Astragalus nurhakdagensis (sect. Hololeuce Bunge / Fabaceae), a new species from Turkey.

Astragalus nurhakdagensis, a new species from the south of Turkey was described, illustrated, and compared to the closest taxa Astragalus hirsutus, A. dumanii and A. cataonicus from which it is set apart by a longer calyx length (13-14 mm) and calyx teeth (7-9 mm, longer than tube), white corolla colour, longer bracts (13-15 mm) and black hairy stripes below the stem nodes. In A. hirsutus, the calyx length (6-10 mm) and calyx teeth are much smaller (2-3 mm long, shorter than tube), with yellow corolla colour and without black hairy stripes. It also differs from A. dumanii with its longer stipules 9-13 mm (not 5-8 mm), bracts 13-15 mm (not 4-6 mm), calyx length 13-14 mm (not 7-10 mm) and calyx teeth 7-9 mm (not 2-4 mm), and also with spreading hairs (not adpressed) on the calyx and 7-9 pairs of leaflets (not 3-7 pairs). It is also differentiated from A. cataonicus with a white corolla colour (not lilac to pink), longer stipule 9-13 mm (not 5-7 mm), bracts 13-15 mm (not 6-12 mm), and longer calyx teeth 7-9 mm (not 5-7 mm). Prolate (A. nurhakdagensis, A. hirsutus and A. cataonicus) and subprolate (A. dumanii) shapes were determined in the tricolporate pollen grains. Perforate, granulate, and reticulate ornamentation types were observed in the pollen grains in SEM. The seed shapes were reniform-globose in A. nurhakdagensis and A. dumanii, whereas they were reniform in A. hirsutus and A. cataonicus. Surface ornamentation of the seeds differed slightly: rugulate in A. nurhakdagensis and A. hirsutus, reticulate-rugulate in A. dumanii and reticulate-striate in A. cataonicus. Taxonomic description, micrographs of seeds and pollen surfaces and geographical distribution of the new species were provided. Conservation status was discussed. [ABSTRACT FROM AUTHOR]