Type: Foliicolous Fungi; Description: Conidiomata acervular, gregarious, subcuticular, multi-loculate, pustulate, more or less circular, black, shiny, often coalescing to form plate-like structures up to 1.5 mm across, opening by irregular splitting of the upper wall; on more or less circular pale brown leaf spots up to 2 mm in diameter, mainly on the upper surfaces of leaves. Conidia of two types: macroconidia broadly cylindrical to subglobose, 0-septate, 5–7 × 4–5 μm, base broadly truncate with a minute frill, smooth, hyaline to pale brown; microconidia cylindrical, 0-septate, 3–5 × 1.5 μm, smooth, hyaline.

Distribution: Marlborough Sounds.; 1st Record: Johnston (1999).

Significance: None.; Host(s): Nothofagus menziesii.

ADDITIONAL SPECIMEN EXAMINED: New Zealand: MARLBOROUGH SOUNDS: track from Titirangi Road to Endeavour Inlet, on Nothofagus menziesii, P.R. Johnston, 11 May 1997 (PDD 68193).

Spots on upper surface of living leaves (rarely on lower surface), up to 2 mm diam., more or less round in outline, pale brown, sometimes coalescing, with one or more black conidiomata developing in the centre, these eventually covering most of spot. Conidiomata initially pustulate, more or less round in outline, becoming less regular in shape with age, often coalescing to form flat, plate-like fruiting bodies up to 1.5 mm across, surface finely undulate, wall black, shiny; opening by irregular splitting of upper wall, conidia being released in clear, translucent masses.

Conidiomata multiloculate, subcuticular, the more or less intact epidermal cells beneath the conidiomata become invaded by hyphae 2-3 µm diam. with brown walls; hypodermal cells only rarely invaded. Between locules the conidiomatal wall is 30-50 µm thick, comprising two layers, a 10-15 µm thick upper layer of dense, black tissue, and a lower layer of 4-6 µm diam. angular cells with dark brown walls, arranged in quite regular vertical columns; upper and lower layers split apart to form the conidiogenous locules, the conidiogenous cells developing on the tops of the columns of angular cells.

Both macroconidia and microconidia are produced, usually, possibly always, in different conidiomata. Macroconidiogenous cells 6-10 x 3-4.5 µm, cylindric, with 2-3 indistinct annellidic wall thickenings near apex, hyaline; solitary, forming a palisade-like layer across base of conidioma. Macroconidia 5-6.5(-7.5) x (3-)4-4.5 µm, broad-cylindric to subglobose, apex rounded, base broadly truncate, with a tiny frill at the base, 0-septate, wall thin, smooth, hyaline to pale brown; when mounted in water the released macroconidia appear to be embedded within a common, loose gelatinous matrix. Microconidiogenous cells 12.5-22 x 2-2.5 µm, long-cylindric with a single apical conidiogenous locus, the wall slightly thickened at the apex; held on irregularly branched conidiophores. Microconidia 3.5-4.5 x 1.5 µm, short-cylindric, 0-septate, wall hyaline.

Maculae epiphyllae vel raro hypophyllae, usque ad 2 mm diam., rotundatae. Conidiomata usque ad 1.5 mm diam., rotundata vel irregularis, nigra, plana, subcuticularia. Cellulae macroconidiogenae 6-10 x 3-4.5 µm, cylindricae, discretae. Macroconidia 5-6.5(-7.5) x (3-)4-4.5 µm, cylindrica lata vel subglobosa, apice rotundato, base truncata lata, 0-septata, hyaline vel brunnea diluta. Cellulae microconidiogenae 12.5-22 x 2-2.5 µm, cylindrice; microconidia 3.5-4.5 x 1.5 µm, cylindrica, 0-septata, hyalina.

Of the relatively few species to have been described in Piggotia (Sutton 1980), most are from the Northern Hemisphere, and none have been described from hosts in the Fagaceae.

New Zealand: Marlborough Sounds: Mt Stokes Track, near road, on living leaves Nothofagus menziesii, P.R. Johnston, 11 May 1997, PDD 68192.