The bee

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...

Ctenoplectrini of the subfamily Apinae, with the two genera ''Ctenoplectra'' and ''Ctenoplectrina'', comprises 9 species in tropical

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

, 10 in

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

, and 1 in

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

Description

The Ctenoplectrini are characterised by short tongues, modified scopae and large comb-like tibial spurs adapted to collect and carry a mixture of floral oils and pollen. The unusual morphology has made it difficult to infer their closest relatives, in turn preventing an understanding of these bees’ geographic and temporal origin and had led early authors to place them in their own family Ctenoplectridae. Recent molecular phylogenetic analyses find Ctenoplectrini to be monophyletic and closest to the long-horned bees, Eucerini. Most of the tribe's species collect floral oil, pollen, and nectar from a few genera of the family

Cucurbitaceae The Cucurbitaceae (), also called cucurbits or the gourd family, are a plant family (biology), family consisting of about 965 species in 101 genera.

. However, three species are thought to be

kleptoparasite Kleptoparasitism (originally spelt clepto-parasitism, meaning "parasitism by theft") is a form of feeding in which one animal deliberately takes food from another. The strategy is Evolutionarily stable strategy, evolutionarily stable when stealin ...

Kleptoparasitic species

The presumably kleptoparasitic species form a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

(''Ctenoplectrina'') that is sister to the remaining genus (''Ctenoplectra''), confirming the independent

evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

of kleptoparasitism in this tribe. Tree topology and molecular dating together suggest that Ctenoplectrini originated in

in the Early

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

and that ''Ctenoplectra'' dispersed twice from

, sometime in the Late

, 30–40 million years ago. From Asia one species reached the Australian continent via

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

and

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...

in the mid-

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

, ''circa'' 13 million years ago. Dry and cool mid-Miocene climates also coincide with the divergence between ''Ctenoplectra bequaerti'' from

West Africa West Africa, also known as Western Africa, is the westernmost region of Africa. The United Nations geoscheme for Africa#Western Africa, United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Gha ...

, and ''Ctenoplectra terminalis'' from

East Africa East Africa, also known as Eastern Africa or the East of Africa, is a region at the eastern edge of the Africa, African continent, distinguished by its unique geographical, historical, and cultural landscape. Defined in varying scopes, the regi ...

and

Southern Africa Southern Africa is the southernmost region of Africa. No definition is agreed upon, but some groupings include the United Nations geoscheme for Africa, United Nations geoscheme, the intergovernmental Southern African Development Community, and ...

, perhaps related to fragmentation of the equatorial African rainforest belt. Nests are known from few species only, which use existing small holes in wood and stone or old nests of other bees, which they provision with a mixture of pollen and floral oil, exclusively gathered from plants of a few genera of the family

Cucurbitaceae The Cucurbitaceae (), also called cucurbits or the gourd family, are a plant family (biology), family consisting of about 965 species in 101 genera.

References

* Michener, C.D. (2000). ''The Bees of the World''. Johns Hopkins University Press. *Stefan Vogel (1990). "Ölblumen und ölsammelnde Bienen. Dritte Folge. Momordica, Thladiantha und die Ctenoplectridae". Trop. u. Subtrop. Pflanzenwelt 73:1-186. * Hanno Schaefer & S. S. Renner (2008). "A phylogeny of the oil bee tribe Ctenoplectrini (Hymenoptera: Anthophila) based on mitochondrial and nuclear data: Evidence for Early Eocene divergence and repeated out-of-Africa dispersal". Molecular phylogenetics and Evolution 47(2): 799–811. Apinae Bee tribes {{Apinae-stub