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Remarks (internal):Type material of C. tenuissimum has been re-examined. Various collections of Cladosporium species hyperparasitic on rust fungi, deposited in herbaria under 'C. tenuissimum', have been examined and all of them prove to be identical with C. uredinicola. Sharma & Heather (1981, 1988) isolated C. tenuissimum and C. herbarum from Melampsora laricis-populina und M. medusae and examined the impact of these fungi on the epidemiology of their host fungi. Morphological data and illustrations have not been published, and cultures could not be traced, so that a verification of the identity of the fungi concerned was not possible. Moricca et al. (1999) dealt with cultures of 'C. tenuissimum' isolated from Cronartium flaccidum and Peridermium pini, and examined them morphologically and molecularly. The description is very close to C. uredinicola (conidiophores frequently geniculate-sinuous, and, compared with non-fungicolous samples of C. tenuissimum, relatively short and narrow, up to 300 µm long and 2-5 µm wide, occasionally branched, and conidiogenous cells also intercalary). Assante et al. (2004) selected one strain of C. tenuissimum out of the material studied by Moricca et al. (1999) and carried out detailed histological examinations by means of TEM. They found close interactions between Cladosporium hyphae and uredo-spores, indicating that the fungus examined was a true hyperparasite. It cannot be excluded that Moricca et al. (1999) and Assante et al. (2004) actually dealt with C. tenuissimum, but it is also possible that the fungus examined was confused with C. uredinicola. The cultures concerned should be morphologically re-examined, and the molecular data have to be compared with other data obtained from non-fungicolous samples.  
Description type:Non-original description 
Description:Cladosporium tenuissimum Cooke, Grevillea 6(40): 140 (1878).
Lectotype (selected here): on leaf sheets of Zea mays (Poaceae), USA, South Carolina, Aiken, H.W. Ravenel, Rav., F. amer. exs. 160 (NY). Isolectotypes: Rav., F. amer. exs. 160 (e.g., K).
Lit.: Saccardo (1886: 365), Oudemans (1919), Ellis (1976: 326), Ho et al. (1999: 140).
Ill.: Ellis (1976: 327, Fig. 245 A), Ho et al. (1999: 143, Figs 46-47).
Colonies greyish to dark brown, confluent, conidiophores erect, solitary or in loose tufts (visible at 10-50X), villose. Mycelium immersed; hyphae branched, 2-7 µm wide, septate, with constrictions at the septa, hyphal cells sometimes irregularly swollen, sometimes irregularly lobed, subhyaline to pale olivaceous-brown, hyphae giving rise to conidiophores darker, medium to dark brown, walls somewhat thickened. True stromata lacking. Conidiophores solitary or in loose groups, mostly two or three, arising from hyphae, on leaves and stems erumpent through the cuticle or emerging through stomata, erect, straight to slightly curved, subcylindrical, unbranched, 49-542(-800) ´ (3-)4-7 µm, at the base often wider, 9-17 µm, somewhat attenuated towards the tip, 3-13-septate, non-constricted at the septa, medium to dark brown, paler towards the tip, smooth, occasionally faintly rough-walled, wall somewhat thickened, but tips usually unthickened, occasionally with unilateral slight swellings. Conidiogenous cells integrated, terminal and intercalary, subcylindrical to subclavate, 27-76 µm long, polyblastic, with 2-5 conidiogenous loci, sympodially proliferating, conidiogenous loci conspicuous, protuberant, thickened and darkened, 1.5-2.5 µm wide. Ramo-conidia s. lat. subcylindrical, 15-31 ´ 4-5 µm, aseptate, basal hilum 2-3.5 µm wide. Conidia usually in branched chains, straight, variable, subglobose, ellipsoid-ovoid, limoniform, 3-13 ´ 2-6 µm, 0(-1)-septate, slightly or nonconstricted at the septa, pale olivaceous to olivaceous, smooth, occasionally faintly rough-walled, wall unthickened to slightly thickened, apex rounded or somewhat irregular by having up to 4 protuberant hila, base truncate to convex or often somewhat attenuated, hila thickened, darkened, 0.5-1.5(-2) µm wide, microcyclic conidiogenesis not observed.
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