Capnokyma S. Hughes, N.Z. Jl Bot. 13(4): 638 (1975).
Saprobic on bark of living trees. Colonies black, shiny, composed of superficial hyphae, erect, creeping, forming velutinous growth on trunks and branches. Sexual morph: Unknown. Asexual morph: Mycelium superficial, composed of repent and erect aerial hyphae. Repent hyphae cylindrical, smooth or faintly roughened, straight or variously bent, pale brown to brown, occasionally anastomosing, branched generally at right angles, septate, not constricted at septa. Cells of repent hyphae conspicuous. At intervals, cells of the repent hyphae are darker, wider and somewhat constricted at the septa; erect hyphae arise singly from one of these more robust cells and rooting hyphae appear to arise from the basal cell. Sterile erect hyphae are up to 1.3 mm long, straight or flexuous, smooth throughout, and positioned at right angles to the substratum. They comprise a main stalk which is almost cylindrical for most of its length, expanding gradually and finally tapering to an almost acute apex: dark brown to almost black at the base, becoming paler toward the apex. Basal cells progressively extend toward the distal end. The main stalk bears towards the apex and produced in the same plane, 1–5, mostly 2 or 3 paired subulate, distally pointed, pale brown to sub–hyaline, lateral branches, the upper ones successively shorter: these branches are upwardly curved and the stronger ones may bear secondary paired lateral branches. Most erect hyphae bear at least one pair of opposite branches. Outer wall of all lateral branches continuous with the inner wall of the main stalk bursting through the outer wall layer; at the base of lateral branches the torn remains of the outer wall of the main stalk appear as an irregular frill. Erect hyphae turn entirely into conidiophores, often darker throughout than sterile hyphae, almost cylindrical, expanding gradually about half way along their length and then tapering gradually at the apex. Conidiophores unbranched bearing a terminal conidium, or may produce solitary or paired lateral, cylindrical, upwardly curved branches which also bear a terminal conidium. Cylindrical lateral branches can take the place of one or more of the subulate lateral branches of otherwise sterile erect hyphae. Sterile subulate paired or solitary branches may develop on otherwise simple conidiophores. Conidia blastic, darker on both apical cell of the conidiophore and basal cell of the conidium. At maturity, conidia pale brown to brown, smooth, obclavate, slightly or markedly curved, (6 –)8–10(–1l)-septate, barely or only slightly constricted at the septa. Occasionally, a conidiophore proliferates through the terminal scar left by a seceded conidium and the extension produces another terminal conidium. Any cell of a conidium can germinate and paired hyphae arise from a single cell. Erect hyphae may bear hormisciomyces phialidic state, terminally on one or more lateral branches. Phialides borne in a whorl of 6 or 7, pale brown, flask-shaped with the venters directed inwards toward the center of the whorl. Phialoconidia hyaline, broadly ellipsoidal, produced in a slimy head. Hormisciomyces phialides sometimes formed on simple and on branched hyphae arising from germinating Capnokyma conidia (adapted from Hughes 1975).
Type species: Capnokyma corticola S. Hughes
Notes: Capnokyma is characterised by erect setae-like conidiophores, blastic conidiogenesis and hyaline, broadly ellipsoidal, phialoconidia produced in a slimy head (Hughes 1975). Capnokyma resembles Acrogenotheca in the production of cylindrical, repent hyphae and distinctive erect, branched aerial hyphae. In Acrogenotheca, however, the erect hyphae, are generally much longer (up to 4.1 mm) and never oppositely branched, microconidia are produced in pycnidia, and branches of the erect hyphae can secede and function as conidia, while in Capnokyma branching of the erect hyphae is typically opposite, and microconidia are produced by Hormisciomyces phialides borne on the erect hyphae. Hughes (1975) placed Capnokyma in Euantennariaceae based on the evidence of conidial and vegetative states but molecular data is needed to confirm this placement.