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Pollinator-mediated selection toward larger and abundant flowers is common in naturally pollen-limited populations. However, floral antagonists may counteract this effect, maintaining smaller-and few-flowered individuals within populations. We quantified pollinator and antagonist visit rates and determined a multiplicative female fitness component from attacked and non-attacked flowers of the Brazilian hummingbird-pollinated shrub Collaea cipoensis to determine the selective effects of pollinators and floral antagonists on flower size and number. We predicted that floral antagonists reduce the female fitness component and thus exert negative selective pressures on flower size and number, counteracting the positive effects of pollinators. Pollinators, mainly hummingbirds, comprised 4% of total floral visitation, whereas antagonist ants and bees accounted for 90% of visitation. Nectar-robbers involved about 99% of floral antagonist visit rates, whereas florivores comprised the remaining 1%. Larger and abundant flowers increased both pollinator and antagonist visit rates and the female fitness component significantly decreased in flowers attacked by nectar-robbers and florivores in comparison to non-attacked flowers. We detected that pollinators favored larger-and many-flowered individuals, whereas floral antagonists exerted negative selection on flower size and number. This study confirms that floral antagonists reduce female plant fitness and this pattern directly exerts negative selective pressures on flower size and number, counteracting pollinator-mediated selection on floral attractiveness traits.

The genus Collaea belongs to tribe Diocleae (Leguminosae subfamily Papilionoideae) and includes eight species from South America. A new species from South Brazil was discovered during a taxonomic revision of the genus and is formally described as Collaea caerulea. This species is found in a small area of Santa Catarina State, near the border with Paraná State, in regenerating secondary forests. It can be differentiated from other species from South Brazil by the combination of narrowly elliptical leaflets with an acuminate apex and bluish-lilac to bluish petals. The region where the species was discovered has only been recently explored by botanists and its natural vegetation is currently highly fragmented. Considering these factors, we propose that this species be classified as critically endangered. Here, we present a morphological description, geographical distribution, preliminary conservation assessment, and illustrations of the new species. We have also included an identification key for all Brazilian species of the genus.

Flowers may be interpreted as complex combinations of organs functionallycoordinated to attract pollinators and to mechanically interact with the pollinator?s body,particularly when flower mechanisms are actively handled by pollinators. Thus, a functional modularity of traits in keel flowers (Fabaceae) was expected because of a compartmentalization between attraction and mechanical functions. To test this hypothesis, we used Collaea argentina, a Fabaceae that exhibits typical keel flowers. The force needed to open keels, the keel displacement angle and floral morphometric traits in 100 plants from a natural population were measured to detect floral characters correlated with the biomechanical variables. Furthermore, we examined the relationships among this functional module, biomechanical variables and female reproductive success to explore whether these traits are the targets of pollinator?mediated phenotypic selection, and used path analysis to examine the causal relationship among these variables. A functional module formed by two morphometric traits of the petals directly involved in the floral mechanism (keel and wings) was found, but no flag trait was involved in this module. Even though the functional module had a positive effect on force and there were significant relationships between the displacement angle and fruit set, no significant effect of force on female reproductive success was detected. These results question whether selection currently plays a role favouring the integration of this module, but this may be consistent with a past stabilizing selection on the force needed to open the keel.

• Background and Aims A test was made of the hypothesis that papilionate legume flowers filter pollinators according to their ability to exert strength to open flowers to access rewards. In addition, interactions with pollen vectors were expected to explain the structural complexity of the architecture of these flowers since operative flower strength may be determined by a combination of morphological traits which form part of an intrafloral functional module. • Methods Six papilionate species were studied: Collaea argentina, Desmodium uncinatum, Galactia latisiliqua, Lathyrus odoratus, Spartium junceum and Tipuana tipu. Measurements were made of the strength needed to open keels and the strength that pollinators were capable of exerting. Morphological traits of all petals were also measured to determine which of them could be either mutually correlated or correlated with operative strength and moment of strength and participated in a functional module. • Key Results It was observed that pollinators were capable in all cases of exerting forces higher and often several times higher than that needed to access floral rewards, and no association could be detected between floral operative strength and strength exerted by the corresponding pollinators. On the other hand, strong and significant correlations were found among morphometric traits and, of these, with operative strength and moment. This was particularly evident among traits of the keel and the wings, presumably involved in the functioning of the floral moveable mechanism. • Conclusions Though visitors are often many times stronger than the operative strength of the flowers they pollinate, exceptionally weak bees such as Apis mellifera cannot open the strongest flowers. On the other hand, strong correlations among certain petal morphometric traits (particularly between the keel and wings) give support to the idea that an intrafloral module is associated with the functioning of the mechanism of these legume flowers. In addition, the highly significant correlations found across petals support the view of functional phenotypic integration transcending the ontogenetic organization of flower structure.

Some species belonging to the genera Galactia, Camptosema and Collaea from southern Brazil, Paraguay, Argentina, and Uruguay are grouped into a complex based on exomorphological affinities. The diagnostic morphological features sometimes overlap among species of different genera and dissimilar criteria have been adopted to delimit them, thus generating great taxonomic uncertainty. The aim of this work was to clarify the genetic relationships of the species within the complex as well as to analyze the infraspecific variability by means of analysing the AFLP band patterns. We examined 378 AFLP markers generated after amplification using six primer combinations. The monophyly of Collaea was supported, corroborating the present morphological classification. On the other hand, the results are not congruent with the current circumscription of Galactia and Camptosema, in agreement with previous phylogenetic hypotheses based on morphological characters and karyological studies, as both genera are polyphyletic.