• Geometric morphometrics
• Lentibulariaceae
• phylogenetic network
• quadrifid glands

Utricularia is a genus of carnivorous plants catching its preys using small traps. In Europe, seven aquatic species occur. They rarely flower and the species identification, using only vegetative parts, is difficult. Except flowers, according to literature, teeth on the lateral margin of the ultimate leaf segments should discriminate U. australis from U. vulgaris (“U. vulgaris aggregate”). Concerning U. intermedia/U. ochroleuca/U. stygia complex (“U. intermedia aggregate”), the number of teeth on the leaf margin, the ultimate leaf segment apex shape and the quadrifid gland features are considered crucial for species distinction. However, the reliability of these features has never been tested from a quantitative and statistical perspective. About quadrifid glands inside traps, previous authors stated that all the Scandinavian species might be distinguished by their features. The present study was focused on morphological and geometric morphometric investigations in order to quantitatively test the reliability of the features of vegetative parts reported as diagnostic in literature. Also, molecular analysis were performed to the search for DNA barcodes and to reconstruct the phylogenetic relationships, using nuclear ITS and plastidial trnL-F IGS and rps16 intron markers. Some morphological characters revealed to be potentially useful for species discrimination (e.g. teeth on leaf margin in U. intermedia aggregate), while others resulted unreliable. Morphometric analysis of the quadrifid glands was not able to discriminate between the whole set of species, but may be diagnostic for species in U. intermedia aggregate. Generally, Barcoding approach failed to discriminate species, even if it could be of some help in U. minor aggregate. Indeed, with few exceptions, U. bremii shows peculiar DNA regions different from U. minor for both plastidial markers investigated. However, interesting hypotheses could be derived from phylogenetic networks and trees obtained, including hybridization events to explain the rise of the mostly sterile species, such as U. stygia. This species clusters with the other species of U. intermedia aggregate in plastidial phylogenies, while it is closely related to species of U. minor aggregate in ITS phylogeny. Also U. ochroleuca shows some incongruences considering the different markers, at least for some accessions, pointing to the possible occurrence of hybrids.