Evolution
Early molecular work suggested that the family Melittidae was sister to all other bees, and also that it was paraphyletic. Because of this finding, it was suggested that the three subfamilies of Melittidae should be elevated to family status. Neither study included many melittids, due to their rarity. Later studies suggested that the family could still be monophyletic and a 2013 investigation including a greater number of melittid bees further supports this.
Recent research has shown that Melittids have a lower extinction rate compared to other hymenopterans, yet this family is considered species-poor. This is attributed to a significantly lower diversification rate as seen in other bee families. Danforth et al. suggests that this is because they are oligoleges, whereas other bees express polylecty (diverse host-plant preferences) allowing them to increase their diversification rate compared to melittids.
Evidence of oil-collection behaviour has been present in melittids since the early Eocene. Amber from Oise, France provided the oldest record of Melittidae and the fourth oldest fossilized bee specimen.
Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyletic lineage within the superfamily Apoidea. They are currently considered a clade, called Anthophila. There are over 20,000 known species of bees in seven recognized biological families. Some species – including honey bees, bumblebees, and stingless bees – live socially in colonies while most species (>90%) – including mason bees, carpenter bees, leafcutter bees, and sweat bees – are solitary.
Apidae is the largest family within the superfamily Apoidea, containing at least 5700 species of bees. The family includes some of the most commonly seen bees, including bumblebees and honey bees, but also includes stingless bees, carpenter bees, orchid bees, cuckoo bees, and a number of other less widely known groups. Many are valuable pollinators in natural habitats and for agricultural crops.
The superfamily Apoidea is a major group within the Hymenoptera, which includes two traditionally recognized lineages, the "sphecoid" wasps, and the bees. Molecular phylogeny demonstrates that the bees arose from within the traditional "Crabronidae", so that grouping is paraphyletic, and this has led to a reclassification to produce monophyletic families.
Halictidae is the second-largest family of bees with nearly 4,500 species. They are commonly called sweat bees, as they are often attracted to perspiration. Halictid species are an extremely diverse group that can vary greatly in appearance. These bees occur all over the world and are found on every continent except Antarctica. Usually dark-colored and often metallic, halictids are found in various sizes, colors and patterns. Several species are all or partly green and a few are red, purple, or blue. A number of them have yellow markings, especially the males, which commonly have yellow faces, a pattern widespread among the various families of bees. The family is one of many with short tongues and is best distinguished by the arcuate basal vein found on the wing. Females in this family tend to be larger than the males. They are the group for which the term 'eusocial' was first coined by entomologist, Suzanne Batra.
The Stenotritidae is the smallest of all formally recognised bee families, with only 21 species in two genera, all of them restricted to Australia. Historically, they were generally considered to belong in the family Colletidae, but the stenotritids are presently considered their sister taxon, and deserving of family status. Of prime importance is that the stenotritids have unmodified mouthparts, whereas colletids are separated from all other bees by having bilobed glossae.
Melittinae is a small melittid subfamily, with some 60 species in four genera, restricted to Africa and the northern temperate zone. They are typically small to moderate-sized bees, which often have shaggy scopae, and are commonly oligolectic; several species further specialize on floral oils as larval food rather than pollen, including Rediviva emdeorum, a highly unusual species in which the forelegs are longer than the entire body, and used to sponge up the floral oil at the end of elongated corolla spurs of the host plant, Diascia.
The Andrenidae are a large, nearly cosmopolitan family of solitary, ground-nesting bees. Most of the family's diversity is located in temperate or arid areas. It includes some enormous genera. One of the subfamilies, Oxaeinae, is so different in appearance that they were typically accorded family status, but careful phylogenetic analysis reveals them to be an offshoot within the Andrenidae, very close to the Andreninae.
Andrena is a genus of bees in the family Andrenidae. With over 1,500 species, it is one of the largest genera of animals. It is a strongly monophyletic group that is difficult to split into more manageable divisions; currently, Andrena is organized into 104 subgenera. It is nearly worldwide in distribution, with the notable exceptions of Oceania and South America. Bees in this genus are commonly known as mining bees due to their ground-nesting lifestyle.
The subfamily Dasypodainae is a small subfamily of melittid bees, with more than 100 species in eight genera, found in Africa and the northern temperate zone, primarily in xeric habitats.
Meganomiinae is a subfamily of melittid bees, with 10 species in four genera, found only in Africa, primarily in xeric habitats, with the distributional limits in Yemen and Madagascar. They are rather different in appearance from the other groups of past/present melittids, being large bees (10–22 mm), mostly black with strong yellow markings, resembling anthidiine megachilids. Males of this subfamily are known to have hidden sterna.
Macropis is a genus of bees in the family Melittidae. They are very rare and were likely more common in the past. They are associated with yellow loosestrife plants in the genus Lysimachia.
Dasypoda is a genus of bees in the family Melittidae.
Bombus randeckensis is an extinct bumblebee from the Miocene rocks of the Randeck Maar in southwestern Germany. It was discovered in 2012, and initially placed in the subgenus Bombus, however, review of the Bombini fossil record by Dehon et al in 2019 concluded B. randeckensis should be placed in Bombus subgenus Cullumanobombus.
Hesperapis is a genus of bees in the family Melittidae. There are at least 30 described species in Hesperapis. The genus is very uncommon and is restricted only to coastal barrier islands in the Gulf of Mexico and dunes of the Great Lakes. Its abdomen is flattened and its integument or "skin" is soft compared to other groups of bees.
Macropis nuda is a ground nesting, univoltine bee native to northern parts of North America. Thus, this species cocoons as pupae and hibernates over the winter. The species is unusual as it is an oligolectic bee, foraging exclusively for floral oils and pollen from Primulaceae of the species Lysimachia ciliata.
Melitta eickworti is a species of melittid bee in the family Melittidae. It is found in North America.
Hesperapis oraria, or Gulf Coast solitary bee is a rare species of bee in the family Melittidae. It was first described in 1997. The bee's current known range is on the barrier islands and coastal mainland secondary dunes on the Gulf Coast of the United States in Florida, Alabama, and Mississippi. The Gulf Coast solitary bee is the only known member of its subfamily in the eastern United States, and it is a monolege of the coastal plain honeycomb head.
Dasypoda delectabilis, the delightful pantaloon bee, is a species of solitary bee from the family Melittidae. It was described in 2023 based on a single male specimen caught in arid areas of south-eastern Iran.
Dasypoda radchenkoi, also known as Radchenko's pantaloon bee, is a species of solitary bee from the family Melittidae. It was described in 2023 in the scientific journal Osmia based on specimens caught in the limestone areas of southern Spain.
Andrena ghisbaini, Ghisbain's mining bee, is a species of solitary bee from the family Andrenidae. It was described in 2023 based on specimens collected in southern Spain.
