulosus as type species. Endococcus is characterized by perithecioid, black, subglobose ascomata, elongate-clavate to sub-cylindrical asci and dark brown, ellipsoidal, with rounded or somewhat pointed apices, l-septate ascospores without a sheath or appendage. Several taxa previously placed in Tichothecium were transferred to Endococcus based on ascus structure (Hawksworth 1979). Fungi with - or 8-spored, bitunicate asci were accommodated in Endococcus (syn. Discothecium) while those with multi-spored asci producing spores via bursting of the apex were placed in Muellerella. Endococcus comprises two groups, one with spores having rounded ends and barely constricted at the septum and other one with spores having pointed apices and noticeably constricted at the septum (Hawksworth 1979). Sérusiaux et al. (1999) and Kocourková (2000) reported that Endococcus species are host-specific and the name Endococcus rugulosus (≡ Verrucaria rugulosa) was used for the genus Verrucaria (Verrucariaceae). Hawksworth (1979) placed Endococcus in Dothideales while Lumbsch and Huhndorf (2010) and Hyde et al. (2013) referred it to Dothideomycetes genera incertae sedis. Jayasiri et al. (2016) re-examined the isotype specimen of Endococcus under the code K(M): 155758 and referred the genus to Lichenotheliaceae based on morphological similarity with the type species of Lichenothelia, L. scopularia namely the perithecioid ascomata with widely porate ostioles, globose to broadly clavate asci and hyaline or brown, 1-septate ascospores. Only ITS sequence of E. fusigera is available in Genbank. Endococcus needs to be epitypified. Fresh collections with DNA sequence data are needed to confirm the taxonomic placement of the genus.