Megachile (Hackeriapis)

Megachile oblonga, from PaDIL.

Belongs within: Megachilini.

The subgenus Hackeriapis of the genus Megachile is an Australasian group of relatively small resin bees, most of which (excepting some larger species) have strong transverse grooves on the second and third metasomal tergites (Michener 1965).

Resinous confusion
Published 12 February 2024

Australia (like most other parts of the world) is home to a wide diversity of solitary bees. These are often less remarked upon than their social relatives, but among those more likely to attract attention are the resin and leaf-cutter bees of the family Megachilidae. And among the more diverse subgroups of this family in Australia are the species of Hackeriapis.

Megachile tosticauda, copyright Laurence Sanders.

Recognised by Michener (2007) as a subgenus of the broad genus Megachile, Hackeriapis is an assemblage of resin bees found across Australia as well as in savannah habitats in New Guinea. Almost ninety species were listed in Hackeriapis by Michener (1965). King (1994) would later cut the subgenus down to a much more restricted seventeen species but the status of many of the remaining species remains undetermined. In the broad sense, Hackeriapis is hard to confidently define but its representatives are smaller resin bees with a characteristic cylindrical body form. They can typically be distinguished from other Australian megachilids by the presence of deep grooves across the dorsal surface of the second and third metasomal tergites, and/or a basal tooth on the tarsal claws (Michener 2007). Most species have a more or less greyish appearance, with pale pubescence over a black integument, though a number have a bright reddish patch at the end of the metasoma. Females may have the clypeus modified with the sides or the centre produced into grotesque horns (King 1994). Males may exhibit flattened expansions of the fore tarsi or distal segments of the antennae, possibly using them as banners to signal to females or other males (Houston 2018).

Megachile aurifrons stocking its nest, copyright Sam Gordon.

Nesting behaviour has been described for only a small number of Hackeriapis species but most examples known appear typical for resin bees (Houston 2018). Cells are constructed in pre-existing holes using resin that the female bee collects from the surrounding environment, such as gum seeping from eucalypts or from spinifex and grass trees. In those species with a modified clypeus, the projections may assist in carrying resin. In most species, each cell will contain a store of pollen pudding and a single egg. One Hackeriapis species, Megachile aurifrons, is exceptional in not constructing individual cells; instead, it fills a hollow with a uniform mass of pudding into which eggs are deposited in separate cavities. Communal nesting is not uncommon, particularly in smaller species, with multiple females constructing cells in close proximity.

Megachile canifrons, copyright Kerry Stuart.

The broader relationships of Hackeriapis have been the subject of some speculation. Because of the variability of its members, it has been suggested that other Australian Megachile subgenera may be derived within it. However, Hackeriapis species also bear a remarkable resemblance to North American megachilids of the subgenus Chelostomoides, raising the question of some sort of cross-Pacific connection. Gonzalez et al. (2019), in an analysis of phylogenetic relationships within Megachilidae, preferred an association of Hackeriapis representatives with other Australian taxa rather than with Chelostomoides. Are the shared features of Hackeriapis and Chelostomoides the result of convergence, perhaps reflecting their shared associations with arid environments? If so, what is it about a dry landscape that makes bees get groovy?

Systematics of Megachile (Hackeriapis)

Characters (from Michener 1965): Usually small, slender bodied, parallel sided; posterior end of scutellum sloping (not strongly curved down), metanotum sloping (not vertical), basal part of propodeum subhorizontal; postgradular grooves usually present on second and third terga, usually not fasciate; terga often with apical pubescent fasciae; head little to much developed posteriorly, preoccipital carina occasionally present; pronotal lobe carinate.

<==Megachile (Hackeriapis Cockerell 1922)H18, M65
    |--M. (*H.) rhodura Cockerell 1906 [=Chalicodoma (*H.) rhodura]M65
    |--M. (H.) alani Cockerell 1929 [=Chalicodoma (H.) alani]M65
    |--M. (H.) alleynae Rayment 1935 [=Chalicodoma (H.) alleynae]M65
    |--M. (H.) apicata Smith 1853 [=Chalicodoma (H.) apicata]M65
    |--M. (H.) apposita Rayment 1939 [=Chalicodoma (H.) apposita]M65
    |--M. (H.) argentifer Cockerell 1910 [=Chalicodoma (H.) argentifer]M65
    |--M. (H.) atrella Cockerell 1906 [=Chalicodoma (H.) atrella]M65
    |--M. (H.) aurifrons Smith 1853 [=Chalicodoma (H.) aurifrons]M65
    |--M. (H.) axillaris Meade-Waldo 1915 [=Chalicodoma (H.) axillaris]M65
    |--M. (H.) barvonensis Cockerell 1914 [=Chalicodoma (H.) barvonensis]M65
    |--M. (H.) beutenmulleri Cockerell 1907 [=Chalicodoma (H.) beutenmulleri]M65
    |--M. (H.) calida Smith 1879 [=Chalicodoma (H.) calida]M65
    |--M. (H.) callura (Cockerell 1914)H18, M65 [=Thaumatosoma callurumM65, Chalicodoma (H.) calluraM65]
    |--M. (H.) canifrons Smith 1853 [=Chalicodoma (H.) canifrons]M65
    |--M. (H.) cliffordi Rayment 1953 [=Chalicodoma (H.) cliffordi]M65
    |--M. (H.) clypeata Smith 1853 [=Chalicodoma (H.) clypeata; incl. M. grandis Rayment 1934 non Lepeletier 1841]M65
    |--M. (H.) derelicta Cockerell 1913 [=Chalicodoma (H.) derelicta]M65
    |--M. (H.) dinognatha Cockerell 1929 [=Chalicodoma (H.) dinognatha]M65
    |--M. (H.) erythropyga Smith 1853 [=Chalicodoma (H.) erythropyga]M65
    |--M. (H.) eucalypti Cockerell 1910 [=Chalicodoma (H.) eucalypti]M65
    |--M. (H.) ferox Smith 1879 [=Chalicodoma (H.) ferox]M65
    |--‘Chalicodoma’ (H.) franki (Friese 1920) [=Thaumatosoma franki]M65
    |--M. (H.) fultoni Cockerell 1913 [=Chalicodoma (H.) fultoni]M65
    |--M. (H.) fulvomarginata Cockerell 1906 [=Chalicodoma (H.) fulvomarginata]M65
    |--M. (H.) fumipennis Smith 1868 [=Chalicodoma (H.) fumipennis]M65
    |--M. (H.) gilbertiella Cockerell 1910 [=Chalicodoma (H.) gilbertiella]M65
    |--M. (H.) hackeri Cockerell 1913 [=Chalicodoma (H.) hackeri]M65
    |--M. (H.) hardyi Cockerell 1929 [=Chalicodoma (H.) hardyi]M65
    |--M. (H.) heliophila Cockerell 1913 [=Chalicodoma (H.) heliophila]M65
    |--M. (H.) henrici Cockerell 1907 [=Chalicodoma (H.) henrici]M65
    |--M. (H.) heriadiformis Smith 1853 [=Chalicodoma (H.) heriadiformis]M65
    |--M. (H.) holura Cockerell 1912 [=Chalicodoma (H.) holura]M65
    |--M. (H.) horatii Cockerell 1913 [=Chalicodoma (H.) horatii]M65
    |--M. (H.) ignita Smith 1853 [=Chalicodoma (H.) ignita]M65
    |--M. (H.) latericauda Cockerell 1921 [=Chalicodoma (H.) latericauda]M65
    |--M. (H.) latipes Smith 1853 [=Chalicodoma (H.) latipes]M65
    |--M. (H.) leeuwinensis Meade-Waldo 1915 [=Chalicodoma (H.) leeuwinensis]M65
    |--M. (H.) leucopyga Smith 1853 [=Chalicodoma (H.) leucopyga]M65
    |--M. (H.) longiceps Meade-Waldo 1915 [=Chalicodoma (H.) longiceps]M65
    |--M. (H.) lucidiventris Smith 1853 [=Chalicodoma (H.) lucidiventris]M65
    |--M. (H.) mackayensis Cockerell 1910 [=Chalicodoma (H.) mackayensis]M65
    |--M. (H.) macleayi Cockerell 1907 [=Chalicodoma (H.) macleayi]M65
    |--M. (H.) micrerythrura Cockerell 1910 [=Chalicodoma (H.) micrerythrura]M65
    |--M. (H.) modesta Smith 1862 [=Chalicodoma (H.) modesta]M65
    |--M. (H.) monkmani Rayment 1935 [=Chalicodoma (H.) monkmani]M65
    |--M. (H.) mundifica Cockerell 1921 [=Chalicodoma (H.) mundifica]M65
    |--M. (H.) nasuta Smith 1868 [=Chalicodoma (H.) nasuta]M65
    |--M. (H.) nigrovittata Cockerell 1906 [=Chalicodoma (H.) nigrovittata]M65
    |--M. (H.) ‘nuda’ Rayment 1935 non Mitchell 1930M65 [=M. lucidiventris nudaR35, Chalicodoma (H.) nudaM65]
    |--M. (H.) oblonga Smith 1879 [=Chalicodoma (H.) oblonga]M65
    |--M. (H.) oculiformis Rayment 1956 [=Chalicodoma (H.) oculiformis]M65
    |--M. (H.) oculipes Cockerell 1910 [=Chalicodoma (H.) oculipes]M65
    |--M. (H.) ordinaria Smith 1853 [=Chalicodoma (H.) ordinaria]M65
    |--‘Chalicodoma’ (H.) papuae Michener 1965M65
    |--M. (H.) paracallida Rayment 1935 [=Chalicodoma (H.) paracallida]M65
    |--M. (H.) pararhodura Cockerell 1910 [=Chalicodoma (H.) pararhodura]M65
    |--M. (H.) paratasmanica Rayment 1955 [=Chalicodoma (H.) paratasmanica]M65
    |--M. (H.) phillipensis Rayment 1935 [=Chalicodoma (H.) phillipensis]M65
    |--M. (H.) preissi Cockerell 1910 [=Chalicodoma (H.) preissi]M65
    |--M. (H.) punctata Smith 1853 [=Chalicodoma (H.) punctata]M65
    |--M. (H.) ramulipes Cockerell 1913 [=Chalicodoma (H.) ramulipes]M65
    |--M. (H.) relicta Cockerell 1913 [=Chalicodoma (H.) relicta]M65
    |--M. (H.) revicta Cockerell 1913 [=Chalicodoma (H.) revicta]M65
    |--M. (H.) rufapicata Cockerell 1929 [=Chalicodoma (H.) rufapicata]M65
    |--M. (H.) rufolobata Cockerell 1913 [=Chalicodoma (H.) rufolobata]M65
    |--M. (H.) rugosa Smith 1879 [=Chalicodoma (H.) rugosa]M65
    |--M. (H.) semicandens Cockerell 1910 [=Chalicodoma (H.) semicandens]M65
    |--M. (H.) semiluctuosa Smith 1853 [=Chalicodoma (H.) semiluctuosa; incl. M. blackburnii Froggatt 1893]M65
    |--M. (H.) sericeicauda Cockerell 1910 [=Chalicodoma (H.) sericeicauda]M65
    |--M. (H.) silvestris Erickson & Rayment 1951M65 [=M. gilbertiella silvestrisER51, Chalicodoma (H.) silvestrisM65]
    |--M. (H.) simpliciformis Cockerell 1918 [=Chalicodoma (H.) simpliciformis]M65
    |--M. (H.) speluncarum Meade-Waldo 1915 [=Chalicodoma (H.) speluncarum]M65
    |--M. (H.) stalkeri Cockerell 1910 [=Chalicodoma (H.) stalkeri]M65
    |--M. (H.) subabdominalis Rayment 1935 [=Chalicodoma (H.) subabdominalis]M65
    |--M. (H.) subremotula Rayment 1934 [=Chalicodoma (H.) subremotula]M65
    |--M. (H.) subserricauda Rayment 1935 [=Chalicodoma (H.) subserricauda]M65
    |--M. (H.) suffusipennis Cockerell 1906 [=Chalicodoma (H.) suffusipennis]M65
    |--M. (H.) tasmanica Cockerell 1916 [=Chalicodoma (H.) tasmanica]M65
    |--M. (H.) tomentella Cockerell 1906 [=Chalicodoma (H.) tomentella]M65
    |--M. (H.) tosticauda Cockerell 1912H18, M65 [=Chalicodoma (H.) tosticaudaM65]
    |--M. (H.) trichognatha Rayment 1930 [=Chalicodoma (H.) trichognatha]M65
    |--M. (H.) trichomarginata Rayment 1930 [=Chalicodoma (H.) trichomarginata]M65
    |--M. (H.) turneri (Meade-Waldo 1913)H18, M65 [=Thaumatosoma turneriM65, Chalicodoma (H.) turneriM65]
    |--M. (H.) ustulata Smith 1862 [=Chalicodoma (H.) ustulata]M65
    |--M. (H.) victoriae Cockerell 1913 [=Chalicodoma (H.) victoriae]M65
    `--M. (H.) wilsoni Cockerell 1929 [=Chalicodoma (H.) wilsoni]M65

*Type species of generic name indicated

References

[ER51] Erickson, R., & T. Rayment. 1951. Simple social bees of Western Australia. Western Australian Naturalist 3 (3): 45–58.

Gonzalez, V. H., G. T. Gustafson & M. S. Engel. 2019. Morphological phylogeny of Megachilini and the evolution of leaf-cutter behavior in bees (Hymenoptera: Megachilidae). Journal of Melittology 85: 1–123.

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

King, J. 1994. The bee family Megachilidae (Hymenoptera: Apoidea) in Australia. I. Morphology of the genus Chalicodoma Lepeletier, and a revision of the subgenus Hackeriapis Cockerell. Invertebrate Taxonomy 8: 1373–1419.

[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 2nd ed. John Hopkins University Press: Baltimore.

[R35] Rayment, T. 1935. A Cluster of Bees: Sixty essays on the life-histories of Australian bees, with specific descriptions of over 100 new species. Endeavour Press: Sydney.

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