Stroma cream or ochraceous when young, becoming vinaceous brown or fuscous when mature, often tuberculate with superficially immersed perithecia, pulvinate, 0.25-0.5 mm diameter, 0.25 mm thick, scattered, sometimes gregarious, then confluent with one another, margins thin, recurved, free, stroma centrally attached, psendoparenchymatous, outer cells small, 4-6 µ, pigmented and thickened, inner cells 10-15 x 10 µ hyaline, thin walled. Perithecia oval, 0.1-0.15 x 0.2-0.25 mm irregularly arranged but closely compacted in a superficial zone of the stroma, perithecial wall 7-12 µ, pigmented, ostiole 40-50 µ papillate. Asci cylindrical 75-100 x 4 µ with 14-16 part-spores, pseudoparaphyses evanescent. Part-spores globose or cuboid, 3.5-4 µ, oval or pyriform then 4-6 x 3-3.5 µ, olivaeeous, coarsely echinulate.

Stroma pulvinatum 0.25-0.5 mm, 0.25 mm crassum, gregarium saepe confluens, cremeum sed maturitate brunneo-vinosum, tuberculatum, peritheciis in superficie immersis, marginibus tenuibus recurvis sed liberis. Stroma pseudoparenchymatum, cellulis exterioribus 4-6 µ, tinctis et densatis, interioribus 10-15 x 10 µ, hyalinis, parietibus tenuibus. Perithecia ovalia 0.1-0.15 x 0.2-0.25 mm inaequaliter ordinata, bene compacta, ostiolo 40-50 µ papillato. Asci cylindrici 75-100 x 4 µ, 14-16 sporis divisis, paraphysibus evanescentibus. Sporae divisae, globosae, vel cuboides, 3.5-4.5 µ ovales vel pyriformes, 4-6 x 3-3.5 µ, olivaceae, crasse echinulatae.

A collection listed as H. jecorina Berk. & Br. (Dingley, 1952a) is included under this species. It is similar to both H. rufa (Tode ex Fr.) Fr. and to H. gelatinosa (Tode ex Fr.) Fr. differing from the former in that spores are pigmented and from the latter in that the outer layer of the pseudoparenchymatous tissue is pigmented. It seems possible from descriptions that H. atrogelatinosa may be a synonym of H. stereorum Berk. & Curt., but Seaver (1910) included the latter as a synonym of H. rufa. Unfortunately type material has not been examined.

Type collection: Auckland, Hunua Ra., Otau, April 1950, J.M.D. (10471).