Forest Matrix Fosters High Similarity in Bee Composition Occurring on Isolated Outcrops Within Amazon Biome.

Most studies analyze fragmentation due to habitat loss caused by anthropogenic activities and few of them analyzed fragmentation on naturally fragmented areas. In the Eastern Amazon, it is possible to find areas naturally open and surrounded by pristine forest. Understanding how species respond to isolation in these areas is an important challenge for decision-making processes aiming conservation and restoration. Using standardized methods of bee collection (entomological nets, bait trap, pan trap, and nest trap), the objective of this study was to analyze the composition and diversity of bees occurring on six isolated outcrops located in two protected areas within Amazon biome. More specifically, we tested 1) if the dissimilarity in bee species composition is explained by the isolation of outcrops and 2) if bee richness, abundance, and Shannon diversity can be explained by the outcrop size. We found 118 species, with the Meliponini and Euglossini (Hymenoptera: Apidae) tribes representing the highest number of species. The similarity in species composition across all outcrops is high and is not explained by the isolation. In addition, the richness, abundance, and Shannon diversity are not explained by outcrop size. Forest does not seem to be a barrier to bee movement, and although most species probably nest in the forests, they use the highly diverse plants of the outcrops as a complementary food source.

A new group of species within the bee genus Ruizantheda, with a revised key to the males of the genus (Hymenoptera: Halictidae: Caenohalictini).

Males of the neotropical bee genus Ruizantheda Moure sensu lato (Halictinae: Caenohalictini) differ from those of other caenohalictine genera in having the outer gonostylar plate with a large membranous region that extends to the ventral region, and the ventral gonostylar lobe retrorse. These features permit the placement of six additional species described here, four of which are new, in the genus in this broader sense. The males of these six species share the following characteristics: profemur swollen; mesofemur exceedingly swollen; mesotibia slightly swollen with flat, minutely ridged ventral area and small apical tooth; S4 shortened medially, commonly largely hidden under S3, with transverse median depression and apical margin emarginate; apicolateral lobes of S4 with tuft of branched setae and stout, simple, recurved setae on margin; S5 with U-shaped gradulus and setal patch, sometimes inconspicuous; outer lateral expansion of penis valve bilobed, and median posterior margin of volsella strongly angulate. Together, these species constitute a new group within Ruizantheda and share with the previously known Ruizantheda inca Coelho, Felizardo, Engel, R. aerugineus Coelho, Felizardo, Engel, and R. kallos Coelho, Felizardo, Engel, a short outer gonostylar plate, terminating before the apex of the main gonostylar lobe as well as the presence of long setae on its dorsal surface. In other species of Ruizantheda the outer gonostylar plate extends beyond the apex of the main gonostylar lobe and lacks setae. The species comprising this distinctive subgroup of Ruizantheda, and treated herein, are: R. nigra n. sp., R. colombiana n. sp., R. venezuelana n. sp., R. baeri (Vachal) n. comb., R. pilosa n. sp., and R. gaullei (Vachal) n. comb. Two of the new species expand the distribution of the genus northward into Colombia and Venezuela. In addition to the description and illustration of the species, an updated key to the species of Ruizantheda s. l. is provided.

Three new species of the bee genus Ruizantheda sensu lato (Hymenoptera: Halictidae: Caenohalictina).

Males of Ruizantheda Moure sensu lato differ from males of other Caenohalictina in having the outer gonostylar plate with a large membranous region that extends to the ventral region, and the ventral gonostylus in the form of a retrorse lobe. These features permit the placement of three new species described here in the genus in this broader sense. However, despite having simple mandibles, they do not have the traits considered as apomorphies of Ruizantheda s. str. or Ruizantheda + Oragapostemon Cure by earlier authors, and neither do they possess features of Ruizanthedella Moure. Moreover, in the new species, the outer gonostylar plate is short, ending before the apex of the main gonostylar lobe and has long setae on its dorsal surface, while in other Ruizantheda, the outer gonostylar plate extends beyond the apex of the main gonostylar lobe and lacks setae. Additionally, two of the new species have a distribution different from those of most Ruizantheda-Ruizantheda inca n. sp. is found in Ancash, Peru and R. aerugineus n. sp. in the state of Minas Gerais, Brazil. Instead of including the three species in a new genus, we believe that it is more reasonable to maintain the status of Ruizantheda sensu Michener and until a new phylogenetic analysis of the entire subtribe, inclusive of the species newly established here, is completed. The three new species, known only by the male, are described and illustrated, and a key to the species of Ruizantheda s. l. is provided. The homologies between the gonostylar structures, mainly those related to the dorsal gonostylar process, of males of Ruizantheda, Caenohalictus Cameron, and Pseudagapostemon Schrottky are discussed.