Nectria freycinetiae Samuels 1976
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Nomenclature
Classification
Associations
Descriptions
Nectria freycinetiae Samuels 1976
CONIDIAL STATE: Acremonium sp.
Mycelium white, forming a ring around the base of each perithecium, not visible apart from the perithecia. Perithecia solitary or in caespitose clusters of up to 10, orange, globose, 260-370 µm diam., becoming collabent when dry, not changing colour in 3% potassium hydroxide. Perithecial wall 50-80 µm wide. Surface view: cells obscured by the hyphal covering. Longitudinal section: outer region 40-60 µm wide, cells prosenchymatous to loose and hyphal, walls c. 3 µm thick, cells becoming progressively more compacted toward the interior of the perithecial wall. Inner region 15-20 µm wide; cells elliptic, 5-7 µm long x 2-3 µm wide, walls 1-2 µm thick and pigmented; cells becoming progressively more flattened, thin-walled, and non-pigmented toward the interior. Hyphal covering white, composed of branched septate, spinulose, straight, flexuous, 2-3-µm-wide hyphae with walls 0.5-1.0 µm thick, growing outwardly from the surface of the perithecial wall to a length of 40-60 µm, many free ends visible. Perithecial papilla lacking; ostiolar canal formed by narrow hyphal elements arising from the inner region of the perithecial wall, periphysate. Asci clavate, 100-110 x (8-) 11-17 µm, 8-spored; apices rounded, simple; bases rounded; ascospores biseriate, forming throughout the length. Ascospores fusiform, straight or slightly curved, 26-32 x 6-7 (-8) µm, equally 2-celled, two to three drops in each cell, striate, non-constricted at the septum, hyaline.
CHARACTERISTICS IN CULTURE CMD: Ascospores germinating in high percentage overnight, 3-4 germ tubes arising laterally from each ascospore. Colonies 2.5-3 cm diam., translucent, pale pink, aerial mycelium sparse, margin undulate, non-aromatic, medium non-pigmented. ME: 1 cm diam., opaque, white; aerial mycelium as loose, erect, outwardly directed hyphae; margin undulate, non-aromatic, medium non-pigmented. OA: 2.5 cm diam., opaque, pale pink, aerial mycelium compacted, margin slightly undulate, non-aromatic, medium non-pigmented. WAS: 2.5 cm diam., transparent, white, aerial mycelium sparse, loose, forming indistinct concentric rings, margin entire, non-aromatic, medium non-pigmented. Phialophores forming only on CMD from the surface of the medium and from the aerial mycelium, monophialidic unbranched or branched once, 4-6 septate, straight, coarsely spinulose, 60-90 µm long, 3 µm wide basally, subtending hypha 3 µm wide. A solitary, coarsely spinulose phialide constituting the terminal (23-) 35-40 (-50) µm of each phialophore, 2 µm wide at the unflared tip. Conidial production sparse after 2 weeks, but abundant after 6 weeks. Phialoconidia ellipsoidal, 6.5-9.5 (-11) x (2-) 3-3.5 (-4) µm, unicellular, hyaline, with or without a protuberant, flattened, basal abscission scar. Arising in basipetal succession and held in a single, terminal, hyaline drop of liquid.
Nectria freycinetii and N. foliicola are closely related. The perithecial wall of N. foliicola is orange to brown and the perithecial hairs are tan and smooth; the asci measure (51-) 60-80 (-85) x 10-12 (-16) µm and each has a simple apex; the fusiform ascospores measure (17-) 21-27 (-30) x (4-) 5 µm and are striate. A conidial state has not been recorded for N. foliicola and conidia did not form in cultures made from South american material (Samuels 1976). Perithecia formed in cultures derived from solitary ascospores on OA and CMD. I did not see conidia on any of six, including Holotype (K) and Isotype (FH), fresh or dried neotropical collections of this species. N. foliicola is apparently known only from the neotropics and has been described and illustrated by Samuels (1976).