Additional specimens examined: NEW ZEALAND: Auckland, Pukekohe, on dead culms of Bambusa oldhamii Munro, E.H.C. McKenzie, Feb. 1975 (PDD 41012), 10 Jul. 1975 (PDD 41013); Mt Albert Research Centre, on Bambusa sp., F. J. Morion, 12 Jul. 1963 (PDD 21981), E.H.C. McKenzie, 8 Jul. 1975 (PDD 41014); Grey Lynn, on dead culms of Bambusa sp., G. J. Samuels, Sep. 1979 (PDD 41015); Auckland Domain, on dead culms of Bambusa sp., E.H.C. McKenzie, 7 Nov. 1979 (PDD 41016).

Ascomata forming on culms of bamboo in groups of 3-5, arranged linearly and forming black, lenticular spots parallel to the long axis of the host, 1-2 mm long x 0.5 mm wide x 0.25-0.5 mm high; subepidermal, covered with a thin, black stroma that opens by a cleft-like slit, at maturity. Ascomatal black subglobose to globose with a flattened base, 125-225 µm high x 170-340 µm wide. Ascomatal wall uniform in width, 10-15 µm wide, thinnest basally; cells elliptic to fusiform, 8-10 µm long x 4-5 µm wide, light brown; cells at base somewhat smaller. Ostiolar region continuous with the surrounding stromal cells and pierced by the ostiolar canal; ostiolar canal periphysate; periphyses stout, c. 2 µm wide. Cells between ascomata vertically oriented, loosely arranged, thin-waned, lighter brown than cells of the ascomatal wall, crushed between walls of adjacent ascomata; cells surrounding the upper third of the ascoma elliptic, 4-5 µm x 3-4 µm; toward the stromal surface cell walls thicker, 1.5-2.0 µm; cells surrounding the ostiolar canal hyphal, vertically oriented, 6-8 x 2.5-3.5 µm, thin-walled, colourless. Cells of the upper c. 20 µm of the stromal surface angular, 5-7 µm across, heavily pigmented, arranged in a layer continuous between ascomata, subepidermal. Cells at the periphery of the ascomatal aggregate vertically oriented and bricklike, 11-12 x c. 6 µm. Asci forming in a continuous layer covering the lower ascomatal wall, broadly cylindrical, 65-85 (-100) x 20-28 µm; unitunicate, apex broad, I-, an apical ring sometimes seen; base broadly pedicellate with two pores, each corresponding to one of the two septa separating the tip, penultimate and basal cells of the crozier; ascospores biseriately arranged. Ascospores naviculate, (19-)21-26(-33) x (7-) 8-10(-12) µm at widest point x (3-)5-6(-7) µm at septum (mean of 147 ascospores = 24.4 x 9.2 µm); 2-celled, lower cell 5-6 µm long; straight, hyaline, smooth. Paraphyses attached basally, apically free, sparingly branched, thin-walled, septate, extending slightly above ascal apices, 5-7 µm wide, tips slightly tapering.
Anamorph. Arthrinium sp.
Conidiomata superficially resembling ascostromata, subepidermal, parallel to the long axis of the host, opening by longitudinal splitting of the epidermis and revealing a black conidial mass. Setae, stiff, (11-)100-300(-450) µm long x 4-6 µm wide basally, walls 2-3 µm thick, erect, black, unbranched, septate with pointed tips, scattered over substrate, may or may not be associated with conidiomata or ascomata. Conidiogenous cells arising in a single layer from a pseudoparenchymatous base, cells of the base thin-walled, lightly pigmented, c. 5 µm across. Conidiophores arising singly from pseudoparenchymatous to ampulliform mother cells, basauxic, straight or slightly flexuous, unbranched, cylindrical, colourless to light brown, smooth; septate, septa not markedly thickened or pigmented: polyblastic. Conidia borne singly apically and laterally, the oldest aat the tip of the conidiophore; holoblastic; elliptic in face view, 15.5-19(-27) x 9.5-11(-12) µm (mean of 158 conidia = 17.5 x 10.1 µm) with a light coloured, equatorial rim; circular in surface view with a circular, 2-3 µm diam. abscission scar on the underside, brown, smooth.
Characteristics in culture: Colonies grown for 1 week at 18-20°c, diffused daylight; CMD (cornmeal dextrose agar, Difco): colonies 4-5 cm diam. felty, very pale pink, transparent; PDA (potato dextrose agar, Difco): colonies 2-5 cm diam., cottony, slightly raised, pale pink, opaque; ME (malt extract agar: 40g "Maltexo" brand malt extract, 12g agar, 1l distilled water, pH adjusted to 6.5 before autoclaving): colonies 2-3.5 cm diam., intermediate between colonies on CMD and on PDA, pale pink. Conidia forming after 2 weeks in white hyphal tufts. Setae scattered throughout the colony, sometimes forming in only small numbers.

Habitat: On dead culms of Bambusa spp.

Ascomata stromate atrotecta, nigra, in strias paralleles, lineares, 1-2 mm long, per rimas epidermidis erumpentia. Asci unitunicati, hymenium formantes, clavati, 65-85 (-100) x 20-28 µm, parti apicati iodo non coeruiescenti. Ascosporae oblongo-clavates, basi uniseptates, hyalinae, (19-)21-26(-33) x (7-)8-10(-12) µm. Paraphyses pauciramosae, hymenio affixae.
Status conidialis ad Arthrinium (≡ Cordella johnstonii M.B.Ellis) referabilis.
Holotypus. PDD 41017.

Etymology of the specific epithet: Refers to the setae that form on the substrate.

Holotype: NEW ZEALAND: Auckland, Kohimarama, on dead culms of Bambusa sp., G.J. Samuels (79-147), Nov. 1979 (PDD 41017).