Didymella nigricans (P.R. Johnst. & Boerema) Q. Chen & L. Cai 2015

Type: Foliicolous Fungi; Description: Conidiomata pycnidial, often aggregated into groups of 4–6 with confluent walls, globose or irregular in shape, pale brown, 0.1–0.3 mm in diameter; on leaf spots or on necrotic tissue of twigs. Conidia oblong-elliptic, 0-septate, 5–9 × 2–3 μm, smooth, hyaline.

Distribution

Distribution: Auckland.; 1st Record: Johnston & Boerema (1982).

Notes

Pathogenicity

Significance: None.; Host(s): Actinidia deliciosa, Citrus sp., Coprosma sp., Feijoa sellowiana, Psidium guajava.

Johnston, P.R.; Boerema, G.H. 1982: Phoma nigricans sp. nov. and P. pratorum sp. nov., two common saprophytes from New Zealand. New Zealand Journal of Botany 19(4): 393-396.

Phoma nigricans P.R. Johnst. & Boerema 1982 [1981]

Description

CULTURAL CHARACTERISTICS: OA; colonies 55-65 mm diam. after growing 7 days in darkness at 20°C; mycelium cottony, grey or olivaceous at centre, white at margin; agar surface pink toward margin; reverse grey. After 4-7 days in daylight pink colour fades; agar surface covered with black pycnidia, sometimes confined to a band up to 15 mm broad halfway between centre and edge of colony; conidial slime pink. ME; 50-60 mm diam. after 7 days; aerial mycelium sparse; agar olivaceous. Scattered pycnidia formed after 7 days in daylight. Pycnidia 100-300 µm diam., 1-several ostioles, globose or irregular in shape, often aggregated into clumps of 4-6 pycnidia with confluent walls. Walls of 2-3 layers of pale brown pseudoparenchymatous cells. Conidiogenous cells hyaline, ampulliform, phialidic. Conidia hyaline, oblong-elliptic, nonseptate, (4-)5-8.5(-10) x (1.5-)2-3(-4) µm.

INOCULATIONS: The fungus did not initiate an obvious disease reaction in any of the test plants. However, pycnidia sometimes formed in the narrow band of dead tissue immediately surrounding wound sites. There was no apparent effect on the growth of the plants.

Habitat

HABITAT: Common in dead twigs and necrotic leaf tissue of various woody plants, both indigenous and introduced. Occasionally isolated from herbaceous. plants. This fungus has been isolated from Acca sellowiana, Actinidia chinensis, Arrhenatherum elatius (L.) Beauv. ex J. et C. Presl., Citrus spp., Coprosma sp., Lolium perenne, Malva sp., Paspalum dilatatum Poir., Pennisetum clandestinum Hochst. ex Chiov., and Psidium guajava L.

Latin

Coloniae in agaro farinae avenae 55-65 mm diam per 7 dies, 20°C; mycelium floccosum, griseum vel olivaceum; superficie agari rosea. Pycnidia 100-300 µm diam, uni- vel multi-ostiolata, globosa vel irregularia; paries e 2-3 stratis, ampulliformes. Conidia hyalina, oblonga vel ellipsoidea, simplicia, (4-)5-8.5(-10) x (1 .5-)2-3(-4) µm.
Holotypus: PDD 39949 (PDDCC 6546) ex Actinidia chinensis Planch.

Notes

NOTE: Colony appearance changes with repeated subculturing of isolates. Pycnidial formation is reduced, and dense, white, cottony mycelium, often with narrow olivaceous sectors, is formed.

Typification

Holotype: PDD 39949 (PDDCC 6546), isotype CBS 444.81 collected P. R. Johnston, Actinidia chinensis leaf, Mt Albert, Auckland, N.Z., April 1979.