A taxonomic study of Melanelixia fuliginosa in Europe

For a long time it has been discussed as to whether Melanelixia fuliginosa comprises one or two species: one darker, mainly saxicolous, and one lighter, mainly corticolous. To settle the question, a morphometric and a molecular analysis were carried out and analyzed using a principal component analysis (PCA). The morphometric analysis indicates a differentiation in several characters between material previously recognized as subspecies fuliginosa and glabratula, but also a considerable overlap in some of them. The molecular analysis of the nrITS DNA gene reveals a clear division of the taxa. Specimens belonging to Melanelia fuliginosa fall out in two different clades, which have good bootstrap support, corresponding to the subspecies fuliginosa and glabratula. Accordingly, we propose that the subspecies should be acknowledged as separate species, Melanelixia fuliginosa (Fr. ex Duby) O. Blanco et al. and Melanelixia glabratula (Lamy) Sandler & Arup

Pollination ecology of Desmodium setigerum (Fabaceae) in Uganda; do big bees do it better?

Explosive pollen release is documented in many plant families, including the Fabaceae. Desmodium setigerum E. Mey (Fabaceae) is a perennial herb with single trip explosive pollen release found in eastern Africa, and the unique ability to reverse floral colour change if insufficient pollination has occurred. However, little else is known about the pollination ecology of this species, what visitors can trigger explosive pollen release, and whether bee body size is related to pollination efficiency. We investigated: 1) the breeding system of D. setigerum, and whether it is pollen limited; 2) whether flowers are visited early in the day allowing sufficient time for a second opportunity for pollination; and 3) what insect species visit D. setigerum and the relative efficacy of different flower visitors in relation to visitor size and pollination success. We found that although self-compatible, D. setigerum requires insect visitation to set seed as explosive pollen release is needed even for selfing. Most flowers are initially visited before 1400h, and by 1800h nearly all flowers have been tripped. Flowers were not pollen limited in this study, and were visited primarily by bees. We observed 16 visiting species, and there was a wide variation (0-404 grains) in the amount of pollen deposited on stigmas. Although almost all bees deposited some pollen, the mean number of pollen grains deposited in a single visit per species was negatively related to body size. However, one particular megachilid species deposited significantly more pollen grains than any other visitor and so is likely an important pollinator of this species. This provides insights into the pollination biology of this unique plant species, and adds to increasing literature on the relationships between bee body size, explosive pollen release and pollination effectiveness