The three collections of this taxon from Victoria agree closely in most respects with the type material from New Zealand. However, in two of them, Beaton 13 and Beaton 95, the ascospores are budding, though not whilst still within the ascus. This is best observed in Beaton 13, in which the secondary spores are nearly always budded at or near the distal end of the spore. They are subglobose or broadly ellipsoid and frequently truncate at the point of attachment.

Dennis (1961) compared the structure of this taxon with that of Rutstroemia fusco-brunnea (Patouillard & Gaillard) Le Gal, which has similar but narrower and often slightly curved ascospores. The latter has been redescribed by Dumont (1981), who has shown the ectal excipulum to be composed of globose cells and has transferred the name to Moellerodiscus.

Amongst the species referred by Dennis (1964) to Hymenoscyphus series Prasinum, one other species, H. microspermus (Speg.) Dennis from Argentina, has small ascospores. This was referred to Rutstroemia by Gamundi (1962). From the description and figures she has supplied, the species is very similar to the present taxon, having yellowish apothecia with superficial dark brown fibrils, but less clavate and smaller ascospores 3.2-4.8(-5.6) x (1.3-)1.6-2.4 µm. The dark brown superficial hyphae have granulate walls, and a basal stroma is present. Clearly the species belongs in the Sclerotiniaceae. The single collection at Kew, cited by Gamundi, closely matches the type description and has, as she has described, caespitose apothecia which arise from a common sclerotioid mass. The species probably belongs in Lanzia, though such development is not characteristic of the genus. It does not occur in L. prasinum, and it is certain that these taxa are specifically distinct.

Helotium ambiguum Rick, on dead wood from Brazil, was described as having ascospores 7 x 3 µm. Dumont (1981) was unable to locate type material, so the taxonomic position of this species, and its possible relationship with L. prasinum, remains uncertain. Lanzia ambigua (Bresadola & Hennings) Carpenter, also from Brazil, is quite distinct on account of its brown apothecia up to 4 mm diam. and ascospores, 12-15 x 2.5-3.0 µm.

[notes from Lanzia prasinum description]

The small ascospores of L. prasinum are unusual but not diagnostic as a single criterion. Helotium novae-zealandiae is a very similar taxon which exhibits comparable stromatic development and cannot be distinguished from L. prasinum on ascospore characters alone. Dennis (1964) considered it to be a synonym. However, there are structural differences between these taxa which are reflected in the external appearance of the apothecia. Dried apothecia of L. prasinum bear an olive-yellow furfuraceous covering which microtome sections reveal to be due to ectal hyphae which terminate in clavate, free tips which are hyaline or very faintly pigmented. The disc of this taxon was described by Massee (1901) as chlorinous and, when rehydrated, now appears pale lemon-yellow. The margin is crenulate and the receptacle yellow or yellowish brown, becoming lemon-yellow towards the margin, the stipe is largely concolorous, being dark only at the extreme base. There are three collections in K, in addition to the type, which are referable to H. novae-zealandiae. These agree well with the type collection and differ from L. prasinum in having a yellow disc which is whitish when rehydrated, and in lacking an olive yellow furfuraceous surface. Instead, the receptacle is yellow, streaked conspicuously with dark brown or blackish fibrils which are most densely set in the lower part. The stipe is slightly downy and either dark brown to blackish throughout, or pale only at the extreme apex. The dark brown ectal hyphae of the stipe terminate in concolorous, cylindrical or only slightly clavate free tips. The striate appearance of the receptacle is produced by adpressed, cylindrical, 1-2-septate hair-like hyphae. These collections differ further from L. prasinum in having asci with an apical pore which does not stain blue in Melzer's reagent. Though Massee (1901) described the asci of L. prasinum as non-staining, the pore is, in fact, clearly outlined blue in Melzer's reagent.

Lanzia prasinum and H. novae-zealandiae are undoubtedly very closely related, but available evidence indicates that they can be distinguished. The observable differences seem unlikely to be the result of variation within a single taxon, but are scarcely sufficient to warrant recognition of two species. I propose, accordingly, to treat H. novae-zealandiae as a variety of L. prasinum. Because H. novae-zealandiae has proved not to be restricted to New Zealand, and as the visible distinction between the taxa is one of colour, I propose a new name Lanzia prasinum var. nigripes for this taxon.