Little blue carpenter bee Ceratina cyanea, copyright Gilles San Martin.

Belongs within: Xylocopinae.

The Ceratinini are a cosmopolitan group of small carpenter bees, typically black or metallic green in colour.

Small carpenters
Published 10 September 2020

It’s time for another dip into the wide diversity of bees. The small carpenter bees of the tribe Ceratinini are small (often less than a centimetre in length), slender bees found on all continents except Antarctica, though their toehold in Australia is a very tenuous one indeed with only a single known species there. Though diverse, with hundreds of known species, the difficulty of breaking the tribe into clearly defined, monophyletic groups has lead recent authors to recognise a single genus Ceratina (Michener 2007). Distinctive subgroups previously treated as separate genera, such as the relatively large Megaceratina and the heavily punctate Ctenoceratina of Africa, and the both bright metallic and heavily punctate Pithitis of Africa and southern and eastern Asia, are now treated as subgenera. There are a lot of recognised subgenera, over twenty at last count, but there are also a lot of species not yet assigned to subgenus. Phylogenetic analysis of the ceratinins supports monophyly of most subgenera and a likely African origin for the clade as a whole, with multiple dispersals into Eurasia followed by a single dispersal to the Americas (Rehan & Schwarz 2015).

Ceratina sp., possibly C. smaragdula, copyright Vengolis.

Distinctive features of Ceratina compared to other bees include the absence of a pygidial plate, a flattened and hardened patch on the tip of the abdomen in females. As members of the family Apidae, Ceratina are long-tongued bees with a scopa (cluster of pollen-carrying hairs) on the hind legs, though the scopa does not enclose a bare patch for carrying a shaped pollen ball as in some other apids (for instance, the familiar honey bees). The scopa is less extensive in small carpenter bees than it is in other apids and the hairs on the body as a whole are rather short, so Ceratina look much shinier and less fuzzy than other bees. Ceratina are black or metallic green in colour (on rare occasions, the metasoma is red) and usually have yellow patches, particularly on the face.

Ceratina nest in a fennel stem, copyright Gideon Pisanty.

The name ‘carpenter bee’ refers to their practice of nesting in hollow stems or twigs, entered at broken ends. The absence of the pygidial plate is probably related to this manner of nesting: it is normally used by ground-nesting bees to tamp down soil when closing the nest. Most of the time, Ceratina are solitary nesters but two or more females may sometimes work on a nest together. In these cases, they adopt a proto-eusocial division of labour with one female laying eggs while the others act as ‘workers’ (I have no idea how they decide who gets to do what). Though a reduction in hairiness in bees is often associated with kleptoparasitism, no Ceratina species are known to behave in that manner (though some kleptoparasites are known among the members of the closely related and very similar tribe Allodapini). The reduction of the scopa may instead be associated with the bees carrying food supplies for the nest in their crop as well as on the legs. Cells are lined up in the nest stem with only simple partitions between them. These partitions are made from loose particles, mostly the pith of the stem, with no obvious adhesive holding them together. In at least some species, females will return to the nest after completion, dissembling and reassembling cell walls in order to clean out dead larvae and faeces that are then incorporated into the partitions. As such, while small carpenter bees are not directly on the evolutionary line leading to the more integrated colonies of the social bees, they do provide us with a model of what one stage in their evolution may have looked like.

Systematics of Ceratinini

Characters (from Houston 2018): Marginal cell broadly rounded at apex; three submarginal cells and both recurrent veins present; upper half of clypeus only about half as wide as lower half, so clypeus has form of a thick inverted T; apical tergites of abdomen convex in female; T6 of male with apical spine.

<==Ceratinini [Ceratinae]
    |--Nasutapis Michener 1970M70
    |    `--*N. straussorum Michener 1970M70
    |--Eucondylops Brauns 1902M70
    |    |--*E. konowi Brauns 1902M70
    |    `--E. reducta Michener 1970M70
    |--Allodapula Cockerell 1934M65
    |    |--*A. variegata (Smith 1854) [=Allodape variegata]M65
    |    |--A. associata Michener 1961M65
    |    |--A. biroi (Friese 1909) [=Allodape biroi]M65
    |    |--A. boharti Krombein 1951M65
    |    |--A. clarissima (Cockerell 1929) [=Allodape clarissima]M65
    |    |--A. diminuta (Cockerell 1915) [=Allodape diminuta]M65
    |    |--A. grisea (Alfken 1907) [=Allodape grisea]M65
    |    |--A. guillarmodi Michener 1970M70
    |    |--A. melanopusM70
    |    |--A. minor Michener & Syed 1962M65
    |    |--A. nitida (Smith 1859) [=Allodape nitida]M65
    |    |--A. occidentalis Michener & Syed 1962M65
    |    |--A. perkinsiella Michener & Syed 1962M65
    |    |--A. plebeia (Cockerell 1929) [=Allodape plebeia]M65
    |    |--A. praesumptiosa Michener 1961M65
    |    |--A. simillima (Smith 1854) [=Allodape simillima]M65
    |    |--A. unicolor (Smith 1854) [=Allodape unicolor]M65
    |    `--A. variegataM70
    `--Ceratina Latreille 1802TO-S04 [=Clavicera Latreille 1802M65]
         |  i. s.: C. acuta Friese 1896TO-S04
         |         C. duplexBD17
         |           |--C. d. duplexBD17
         |           `--C. d. calcarata Robertson 1900BD17, CSD10
         |         C. loewi Gerstaecker 1869TO-S04
         |         C. maghrebensis Daly 1983TO-S04
         |         C. mauritanicaL49
         |         C. nanulaR35
         |         C. neomexicanaR35
         |         C. viridissimaR35
         |--C. (Ceratina)TO-S04
         |    |--C. (C.) cucurbitina (Rossi 1792)TO-S04 (see below for synonymy)
         |    |--C. (C.) bispinosaM65
         |    |--C. (C.) dentipes Friese 1914M65
         |    |--C. (C.) palauensisM65
         |    |--C. (C.) parvula Smith 1854TO-S04
         |    `--C. (C.) propinquaM65
         |--C. (Ceratinidia Cockerell & Porter 1899)M65
         |    |--C. (*C.) hieroglyphica Smith 1854M65
         |    |--C. (C.) interrupta Alfken 1926M65
         |    `--C. (C.) papuana van der Vecht 1952M65
         |--C. (Ceratinula Moure 1941)TO-S04
         |    `--C. (*C.) lucidula Smith 1854M65
         |--C. (Euceratina Hirashima, Moure & Daly 1971)TO-S04
         |    |--C. (E.) albosticta Cockerell 1931TO-S04
         |    |--C. (E.) callosa (Fabricius 1794)TO-S04
         |    |--C. (E.) chalcites Germar 1839TO-S04
         |    |--C. (E.) chalybea Chevrier 1872TO-S04
         |    |--C. (E.) cyanea (Kirby 1802)TO-S04
         |    |--C. (E.) dallatorreana Friese 1896TO-S04
         |    |--C. (E.) dentiventris Gerstaecker 1869TO-S04
         |    |--C. (E.) gravidula Gerstaecker 1869TO-S04
         |    |--C. (E.) mocsaryi Friese 1896TO-S04
         |    |--C. (E.) nigrolabiata Friese 1896TO-S04
         |    `--C. (E.) saundersi Daly 1983TO-S04
         |--C. (Neoceratina Perkins 1912)H18, M65
         |    `--C. (*N.) australensis (Perkins 1912) (see below for synonymy)M65
         `--C. (Pithitis Klug 1807)M65
              |--C. (*P.) smaragdula (Fabricius 1787) [=Apis smaragdula]M65
              |    |--C. s. smaragdulaM65
              |    `--C. s. aurata Friese 1909M65
              `--C. (P.) fastigataM65

Ceratina (Ceratina) cucurbitina (Rossi 1792)TO-S04 [=Apis cucurbitinaM65; incl. Hylaeus albilabris Fabricius 1793M65, *Clavicera albilabrisM65, Prosopis albilabrisL49, Xylocopa (*Ceratina) albilabrisG20, M65, Ceratina nitidulaL49]

Ceratina (*Neoceratina) australensis (Perkins 1912) [=*Neoceratina australensis; incl. Allodape bribiensis Cockerell 1914]M65

*Type species of generic name indicated


[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.

[CSD10] Cardinal, S., J. Straka & B. N. Danforth. 2010. Comprehensive phylogeny of apid bees reveals the evolutionary origins and antiquity of cleptoparasitism. Proceedings of the National Academy of Sciences of the USA 107 (37): 16207–16211.

[G20] Goldfuss, G. A. 1820. Handbuch der Naturgeschichte vol. 3. Handbuch der Zoologie pt 1. Johann Leonhard Schrag: Nürnberg.

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

[L49] Lucas, H. 1849. Exploration Scientifique de l’Algérie pendant les années 1840, 1841, 1842 publiée par ordre du gouvernement et avec le concours d’une commission académique. Sciences physiques. Zoologie. II. Histoire naturelle des animaux articulés. Troisième partie. Insectes (suite). Imprimerie Nationale: Paris.

[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.

[M70] Michener, C. D. 1970. Social parasites among African allodapine bees (Hymenoptera, Anthophoridae, Ceratinini). Zoological Journal of the Linnean Society 49: 199–215.

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.

Rehan, S., & M. Schwarz. 2015. A few steps forward and no steps back: long-distance dispersal patterns in small carpenter bees suggest major barriers to back-dispersal. Journal of Biogeography 42: 485–494.

[TO-S04] Terzo, M. & F. J. Ortiz-Sánchez. 2004. Nuevos datos para las especies de Ceratinini de España y Portugal, con una clave para su identificación (Hymenoptera, Apoidea, Xylocopinae). Graellsia 60 (1): 13–26.

[WE03] Wappler, T., & M. S. Engel. 2003. The Middle Eocene bee faunas of Eckfeld and Messel, Germany (Hymenoptera: Apoidea). Journal of Paleontology 77 (5): 908–921.

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