Diversity and biological traits of bees visiting flowers of Cucurbita maxima var. zapallito differ between biodiversity-based and conventional management practices.

Low diversity of pollinators and the modified composition of functional groups of bees have been proposed as the causes of pollination deficiency in cultivated Cucurbitaceae species. Functional groups of bees are determined by traits, such as body size, nesting site, and social behavior. The presence of bees with specific traits can be differentially affected by agricultural management practices. This work aimed to assess how management types (agroecological and conventional) in Cucurbita maxima var. zapallito crops affect the abundance of bees with different biological traits. The study was conducted on four farms located in horticultural areas of central-eastern Santa Fe province, Argentina. A total of 108 10-min censuses were conducted to record bee species abundance in flowers. The species were assigned to categories for each of the three biological traits. A total of 552 individuals, belonging to 16 bee species, were recorded. Honey bees were more abundant under conventional management, whereas the native bees Eucera fervens and other species were more abundant under agroecological management. Species of the categories analyzed (body size: small, medium, and large; nesting site: above-ground cavities or ground-nesting; and social behavior: solitary or social) were present on farms under both management types. We found that management type affected bees, and their effects differed among bees with specific biological traits. Medium-sized and small bees, ground-nesting bees, and solitary bees were found in greater abundance on agroecological farms than on conventional farms. Our data allowed us to explain the diversity and abundance of bees relative to the management type and biological traits of the species. Implications for insect conservation: This study suggests that incorporating biodiversity-based management strategies might increase abundance and richness of native bees with different biological traits, ensuring the free pollination service they provide and a taxonomically and functionally diverse assemblage.

DNA barcoding as a useful tool in the systematic study of wild bees of the tribe Augochlorini (Hymenoptera: Halictidae).

Special care is needed in the delimitation and identification of halictid bee species, which are renowned for being morphologically monotonous. Corynura Spinola and Halictillus Moure (Halictidae: Augochlorini) contain species that are key elements in southern South American ecosystems. These bees are very difficult to identify due to close morphological similarity among species and high sexual dimorphism. We analyzed 170 barcode-compliant COI sequences from 19 species. DNA barcodes were useful to confirm gender associations and to detect two new cryptic species. Interspecific distances were significantly higher than those reported for other bees. Maximum intraspecific divergence was less than 1% in 14 species. Barcode index numbers (BINs) were useful to identify putative species that need further study. More than one BIN was assigned to five species. The name Corynura patagonica (Cockerell) probably refers to two cryptic species. The results suggest that Corynura and Halictillus species can be identified using DNA barcodes. The sequences of the species included in this study can be used as a reference to assess the identification of unknown specimens. This study provides additional support for the use of DNA barcodes in bee taxonomy and the identification of specimens, which is particularly relevant in insects of ecological importance such as pollinators.

Second species of Augochlorodes (Hymenoptera: Halictidae: Augochlorini) with known males and first record for the genus in Argentina.

The bee genus Augochlorodes Moure, up to now only known from Brazil, is recorded for the first time for Argentina. Augochlorodes politus Gonçalves & Melo was found in the south of the province of Buenos Aires, mideastern Argentina, being the southernmost record for the genus. The female of A. politus is redescribed and the male described for the first time, being the second male known for this genus. The phylogenetic position of Augochlorodes among Augochlorini is briefly discussed.

Revision of the species of the bee genus Caenohalictus (Hymenoptera: Halictidae) occurring in Argentinean Patagonia.

The species of the halictid bee genus Caenohalictus Cameron occurring in Argentinean Patagonia are revised. Eight species are recognized, one of them here described as new: Caenohalictus flammeus n. sp. The female of C. turquesa Rojas & Toro 2000 is described for the first time. Pseudagapostemon babuarus Jörgensen 1912, based on the male holotype, is synonymized under Augochlora (Pseudaugochloropsis) thamyris Jörgensen 1912, based on the female lectotype. Lectotypes are designated for Augochlora (Pseudaugochloropsis) thamyris Jörgensen 1912 and Halictomorpha autumnalis Jörgensen 1912. Caenohalictus cyanopygus Rojas & Toro 2000, C. galletue Rojas & Toro 2000, C. iodurus (Vachal 1903), C. opaciceps (Friese 1916), and C. turquesa Rojas & Toro 2000, all known from Chile, are cited for Argentina for the first time. Notes on the variation observed within species, images of diagnostic structures, a key to the species and distributional data are provided. In addition, DNA barcoding results for four species are briefly discussed.

Revision of the ocellatus species-group of the genus Plumarius Philippi 1873 (Hymenoptera, Chrysidoidea, Plumariidae), with description of three new species from Argentina.

This contribution presents the study of species-group of Plumarius Philippi 1873, as the result of a survey of the morphological variation in males. The group is characterized by the large ocelli and transverse head. It consists of the following three new species: P. culminatus Diez, Fidalgo & Roig-Alsina, sp. nov., P. ocellatus Diez, Fidalgo & Roig-Alsina, sp. nov., and P. stangei Diez, Fidalgo & Roig-Alsina, sp. nov. A characterization of the group, descriptions, and illustrations are provided.

The bee Ruizanthedella mutabilis Spinola (Hymenoptera: Halictidae): a very common but poorly known species studied using integrative taxonomy.

Ruizanthedella mutabilis (Spinola) is a very abundant species in Chile and the northwest of Argentinean Patagonia. In this contribution, Halictus nigrocaeruleus Spinola 1851 is established as a junior synonym of R. mutabilis (Spinola 1851), after considering morphological data, DNA barcoding results, and biological observations. The variability in the colouration of the metasoma has been incorrectly used to distinguish these colour forms as valid species. New records enlarge the distribution of the species in Argentina, from the Andes to the Atlantic coast.

Southern distributional limits of Meliponini bees (Hymenoptera, Apidae) in the Neotropics: taxonomic notes and distribution of Plebeia droryana and P. emerinoides in Argentina.

The southern distribution of stingless bees in the Neotropics reaches the province of Buenos Aires, Argentina, up to 34°51' S in latitude, where two species of Plebeia are found on the west margin of the Río de La Plata: P. emerinoides (Silvestri), and P. droryana (Friese). In this area some relicts of gallery forest occur and the climate is moderated by the large water mass of the river. The taxonomy of both species is discussed. Diagnoses, updated distribution, and illustrations of some morphological features are given for both species.

Revision of Plumarius Philippi 1873 (Hymenoptera: Chrysidoidea, Plumariidae) from Argentina north of Patagonia, with description of eighteen new species.

Twenty six species of Plumarius from Argentina north of Patagonia are revised. Eighteen new species: Plumarius politus sp. nov., P. sarophorus sp. nov., P. globulosus sp. nov., P. angulatus sp. nov., P. noa sp. nov., P. divergens sp. nov., P. malaris sp. nov., P. gracilior sp. nov., P. riojanus sp. nov., P. exophthalmus sp. nov., P. planatus sp. nov., P. albinervis sp. nov., P. truncatus sp. nov., P. mikrommatus sp. nov., P. obscurus sp. nov., P. gracilis sp. nov., P. fidalgoi sp. nov., and P. ocellulatus sp. nov. are described and illustrated. A new record for known species as well as a key to 26 known species in the region is given. A redescription of P. tumidulus Papp, 2000, which is the first record of the family Plumariidae from Uruguay, is done.

Review of the genus Eotilla Schuster, 1949 (Hymenoptera: Bradynobaenidae: Typhoctinae: Eotillini) and description of new species from Argentina.

Diagnoses for the genus Eotilla Schuster, 1949 based on males and females, new generic and specific characters, descriptions of two new Argentinian species (Eotilla schusteri Torréns, Fidalgo, Roig-Alsina & Brothers, sp. nov. and E. medanito Torréns, Fidalgo, Roig-Alsina & Brothers, sp. nov., based on both sexes), a description of the female of E. superba Brothers, 1974 and redescriptions of the males of E. mickeli Schuster, 1949 and E. superba are provided. A key to the species of Eotilla is presented.

Distribution and morphometric studies of flagellar sensilla in Emphorini bees (Hymenoptera, Apoidea).

The tribe Emphorini is a group of pollen-collecting solitary bees with a geographical distribution restricted to the western hemisphere. Most of the Emphorini bees collect Page 10 linepollen from a few specific plant families and display specialized behaviors for constructing their nests. Insect sensilla are the basic structural and functional units of cuticle receptors, serving mainly mechano- and chemo-receptor functions. The external morphology of the antennal sensilla has been well characterized in species of different families of Apoidea, however there is scarce information about this issue in solitary bees of the family Apidae. For a better understanding of the association between the external sensory system and several types of behaviors which emerged along the evolutionary history of bees, it is important to characterize the antennal receptors in several representative species of this tribe. The distribution of the antennal sensilla on the dorsal flagella of 18 taxa was studied in insects of both sexes, using light and scanning electron microscopy. There were six types of sensilla and setae on the antennae, which were identified as sensilla placodea, trichodea, basiconica, coeloconica, coelocapitular and ampullacea. The sensilla trichodea were classified into subtypes, A, B, C-D. Sensilla subtype A were the most abundant sensilla and were distributed over the entire antennae, while sensilla placodea and sensilla trichodea type B, showed a restricted distribution on specific areas of the flagella. We have recognized four patterns of spatial distribution of setae on dorsal flagella. Species having setae on the distal part of the flagellomeres tended to contain a low density of sensilla trichodea type A. Females showed a higher number of sensilla subtypes B and C-D than males; instead sensilla trichodea A were more abundant in males. No significant difference was found in the number of sensilla placodea, ampullacea, coeloconica and coelocapitular. Sensilla basiconica were found only in females. Our results showed that gustative and tactile sensilla were more abundant in female bees, as well as, olfactory receptors predominate in the antennal system of males. The possible coevolution of flagellar sensilla in males and females of solitary bees is discussed in light of previous reports. Patterns of distribution of setae determine the relative abundance of the types of sensilla in the flagellum.