Cryptosphaeria nigrescens Lar.N. Vassiljeva & H.X. Ma, 2014

Vasilyeva, Larissa & Ma, Haixia, 2014, Diatrypaceous fungi in north-eastern China. 1. Cryptosphaeria and Diatrype, Phytotaxa 186 (5), pp. 261-270 : 262-264

Cryptosphaeria nigrescens Lar.N. Vassiljeva & H.X. Ma , sp. nov. ( Figs. 3 , 16 ) MB 809638

Type:— CHINA. Jilin Province: Changbai Mountain National Nature Reserve, Huangsongpu area , on dead branch of Populus davidiana Dode , 27 August 2013, L. Vasilyeva, VLA P-2801, holotype !

Differs from Cryptosphaeria lygniota mostly in prominent and furrowed ostioles and slightly wider ascospores.

Stromata immersed in bark, inflated and blackened, irregular, widely effused or spot-shaped, surrounded by a black line deeply in the back, recognized by the crowded and separately emerging tops of short perithecial beaks (ostioles) which are prominent, black and furrowed, up to 300 µm diam.; perithecia monostichous or distichous, scattered or aggregated, singly erumpent, 300–400 µm diam. Asci cylindrical, paraphysate, 45–55 × 9–11 µm in spore bearing part, stalks of different length, containing 8 biseriate or conglobate ascospores, apical ring tiny and non-amyloid. Ascospores one-celled, allantoid or almost straight and ellipsopid, slightly greenish, (7.5–)8–10 × 2.5–3 µm.

Etymology:—Refers the blackening appearance of stromata.

This species seems to be restricted to the area around the Sea of Japan (north-eastern provinces of China, south of eastern Russia). It is more common in the south of the Russian Far East than Cryptosphaeria lygniota , but its concept was not very clear so far, so all the relevant specimens were identified as C. lygniota ( Vasilyeva 1998) . The key to Cryptosphaeria species (l.c., p. 115) divides species into groups with 1) large and cross-shaped, 2) prominent and furrowed and 3) small integrated ostioles, and the group of specimens under the name ‘ C. lygniota ’ was assigned to the second group, although this feature does not suit C. lygniota and characterizes C. nigrescens ( Fig. 3 ). The problems of differentiation of two species were mostly associated with the fact that young specimens of C. nigrescens have ostioles comparable with those in C. lygniota , so there was an impression of transition between the two forms without definite borderline. In addition, the length of ascospores of two species lies in the same range of variability, although ascospores of C. nigrescens are slightly wider (cf. Figs. 15 and 16 ).

Figures

FIGURES. 1–5. Surface of stromata of Cryptosphaeria species: 1. C. exornata. 2. C. eunomia. 3. C. nigrescens. 4. C. ligniota. 5. C.venusta. Scale bars: 1 = 1,4 mm; 2–5 = 1 mm.

FIGURES. 14–22. Ascospores Cryptosphaeria and Diatrype species: 14. C. exornata. 15. C. ligniota. 16. C. nigrescens. 17. C. venusta. 18. D. hypoxyloides. 19. D. platystoma. 20. D. stigma. 21. D. subundulata. 22. D. undulata. Scale bars: 14, 15, 20 = 3.5 µm, 16, 18, 21, 22 = 4 µm, 19 = 5 µm, 17 = 6 µm.