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Corynura bruchiana (Figures 1b, 4, 8a; Tables S6–S7) Nest site Nests of this species were found in vertical banks (Figure 4a) facing north or west, towards main roads of the National Parks sampled, in the permanent shade of trees. Nest aggregations (Figure 4b) contained both active and inactive nests. Bees carrying pollen were observed, flying in close proximity to the bank until they found the entrance of their nest. The nests found in Lake Guillelmo and Villa Mascardi were studied on cloudy, rainy days. Some velvet ants (Hymenoptera: Mutillidae: Euspinolia sp.) were observed walking in the nesting area at Puerto Arrayán, and one specimen was found inside an active nest that was occupied by a bee (Table S6: nest 3), but no evidence of parasitism was found in the cells studied. Nests of Caenohalictus sp. (Halictidae: Caenohalictini) and anthills of Dolichoderinae and Camponotus sp. (Formicinae) were found in the nesting area of Lake Lolog. Nest structure The entrances had a diameter of 5.0 mm (SD = 0.6, n = 15). The nests comprised a horizontal burrow that led to a well-defined chamber (x = 18.8 cm SD = 9.4 from entrance, n = 18) which held an earthen block: the cluster of cells. Since the nests were very close to each other, digging an active nest caused the exposure of tunnels and blocks of nearby nests. Most of these nearby nests were inactive, from past years, and only had open cells with faeces or cells filled with loose soil (Figure 4c). These nests were included in the study, though they lack some measurements (e.g. entrance diameter, chamber depth; see Table S6). No nest had branches from the main burrow, although occasionally a blind burrow extended beyond the cluster for a few centimetres. The earthen block containing the cells rested at the bottom of the chamber (Figure 4d) or was held in place by roots, but there were no earthen pillars to support it, and therefore it was easy to remove clusters intact. The shape of the block was approximately rounded, the surface was rough and the cells’ outlines were not evident from the exterior. The blocks were opened in the laboratory 7 days after extraction, and measurements and contents were recorded (Table S6); no bee emerged in the intervening period. The blocks were carefully scraped with a knife to find the cells, which were orientated in different directions (Figures 4c,e). Some cells contained fungi and dead larvae (Figure 4f), suggesting that this species may be particularly sensitive to changes in environmental conditions and/or manipulation, though it is possible that the larvae were already dead before nest excavation. A few blocks were left intact as voucher material. The blocks had the following measurements: 22–36 mm width, 16–28 mm length, 13–24 mm height (n = 5). Each block had at most six cells (x = 3.5 SD = 1.6, n = 17). The cells were ovoid in shape and had the following measurements: 2.8–3.8 mm width at neck, 4.6–6.0 mm maximum width, 9.4–11.4 mm length (n = 14). Two nests had an earthen block with no cells in it (Table S6: nests 7, 9), and the blocks extracted in December were not smaller than those found at the end of January, though the first ones only had one to three cells. This could be evidence that the bees delimit or build the earthen block first and then dig the cells in it, instead of digging the cells as they enlarge the block, as Claude-Joseph (1926) described for Co. apicata. In active nests, both open cells with faeces and cells filled with loose soil were found. Nesting behaviour Several indicators suggest that Co. bruchiana is a solitary species, at least in the region studied. I never found more than one adult per nest, all of them had some mandible and wing wear (Table S7), and the earthen blocks had relatively few cells, all features of solitary species. The nests dug on 20 December had open cells with pollen, and closed cells with pollen and an egg or small larva on it, evidence that the bees had started the nesting season recently. Only one specimen had fully developed ovaries, which was collected in December. Specimens collected at the end of January had little or no evidence of ovary development (Table S7), but this could be due to the fact that oviposition had already ended. Most nests dug in late January had postdefecating larvae, and two had male pupae (Table S6). These data and the fact that there are no male specimens in collections obtained before February (Table S14) indicate that this species is univoltine in the area studied., Published as part of González-Vaquero, Rocío Ana, 2022, Solitary and semisocial behaviour in the Corynura group: new findings in a clade sister to all other Augochlorini bees (Hymenoptera: Halictidae), pp. 1841-1868 in Journal of Natural History 56 (45 - 48) on pages 1852-1853, DOI: 10.1080/00222933.2022.2134833, http://zenodo.org/record/7389012, {"references":["Claude-Joseph EC. 1926. Recherches biologiques sur les Hymenopteres du Chile (Melliferes). Ann Sci Nat Zool. 10 (9): 114 - 268."]}

Corynura ampliata (Figures 1c, 3, 8e; Tables S4–S 5) Nest site Two nesting areas were studied. One, 0.5 m wide × 0.5 m long, was in a gentle slope facing south, on the northern shore of Lake Huechulaufquen. The other one, 4 m wide × 10 m long, was in a flat area near Lake Lácar (Figure 3a). In the first site the earth was wet and loose, with a few stones; the days before had had intense rains, which explained the humidity of this usually arid area (Devoto et al. 2009). In the second site the earth was dry, and it had a thick (1–2 cm) layer of volcanic ash, which was thicker in some parts of the area. Both sites had cushion plants (Azorella prolifera (Cav.) Plunkett and Nicolas), the exotic Scotch broom (Cytisus scoparius (L.) Link), and some small shrubs. The nests were scattered in both areas, approximately 13 nests/m2. A few nests of H. reticulatus and Lasioglossum (Dialictus) sp. (Halictidae: Halictini), and several anthills of Dorymyrmex sp. (Formicidae: Dolichoderinae) were found at the second site. Nest structure Nest entrances had a radial tumulus of dried soil, diameter 30–40 mm (Figure 3b). Most entrances were totally covered by the soil of the tumulus, but in some nests the entrance was partially exposed and its position could be inferred (Figure 3b, nest at the bottom). When the tumulus was removed, a bee showed her head immediately, and 20–30 seconds later reappeared backwards, moving her metasoma out of the tunnel while carrying some soil with her legs and depositing it at the surface (Figure 1c). This was done twice or thrice until the entrance was fully covered, resulting in a tumulus smaller than the previous one; no further movements were observed after the entrance was occluded. The entrances had a diameter of 4.0 mm (SD = 0.5, n = 10), and immediately below it the tunnel widened slightly (x = 5.2 mm SD = 0.8, n = 10). In only one nest, one cluster was found in a chamber 9.2 cm from the entrance; it was held in place by pillars of soil and contained six horizontally orientated closed cells (Table S4: nest 3). This cluster, which was in a chamber 33 mm high and 17 mm wide, was kept closed and is housed in the collection of MACN; no specimens emerged from it. In two nests (Table S4: nests 9, 10) four and five ovoid cells were found, most of them open, one filled with soil. Notably, no clusters were found in the other nests. Since the nests were dug on windy days, the soil fell permanently over the area that was being excavated, and some old cells (open or filled with soil) may have gone unnoticed – which would not have been the case for cells with pollen and/or immature stages, which are easily seen when a cell is accidentally broken in the process. The nests ended at 17.5 cm (SD = 4.3, n = 10). Nesting behaviour Five females were found in two nests, four females in two more, and the remaining six nests had only one female (Table S5). None of the females had well-developed ovaries. Most of the females had mandibles and wings unworn or with very little wear (Table S5), indicating they had recently emerged, but in two of the multi-female nests (Table S5: nests 8, 10) there was one female with fully worn mandibles and wings. Probably these females had been the founders of the nests, and the other bees were their daughters, which remained in the natal nest. The presence of females of two generations may indicate eusocial behaviour, although division of reproductive labour could not be confirmed. I believe these newly emerged daughters would not have helped their mother to produce a second generation, because the nests were studied at the end of the warm season in Patagonia (beginning of February) when few flowers remain in the field. Considering also that no larvae or pupae were found in the nests and that the first males appear in the field approximately by mid-December (in Los Lagos, Chile, Table S14), I infer that these bees were going to spend the winter as inseminated females, in their natal nests. The following spring these females might either found their own nest or re-use their natal nest. Unfortunately, data are insufficient to conclude whether this species is solitary or social, but it is univoltine in the area studied., Published as part of González-Vaquero, Rocío Ana, 2022, Solitary and semisocial behaviour in the Corynura group: new findings in a clade sister to all other Augochlorini bees (Hymenoptera: Halictidae), pp. 1841-1868 in Journal of Natural History 56 (45 - 48) on pages 1850-1851, DOI: 10.1080/00222933.2022.2134833, http://zenodo.org/record/7389012, {"references":["Devoto M, Medan D, Roig-Alsina A, Montaldo NH. 2009. Patterns of species turnover in plant-pollinator communities along a precipitation gradient in Patagonia (Argentina). Austral Ecol. 34: 848 - 857. doi: 10.1111 / j. 1442 - 9993.2009.01987. x."]}

Halictillus reticulatus (Figures 3a, 7, 8c; Tables S12–S13) Nest site Three nests were found in a slope 4 m wide × 1 m long in the Challhuaco Valley (Río Negro) (Figure 7a). The soil was dry and slightly sandy, and it contained some stones. The nest entrances were 3–4 cm apart. Two additional nests of this species were found in the same flat ground near Lake Lácar where the nests of Co. ampliata were studied (Figure 3a, see Co. ampliata for site description). Nests from both sites were dug by midsummer. Nest structure The nests from the Challhuaco Valley had very small entrances (x = 2.0 mm SD = 0.5, n = 3), but the burrow widened considerably immediately below (x = 3.4 mm SD = 0.2, n = 3) (Table S12). Each nest had 4–9 (x = 7.0 SD = 2.7, n = 3) cells, which were at 4.1 cm (SD = 0.4, n = 3) from the surface. The cells were in a comb-like cluster, horizontally orientated, with their openings facing the tunnel, but the chamber was not clearly defined. One nest (Table S12: nest 1) had two cells on each side of the tunnel, while another nest (Table S12: nest 3, Figure 8c) had two cells with faeces and filled with soil located opposite a cluster with seven cells (four active, closed cells, and three empty, open cells). All the nests had some open cells with faeces. The entrances of the cells that were closed were smooth on the outer side (facing the burrow) and rough on the inner side. The cells were very fragile and only a few were extracted intact. The cells were ovoid in shape, with the following measurements: 2.7–3.0 mm maximum width; 5.5–5.6 mm length (n = 2). The main tunnel turned beyond the cells, and ended in a blind burrow (x = 7.5 cm SD = 1.3, n = 3). The nests of H. reticulatus from the site near Lake Lácar had a radial tumulus of loose soil like the nests of Co. ampliata, but the tumulus was smaller (20 mm diameter) in this species, and the bees did not appear or re-make the tumulus immediately after it was removed. The nests had an entrance of 3.2 mm (SD = 0.3, n = 2) in diameter, and they consisted of a vertical burrow that ended 15 cm (SD = 1.4, n = 2) from the surface (Table S13). In one of the nests the deepest 5 cm of the tunnel was slightly wider, suggesting a poorly defined chamber. No cells were detected in these nests, but some old cells may have gone unnoticed due to weather conditions at the moment of the excavation (see details in Co. ampliata). Nesting behaviour Unfortunately no adults were observed in the nests found in the Challhuaco Valley, but I was able to associate these nests to the species due to the advanced degree of sclerotisation of the pupae (Table S12). One of the nests found near Lake Lácar had 11 females; only one of them had fully worn mandibles and wings, while the remaining specimens had entire mandibles and only some of them had one or two notches in the wings (Table S13: nest 2). Two females were found in the other nest (Table S13: nest 1), both with very low mandible and wing wear. I did not detect clusters or cells in these nests, and none of the females had well-developed ovaries. Data suggest that the female with worn mandibles and wings from Nest 2 could have been the founder of the nest and the mother of the remaining females. As in Co. ampliata, although this could be evidence of eusocial behaviour due to overlap of generations, given the time of the year when the nests were studied it is more plausible that the bees were using their natal nest as a refuge, and were soon to enter diapause. Unfortunately the data are insufficient to infer whether H. reticulatus has some form of social behaviour. Only well-developed pupae were found in the nests dug at the end of January, and 5 days later (2 February 2011) several dozen males were found in flowers of Chrysanthemum sp. (Asteraceae) near the area studied (Figure 7b,c). These data may suggest an explosive peak of males in midsummer, as happened with Ca. aureoviridis, although I observed an unbiased sex ratio in the pupae of the few nests studied (5 f: 5 m). Since males appear in the field at the beginning of January (Table S14), it is inferred that H. reticulatus would be univoltine, like the other species of the Corynura group that inhabit the area., Published as part of González-Vaquero, Rocío Ana, 2022, Solitary and semisocial behaviour in the Corynura group: new findings in a clade sister to all other Augochlorini bees (Hymenoptera: Halictidae), pp. 1841-1868 in Journal of Natural History 56 (45 - 48) on pages 1856-1860, DOI: 10.1080/00222933.2022.2134833, http://zenodo.org/record/7389012, {"references":["Schwarz MP, Richards MH, Danforth BN. 2007. Changing paradigms in insect social evolution: insights from halictine and allodapine bees. Annu Rev Entomol. 52: 127 - 150. doi: 10.1146 / annurev. ento. 51.110104.150950."]}

Halictillus amplilobus (Figures 6, 8f; Tables S10–S11) Nest site In Paititi Natural Reserve, in Sierra de los Difuntos (Figure 6a), I found a slope of wet compact soil facing south (Figure 6c), 3 m wide × 1 m long, which had nests of H. amplilobus and Pseudagapostemon pampeanus (Holmberg) (Halictidae: Caenohalictini). Nests were found on top of the hill, 160 m a.s.l., an area dominated by bushes of Colletia paradoxa (Spreng.) Escal. (Rhamnaceae), Baccharis spp. and Achyrocline satureioides (Lam.) DC. (Asteraceae). Nest structure The three nests that were dug had an entrance diameter slightly narrower (x = 2.3 mm SD = 0.4, n = 2) than that of the main tunnel (x = 3.2 mm SD = 0.6, n = 2) (Table S10). At 9.8 cm (SD = 2.8, n = 4) from the entrance there was a chamber of approximately 12 mm width by 26 mm height which contained a cluster of 4–9 (x = 6.8 SD = 2.2, n = 4) ovoid cells, horizontally orientated, with their openings facing the tunnel (Figure 6b,e). One of the nests had two clusters; the deeper one had only open, empty cells. Apparently the cluster was held only by the walls of the chamber, and in only one case by a pillar of soil. One of the nests had a blind tunnel facing backwards, which extended 2 cm beyond the chamber; the other nests ended at the chamber. The nests ended 16 cm from the surface (SD = 3.8, n = 2). Nesting behaviour Two nests had one cluster of cells and one female bee, whose ovaries were developed and whose mandibles and wings showed some wear (Table S11: nests 1, 2). The other nest had two clusters and a dead female at the end of the tunnel, which had fungi on wings and metasoma but unworn mandibles, so I conclude it had died soon after emerging. Considering that the nests were dug on cold, rainy days, it can be inferred that all occupants were in the nest; therefore, this population of H. amplilobus would be solitary. Many open cells, two male pupae and a small larva were found in the nests. The first record of males flying nearby (Tandil, Table S14) is from spring, probably from a first brood. Considering that the nests were dug in summer and they had recently open cells (they were in good condition) and pupae, it is probable that the species is bivoltine in the area studied., Published as part of González-Vaquero, Rocío Ana, 2022, Solitary and semisocial behaviour in the Corynura group: new findings in a clade sister to all other Augochlorini bees (Hymenoptera: Halictidae), pp. 1841-1868 in Journal of Natural History 56 (45 - 48) on page 1856, DOI: 10.1080/00222933.2022.2134833, http://zenodo.org/record/7389012

Corynura nahuelita (Figures 5, 8b; Tables S8–S9) Nest site The nesting area was in a south-facing slope, 6 m wide × 2 m long, on the northern shore of Lake Traful, on the side of Provincial Route 65 (Figure 5a). The ground was totally exposed to the sun, with almost no vegetation, and the earth was dry with some stones. The nests of Co. nahuelita were scattered, and only occasionally was a female observed entering a nest. A few centimetres away from one of the entrances there was an anthill of Dorymyrmex sp. (Formicidae: Dolichoderinae). Nest structure The entrances of the nests were very small (x = 2.2 mm SD = 0.4, n = 5), but immediately below the burrow widened (Figure 5d) leading to a chamber, located 2.0– 8.8 cm (x = 4.2 cm SD = 2.1, n = 8) from the entrance. Each comb-like cluster had from 2 to 18 (x = 9.2 SD = 4.7, n = 13) cells, which were mostly vertically orientated (Figure 5c,e) with their openings facing the roof of the chamber, and in some cases the cluster followed the outline of some stone on which it was supported. The base and the ends of the clusters were somewhat attached to the substrate, and some of the peripheral cells were broken when extracted. For this reason it is difficult to define the size of the clusters, although the largest (Figure 5c) was 30.2 mm wide, 37.4 mm long and 19.8 mm high, and the upper side, which housed the openings of the cells, was slightly concave. Once the cluster was removed, due to the dry soil and the stones it was not possible to define whether the nest ended there, but in some nests a lower blind burrow that extended 2–3 cm beyond the chamber was observed (Figure 8b). One of the nests (Table S8: nest 2) had two clusters very close to each other, the first one inactive, probably from the previous year. Some clusters were opened 7 days later in the laboratory, and their measurements and contents were recorded (Table S8). The remaining clusters were left untouched, awaiting the emergence of adults. The cells, ovoid in shape (Figure 5b), had the following measurements: 2.0–3.0 mm width at neck; 2.6–4.5 mm maximum width; 7.1–9.5 mm length (n = 12). Some of the cells of active nests had fungi, and some were open and had faeces, while others had been filled with loose soil – clear indicators of a reused nest. Only one nest (Table S8: nest 5) was inactive, with no bees or active cells in it. Nesting behaviour One female was found in each of six nests; all of them had worn mandibles and wings, and well developed ovaries (Table S9). No bees were found in five nests; one of these nests was inactive but the others contained from one to four active cells. These data suggest solitary behaviour, but the study was carried out on sunny days, and some specimens were observed later flying around the area that had been dug. Moreover, one nest had 11 active cells (Table S8: nest 4), which might be too many cells to provision for a single bee. These data suggest that the species probably had solitary and social nests in the area studied. One of the nests had unusual contents: four females with no mandible or wing wear, one of which had no ovary development while the other three had well-developed eggs in their ovaries (Table S9: nest 1). These females were found near the cluster, which had six open cells, but despite the intact wings and mandibles I do not believe these females had recently emerged. The pupae found in all nests studied were unsclerotised, and adults from the clusters that were taken to the laboratory did not emerge until 2 weeks later (after 4 January). It is plausible that the workers of that nest were foraging when the nest was dug, so I infer that this nest was semisocial, with three reproductive females in it. I discard communal behaviour because these females had no visible signs of wear in wings and mandibles, perhaps because foraging and construction were performed entirely by the workers. Bees of both sexes emerged in the laboratory at the beginning of January. This agrees with data taken from collections, suggesting that males appear in the field from that moment on (Table S14). The proportion of pupae (4 f, 5 m) was similar to that of adults emerged from the nests (5 f, 5 m). Although I found several open cells in the nests, many with faeces, they could have been active the previous year, and left untouched by the bees, while others were filled with soil. The data suggest that the species is univoltine in the area studied., Published as part of González-Vaquero, Rocío Ana, 2022, Solitary and semisocial behaviour in the Corynura group: new findings in a clade sister to all other Augochlorini bees (Hymenoptera: Halictidae), pp. 1841-1868 in Journal of Natural History 56 (45 - 48) on pages 1854-1855, DOI: 10.1080/00222933.2022.2134833, http://zenodo.org/record/7389012

Corynura (Corynura) moscosensis n. sp. González-Vaquero (Figs. 1A –C, 1E–G) Diagnosis. Corynura moscosensis n. sp. is a moderate-size bee (7.0– 8.4 mm), black with bluish highlights and an entirely dark-brown metasoma. The females of this species can be distinguished from C. chloromelas and other similar Corynura by the following combination of characters: inner hind tibial spur with many short teeth (Fig. 1 E), malar area at most 1/4 as long as basal mandibular width, apical margin of metapostnotum roughly tessellate, propodeum bearing only plumose hairs, apex of clypeus more weakly tessellate than its base, and S3 bearing mainly simple hairs. Males can be easily identified by the exclusive SP dorsal area almost completely covering the flagellum (Fig. 2 A), the punctures on disc of mesoscutum separated by more than 3 PD, the posterior border of metapostnotum straight (margin not upraised), T2–T3 with short (0.1 MOD), simple hairs, with a few simple and plumose hairs no longer than 0.4 MOD, and the following characters of the genital capsule: dorsal area of the gonostylus triangular in shape, apical region of the ventral area bearing short and simple setae (Fig. 1 C: vag). Description. Male (holotype, Fig. 1A). Length, 7.7 mm; forewing length, 6.4 mm (paratypes, length, 7.0– 8.4 mm; forewing length, 6.1–6.9 mm). Color. Black, with bluish highlights on head and mesosoma, except following areas dark brown: apex of mandible, anterior surface of flagellum, legs, tegula, metasoma. Wings hyaline, with veins and pterostigma dark brown, radial vein dark brown to black. Pubescence. Whitish, with light brown hairs on head and mesoscutum. Head with plumose hairs as long as 2.0 MOD on clypeus, supraclypeal area, upper paraocular area and vertex. Lower part of gena with hairs up to 2.3 MOD. Upper paraocular area, mesoscutum, mesoscutellum and metanotum with dark, short (0.2–0.3 MOD), simple hairs, denser on lower paraocular area. Mesosoma with plumose hairs on mesoscutum and pleura (1.4–1.6 MOD), longer on metanotum (up to 2.2 times MOD). Base of T2–T3 with short (0.1 MOD), simple hairs, scattered with a few simple and plumose hairs as long as 0.4 MOD, longer on T5–T6 ( Sculpture: Clypeus with punctures separated by 1.0–2.0 PD, those on supraclypeal area separated by 2.0–4.0 PD. Lower paraocular area with punctation separated by 1.0–1.5 PD. Punctures on disc of mesoscutum separated by 3.0–5.0 PD, denser at sides, those of the mesoscutellum separated by 2.0–3.0 PD. Dorsal surface of metapostnotum with fine radial striae, surpassing midlength of metapostnotum but not reaching apical margin. Terga with punctures separated by 2.0–3.0 PD, sparser (4.0–5.0 PD) towards apex. Surface between punctures equally tessellate throughout body except: tessellation stronger on frons and upper paraocular area, propodeum minutely wrinkled, metasoma substrigulate. Structure. Head broader than long, width:length = 1.22:1 (paratypes, 1.16–1.24:1). Ratio of lower to upper interocular distance 0.68:1 (paratypes, 0.65–0.69:1). Clypeus broader than long, 1.45:1 (paratypes, 1.42–1.67:1). Ratio of interantennal to antennocular distance, 1.83:1 (paratypes, 1.60–1.84:1). Ratio of posterior interocellar to ocellocular distance, 1.32:1 (paratypes, 1.11–1.32:1). Ratio of length of scape, pedicel, F1 and F2 0.76:0.26:0.34:1 (paratypes, 0.75–0.97:0.21–0.26:0.26–0.34:1). Apical margins of sterna: S1–S4 straight, S5 with a small median notch, S6 produced, with lateral bend. Hidden sterna: S7 long and curved. Posterior margin of S8 with a median, membranous glabrous process. Genital capsule (Fig. 1 C): Volsella short, apical margin of digitus with a mesal process. Inner dorsal margin of gonocoxite straight, both margins converging towards the gonobase. Dorsal area of gonostylus triangular, more sclerotized than ventral area (Fig. 1 C: dag). Ventral area of gonostylus mesally directed, with a small, median, sparsely setose process mesally directed, and apical region with tuft of short, simple setae (Fig. 1 C: vag). Basal process of gonostylus with a few setae (Fig. 1 C: bp). Antennal sensilla. F2–F11 dorsally covered almost exclusively by SP, with a few short ST of one type (ST-C/ D, see below) scattered (Fig. 2 A). Base and apex of each flagellomere covered by ST of two types (A and B, see below), and a few SP. Female (Fig. 1B). Length, 7.2–7.8 mm; forewing length, 6.1–6.6 mm. Color. As in male, except mandible with reddish apex. Pubescence. Light brown, with dark brown hairs on paraocular area. Head with erect, plumose hairs, those on paraocular area and vertex up to 1.7 MOD. Lower part of gena with hairs up to –2.0 MOD. Upper paraocular area with dense, simple, short hairs (0.1–0.2 MOD), longer and sparser on pleura and mesoscutellum (0.3–0.4 MOD). Mesoscutum with scattered, plumose, long hairs (up to 1.2 MOD), longer on pleura (1.6–2.1 MOD) and metanotum (up to 1.5 MOD). Lateral area of propodeum with plumose hairs up to 3.6 MOD. Anterior part of T1 with plumose hairs (1.2–1.5 MOD), shorter and sparser on disk. T2–T4 with simple, short (0.2 MOD) hairs, and some scattered, plumose longer hairs (0.5–1.5 MOD), directed posteriorly; apical impressed areas with simple, short hairs. Sterna glabrous basally, with long (2.7–3.5 MOD), mostly simple hairs on posterior half, those on S2– S3 with their apices bent down, posteroventrally oriented. Sculpture. Labrum with verrucose, median, basal elevation (Fig. 1 F). Clypeus and supraclypeal area with punctures separated by 2.0–3.0 PD, denser on apical half of clypeus. Lower paraocular area with punctures separated by 3.0–4.0 PD; upper paraocular area with punctures separated by 0.5–1.0 PD. Punctures on disc of mesoscutum separated by 4.0–5.0 PD, denser at sides, those of the mesoscutellum separated by 1.0–3.0 PD; punctures evenly distributed. Hypoepimeral area with punctures separated by 4.0–5.0 PD, those on lateral area of propodeum separated by 5.0–7.0 PD. Metapostnotum with fine striae reaching half of length of dorsal surface in some specimens; apical margin roughly tessellate (Fig. 1 G). T2–T4 with punctures separated by 3.0–4.0 PD, sparser on disk of T1 (punctures separated by 5.0–6.0 PD). Surface between punctures tessellate throughout body, except terga and sterna substrigulate. Structure. Head broader than long, 1.29–1.32:1. Ratio of lower to upper interocular distance 0.93–0.98:1. Clypeus broader than long, 1.75–1.83:1. Ratio of interantennal to antennocular distance, 0.52–0.62:1. Ratio of posterior interocellar to ocellocular distance, 0.99–1.10:1. Inner hind tibial spur with many teeth, shorter than diameter of shaft of spur (Fig. 1 E). Antennal sensilla. One individual with a bare area free of sensilla on the most apical flagellomere (i.e. no sensilla occur in an oval-like area on the ventral side of F10), the other two lacking such bare area. SP intermingled with other types of sensilla all throughout all flagellomeres (i. e. no large, distinct areas of exclusive SP were observed as in the male). SP about 15–20 µm long, with longitudinal axis roughly parallel to the longitudinal axis of the antenna (Fig. 2 C). SP denser on the dorsal side of the antennae and on the distal flagellomeres (Fig. 2 D–G). SB (Fig. 2 H–I) with a peg 5–7 µm long, sculptured longitudinally. SB fully erect (Fig. 2 H) or partially curved (Fig. 2 I). SB rare, mostly on the ventral side of the flagellomeres (Fig. 2 E). SAm clearly smaller (about 0.5–1 µm) than SCo (about 1.5 µm) (peg often visible protruding partially from the pit) (Fig. 2 C,J–K). SAm and SCo on the ventral and sometimes the latero-ventral side of most flagellomeres, often in clusters (Fig. 2 C,J). ST-A: 10–20 µm long (Fig. 2 D), very abundant, in particular dorsally (Fig. 2 D). ST-B: 10–20 µm long (Fig. 2 E); found both ventrally and dorsally. ST-C/D: variable in size (from 15 to 40 µm long) (Fig. 2 L); found both ventrally and dorsally and often almost perpendicular to the antenna surface. The antennae are also covered with setae of different shapes and sizes (Fig. 2 F,M). Etymology. This species is named moscosensis after Los Moscos, a lake in Nahuel Huapi National Park (Argentina) where the holotype was collected. Comments. The male designated as the holotype is housed at MACN. This recently collected specimen is in good condition, and it only lacks the mid right leg from the femur, which was removed for DNA barcoding (658 bp: BOLD number HALIC159–11; GenBank accession KU983418). The holotype has the following labels: “ARG. Río Negro, PN Nahuel / Huapi: Lago Los Moscos / –41.346917 –71.664306 / 28–I–2011 R. González V. / Sobre Escallonia virgata ”, “MACN-En / 8207”, “Barcoding of Life / DNA voucher specimen / MACN-En 8207” and “ Corynura (Corynura) / moscosensis n. sp. / HOLOTYPE / González-Vaquero 2016” printed. This species was mentioned as “ Corynura sp3a” in a recent molecular study (González-Vaquero et al., 2016), and it can be distinguished from 14 other Corynura species by its Barcode Index Number (Ratnasingham & Hebert 2013): BOLD:ABW7139. Unfortunately, C. chloromelas was not included in that analysis due to lack of barcode compliant sequences of this species. Besides the holotype, three paratype females from Neuquén (Argentina) have been barcoded, all 658 bp sequences: MACN-En 8163 (BOLD number HALIC140–11; GenBank accession KU983415), MACN-En 8167 (BOLD number HALIC144–11; GenBank accession KU983416), and MACN-En 8168 (BOLD number HALIC145–11; GenBank accession KU983417). These sequences and those studied by González-Vaquero et al. (2016) are publicly available online (project CORYN, http://www.boldsystems.org). In some male specimens, the process on the posterior margin of the S8 is difficult to observe because it is membranous and translucent. This process, which is glabrous in the holotype, may bear one or two apical setae. In the male antennae, although SB, SAm and SCo were not observed, we cannot confirm their absence in the male sex of this species due to the limited sample size (one specimen). Distribution. In Argentina: southwestern Neuquén, western Río Negro and northwestern Chubut. In Chile: from La Araucanía to Los Lagos. This species inhabits in the Andean Nothofagus -dominated forest, in the biogeographic province of the Valdivian Forest, Subantactic sub-region (Morrone 2015). Examined material: Paratypes. ARGENTINA: Neuquén: 7f, Arroyo Pedregoso, 10–XII–2001, D. Medan, N.H. Montaldo, M. Devoto et al. (FAUBA). Lanín National Park: Boquete (Lago Lolog): 1m, 4–IV–1964, M. Gentili (MACN); 1f, 4–IV–1964, M. Gentili (IADIZA); 1f, 25–IV–1964, A.J. Giai (SEMC). 1f, Lago Huechulafquen, margen N, 15–XII–2010, L. Compagnucci & R. González Vaquero (MACN-En 8163; MACN). Lago Queñi: 1f, 16–XII–1999, N.H. Montaldo, M. Devoto & G. Gleiser (FAUBA); 1f, 2–XII–1985, A. Roig Alsina (MACN); 1f, 20–I–1954, M.M. Senkute (SEMC). Nahuel Huapi National Park: Isla Victoria: 4f, Schajovskoi (MLPA); 2f, X–1963 (IADIZA); 1f, X–1963, A.J. Giai (SEMC); 1f, XII–1954, R.N. & J.S. de Orfila (SEMC). 2f, Puerto Arrayán, 20–XII–2010, L. Compagnucci & R. González Vaquero (MACN-En 8167 and MACN-En 8168; MACN); 29f, Puerto Arrayán, 20–XII–2010, L. Compagnucci & R. González Vaquero (MACN). Río Negro: 1f, R.S. Castillo (MACN). Nahuel Huapi National Park: Puerto Blest: 2f, XII–2000, C. Morales & C. Quintero (MACN); 1f, 15–IX–2001, C. Morales & C. Quintero (MACN). Chubut: INTA Trevelin: 10f, 2–XII–2005, A-I. Gravel (MACN); 5f, 6–XII–2006, A-I. Gravel (MACN); 1f, 7–XI–2005, A-I. Gravel (PCYU); 1f, 20–XII–2005, A-I. Gravel (PCYU); 15f, 2–XI / 11–XII–2006, A-I. Gravel (PCYU); 12f, 8–XI / 13–XII–2006, MIK. Gravel (PCYU). Los Alerces National Park: Lago Futalaufquen: 9f, 13/ 18–XII–1997, C. & M. Vardy Malaise trap (BMNH); 10f, 14–XII–1997, C. & M. Vardy (BMNH); 2f, Bahía Mansa, 17–II–2011, J.L. Farina (MMLS); 15f, 14–XII–1997, C. & M. Vardy (MACN). CHILE: Araucanía: 1f, Cabreria, Cordillera Nahuelbuta, 22–XII–1985, A. Roig Alsina (MACN). Los Ríos: 1f, Niebla, 14–XII–1985, A. Roig Alsina (MACN). Los Lagos: 2m, Guabún, W Ancud, 13–I–1981, L.E. Peña (AMNH). 1f 1m, El Chinque, N of Correntoso, 22–I–1980, L.E. Peña (AMNH). 1f, La Picada, NW Volcán Osorno, 16/ 18–I–1980, L.E. Peña (AMNH). 1f 1m, Puyehue, 10–II–1979, L.E. Peña (AMNH). 1m, Río Gol Gol, 8/ 13–II–1957 (SEMC). 2f, Termas de Puyehue, 4/ 5–XII–1985, A. Roig Alsina (MACN). 1f, Anticura on Río Golgo, E of Puyehue, 18/ 29–X–1985, L.E. Peña (AMNH). 1f 1m, Peulla, 7–II–1974, L. Ruz (PCYU). Hualaihué, Estación Científica Huinay, 35 m, nesting aggreg. in path, 21–X–2014, C. Polidori: 5f (MNCN), 2f (MACN). 1m, Huinay, I–1981, O. Martinez (PUCV). 1f, Parque Nacional Puyehue, El Pionero, 16– XI–2000, L. Packer (PCYU). Floral associations. The plants listed below were taken from the specimen labels, which were collected in recent field trips made by RAGV to Neuquén and Río Negro (Argentina): Anacardiaceae: Schinus patagonicus (Phil.) I.M.Johnst.; Asteraceae: Baccharis obovata Hook. et Arn.; Boraginaceae: Phacelia secunda J.F. Gmel.; Elaeocarpaceae: Aristotelia chilensis (Molina) Stuntz; Escalloniaceae: Escallonia virgata (Ruiz & Parv.) Pers.; Fabaceae: Cytisus scoparius (L.) Link, Trifolium repens L., Vicia nigricans Hook. & Arn.; Grossulariaceae: Ribes magellanicum Poir; Malvaceae: Tilia moltkei L.; Proteaceae: Embothrium coccineum J.R.Forst. & G.Forst, Lomatia hirsuta Diels ex J.F.Macbr.; Rhamnaceae: Discaria articulate (Phil.) Miers, D. chacaye (G. Don) Tortosa; Rosaceae: Rosa rubiginosa L.. Nesting biology. The nesting site of C. moscosensis n. sp. consisted of NW-facing earth bank 15.0 m long and 1.6 m tall at the border of a ground path (Fig. 3 B). The bank was bordered by flowering fields with many shrubs mainly belonging to Myrtaceae, and some Nothofagus spp. and Eucryphia cordifolia Cav. trees. The bee nests (92 in total) were found in a smaller area of 6.0 m × 1.6 m (Fig. 3 A) rather than throughout the bank. Nest entrances lacked soil turrets. Nest density in the nesting area was 9.6/m2. Mean distance between pairs of nests was 167.8 ± 141.2 cm, but nests’ nearest neighbours (NND) were only 3.3± 2.1 cm (range: 1.2–14.7 cm), with most NND falling between 1.0 and 3.5 cm (Fig. 3 C). The Clark and Evans’ test (1954) revealed a significantly clumped distribution pattern of nests (R = 17.07, n = 92; C = –13.65, P Foraging activity in 2013 was low during the study, most probably because many days were cloudy, with temperature often below 20 °C, and with some rain. About 5–15 bees were observed returning to their nests with pollen on their scopae in a 4-hour period in sunny or partially cloudy days. The color of pollen brought to the nests ranged from yellow through various tones of orange to fully red. Some bees were observed in the morning or in general under cloudy and cold weather with the head visible at the entrance, possibly waiting for adequate conditions to fly or in a nest-guarding behaviour (Fig. 4A). When exiting from the nests, females sometimes spent a few minutes walking on the ground, presumably to thermoregulate before flying (Fig. 4 B). In 2014 no bees were observed out of the nests due to the frequent and strong rainfalls which occurred on almost every day of the study. In 2013, during nest excavations of an area including 11 nest entrances, a total of 37 brood cells were discovered. These cells were ovoid in shape and were located at 20–40 cm in depth, and at about 5–10 cm from a central tunnel that descended obliquely from the surface. We were unable to find clear clusters of cells, though sometimes cells were quite close to one another. Although we could not get information for individual nests, given the number of entrances in the excavated area we can infer that the minimum number of cells per nest may be around three at this early stage of nest development. Two of the brood cells found contained pollen/nectar stores (yellowish in color). An additional 15 cells were empty but apparently lined (Fig. 4 C), without any faeces and thus possibly new cells to be provisioned, while four cells contained an adult alive bee (Fig. 4 D), with unworn or weakly worn wings (Fig. 4 D). Two other cells included puparia of Diptera, most probably Leucophora spp. (Diptera: Anthomyiidae). Many Leucophora flies were observed performing their typical “satellite flights” (i.e. they reach the bee nests by following the bees returning to the nest in flight) and were determined as L. andicola (Bigot) and L. peullae (Malloch)) (Polidori et al. 2015) (Fig. 4 E). The remaining 10 cells appeared to be old, with remains of faeces and partially filled with soil. In that year, 10 females of C. moscosensis n. sp. were collected from the nest excavations and four females were collected while leaving their nests. In 2014, nest excavations of an area that included 22 nest entrances provided 18 additional females. In that year, the soil was wet and muddy, making the recognition of tunnels and brood cells difficult. The ratio between the number of bees found in the tunnels and the number of nest entrances in the excavated area was 0.9 in the middle of the spring and 0.8 in late spring. In 2013, three females were found together in two tunnels and two females in another one, while the other bees were individually found within indistinguishable tunnels or in brood cells. While we did not found immatures in the bee nests, a further natural enemy of this bee at this locality may be the velvet ant Dimorphomutilla suavissima (Gerstaec

González-Vaquero, Rocío Ana, Polidori, Carlo, Nieves-Aldrey, José Luis (2017): Taxonomy and ecology of a new species of Corynura (Hymenoptera: Halictidae: Augochlorini) from Chile and Argentina. Zootaxa 4221 (1): 95-110, DOI: 10.5281/zenodo.246769

Corynura Spinola, Callistochlora Michener and Halictillus Moure are the only taxa of Augochlorini endemic to southern South America. They are phylogenetically close, comprising a clade sister to all other augochlorines, which are mainly distributed in tropical America. Corynura and Callistochlora are common bees in Chile and the Argentinean Patagonia, while Halictillus inhabits also central Argentina and southern Brazil. A phylogenetic parsimony analysis of 93 morphological characters coded for 25 species supports the monophyly of each of the three taxa, of the clade formed by them, and their sister relationship to the remaining Augochlorini genera. Our analyses suggest Callistochlora as sister to Hallictillus + Corynura. Callistochlora, which has been treated as a subgenus of Corynura, is elevated to genus level. The study of the gradulus of the sterna, a structure usually ignored in morphological analysis, helped in the resolution of the group. A revision of Corynura is presented. We recognize 19 valid species, of which five are described as new: C. callaina sp.n., C. challhuacoensis sp.n., C. condita sp.n., C. luisae sp.n., and C. nahuelita sp.n. The males of C. apicata Sichel, C. patagonica Cockerell and C. spadiciventris Alfken are described for the first time. The following are new synonyms: Rhopalictus callicladurus Cockerell syn.n. is a junior synonym of C. ampliata (Alfken); Halictus analis Herbst syn.n. and C. heterochlora Alfken syn.n. are junior synonyms of C. bruchiana (Schrottky); Rhopalictus corinogaster chiloeensis Cockerell syn.n. is a junior synonym of C. corinogaster (Spinola); R. chloronotus Cockerell syn.n. and R. melanocladus Cockerell syn.n. are junior synonyms of C. herbsti (Alfken). Neotypes are designated to stabilize the usage of three names: Halictus apicatus Sichel, Halictus bruchianus Schrottky, and Corynura gayi Spinola. Lectotypes are designated for six names: Halictus (Corynura) atrovirens Herbst, Halictus analis Herbst, Halictus (Corynura) herbsti Alfken, Halictus spinolae Friese, Corynura lepida Alfken, and Corynura spadiciventris Alfken. Diagnoses, comments on the type specimens, floral associations, notes on variation within species, images, distributional data and a key to the species are provided. Fil: González Vaquero, Rocío Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Roig Alsina, Arturo Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina

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 sequences from 19 species. 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. 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 refer to two cryptic species. The results suggest that Corynura and Halictillus species can be identified through 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. Un soin particulier est requis lors de la délimitation et de l’identification des espèces d’abeilles de la famille des Halicitidae, lesquelles sont reconnues pour être monotones sur le plan morphologique. Les genres Corynura Spinola et Halictillus Moure (Halictidae : Augochlorini) comprennent des espèces qui constituent des composantes clés des écosystèmes de la portion australe de l’Amérique du Sud. Ces abeilles sont très difficiles a` identifier en raison de la grande similarité morphologique entre les espèces et d’un fort dimorphisme sexuel. Les auteurs ont analysé 170 séquences conformes de codes a` barres de l’ADN provenant de 19 espèces. Les codes a` barres ont permis de confirmer les associations entre les genres et pour déceler deux nouvelles espèces cryptiques. Les distances interspécifiques étaient significativement plus grandes que celles rapportées chez d’autres espèces d’abeilles. La divergence intraspécifique était inférieure a` 1 % chez 14 espèces. Des numéros d’index de codes a` barres (BIN) se sont avérés utiles pour identifier des espèces putatives nécessitant des études plus poussées. Plus d’un BIN ont été assignés a` cinq espèces. Le nom Corynura patagonica (Cockerell) réfère vraisemblablement a` deux espèces cryptiques. Les résultats suggèrent qu’il est possible d’identifier les espèces des genres Corynura et Halictillus au moyen de codes a` barres. Les séquences des espèces issues de ce travail peuvent servir de référence pour identifier des spécimens inconnus. Cette étude fournit une preuve additionnelle de l’utilité des codes a` barres de l’ADN pour des fins de taxonomie chez les abeilles et pour l’identification des spécimens, lesquelles sont particulièrement pertinentes chez des insectes pollinisateurs ayant une grande importance écologique. Fil: González Vaquero, Rocío Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Roig Alsina, Arturo Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Packer, Laurence. York University; Canadá

Las abejas silvestres son un grupo de insectos biológicamente muy diverso, que cumple unimportante rol en la polinización de las plantas. La tribu Augochlorini presenta especies desdesolitarias hasta primitivamente eusociales, siendo un grupo ideal para analizar la evolución delcomportamiento social. Corynura Spinola y Halictillus Moure, dos géneros que presentan un altogrado de endemismo en Chile y Argentina, forman parte de la rama basal de la filogenia de losaugoclorinos. En esta tesis se presenta tanto la taxonomía alfa como la filogenia de Corynura,poniendo a prueba la hipótesis de monofilia de sus dos subgéneros: Callistochlora y Corynura s.str. Las especies de Halictillus han sido revisadas recientemente y aquí se abordan sus relacionesfilogenéticas. La revisión de Corynura incluyó el estudio comparado de aproximadamente 8.000especímenes, así como del material tipo de los 37 nombres asociados al género. Se presentandatos morfológicos, de distribución, sinonimias, asociaciones florales, imágenes de estructurasdiagnósticas, descripciones de seis especies nuevas y una clave de identificación de las 22especies de Corynura. Se estudió la arquitectura de los nidos de cinco especies; los resultadossugieren que en Corynura habría tanto especies solitarias como comunales y parasociales,mientras que en Halictillus al menos una de sus especies sería solitaria. De un estudio de redesecológicas para Corynura se concluye que las asociaciones polinizador-planta extraídas decolecciones pueden complementar los datos tomados en el campo. Se obtuvieron 115 códigos debarras pertenecientes a 16 especies. Este método fue útil para detectar dos especies crípticas, yse observó una clara diferencia entre la distancia intra e interespecífica. Para el análisisfilogenético se confeccionó una matriz de 90 caracteres morfológicos. Callistochlora aparece comogrupo hermano del clado Halictillus+Corynura s. str. por lo que se propone elevarlo al nivel degénero. Los códigos de barras no contribuyen a resolver las relaciones entre los géneros. Medianteel mapeo de caracteres comportamentales se infiere que el ancestro de los augoclorinos construíasus celdas en clusters, dispuestas tipo “panal”, en sentido horizontal, en una cámara a la cual seaccedía por el túnel principal, y presentaba un comportamiento comunal o semisocial. Wild bees are a biologically diverse group of insects, which play an important role in plantpollination. The tribe Augochlorini has species from solitary to primitively eusocial, being an idealgroup to analyze the evolution of social behavior. Corynura Spinola and Halictillus Moure, twogenera with a high degree of endemism in Chile and Argentina, are part of the basal branch in thephylogeny of the augochlorines. The alpha taxonomy and phylogeny of Corynura are presented inthis thesis, testing the hypothesis of monophyly of its two subgenera: Callistochlora and Corynura s.str. Halictillus species have been recently reviewed and their phylogenetic relationships areaddressed here. The revision of Corynura included the comparative study of approximately 8,000 specimensand the type material of the 37 names associated with the genus. Morphological and distributionaldata, synonyms, plant associations, images of diagnostic structures, descriptions of six new speciesand a key to the 22 species of Corynura are provided. The nest architecture of five species wasstudied; the results suggest that in Corynura there are solitary as well as communal and parasocialspecies, while in Halictillus at least one species would be solitary. From a study of ecologicalnetworks for Corynura, it is concluded that plant-pollinator associations taken from collections maycomplement the data collected in the field. 115 barcodes belonging to 16 species were obtained. This method was useful to detect two cryptic species, and a clear difference between intra andinterspecific distance was observed. A matrix with 90 morphological characters was built for thephylogenetic analysis. Since Callistochlora results the sister-group to Halictillus+Corynura s. str., itsgeneric status is proposed. The barcodes do not contribute to resolve the generic relationships. Through mapping of behavioral characters, the ancestor of augochlorine bees is inferred: it built itscells in comb-like clusters, horizontally directed, in a chamber directly connected to the mainburrow, and it had communal or semisocial behavior. Fil: González Vaquero, Rocío Ana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; 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. Fil: González Vaquero, Rocío Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "bernardino Rivadavia"; Argentina Fil: Roig Alsina, Arturo Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina

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. Lecto-types are designated for Augochlora (Pseudaugochloropsis) thamyris Jörgensen 1912 and Halictomorpha autumnalis Jör-gensen 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. Fil: González Vaquero, Rocío Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina Fil: Roig Alsina, Arturo Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina

The South American caenohalictine genus Ruizantheda is understood to comprise Halictus proximus Spinola, Halictus divaricatus Vachal, and the new species Ruizantheda centralis from Argentina. The new species is intermediate between the first two, bridging the gap in morphology observed in these rather different species. Diagnostic characteristics for the genus are indicated; a key and a comparative table of characters for the three species are given. The new species, which occurs in the provinces of Santa Fe, Santiago del Estero and Chaco, in Argentina, is described and illustrated. Fil: González Vaquero, Rocío Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Roig Alsina, Arturo Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina