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Page number:667 
Description type:Non-original description 
Description:Alternariaster helianthi (Hansford) E. G. Simmons, comb. nov. - MycoBank 505050
? Helminthosporium helianthi Hansford, Proc. Linn. Soc. London 155: 49. 1943. (Basionym) Type (holotype): IMI 5754 (Helianthus annuus, Kampala, Uganda, C. G. Hansford 910, March 1928; E.G.S. 27-072)
? Alternaria helianthi (Hansford) Tubaki & Nishihara, Trans. Brit. Mycol. Soc. 53: 148. 1969.
~ Embellisia helianthi (Hansford) Pidoplichko, Griby-Parazity Kul'turnykh Rastenii: Opredelitel', tom. 2, Griby Nesovershennye [Fungus Parasites of Cultivated Plants, v. 2, Fungi Imperfecti], p. 186. 1977. (Invalid; lacks reference to place of publication of basionym. ICBN Art. 33.3).
Host/substrate: Helianthus annuus L. (Compositae)
Manual basis: Alt.T&V 19 (fig. 33), Alt.T&V 192; representative isolate E.G.S. 36.007, CBS 119672
Culture at 50X, 5-7d, PCA : 1.5 cm diam, without growth rings; and V-8: colony 3 cm diam, with 4 pairs of narrow but well-defined concentric rings of growth and sporulation. Sporulation on cut agar surface: PCA ++, V-8 +++
The surface colony on PCA consists of an intricate web of branching hyphae that produce a dense turf of suberect, simple or branching conidiophores. Each primary conidiophore and each branch produces a single conidium. The dense mass of conidia almost conceals the underlying structures except at the advancing margin of short procumbent hyphae. All production of conidiophores and conidia in young colonies is on or very near the agar surface. There is no distinctly aerial component of hyphal development and sporulation. The colony and sporulation are much the same on V-8 agar, except that the conidium mass is even more dense and darker.
Sturdy conidiophores enlarge from a narrow base 3-4 µm diam to an apex and to subapical conidiogenous branches that gradually swell to a 6-8 µm width. The apical conidiogenous cell is scarcely differentiated from the conidiophore it terminates; it is neither abruptly swollen nor darker than cells beneath it. The apical conidiophore hilum and the basal conidium hilum are small and inconspicuous, though distinct and slightly darker than the surrounding walls. The kind of conspicuous internal, pigmented, circumhilar ring found so commonly in Alternaria conidia and conidiophores is not present in Alternariaster helianthi. Conidiophores are simple and relatively short or commonly 200-250 µm long overall and include 2-4+ fertile branches 40-80 µm long.
Juvenile conidia are narrow-ovoid with a blunt-conic apex, or ellipsoid with a broadly rounded apex. No conidium has a separately definable beak portion. Conidia sometimes produce germination hyphae in moist active cultures while still attached to a conidiophore, but only rarely does a conidium produce a short apical or lateral secondary conidiophore and a secondary conidium in young colonies under Manual conditions..
Fully developed conidia are ellipsoid, subcylindric, or broad-ovoid, and always have a broadly rounded base and apex. Largest conidia commonly reach a size range of 80-130(-160) x 18-23(-30) µm, with 7-10(-12) transverse septa and no longisepta, or with one longiseptum in 1(-4) of the transverse segments. The conidium body usually is moderately constricted by 5-6 to all of the transverse septa. Eusepta usually are well defined, though thin, weak, and not strongly pigmented. The conidium body color is subhyaline to a very dilute tan, becoming scarcely darker in the most mature conidia. There is no surface ornamentation.
The internal structure of conidia progresses through a condition of distoseptation to eventual euseptation of major transepta and the occasional longiseptum. In addition, conidia produced in culture develop an internal pattern of cytoplasmic partition that appears foam-like or as indistinct bubbles at 780X. This internal pattern appears not to evolve to a euseptate condition. The internal pattern of indistinct partition also is visible to a minor extent in conidia produced in nature. In addition, the lumen of each cell in mature field conidia is surrounded by a conspicuous, hyaline layer ca 1-2 µm thick, which separates it from neighboring eusepta and the outer wall.
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