Cronartium myricae P. Zhao, X. Qi, & L. Cai, sp. nov.,
MycoBank number: MB 842421; Index Fungorum number: IF 842421; Facesoffungi number: FoF 12570;
Spermogonia and aecia not found. Uredinia hypophyllous, 0.2–0.5 mm, not apparently forming columns on leaves, urediniospores ovoid or ellipsoid, 18–30 × 15–20 µm, wall echinulate, with apparent smooth regions, germ pores mostly scattered, inconspicuous, ostiolar cells apparent, erumpent on leaf surface, forced up to dome. Telia with hair-like columns, 0.7–1.0 mm long, straight or slight curved, bright yellow, teliospores oblong, 30–51 × 12–17 µm, catenulate, wall colorless, 0.5–1.3 µm thick, without surface ornamentation.
Material examined: China, Hubei, Shennongjia, III on Myrica gale, 9 Sept 1984, L. Guo, MICH253505 (holotype); Canada, British Columbia, II, III on Myrica gale, 20 Oct 1927, Partington, FLAS-F-24498; Canada, Ontario, II, III on Myrica gale, 6 Aug 1956, R.F. Cain, NYBG449422; Canada, Ontario, II, III on Myrica gale, 17 Sept, 1957, R.F. Cain, NYBG449415; USA, Connecticut, II, III on Myrica sp., 15 Aug 1887, A.B. Seymour, FLAS-F-07017; USA, Michigan, II, III on Myrica asplenifolia, 12 Aug 1922, D.V. Baxter, MICH253485; USA, Maine, II, III on Myrica gale, 12 Oct 1900, P.L. Ricker, FLAS-F-07016; USA, New Hampshire, II, III on Myrica asplenifolia, 1 Sept 1891, W.G. Farlow, HMAS43576; USA, New Hampshire, II, III on Myrica sp., Sept 1891, W.G. Farlow, HKAS35062; USA, Wisconsin, III on Myrica asplenifolia, 31 Aug 1919, J.J. Davis, ISC351966 (ISC-F-0068287).
Distribution: Canada, China, USA.
Sequence data: SSU: OM745996; ITS: OM746428; LSU: OM746593; CO3: OM721419 (holotype).
Notes: In the phylogenetic tree, C. myricae formed an independent clade close to C. mongolicum and C. orientale. Morphologically, it differs from two species in the ornamentation and dimension of urediniospores and teliospores. Previously, C. flaccidum (syn. C. asclepiadeum) was reported on Myricales species (Peterson 1973), but C. myricae was phylogenetically distinct from C. flaccidum. Moreover, it is morphologically distinct in its uredinia with apparent ostiolar cells and urediniospores with smooth regions. The rust fungus on three Myrica species (i.e., M. asplenifolia, M. californica and M. gale) was previously recognized as C. comptoniae, however, our research revealed that C. myricae on Myrica species was phylogenetically distinct from C. comptoniae. Morphologically, C. myricae differs from C. comptoniae in its uredinial morphology.
Fig. 4. Cronartium myricae (holotype). a. Hypophyllous uredinia and telia on Myrica gale; b. Uredinia with apparent ostiolar cells; c. Urediniospores with smooth regions; d. hair-like telia observed by SEM. Scale bars: b = 200 µm; c = 20 µm; d = 200 µm.