Male bombus distinguendus
Within Britain, males can be distinguished from similar looking B. campestris and B. subterraneus by their genitalia, and by details of their colour pattern.However, there are many other similar looking species around the world (Williams, 2007). Therefore, outside Britain, many detailed characteristics need to be checked:Head
- The clypeus is nearly covered in dense, moderately long hair, except in a narrow median band occupying the median quarter in the anterior ventral quarter adjacent to the labrum.
- Hairs are longer than the breadth of the scape in the distal third.
- Gonocoxa with the proximal inner process shorter than broad, apically obliquely truncate.
- Gonocoxa with the sharply-defined dorsal ridge reaching the distal outer margin before the distal extremity, which is flat dorsally.
- Gonostylus broadly triangular, breadth of the inner proximal process about half of the length of the gonostylus.
- Volsella are distally narrowed.
- Penis valve with the ventro-lateral process almost trident-like, usually with only a weak dorsal tooth (cf. B. subterraneus), a strongPenis valve has an almost trident-like ventro-lateral process, with usually only a weak dorsal tooth (cf. B. subterraneus), a strong ventral tooth, and a rounded scarcely marked central projection.
- Penis valve head distally broadly rounded on its outer edge, its outer proximal corner with a flattened process reduced to a dorso-ventral ridge, dorsally with a small tooth and ventrally with a more triangular process.
- Hair generally usually predominantly straw or lemon yellow, paler ventrally, usually with the majority of at least the shorter hairs just dorsal to the antenna base yellow (cf. B. subterraneus), except for a black band between the wing bases, although this black band usually has yellow hairs intermixed at least laterally next to the tegula and sometimes throughout.
- Legs distally and tergum 7 often predominantly black, and although the extent of the black on the metasoma is variable, tergum 2 without black hair (cf. B. subterraneus).
There are many other similar looking species around the world.
B. distinguendus belongs to the subterraneus-group of species.
Female bombus distinguendus
Within Britain, Bombus distinguendus queens and workers are easily distinctive because of their combination of large size, extensively yellow hair, and black band between the wing bases. They have a body length of 12-21mm.However, there are many other similar looking species around the world (Williams, 2007). Therefore, outside Britain, many detailed characteristics need to be checked:Head
- Clypeus shining, in its central half lacking medium or large punctures, with only a few widely scattered micropunctures
- Mid basitarsus with the longest hairs of the posterior margin as long as or longer than the greatest breadth of the basitarsus
- The longest hair near the posterior margin of metasomal tergum 5 about 1.5× as long as the greatest breadth of the hind basitarsus
- Head hair is often predominantly yellow, but variable, with at least some yellow hair intermixed on the vertex posterior to the ocelli.
- Dorsum of the thorax and of the metasoma is predominantly straw yellow, paler posteriorly.
- Tergum 2 is always yellow, with at most a few inconspicuous anterior black hairs (cf. B. subterraneus).
- Black hair forms a band between the wing bases, although usually with yellow hair strongly intermixed in a lateral longitudinal band next to the tegula.
- Legs distally and tergum 6 predominantly black, although the extent of the black on the metasoma is variable, sometimes with black hair intermixed on terga 1-5 anteriorly, and especially broadly on tergum 5, although this black hair rarely forming conspicuous black bands
- Sometimes has black hair intermixed on terga 1-5 anteriorly, and especially broadly on tergum 5, although this black hair rarely forms conspicuous black bands.
- Ventral surface varies from entirely grey-cream to almost entirely black.
Bombus distinguendus is a relatively late-nesting bumblebee species, active between May and September throughout its range.In the late spring, queens (large females) emerge from hibernation and found colonies by rearing a brood of workers (small females) in an underground nest. These workers then take over the foraging and rearing of further worker broods as the colony grows until the end of summer, when broods of males and young queens are reared.Mating takes place outside the nest and queens enter hibernation underground for the next year.
Queens of successful colonies live for a year, but workers and males live as adults for about four weeks.
- Czech Republic
- USA (Attu Island only)
Life History and Behavior
Bumblebees are among the most important pollinators in many natural and agricultural systems.Bombus distinguendus has a relatively long tongue among bumblebees and visits deep flowers like red clover, of which it is a pollinator.Bombus distinguendus also likes other legumes, yellow rattle, marsh woundwort, knapweeds and thistles (so especially species of the plant families Asteraceae, Fabaceae and Lamaceae). Like bumblebees in general, it is not a narrow specialist on a particular plant species.Long-tongued bumblebees tend to collect pollen to feed their larvae from the same flowers from which they collect nectar to fuel flight.
Molecular Biology and Genetics
Statistics of barcoding coverage: Bombus distinguendus
Public Records: 26
Specimens with Barcodes: 36
Species With Barcodes: 1
Bombus distinguendus is a flagship species for the Bumblebee Conservation Trust in Britain and a UK Biodiversity Action Plan species.Bombus distinguendus is classified as Nationally Scarce.
Multiple factors threaten B. distinguendus, chief among which is often habitat removal, particularly with the reduction of red clover cultivation since 1940 due to changes in farming practices.The main driver of decline is believed to be a reduction in the density of food plants with deep flowers over large areas of suitable grassland habitat (Williams & Osborne, 2009). Continuous availability of suitable habitat within and across years is important, because the bees may not be good dispersers, and are not known to have colonised any new areas across barriers of unsuitable habitat.Climate change is unlikely to have been the main driver of decline in the past. Although there is an interaction between the effect of food-plant availability and climatic specialisation and a future impact is possible (Williams et al., 2007). The impact of pesticides is unknown.
B. distinguendus is showing a gradual decline in recorded distribution range within Britain against a background of increasing recorded ranges for the common species.
See the UK Biodiversity Action Plan.
The great yellow bumblebee, Bombus distinguendus, is a species of bumblebee found in Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Great Britain, Hungary, Lithuania, Poland, Romania, Slovakia, Switzerland, northern Russia, and North America.
- "Bombus distinguendus". Integrated Taxonomic Information System.
- "Bombus distinguendus Morawitz 1869". Fauna Europaea. Retrieved 3 July 2012.
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