PHYTOLOGIA BALCANICA 17 (3): 291 – 314, Sofia, 2011 291 Galium sect. Leiogalium (Rubiaceae) in the Bulgarian flora Minčo Ančev1 & Franz Krendl2 1 Department of Plant and Fungal Diversity and Resources, Institute of Biodiversity and Ecosystem Resarch, Bulgarian Academy of Sciences, Acad. Georgi Bonchev St., bl. 23, 1113 Sofia, Bulgaria, e-mail:
[email protected] 2 Botanische Abteilung, Naturhistorisches Museum Wien, Burgring 7, A 1010 Wien, Austria Received: June 06, 2011 Accepted: November 17, 2011 Abstract. The work contains the results from the investigation of morphological variation, chromosome numbers and ploidy levels, distribution, phytogeographic and phylogenetic relationships of the species of genus Galium sect. Leiogalium, occuring on the territory of Bulgaria. The section includes 18 species and two non-nominal subspecies. Morphologically, phytogeographically and supposedly phylogenetically related species are divided into five species groups. The species are cross-pollinated entomophilous plants, which reproduce sexually and vegetatively by underground runners.The mesophilous species with white flowers, G. album, G. intermedium, G. lucidum, G. pashale, and G. procurrens, are pollinated chiefly by flies of Syrphidae, Muscidae and Larvivoridae. The xerophilous G. aegeum, G. mirum, G. asparagifolium, G. flavescens, G. rhodopeum with pale yellowish to greenish corolla are visited mostly by small coleopterans of the genera Strangalia, Agriotes, Mordelis, etc. Six species are Balkan endemics: G. mirum, G. macedonicum, G. rigidifolium, G. rhodopeum, G. aegeum and G. procurrens. Galium velenovskyi is a local endemic, restricted in its occurence to the calcareous slopes of E Rhodopi Mts. The chromosome numbers and the ploidy levels of 18 species and two subspecies studied in 95 populations are reported in the article.