Ascocarps scattered to clustered, immersed, globose to subglobose and laterally compressed between vascular strands of host, 190-330 µm long and 200 µm high, non-papillate. Ascocarp in section broadly elliptic to depressed ovate; ascocarp wall 10-20 µm and 3-5 cells wide, textura prismatica; cell walls evenly thickened and pigmented, but slightly thicker and more heavily pigmented surrounding the ostiole; cells 5-11.5 x 4.5-6.5 µm. Asci numerous, bitunicate, narrowly obovate, short stalked, 8-spored, 75.5-108.5 x 15-17.5 µm. Ascospores irregularly tristichous, narrowly elliptical, 3-septate, constricted at all septa, second cell slightly swollen, (note: old ascospores elliptic oblong, and all cells slightly swollen), straight to slightly curved, punctate, luteous, at first guttulate, later non-guttulate, 29-33.5 x 5-7 µm; gelatinous sheath entire, broadest at the second cell. Physes numerous, septate, sparsely branched, hyaline, 2-3 µm wide. Hyphae darkening epidermis surrounding ostiole.

Ascocarpia sparsa ad gregaria, iminersa, globosa ad subglobosa, a latere compressa, 190-330 µm lata, 200 µm alta, non-papillata, muri 10-20 µm crassi. Asci numerosi, bitunicati, anguste obovati, breviter stipitati, octospori, 75.5-108.5 x 15-17.5 µm. Ascosporae irregulariter tristichae, anguste ellipticae, triseptatae, in septis omnibus constrictae, rectae vel leniter curvatae, punctatae, luteae, primo guttulatae, postea non-guttulatae, 29-33.5 x 5-7 µm; loculus secundus leniter inflatus; vagina gelatinosa continua praeditae. Physes numerosae, septatae, tenuiter ramosae, 2-3 µm crassae.
Holotypus: PDD50249 ex Scirpus nodosus Rottb.

Only three species of Phaeosphaeria are recorded on Scirpus, these are P. eustoma on S. holoscheonus from Italy, P. caricus on S. silvaticus from Switzerland (Leuchtmann 1984), and P. papua-alpina on Scirpus sp. from Papua New Guinea (Kobayasi & Otani 1971). P. kukutae is easily distinguished from these by its three-septate, fusiform, punctate ascospores.
Etymology: kukuta, Maori for Scirpus.

Specimens examined, New Zealand: on Scirpus nodosus Rottb., east of Sinclair Head, Wellington south coast, 17 June 1984, G. S. Ridley, PDD50248; and 22 September 1985, PDD50249 Holotype.

Ascocarps scattered to clustered, immersed, subglobose, c. 250 µm diam. and 60 µm high, ostiole with short papilla; ascocarp in section depressed ovate; ascocarp wall 10-20 µm and 7 cells wide, textura prismatica, cell wall thickening and pigmentation angular to more evenly distributed in cells surrounding the ostiole; cells of ascocarp base tending to textura angularis; cells 4-8 µm diam. Asci numerous, bitunicate, narrowly oblong elliptic, very short-stalked, 8-spored, 56-85 x 11-17.5 µm. Ascospores irregularly biseriate, narrowly elliptic, 3-septate, slightly constricted at the septa, straight to slightly curved, smooth, very pale luteous, guttulate, 22.5-29 x 4-5 µm; gelatinous sheath thin and entire. Physes numerous, septate, sparsely branched, 1-2 µm wide.

Ascocarpia sparsa ad gregaria, immersa, subglobosa, circa 250 µm in linea media et 60 µm alta, non ad breviter papillata, paries 10-20 µm crassa. Asci numerosi, bitunicati, anguste oblongi elliptici, breviter stipitati, octospori, 56-85 x 11-17.5 µm. Ascosporae irregulariter distichae, anguste ellipticae, triseptatae, rectae vel leniter curvatae, laeves, satis luteolae, guttulatae, 22.5-29 x 4-5 µm; ad septa leniter constricta; vagina gelatinosa tenuis, continua praeditae. Physes numerosae, septatae, tenuiter ramosae, 1-2 µm crassus.
Holotypus: PDD50261 ex ligno decorticato.

P. waikanaensis fits the generic concept with a typical Phaeosphaeria hamathecium of distinct and sparsely branching physes. It differs from other members of the genus in the darker brown thickening concentrated in the ostiole region of the ascocarp (Dr 0. Eriksson pers. comm.). P. waikanaensis is the only member of the genus to be found on wood rather than on the typical graminicolous or herbaceous substrates.
Etymology: Waikanae, Maori place name

Specimens examined. New Zealand: on decorticated wood collected at high tide mark, Waikanae River estuary, Waikanae, February 1982, G. S. Ridley, PDD50261 Holotype.