Apothecia developing within leaf tomentum on undersides of living leaves of Olearia species (Asteraceae). Apothecia 0.1-0.15 mm diam., 0.2 mm high, black with numerous stiff, black setae, urn-shaped, tapering suddenly to a short, stipe-like base. Setae near top of apothecium extending outwards across top of leaf tomentum.

Ectal excipulum 2-layered. Inner layer 6-10 µm wide, in vertical section comprising 2 or 3 rows of brick-shaped cells 4.5-6 µm diam., with thin, brown walls. Outer layer patchy in development, comprising a single layer of cylindric cells 2.5-3 µm diam., with pale brown, irregularly encrusted walls, and with setae arising from these cells. Setae mostly near top of apothecium, 60-80 x 5-6.5 µm, often distinctively sickle-shaped, with very dark, thick walls, probably 0-septate. Seta-like or hair-like elements at sides and near base of apothecium, 12-20 x 2-3 µm, irregularly cylindric, with brown, slightly thickened walls, usually 2 or 3-septate. Medullary excipulum poorly developed, comprising 2 or 3 rows of hyaline, narrow-cylindric cells.

Paraphyses 2-2.5 µm diam., undifferentiated to slightly swollen near apex, about same length as the asci. Asci 55-70 x 6.5-7.5 µm, cylindric, tapering to slightly truncate apex, wall thickened at apex, non-amyloid, 8-spored. Ascospores 6.5-8 x 3-4 µm, broadly rounded at both ends, subclavate, slightly wider in upper half, hyaline, 0-septate.

Cultures approximately 50 mm diam. after 4 weeks. On OA with low, dense, felted, pale pinkish-grey mycelium; yellowish in reverse. On MEA with dense, cottony, white to pale grey mycelium; grey brown in reverse. Cultures remained sterile.

NOTES: Together with the unusual host substrate, ascospore size and shape differentiate C. falcata from the species treated by Nannfeldt (1985). Although most of these were also found on Asteraceae, all developed on dead leaf and stem tissue rather than the tomentum of living leaves. The asci of P. falcata appear to mature and discharge their spores while the leaves of the host plant are still alive, since all apothecia examined from fallen leaves were over-mature.

Several other species of Leotiales are associated with the leaf tomentum of Asteraceae in New Zealand. Johnston (1989) described three Crocicreas species and recorded C. epitephrum (Berk.) S.E. Carp., first described from Australia, from the leaf tomentum of various species. Another Australian species, Lachnum willisii (G.W. Beaton) Spooner, described from the leaf tomentum of Celmisia asteliifolia from Australia, also occurs on the tomentum of living leaves of Celmisia in New Zealand (MID CANTERBURY: Craigieburn Forest Park, near skifield, on Celmisia discolor, P.R. Johnston & E.H.C. McKenzie, 24 Feb 1988 (PDD 48634); Craigieburn Forest Park, near skifield, on Celmisia angustifolia, P.R. Johnston & E.H.C. McKenzie, 24 Feb 1988 (PDD 48458). NORTH CANTERBURY: Arthurs Pass National Park, Nature Trail near Temple Basin, on Celmisia discolor var. intermedia, P.R. Johnston & E.H.C. McKenzie, 25 Feb 1988 (PDD 48461). WELLINGTON: Tararua Ranges, vic. Dundas Hut, Pukemoremore summit, on Celmisia sp., P.R. Johnston, 10 Feb 1985 (PDD 49055)), and there remain many other undescribed leotiaceous species on this substrate in New Zealand (P.R. Johnston, unpubl. data).

Johnston (1998) described Pirottaea falcata from the leaf tomentum of Asteraceae in New Zealand (from species of both Olearia and Celmisia). The descriptions and illustrations of Johnston (1998; Fig.1) and Sydow (1924; Fig. 2) clearly represent the same fungus, characterised by small apothecia witha short, stipe-like base, and sickle-shaped setae, embedded within the leaf tomentum on the undersides of leaves of Asteraceae. The ascospore sizes given in Sydow's (1924) description are slightly longer and narrower than those given by Johnston (1998). This may reflect differences in mounting media used in the studies, or could reflect differences in the level of maturity of the material examined. Johnston (1988) saw ascospores only within the asci, possibly indicating that the material examined was slightly immature. The type specimen of Chaetoscypha nidulans was not able to be examined. Although listed in the PDD herbarium catalogue, the type specimen of C.nidulans was noted as missing from PDD by McKenzie et al. (1992). Duplicates of this specimen are not present in either of the European herbaria with major Sydow holdings, S and W.Sydow (1924) considered that C. nidulans could not be placed in the genus Pirottaea Sacc. because of what he described as a prosenchymatous excipulum, in contrast to the parenchymatous excipulum that he considered characteristic ofPirottaea. The illustrations of Johnston (1998; Fig.1) show that the excipular structure in fact appears to match Pirottaea well, although the excipulum is extremely reduced (in places the ectal excipular layer being a single cell wide), and there is a poorly developed outer layer comprising meandering hyphae across the surface of the receptacle. The dark,thick-walled setae are quite unlike the hair-like elements characteristic of Hyaloscyphaceae. Chaetoscypha was not treated by Nannfeldt (1932,1985) in his detailed treatments of Pirottaea and related genera.

Sydow (1924) described the genus Chaetoscypha, with the New Zealand fungus C. nidulans Syd. as the type species. No further species have been added to the genus, and its position remains uncertain. Kirk et al. (2001) considered that it may be a synonym ofLachnum Retz., possibly following Sydow's suggestion that this species belonged in his higher taxonomic group "Dasyscyphearum", a group similar in concept to the modern Hyaloscyphaceae. Chaetoscypha nidulans was described from a single collection made from fallen leaves of the alpine tree daisyOlearia colensoi. C. nidulans develops within the tomentum on the lower leaf surface, a feature well developed on O. colensoi and many other New Zealand alpine Asteraceae.

TAXONOMIC TREATMENTPirottaea nidulans (Syd.) P.R.Johnst., comb. nov.ç Chaetoscypha nidulans Syd., Annales Mycologici 22, 305 (1924).= Pirottaea falcata P.R.Johnst., New Zealand Journal of Botany 36, 645 (1998).

As Chaetoscypha nidulans is the type (and only) species of Chaetoscypha Syd. 1924, this genus is now a synonym of Pirottaea Sacc. 1878.

Die im dichten Blattfilze nistenden schwarzen, punktförmigen Fruchtkörper erwecken zunächst durchaus nicht den Eindruck eines Discomyzeten, ,doch ist deren wahre Natur unter dem Mikroskop sofort zu erkennen. Durch die starren dunkel gefärbten Borsten erinnert der Pilz etwas an Pirottaea. Diese Gattung besitzt jedoch durchweg parenchymatisch gebaute Gehäuse, während die Gehäuse des vorliegenden Pilzes durchaus einen prosenchymatischen Aufbau erkenhen lassen. In Betracht zu ziehen sind auch die Gattungen Dasyscypha und Unguicularia. Beide Gattungen enthalten jedoch fast aussehliesslich hell gefärbte Pilze. Ausserdem sind die Dasyscyphen mit meist septierten, stumpfen Haaren, aber nicht mit so starren, zugespitzten Borsten besetzt, wie solche der neue Pilz aufweist. Unguicularia weist zwar zugespitzte 1-zellige Haare auf, doch sind dieselben hier hyalin und auch wesentlich anders beschaffen. Der kleine völlig oberflächlich wachsende neuseeländische Pilz muss daher als Vertreter einer eigenen Gattung angesehen werden.

Zu beachten ist noch, dass die im oberen Teil völlig frei stehenden Borsten des neuen Pilzes sich nach unten bis fast zum Grund des Gehäuses verlängern und auf diese Weise die äussere Wand der Apotbezien bilden, die demnach langfaserig und dunkel erscheint. Darunter liegt eine hellere, aus kürzeren, faserigen Zellen gebaute Innenschicht.