Cronartium floridanum (Hedgc. & G. Hahn) P. Zhao & L. Cai. comb. nov.,
MycoBank number: MB 842418; Index Fungorum number: IF 842418; Facesoffungi number: FoF 00010;
Basionym – Peridermium floridanum Hedgc. & G. Hahn, Mycologia 12(4): 194. 1920.
Spermogonia not found. Aecia caulicolous, erumpent from the bark, on trunks or branches, 1.0–4.5 mm long, peridia flattened laterally, rupturing longitudinally at the apex, peridial cells ellipsoid, ovoid, rhomboid, 31–74 × 16–34 µm, cell walls about 4–8 µm thick, verrucose, aeciospores ellipsoid or obovoid, 18–38 × 10–23 µm, walls 1.5–4 µm thick, most of their surface verrucose, warts annulate, 1–2 annuli, cylindrical. Uredinia and telia not found.
Material examined: USA, Florida, 0, I on P. palustris, 6 Nov. 1896, P.H. Rolfs, FLAS-F-05303; USA, Florida, 0, I on P. palustris, date and collector unknown, FLAS-F-04914; USA, Florida, 0, I on P. palustris, date unknown, S.M. Tracy, MICH300092; USA, Florida, 0, I on P. palustris, date unknown, G.G. Hedgcock, MICH299992.
Sequence data: SSU: OM745976; ITS: OM746408; LSU: OM746576; CO3: OM721401 (MICH299992).
Notes: Cronartium floridanum was first reported (as Per. floridanum) on P. palustris in Florida, USA (Hedgcock et al. 1920). In this study, several specimens of P. palustris fitted well with the morphological description of Per. floridanum, and they clustered together within Cronartium clade. Our phylogenetic results confirmed Per. floridanum to be a member of Cronartium, thus we propose the new combination.
To date, three Cronartium species (i.e., C. cerebrum, C. quercuum, C. strobilinum) have been reported on P. palustris (Hiratsuka 1995). Cronartium floridanum differs from C. cerebrum in the length of the peridial cell (31–74 µm vs 35–50 µm, Peterson 1967) and the dimension of aeciospores (18–38 × 10–23 µm vs 26–28 × 17–20 µm, Peterson 1967); from C. quercuum in shape and dimension of peridial cells (31–74 × 16–34 µm vs 32–57 × 12–22 µm); from C. strobilinum in the dimension of peridial cells (31–74 × 16–34 µm vs 21–52 × 11–23 µm) and the shape of aeciospores.