Colony effuse, irregular, brown, hairy, with a downy aspect due to a whitish cover of chains of conidia. Superficial mycelium loosely aggregated; hyphae appearing nodulose due to constriction of the wall at septa, brown and asperate, up to 4 µ wide. Phialophores arising from segments of hyphae, with a short stalk of 1-2 cells, or often reduced to sessile phialides; 40-52 µ long, 4-4.5 µ wide below except for the swollen, asperate, basal cell which is up to 7.5µ wide. Phialides subcylindrical, 33-44 [38.6] µ long, pale brown, becoming lighter at the apex; venter subcylindrical to conic, slightly bulbous in the submedian part, smooth-walled, 13-18 [15.3] x 3.5-4.5 [4.1] µ; collarette cylindrical, smooth, 20-27 (29) [23.3] x 2-2.5 µ; transition from venter to collarette gradual; ratio of mean lengths of collarette/venter = 1.5:1. Phialoconidia extruded singly or in short chains; cylindrical, apex rounded, base truncate with minute marginal frill; 1-septate, hyaline, smooth; 9-17 [14] x 1.5-2 [1.8] µ; mean conidium length/width ratio = 7.7:1.

Habitat: On dead leaves of Knightia excelsa.

Colonia effusa, irregularis, brunnea, velutina, propter stratum albidum catenarum conidiorum pubescenti aspectu. Mycelium superficiale laxe aggregatum; hyphae noduliformes ob constrictiones parietis ad septa, brunneae et asperae, usque ad 4 µ lat. Phialophora ex segmentis hypharum orientia, brevi stipite 1-2-cellularum, vel plerumque ad sessiles phialides redacta; 40-52 µ long., infra 4-4.5 µ lat., praeter sufflatam asperam cellulam basalem, usque ad 7.5 µ lat. Phialides subcylindraceae; 33-44 [38.6] µ long., pallide brunneae, ad apicem pallescentes; venter subcylindraceus vel conicus, leniter bulbosus parte submediana, laevis, 13-18 [15.3] x 3.5-4.5 [4.1] µ; collum cylindraceum, laeve, 20-27 (-29) [23.3] x 2-2.5 µ; transitio ex ventre ad collum gradatim; ratio long. colli et ventris = 1.5:1. Phialoconidia singulatim vel in catenas breves extrusa, cylindracea; apice rotundato, base truncata, minutam fimbriam marginalem ferente, 1-septata, hyalina, laevia, 9-17 [14] x 1.5-2 [1.8] µ; ratio conidii long./lat. = 7.7:1.

C. gracilis is distinct from all other species of Chalara by virtue of its slender phialides, narrow venter that is bulbous in the submedian part; and narrow conidia.

Specimen examined: PDD 32872 [Holotype], Fairy Falls Tr., Waitakere Ra., Auckland, N.Z., 14.II. 1974, B. Kendrick (KNZ 315).