Halictinae

Belongs within: Halictidae.
Contains: Augochlorini, Homalictus, Lasioglossum, Halictus, Sphecodes.

The Halictinae are a group of short-tongued bees commonly known as ‘sweat bees’, due to their habit of lapping perspiration from animals in order to collect salts. They are distinguished from other bees by the combination of a strong episternal groove continuing well below the level of the scrobe, and a strongly curved basal vein in the fore wing. Halictines may provide some of the earliest evidence for bees in the fossil record: the Late Maastrichtian (latest Cretaceous) fossil nest Uruguay has been compared to nests of the halictine tribe Augochlorini (Engel 2001). The majority of halictines nest in burrows in the ground except for some that nest in rotting wood. Some genera are parasitic, with the scopa reduced or absent.

Members of the neotropical tribes Caenohalictini and Augochlorini are commonly bright metallic in coloration. Females of the Halictini,

Sweat bees

9 August 2018

For many people, the common domestic honey bee may be the only bee species that they are aware of. In fact, bees are incredibly diverse, with well over 17,000 species known worldwide (and counting). Not all bees live in social hives like honey bees: the majority are solitary, with individual females each constructing their own nest and stocking it with food stores for their young. One particularly diverse group of bees is the Halictinae.

Halictines are mostly small bees, sometimes referred to as ‘sweat bees’ owing to the predilection of many species for lapping up sweat from the skin of hot humans and other animals (a habit that, while generally harmless, can be rather annoying). They can be distinguished from other bees by a distinctive curve at the base of the basal vein in the forewing. Michener (2007) recognised two tribes within the Halictinae, the cosmopolitan Halictini and the strictly Western Hemisphere Augochlorini. Augochlorins are often bright metallic in coloration; Halictini are less commonly so. Even among bee specialists, halictines can be notorious for the difficulties involved in trying to make sense of them. For instance, the cosmopolitan genus Lasioglossum alone comprises over 1300 known species, and having spent my own time attempting to identify bee specimens back in Australia I can confirm that there are times when it feels like all Lasioglossum, all the time. The majority of halictines construct their nests in burrows in soil; some species build in rotting wood.

The Halictinae are a particularly interesting group for studies of bee evolution because they include both solitary and social species. Indeed, some species may be either depending on circumstances. The most common nest type in Halictinae involves a long central tunnel with radiating side branches leading to globular brood cells. In most Augochlorini and species of the genus Halictus, however, the cells are arranged in a single cluster that is suspended within an underground cavity, held in place by earthen struts or by the rootlets of plants. The cells are lined with a protective waxy membrane rich in lactones, secreted by the builder from a gland near the base of the sting. Some species may be communal, with more than one female sharing a single burrow but each building and laying in its own cells (such communality is not necessarily a step on the road towards true sociality but may be a response to a shortage of good nesting opportunities). In social species, the queen is commonly not that different in appearance from associated workers, and if the queen dies the workers may begin producing eggs of their own (if, indeed, they were not already doing so while the queen was alive). Some species, though, may exhibit development of a distinct soldier or major class among the workers with massively enlarged heads and mandibles. In the Australian species Lasioglossum hemichalceum, there may be similarly large-headed males. These big-headed males also have reduced wings, rendering them flightless and bound to the nest. No more than one major male may be present in a colony; if another such male is present, the two will fight to the death. Unlike honey bees, halictine colonies do not often live for more than one season; instead, males and reproductive females usually mate near the end of the growing season, followed by the death of the males. The females hibernate over winter before beginning construction of their own nests the following spring.

In contrast, a number of halictine species, such as members of the genus Sphecodes, do not construct their own nests but instead lay their eggs in the nests of other bees. This behaviour, known as kleptoparasitism, has arisen in many bee lineages and is usually associated with a recurring set of evolutionary trends. Many kleptoparasites are closely related to their hosts: most kleptoparasitic halictines attack the nests of other halictines though some Sphecodes species mooch off bees in more distant subfamilies and families. Kleptoparasitic bees are commonly less hairy than their self-sufficient relatives, as they have little or no need of the pollen-carrying hairs used by other bees. Many kleptoparasites are more heavily armoured than other bees, to protect them against host resistance. Female Sphecodes have blunt spines on the outside of the hind tibia that may help them push into a host nest. Females of most kleptoparasitic halictines destroy the host egg in a nest cell before laying their own egg; in contrast, bees of other kleptoparasitic lineages usually leave the host egg undisturbed and it is the parasitic larva that executes the host. In most cases, the kleptoparasitic female abandons the nest once she has laid there, but in some species parasitising social hosts, the kleptoparasite may remain in the nest and inveigle herself into society there, continuing to enjoy the fruit’s of her hosts’ labours.

Systematics of Halictinae

Characters (Engel 2001): Labrum of female with distal process. Clypeus longer than labrum. Pre-episternal groove strongly impressed below level of scrobe. Basal vein strongly arcuate; first submarginal cell longer than third submarginal cell. Scopa developed on metacoxa, metatrochanter, metafemur, and to varying degrees on metatibia in nonparasitic females; metabasitarusus with distal process and penicillus. Prepygidial fimbria of female distinctly divided by pseudopygidial area.

<==Halictinae [Augochloridae]
    |  i. s.: Echthralictus Perkins & Cheesman 1928M65
    |           |--*E. extraordinarius (Kohl 1908) [=Halictus extraordinarius]M65
    |           |--E. latro Perkins & Cheesman 1928M65
    |           `--E. stevensoni (Cockerell 1924) [=Halictus stevensoni]M65
    |         Seladonia hotoniH18
    |--+--Caenohalictini [Caenohalictina]E01
    |  |    |--Eickwortapis Michener & Poinar 1996E01
    |  |    |    `--*E. dominicana Michener & Poinar 1996E01
    |  |    |--CaenohalictusE00
    |  |    |    |--C. eberhardorumE00
    |  |    |    `--C. oblitus Moure & Hurd 1987 [incl. Halictus nigromarginatus Spinola 1851 non Spinola 1841]E00
    |  |    `--HabralictusE00
    |  |         |--H. bimaculatusE00
    |  |         `--H. canalictulatusE00
    |  |--AgapostemonGE05 [Agapostemonina, AgapostemoniniE01]
    |  |    |--A. brachycerusCo12
    |  |    |--A. nasutusWP99
    |  |    |--A. poeyiE00
    |  |    |--A. sericeusE00
    |  |    |--A. texanusC01
    |  |    |--A. tyleriBD17
    |  |    |--A. viequesensisE00
    |  |    |--A. virescensGE05
    |  |    `--A. viridulusCr12
    |  `--AugochloriniE01
    `--Halictini [Sphecodidae, Thrinchostomini]E01
         |  i. s.: Patellapis (Pachyhalictus Cockerell 1928)H18, M65
         |           |--‘*Pachyhalictus’ merescens (Cockerell 1919)M65 (see below for synonymy)
         |           |--P. (P.) albipilatusH18
         |           |--P. (P.) binghami (Kirby 1900) [=Halictus binghami, Homalictus binghami]JG19
         |           |--‘Pachyhalictus’ buruanus (Blüthgen 1926) [=Halictus buruanus, Lasioglossum buruanum]M65
         |           |--‘Pachyhalictus’ kalutarae [=Lasioglossum kalutarae]M65
         |           |--‘Pachyhalictus’ reticulosus [=Lasioglossum reticulosum]M65
         |           |--‘Pachyhalictus’ sigiriellus [=Lasioglossum sigiriellum]M65
         |           |--P. (P.) stirlingi (Cockerell 1910)H18, M65 [=Halictus stirlingiM65, Lasioglossum stirlingiM65]
         |           |--‘Pachyhalictus’ trizonulus (Friese 1909) [=Halictus trizonulus, Lasioglossum trizonulum]M65
         |           `--‘Pachyhalictus’ vinctus [=Lasioglossum vinctum]M65
         |         HomalictusN91
         |         Electrolictus Engel 2001E01
         |           `--*E. antiquus Engel 2001E01
         |         Cyrtapis Cockerell 1908E01
         |           `--*C. anomalus Cockerell 1908E01
         |         Prohalictus Armbruster 1938E01
         |           `--*P. schemppi Armbruster 1938E01
         |         Ceylonicola Friese 1918B26
         |           `--C. atra Friese 1918B26
         |         DialictusE00
         |           |--D. anomalusCr12
         |           |--D. breediE00
         |           |--D. busckiellusE00
         |           |--D. mestreiE00
         |           |--D. ornduffiM76
         |           |--D. parvusE00
         |           `--D. proangularisE00
         |         Habralictellus auratusE00
         |         MexalictusE00
         |           |--M. arizonensisE00
         |           |--M. mexicanusE00
         |           `--M. micheneriE00
         |         RuizanthedellaE00
         |           |--R. mutabilisE00
         |           `--R. nigrocaeruleaE00
         |         ZonalictusE00
         |           |--Z. rufobasalisE00
         |           `--Z. viridifilosusE00
         |--+--LasioglossumPK17
         |  `--HalictusPK17
         `--+--SphecodesPK17
            `--Thrinchostoma Saussure 1890BD17, E01 [incl. DiagozonusB26, Rostratilapis Friese 1914B26]
                 |--T. assamense Sladen 1915B26
                 |--T. bicometesB26
                 |--T. bryanti Meade-Waldo 1914B26
                 |--T. flaviscapus Blüthgen 1926B26
                 |--T. macrognathum (Friese 1914) (see below for synonymy)B26
                 |--T. orchidarumC13
                 |--‘Halictus’ patriciusB26
                 |--T. perinetiBD17
                 |--T. sladeni (Friese 1914) [=Halictus (Rostratilapis) sladeni]B26
                 `--T. tonkinense Blüthgen 1926B26

Nomen nudum: Agapostemon nasutus gualanensis Cockerell 1912Co12

‘*Pachyhalictus’ merescens (Cockerell 1919)^M65 [=Halictus thoracicus merescens^{M65, B26}, Lasioglossum merescens^M65]

Thrinchostoma macrognathum (Friese 1914) [=Halictus (Rostratilapis) macrognathus; incl. T. macrognathum var. brunnea Blüthgen 1926]^B26

*Type species of generic name indicated

References

[B26] Blüthgen, P. 1926. Beiträge zur Kenntnis der indo-malayischen Halictus– und Thrinchostoma-Arten. (Hym. Apidae. Halictini.). Zoologische Jahrbücher: Abteilung für Systematik, Geographie und Biologie der Tiere 51: 375–698.

[BD17] Branstetter, M. G., B. N. Danforth, J. P. Pitts, B. C. Faircloth, P. S. Ward, M. L. Buffington, M. W. Gates, R. R. Kula & S. G. Brady. 2017. Phylogenomic insights into the evolution of stinging wasps and the origins of ants and bees. Current Biology 27: 1019–1025.

[C01] Cockerell, T. D. A. 1901. Contributions from the New Mexico Biological Station.—X. Observations on bees collected at Las Vegas, New Mexico, and in the adjacent mountains. Annals and Magazine of Natural History, series 7, 7: 125–131.

[C13] Cockerell, T. D. A. 1913. The bee-genus Thrinchostoma in Asia. Canadian Entomologist 45 (2): 35–36.

[Co12] Cockerell, W. P. 1912. Collecting bees at Gualan, Guatemala. Canadian Entomologist 44 (9): 277–282.

[Cr12] Crawford, J. C. 1912. Notes on some Canadian bees. Canadian Entomologist 44 (12): 359–360.

[E00] Engel, M. S. 2000. Classification of the bee tribe Augochlorini (Hymenoptera: Halictidae). Bulletin of the American Museum of Natural History 250: 1–89.

[E01] Engel, M. S. 2001. A monograph of the Baltic amber bees and evolution of the Apoidea (Hymenoptera). Bulletin of the American Museum of Natural History 259: 1–192.

[GE05] Grimaldi, D., & M. S. Engel. 2005. Evolution of the Insects. Cambridge University Press: New York.

[H18] Houston, T. 2018. A Guide to Native Bees of Australia. CSIRO Publishing.

[JG19] James, D. J., P. T. Green, W. F. Humphreys & J. C. Z. Woinarski. 2019. Endemic species of Christmas Island, Indian Ocean. Records of the Western Australian Museum 34 (2): 55–114.

[M65] Michener, C. D. 1965. A classification of the bees of the Australian and South Pacific regions. Bulletin of the American Museum of Natural History 130: 1–362.

Michener, C. D. 2007. The Bees of the World 2^nd ed. John Hopkins University Press: Baltimore.

[M76] Moldenke, A. R. 1976. California pollination ecology and vegetation types. Phytologia 34 (4): 305–361.

[N91] Naumann, I. D. 1991. Hymenoptera (wasps, bees, ants, sawflies). In: CSIRO. The Insects of Australia: A textbook for students and research workers 2^nd ed. vol. 2 pp. 916–1000. Melbourne University Press: Carlton (Victoria).

[PK17] Peters, R. S., L. Krogmann, C. Mayer, A. Donath, S. Gunkel, K. Meusemann, A. Kozlov, L. Podsiadlowski, M. Petersen, R. Lanfear, P. A. Diez, J. Heraty, K. M. Kjer, S. Klopfstein, R. Meier, C. Polidori, T. Schmitt, S. Liu, X. Zhou, T. Wappler, J. Rust, B. Misof & O. Niehuis. 2017. Evolutionary history of the Hymenoptera. Current Biology 27 (7): 1013–1018.

[WP99] Walter, D. E., & H. C. Proctor. 1999. Mites: Ecology, Evolution and Behaviour. CABI Publishing: Wallingford (UK).