Type: Sooty Moulds and Similar Fungi; Description: Subiculum circular, velutinous, up to 6 mm in diameter, black; on leaves. Mycelium reticulate, composed of brown to dark brown, straight, cylindrical, 6–7.5 μm wide hyphae which become paler towards their distal ends. Stomatopodia common, ellipsoidal to obovoid, entire or once-lobed, 8–25 × 6–11 μm, sessile or on a 2–3-celled stalk. Ascomata perithecial, black, subglobose, up to 0.4 mm in diameter, ostiolate, bearing on the upper part dark brown, simple, straight or curved, thick-walled setae, up to 200 μm long. Ascospores subcylindrical, straight, 3-septate, 61–75 × 16–20 μm, brown to dark brown.

Distribution: Westland.; 1st Record: Hughes (1993).

Significance: A mild pathogen (McKenzie et al. 1999).; Host(s): Metrosideros umbellata.

Colonies are black, circular up to 6 µn diam., velutinous with a fringe of radiating appressed hyphae but velutinous to the margin with age. Superficial hyphae are apparently derived entirely from egress cells. Hyphae are much branched and form an irregular reticulum, occasionally stranded, cylindrical, more or less straight, here and there slightly flexuous, 5.7-7.5 µm wide, brown to dark brown at their origin from egress cells, then brown to very pale brown toward their ends. Cells of hyphae are as short as 18 µm near egress cells but distally up to 80 µm long. Stomatopodia are common, ellipsoidal to subcylindrical to obovoid, entire or once lobed, 8-25 µm long and 6-11 µm wide, sessile or on a 2- or 3-celled stalk. Ingress cells are subhyaline to brown, ellipsoidal and up to 7.2 µm long and 4-5 µm wide or subglobose and 5-6 µm diam.: they may develop singly from intercalary cells of superficial hyphae or on a small lobe of such cells. The narrow hypha arising from the ingress cells penetrates between the guard cells and expands abruptly to 14-22 µm wide within the substomatal chamber; here it branches to form several subhyaline to brown loose hyphae composed of cylindrical to moniliform cells 6.5-15 µm wide which penetrate the mesophyll intercellularly and irregularly. Egress cells are abundant. They are subglobose to ellipsoidal, 16-23 x 11-16 µm, dark brown, thick-walled, and give rise to 2 to 4 branching, brown, distally stomatopodiate hyphae which radiate over the leaf surface to form mini-colonies which are soon confluent. Phialophores are scattered, sometimes denser on hyphae near egress cells. They are up to 250 µm long, 1-3-dichotomously branched and arborescent, rarely simple: toward the base they are 7-8.5 µm wide and dark brown, tapering gradually to 5.2-6 µm toward the brown ends of the branches, most of which bear a single phialide. Phialides are 36-47 µm, long, brown to pale brown below and distally paler to subhyaline, more or less subulate or subcylindrical in the lower part, then tapering to 2.7-3.2 µm wide below a funnel-shaped collarette. Phialoconidia not seen. Perithecia (overmature) are black, subglobose, dorsiventrally flattened, ca 380 µm wide, ostiolate at maturity, bearing on their lower part, irregularly radiating, simple, cylindrical, straight or sinuous hyphae 5.5-6 µm wide. On their upper part perithecia bear thick-walled, septate setae which are dark brown, simple, straight or curved and 7-8 µm wide toward the base: they are up to 200 µm long and tapered to a bluntly rounded apex 3.5-4.5 µm wide. Paraphyses and asci were not seen. Ascospores are subcylindrical, straight, brown to dark brown, slightly constricted at the septa. Central cells doliiform to subcylindrical, longer than wide, and the end cells hemi-ellipsoidal and shorter than the central cells. Polar caps are dark brown and convex. A conspicuous, narrow, subhyaline band is found immediately below the polar caps and near the septum of each end cell. Slightly thinner zones of wall sometimes occur next to the septa of the central cells but pale bands, if present, are not conspicuous. Ascospores measure (59-)61-75.5(-81) x (15.3-)16.2-20(-21.5) µm.

Distribution: New Zealand (Westland).

Host species: Metrosideros umbellata.

Coloniae hypophyllae, atrae, ad 6 mm diam., initio ad centrum phialophoris velutinae et ad marginem hyphis appressis fimbriatae, deinde ad marginem velutinae. Mycelium superficiale ex hyphis cylindricis, rectis vel hic illic flexuosis, aliquando funiculosis, brunneis vel atrobrunneis 5.7-7.5 µm cr. cellulis ad 80 µm long. praeditum. Stomatopodia ellipsoidea vel subcylindrica vel obovoidea, integra vel unilobata, 8-25 µm long., 6-11 µm lat., sessilia vel in ramulo 1- vel 3-cellularia. Cellulae ingredientes subhyalinae vel brunneae, ellipsoideae, ad 7.2 µm long., 4-5 ~tm lat., vel globosae 5-6 µm diam.: aliquando singulariter ex cellulis longis intercalaribus hypharum orientes. Cellulae egredientes abundantes, subglobosae vel ellipsoideae, 16-23 x 11-16 µm, atrobrunneae, crasso-tunicatae, 2-4 hyphas repentes gerentes. Phialophora ad 250 µm alt., setiformia, arborescentia, 1-3-dichotome ramosa, raro simplicia, basim versus atrobrunnea, 7-8.5 µm cr., apicem versus brunnea, angustata 5.2-6 µm cr.; rami in phialide unica terminantes. Phialides 36-47 µm long., plerumque rectae, subulatae vel basim versus subcylindricae, brunneae, apicem versus pallide brunneae vel subhyalinae 2.7-3 µm angustatae, et collano praeditae. Phialoconidia non visa. Perithecia atra, subglobosa, ostiolata, setis supra lateraliterque, crasso-tunicata, simplicibus, atrobrunnea, rectis vel curvatis, ad 200 µm long., basim versus 7-8 µm cr., apicem versus angustatis ad 3.5-14.5 µm cr. praedita. Paraphyses et asci non visae. Ascosporae subcylindricae, rectae, brunneae vel atrobrunneae cum taenia alra angusta super septa, (59-)61-75.5(-81) x (15.3-)16.2-20(-21.5) µm, ad septa leniter constricta. Cellulae centrales doliiformes, longiores quam latiores. Cellulae terminales hemi-ellipsoideae utraeque cum zonis 2 subhyalinis, angustis, tenui-tunicatis, una sub disco terminali et altera prope septum. Aliquando cellulae centrales utraeque cum zonis 2 tenui-tunicatis prope septa praeditae sed zonae pallide aut haud manifestae.

Notes: Hansford (in herb.) assigned this collection to Meliolina novae-zealandiae Hansf., but the latter has larger colonies and shorter and wider ascospores. Ascospores of
M. metrosideri somewhat resemble those of M. leptospermi, but in the latter species they are smaller and the end cells are longer than the central cells: furthermore, the colonies of M. leptospermi are much smaller.

Typification: New Zealand: Waiho, Nov. 1954, J.M. Dingley (PDD 17250, holotypus, DAOM 142249 and IMI 86117, isotypi).