Dichotomous key to European Biscogniauxia

           

Illustration of characters
Stromata applanate to slightly convex, with low margins A
Stromata more or less cupulate, with raised margins B
 
A1- Stromata purplish brown to grey, on Tilia. B. cinereolilacina
A1- Stromata black, host different A2
 
A2- Ascospores mostly hyaline, two-celled B. anceps
A2- Ascospores brown to dark brown, one-celled A3
 
A3- Ostioles coarsely papillate, conical; ascospores 15.5-21 x 7-10 Ám B. mediterranea
A3- Ostioles discoid to slightly papillate, ascospores shorter A4
 
A4- Restricted to Fagus sp.; ascospores 10-13 x 7.5-8.5 Ám. B. nummularia
A4- Restricted to Prunus sp.; ascospores 10.5-14.5 x 5-7 Ám B. granmoi

           

B1- Ostioles opening at the same level as the stromatal surface, discoid B2
B1- Ostioles opening higher than the stromatal surface, coarsely papillate B4
 
B2- Ascospores subglobose, dark brown, 13-16.5 x 9.5-13.5 Ám, with sigmoid germ slit; mostly on Rosaceae B. marginata
B2- Ascospores ellipsoid, brown, with straight germ slit B3
 
B3- Ascospores 13-17 x 5.5-6.5 Ám, with germ slit on one side; specific for Rhamnus catharticus B. simplicior
B3- Ascospores 9-14 x 4.5-6 Ám, with germ slit on both sides; mostly on Sorbus B. repanda
 
B4- Stromatal surface plane to slightly convex B. mediterranea
B4- Stromatal surface more or less concave B5
 
B5- Ascospores narrowly ellipsoid with germ slit on both sides, 9-14 x 4.5-6, mostly on Rosaceae B. repanda
B5- Ascospores broadly ellipsoid, larger B6
 
B6- Ascospores 15.5-21 x 10.5-13.5 Ám, with straight germ slit on one side; plurivorous, but mostly on Ulmus B. dennisii
B6- Ascospores 17-22 x 11-14 x 9-10 Ám, laterally compressed, with straight germ slit circular on narrow edges; known on Quercus B. querna