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Remarks (internal):Literature records and herbarium specimens 2) reveal that several described species are synonymous with A. crocea. These include: Rhinotyichum fulvum BERK. & CURT. in BERK., Grevillea 3: 108, 1875; Allescheriella uredinoides P. HENN. in Hedwigia 36: 244, 1897; Coccospora sinensis TEND in Sinensia 7: 782, 1936; and Oidium simile sensu LINDER in Lloydia 5: 175, 1942, non O. simile BERK. in J. Bot. 4: 310, 1845. C. sinensis was placed in synonymy with A. crocea by DAMON & DOWNING (1954). CLEMENTS & SHEAR (1931) included Allescheriella P. HENN. as synonymous with Coccospora WALLR. in the family Tuberculariaceae of the order Moniliales.
According to TUBAKI (1963), the conidia of Allescheriella are formed as solitary aleuriospores, which terminate the hyphal branches on which they are produced. Only a single aleuriospore is formed at the apex of a particular hyphal branch, so the branch tips do not become annellate. Some of the conidia of A. crocea may become unusually long and slender, as illustrated by HUGHES (1951a, Fig. 1). Conidia of this shape are rare in specimens available from Mississippi, but they are abundant in a Chinese collection that TENG determined as C. sinensis.
The contrast between the thick wall and the thin basal septum of a conidium of A. crocea is significant when compared with the uniform thickness of the spore covering of Oidium simile BERK., non sensu LINDER, with which A. crocea may be confused. In addition, as noted by LINDER (1942), a short length of the subtending sporiferous hyphal cell of A. crocea may remain attached at the base of the conidium when the conidium breaks loose from the conidiophore. Hyphal tags are not found on dislodged conidia of O. simile.
When thick walled conidia of A. crocea are broken, as illustrated in microscopic preparations of a specimen from Alabama, the spore contents may partially or entirely extrude. In such instances, the protoplasmic mass is bounded by a very thin, colorless, flexible membrane. Phloxine stain does not penetrate the thick outer wall of an unbroken spore but passes easily through the inner membrane of a broken spore and stains the cytoplasm. The double spore wall of A. crocea previously was noted by HUGHES (1951a), but he did not mention the contrast in staining characteristics between intact and broken spores.
Broad subicular hyphae with relatively numerous H-branches are characteristic of A. crocea. Hyphae of the basal subiculum are notably broader than the conidiophores. In one specimen from Mississippi, as contrasted with the five other collections that were examined, subicular hyphae were not limited to the region beneath the conidiophores. Instead, they spread over much of the small piece of substratum, where they formed a thin Light Buff subiculum somewhat less compact than that beneath the conidiophores. The hyphae of this diffused subiculum were, in every respect, anatomically identical with those from which the conidiophores originated.
In various areas of the subiculum of the specimen from Mississippi, basidia of a Botryobasidium subgenus Brevibasidium developed from exactly the same kind of hyphae that bore the conidiophores of A. crocea. No such basidial stage was found in association with any other specimen of A. crocea, but several species of Brevibasidium are known to have genetical connections with conidial fungi more or less similar to A. crocea. Usually these conidial fungi are referred to Oidium sensu LINDER (or Rhinotrichum). According to ERIKSSON (1958), "All hitherto established connections of Botryobasidium with imperfect states (genus Oidium) refer to species of Brevibasidium".
A. crocea apparently is more or less restricted to tropical and subtropical regions, and the majority of collections are from the American tropics. In the United States collections have been recorded from North and South Carolina, Alabama, and Louisiana (cf. LINDER, 1942; HUGHES, 1951a). The preceding formal description was based primarily on a specimen collected at Huntington Point, near Greenville, Mississippi, F.P. 110394. This collection also is the one that bears the basidia of Brevibasidium. Additional collections from Mississippi are from Stoneville, F.P. 110111, and from Catfish Point, near Greenville, F.P. 110465. These are the first recorded collections from Mississippi. Additional specimens of A. crocea on file in the National Fungus Collections include one as A. uredinoides, R. P. BURKE 138, Montgomery, Alabama; another as A. uredinoides, E. ULE in Appendix Mycol. Brasil. 36; and a third as Coccospora sinensis, S. Q. DENG 711, det S. C. TEND 6086, Loping, Kiangsi, China. LINDER (1942) listed a collection from Ohio, but that collection is the type of Oidium simile BERK., non sensu LINDER. According to HUGHES (1951a), the concept of O. simile that LINDER published does not agree with the morphology of the collection from Ohio, but he says that it does agree with A. crocea. The true O. simile BERK. has conidia formed in chains and is most commonly found in temperate areas of North America.
Description type:Non-original description 
Description:Allescheriella crocea (Figs. 1 A; 2, A-C) Allescheriella crocea (MONT.) HUGHES, in BAKER & DALE, Kew Mycol. Papers 33: 97, 1950.
Conidial fructifications (Fig. IA) originating as thin, compact aggregations of whitish subiculum, then developing as minute conidiiferous cushions, spreading and becoming confluent as effuse plaques a few millimeters in extent, or forming colonial aggregations of many gregarious cushions; fertile areas becoming ochraceous, then reddish brown, eventually Mahogany Red 1) or Burnt Sienna; underlying subicular mass remaining pale, commonly obscured by the densely colored covering of conidia, or remaining visible at the margins.
Hyphae of the subicular interior (Fig. 2A) interwoven and more or less prostrate, in some instances becoming laterally joined in strands, branching profusely and at broad angles, forming abundant H-branches, septate, thin walled or with walls as much as 1 µm thick, usually colorless, yellowish, or yellowish olive, or more deeply colored near the substratum, (4-)7.5-9(-11) a in diameter.
Conidiophores (Fig. 2B) developing at superficial levels of the subiculum as erect, unbranched or sparsely branched hyphae, septate, thin walled, characteristically colorless, relatively uniform in diameter or gradually tapering distally, 3-5 µm in diameter.
Conidia (Fig. 2C) developing singly on conidiophores as blownout protrusions from the apices of main axes or branches or along the sides of main axes, where each conidium characteristically originates as a ballooning outgrowth from the side wall of the conidiophore just below the apex of the particular conidiophore cell from which it develops, eventually forming a basal septum and broadening to become globose, obovoid, pyriform, or inversely flask shaped, smooth, non-septate, originally thin walled and pale, remaining very thin and pale at the basal septum, but elsewhere attaining a thickness of as much as 2.25 µm, becoming yellow and eventually reddish brown, with numerous perpendicularly-oriented indistinct internal striations extending from the inner surface of the wall nearly or entirely to the outer surface, conidial contents commonly including spherical oily globules, conidia (14-)20-28(-31) x (9-)11-18(-21) µm.
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