Chrysomyxa diebuensis C. J. You & J. Cao, 2017

Cao, Jing, Tian, Cheng-Ming, Liang, Ying-Mei & You, Chong-Juan, 2017, Two new Chrysomyxa rust species on the endemic plant, Picea asperata in western China, and expanded description of C. succinea, Phytotaxa 292 (3), pp. 218-230 : 221-222

Chrysomyxa diebuensis C. J. You & J. Cao , sp. nov. ( Fig. 1 )

MycoBank no.:—MB819569

Etymology:— diebuensis , referring to the location of the type specimen.

Diagnosis:— Chrysomyxa diebuensis differs from all other Chrysomyxa species on Picea in possessing aeciospores with nailhead to peltate processes and larger spores.

Type:— CHINA. Gansu Province: Diebu County, on Picea asperata Mast. ( Pinaceae ), 9 August 2012, coll. Y.M. Liang & T. Yang (Holotype: BJFC-R00556). Gansu Province: Diebu County, I on Picea asperata Mast. ( Pinaceae ), 9 August 2012, coll. Y.M. Liang &T. Yang (Paratype: BJFC-R00220).

Spermogonia, uredinia and telia unknown.

Aecia discrete, not confluent, tubular or tongue-like. Aeciospores yellowish or orange, globoid, subgloboid, ellipsoid, or slightly ovoid, 27–43 × 22–33 μm, with wall 4.5 μm thick ( Figs 1A, 1B ), nailhead or peltate ornamentation, 0.3–0.6 μm in height, 0.8–1.2 μm in width, with flat, smooth and broad heads ( Figs 1C, 1D ). Aecial peridium persistent, cells overlapping, round, square, or polygonal, outer surface shallowly concave, coarsely striate, inner surface flat or slightly convex, densely warted ( Figs 1E, 1F ).

Notes:— Chrysomyxa diebuensis can be distinguished from the other five Chrysomyxa species producing aecial stage on spruce needle, except for C. qilianensis in its unique nailhead to peltate processes on aeciospores surface. Most other Chrysomyxa species have aeciospores with annulate warts on spore surface ( Table 2). Furthermore, the peridial cells of C. diebuensis are remarkably different to those of some known Chrysomyxa species ( Figs 1C, 1D ).

Chrysomyxa qilianensis was described first by Wang et al. in 1987, which is one of the most prevalent Chrysomyxa species on P. crassifolia in China ( Zhang 2005, Liu & Nan 2011). It is characterized by densely verrucose aeciospores, with single central spine arised frequently from an individual flat columnar verruca ( Figs 3C, 3D ). Chrysomyxa diebuensis is distinct in aeciospore morphology from C. qilianensis . The aeciospores of C. diebuensis are larger (27–43 × 22–33 μm) ( Figs 1A, B ) than those of C. qilianensis (26–34 × 17–24 μm) ( Fig. 3B ). SEM clearly demonstrates the morphological differences, especially of the aeciospore surface ornamentation and peridial cells shape. The processes of C. diebuensis aeciospores are nailhead to peltate, without the central spine supported on peltate base, and the peridial cells are round or square, which are remarkably distinct from the rectangular cells of C. qilianensis ( Figs 3E, 3F ).

Figures

FIGURE 1. Chrysomyxa diebuensis (BJFC-R00556, holotype). A. Aeciospores observed by LM. B. Aeciospores observed by SEM. C. Surface ornamentation of single aeciospores. D. Aeciospores with nailhead processes surface. E. Aecial peridium with coarsely striate outer surface. F. Aecial peridium with warted inner surface. Scale bars: A = 30um; B = 20 μm; C= 10um; D = 2 μm; E and F = 10 μm.

FIGURE 3. Chrysomyxa qilianensis (HMAS-52077, holotype). A. Infected needles of P. crassifolia with aecia. B. Aeciospores observed by LM. C. Aeciospores observed by SEM. D. Aeciospores with single echinae on peltate base. E. Aecial peridium with coarsely striate outer surface. F. Aecial peridium with warted inner surface. Scale bars: A = 100um; B = 30 μm; C = 10um; D and E = 10μm; F = 10 μm.