VIRTUAL MYCOTA: NZ Fungi Identification: Pureke zelandicum

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Pureke zelandicum

Biostatus

Present in region - Indigenous. Non endemic

Images (click to enlarge)


Caption: Fig. 1 Pureke zelandicum. A-C, ascomata in vertical section at different stages of maturity. (A-C, PDD 49245).	Caption: Fig.2 Pureke zelandicum. A, asci. B, apices of asci and paraphyses. C, released ascospores. (A-C, PDD 54780).	Caption: Fig.7 Macroscopic appearance of ascomata (xl5). Pureke zelandicum (PDD45591).	Caption: on Nothofagus menziesii Owner: Herb. PDD

Article: Johnston, P.R. (1991). Rhytismataceae in New Zealand. 4. Pureke zelandicum gen. and sp. nov. plus additional species in Hypoderma, Lophodermium, and Propolis. New Zealand Journal of Botany 29: 395-404 (http://www.rsnz.org/publish/abstracts.php).
Description: Ascomata and structures resembling conidiomata of Rhytismataceae develop in slightly paler areas of fallen leaves, these areas sometimes surrounded by incomplete, narrow, black zone lines. Ascomata 0.7-2.0 x 0.4-0-5 mm, broad-elliptic in outline with rounded ends, walls pale to dark grey, in unopened ascomata with a broad paler zone along the future line of opening, the outside edge of the ascomata marked by a narrow, black line. Ascomata open by a single longitudinal slit, the edge of the opening is lined with a narrow, yellowish to dark grey zone. Ascomata initially subepidermal, but often the epidermal cells becoming filled with fungal cells as the ascomata mature. In vertical section, at a stage when paraphyses are first differentiating, the upper wall is 20-30 µm thick, comprising 4-6 rows of hyaline to pale brown, thin-walled, angular cells. At the same stage the lower wall is 5-15 µm thick, comprising 1-3 rows of brown to dark brown, thick-walled, angular cells. As the ascomata mature the upper wall becomes darker and thicker, while the lower wall remains more or less unchanged. Prior to opening, the upper wall of the ascomata is up to 60 µm thick, slightly thinner toward the edges, and comprises mostly dark brown, thick-walled, angular cells, but with a line of pale, thin-walled cells extending through the wall along the future line of opening. A patch of very dark tissue, in which the cellular structure is obscured, develops in the inner half of the wall adjacent to the paler cells marking the future line of opening. In opened ascomata the upper wall is 60-80 µm thick, comprising mostly dark brown, thick-walled, angular cells, but with a patch of very dark tissue in the inner half of the wall near the ascomatal opening. The exposed face of the broken upper wall is lined with a persistent palisade-like layer of thin-walled, pale, cylindric cells.
Paraphyses 1.5-2 µm diam., increasing in width suddenly to 6-10 µm at the knob-like apex, extending 10-15 µm beyond asci. Asci 140-185 x 11-14 µm, clavate-stipitate, tapering to small, rounded apex, wall undifferentiated at apex, 8-spored, spores confined to upper half of ascus, development of asci sequential. Ascospores 35-60 x 2.5-3.5 µm, apex rounded, tapering to base, bifusiform, with abrupt constriction to 1-1.5 µm diam. near centre, 0-1 septate, surrounded by a gelatinous sheath.
Conidiomata-like structures 0.2 mm diam., round in outline, pale brown with darker line around outside edge, subepidermal. In vertical section lenticular, upper wall lacking, lower wall 5-10 µm thick, of 1-3 rows of dark brown, thick-walled, angular cells. Conidiogenous cells and conidia not seen.
Habitat: Fallen leaves of Dacrycarpus dacrydioides, Knightia excelsa, and Nothofagus menziesii.
Notes: ETYMOLOGY: refers to geographic distribution of this species.
NOTES: The distinctive shape of the ascospores and of the paraphysis tips makes this an easy species to identify microscopically. It is the only species of Rhytismataceae known from Dacrycarpus, but it could be confused macroscopically with others on Nothofagus menziesii (e.g., Lophodermium medium Johnston) and Knightia excelsa (e.g., Lophodermium brunneolum Johnston).
The collection on Dacrycarpus had longer ascospores (45-60 µm) than all the other collections (35-45 µm). However, as this was the only morphological difference between the collections it is considered to represent variation within a single species.
The occurrence of one species on both conifer and angiosperm hosts is unusual in the Rhytismataceae. However, within New Zealand this kind of host distribution is also seen with the species Lophodermium agathidis and L. mahuianun (Johnston 1989a).