Are shoots of diagnostic value in Central European bladderworts (<i>Utricularia</i> L., Lentibulariaceae)?

2018-02-13T05:00:24Z (GMT) by G. Astuti L. Peruzzi
<p>In central Europe, seven native species of <i>Utricularia</i> occur, mainly distinguished by flower features. They can be subdivided in three aggregates according to shoot morphology: (1) <i>Utricularia intermedia</i> aggr., also comprising <i>Utricularia ochroleuca</i> and <i>Utricularia stygia</i>, (2) <i>Utricularia vulgaris</i> aggr., also comprising <i>Utricularia australis</i> and (3) <i>Utricularia minor</i> aggr., also comprising <i>Utricularia bremii</i>. We tested some shoot features as identification tools and investigated quadrifid digestive glands in all the studied species, using geometric morphometrics. For <i>U. intermedia</i> aggr., in most cases, the tooth number per ultimate leaf segment may be diagnostic. The three species of this aggregate overlap in terms of gland shape, but averaging measurements by traps and individuals, a decrease of overlapping among species was found. The shape and the centroid size of quadrifid glands in <i>U. minor</i> aggr. is unsuitable for discriminating species. Concerning <i>U. vulgaris</i> aggr., <i>U. vulgaris</i> bears a higher ratio of setula length to tooth length than <i>U. australis</i> (which is more toothed). This feature may help to distinguish species, but conflicting results were found in one studied population. The relevance of quadrifid gland features as identification tool and the puzzling systematic circumscriptions of the target species are discussed.</p>