Rhizosphaera L. Mangin & Har., Bull. Soc. mycol. Fr. 23(1): 56 (1907)
Index Fungorum Number: IF 9728; Facesoffungi Number: FoF 11111
Note – Rhizosphaera species occur on conifers and are produced characteristically within the stomata. The defining characteristics of the genus, especially the production of conidia from the tips of inner hyphae, were described in detail by Kobayashi (1967). Gourbie’re & Morelet (1980) made an important contribution by dealing with the types of wall structures exhibited by Rhizosphaera species. According to the developmental patterns presented by Gourbie’re & Morelet, R. pseudotsugae belongs to a type possessing primitive, mainly acellular wall structure, the wall, in this case, being replaced by an amorphous coat more or less firmly attached to the outer cells of the inner hyphae. The identification of different Rhizosphaera species is based mainly on conidial size (Sutton 1980), and this characteristic is well suited for defining R. pseudotsugae as a separate species.
Key to Rhizosphaera species
1 Conidia 5–7¬2±5–3 µm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .kalkhoffii
Conidia “8 µm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .2
2(1) Conidia up to 13 µm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Conidia “13 µm long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
3(2) Conidia 4–5±5 µm wide …………………………………………………. pseudotsugae
Conidia 6±5–8 µm wide …………………………………………………….. oudemansii
4(2) Conidia globose, 16–22¬16–20 µm …………………………………….. macrospora
Conidia elliptical or ovoid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
5(4) Conidia elliptical, rounded at both ends, 17–25¬7–10 µm. . . . . . . . . . . . . pini
Conidia ovoid, truncate at the base, 20–36¬8–12 µm……………….. kobayashii
Species
Rhizosphaera abietis