Apidologie (2013) 44:121–132
Original
* The Author(s) 2012. This article is published with open access at Springerlink.com
DOI: 10.1007/s13592-012-0161-x
article
Bombus cullumanus—an extinct European
bumblebee species?
Paul H. WILLIAMS1 , Alexandr BYVALTSEV2 , Cory SHEFFIELD3 , Pierre RASMONT4
1
Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
Department of General Biology and Ecology, Novosibirsk State University, ul. Pirogova 2, Novosibirsk 630090, Russia
3
Royal Saskatchewan Museum, 2340 Albert Street, Regina, Saskatchewan S4P 2V7, Canada
4
Laboratoire de Zoologie, Université de Mons, Place du Parc 20, 7000 Mons, Belgium
2
Received 8 February 2012 – Revised 22 June 2012 – Accepted 18 July 2012
Abstract – Bombus cullumanus s. str. has attracted some of the greatest conservation concerns among
bumblebees in Europe because it might now be extinct. However, there has been long-standing disagreement
about whether it is conspecific with other eastern pale-banded bumblebees. We investigate these relationships
using new data from DNA (COI) barcodes. The results support a Nearctic rufocinctus-group (Bombus
rufocinctus) and a Palaearctic cullumanus-group, the latter with just three species: Bombus semenoviellus,
Bombus unicus and B. cullumanus s. l. (including several differently coloured taxa). We conclude that, although
any persisting B. cullumanus cullumanus s. str. might be a regional conservation priority within Europe,
nevertheless, because the species remains common elsewhere within its range in Asia, globally a higher
conservation priority should be given to B. unicus, which is genetically more distinct and appears to have a
much smaller population in the Russian Far East.
bumblebee / Bombus / barcode / taxonomy / conservation
1. INTRODUCTION
The species in the cullumanus-group include
perhaps the most threatened bumblebees in
Europe. However, there have been strongly
differing interpretations of the number of species,
so we urgently need to resolve this taxonomic
confusion, particularly when seeking to formulate much-needed conservation measures.
Apis cullumana Kirby (1802) was first
described from a yellow-banded male from
Witnesham, in Suffolk, Britain (the holotype:
Yarrow 1968). It was named after Sir Thomas
Cullum, seventh Baronet, who was a local
natural historian. But it was not until more than
a century later that these males and the name
Corresponding author: P.H. Williams,
paw@nhm.ac.uk
Manuscript editor: James Nieh
were associated in Britain with the conspecific
unbanded, red-tailed females (Richards 1926).
The species has always been rare in Britain,
which, when compounded with the challenge of
the close resemblance in colour pattern and
morphology of the females to those of the
widespread and abundant Bombus lapidarius
(Linnaeus), has resulted in very few British
females of Bombus cullumanus ever having
been recognised (Yarrow 1954). The last record
of the species in Britain was in ‘c. 1941’
(BMNH collection: Williams and Osborne,
2009), and it is widely believed that B. cullumanus has been extirpated there.
Taxonomic disagreements centre on the relationship between the British population of B.
cullumanus s. str. and its close relatives elsewhere. Bumblebees with similar morphology and
a dark unbanded female colour pattern of the pile
have been recorded in a few places in Western
122
P.H. Williams et al.
Europe: in France, Belgium, Denmark, northwest
Germany and Sweden (e.g. Nevinson 1923;
Skorikov 1923; Richards 1926; Rasmont et al.
2005a), and these have been accepted universally
as parts of the same species. However, several
other similar taxa with female colour patterns
with broad light yellow bands (Bombus serrisquama Morawitz from Kazakhstan), darker or
reduced yellow bands (e.g. Bombus silantjewi
tenuifasciatus Vogt [a junior homonym] and
Bombus silantjewi nigrotaeniatus Vogt from
Kazakhstan, Bombus popovi Panfilov from Tajikistan, and Bombus praemarinus Panfilov possibly from Primorsky), or broad white bands
(Bombus apollineus Skorikov from Armenia)
have been described from across the Palaearctic
region (Vogt 1911; Panfilov 1951: mapped in his
Figure 7). The type material for B. popovi cannot
be found at present, so we cannot be sure of its
identity. Closely similar to B. silantjewi nigrotaeniatus, B. praemarinus (Panfilov 1951) has
reduced yellow bands on the thorax and very
little yellow pile on the metasoma. It was
described from only two Russian specimens:
the holotype female, collected in 1903 from
Vladivostok, Primorsky (Institute of Zoology,
St Petersburg, PW examined) and another
female described in a note added in press,
collected in 1947 from Mondy, Buryatia
(Zoological Museum, Moscow State University, AB examined). No further individuals
from near the published type locality in
Primorsky have been recorded since (M.
Proshchalykin, in lit.). These bees have a
dark colour pattern with very little yellow
pile on the scutellum and metasoma. Although according to the description, they
have especially dense punctures on the
clypeus and temples, the differences do not
appear to be large. However, the precise size
and pattern of these punctures varies among
all of these bees, although this has not yet
been assessed quantitatively.
The taxa were first revised as a group in
detail by Panfilov (1951), who interpreted them
as separate species (a view shared by Skorikov
1923; Yarrow 1954), arguing that this is
evidenced by small differences in morphology.
Rasmont (1988), reviewing the fauna of France,
commented on how difficult it was to draw
conclusions for such rare taxa with very few
specimens, but believed that the colour-based
taxa are likely to be separate species because
there was no evidence of intermediates from the
few regions where they occurred in close
proximity that had been sampled (e.g. Pyrenees,
Elburz), and because they appeared to occupy
slightly different habitats. Williams (1998),
reviewing the world fauna, interpreted several
of these taxa as parts of a single broadly
distributed Palaearctic species (a view shared
earlier by Kruseman 1959; Tkalcu 1969; Reinig
1971; Løken 1973; Ornosa 1986), arguing that
there were no clearly distinct morphological
character states other than colour from which to
diagnose them. The distinctive male labial gland
secretions of B. cullumanus and Bombus semenoviellus have been characterized by Hovorka
et al. (2006), and similar studies of other taxa in
this group are in progress.
DNA analysis has recently added a potential
source of large numbers of new characters for
informing these taxonomic questions as applied
to bees (Gibbs 2009; Packer et al. 2009).
Several different genes have been used successfully in phylogenetic studies of bumblebees,
although for particularly closely related taxa
(such as within the cullumanus-group), the most
information-rich sources are the fast-evolving
mitochondrial genes (Cameron et al. 2007),
which include COI. Even very short sequences
of COI can diagnose the majority of species
tested by Meusnier et al. (2008), making COI
barcoding a cost-effective approach to this kind
of problem, especially as it can often be applied
easily to pinned specimens if they are less than
20 years old. Barcoding bumblebees of the
subgenus Subterraneobombus worldwide has
demonstrated that COI can help to diagnose
conventional morphological species while, in
that case, at least not resulting in recognising
many apparently new but artifactual ‘cryptic
species’ (Williams et al. 2011). Therefore, in
this study, we use COI barcoding of recent
museum specimens to explore whether DNA
data can provide evidence to illuminate the
Is Bombus cullumanus extinct?
question of the status of taxa within the
cullumanus-group. In particular, we ask what
the taxonomic limits of the species B. cullumanus are and what the consequences are of
that for conservation planning?
123
LepF1 and LepR1; Hebert et al. 2004). No amplification of Wolbachia (or other obviously non-target
DNA) was detected. Data for the specimens processed at Guelph have been uploaded to the BOLD
online database (boldsystems.org; Ratnasingham and
Hebert, 2007) and GenBank.
2. METHODS
2.3. Reconstructing phylogeny
2.1. Material
Bombus eximius Smith and Bombus sibiricus
(Fabricius) are used here to represent outgroups to
the cullumanus-group based on the estimate of
phylogeny for nearly all bumblebee species obtained
from five genes by Cameron et al. (2007). Following
the same phylogenetic estimate, we include Bombus
morrisoni Cresson and Bombus crotchii Cresson to
represent the rest of the subgenus Cullumanobombus
in the broad sense of Williams et al. (2008). Samples
were obtained from 49 individuals showing differing
morphology and colour pattern of the pile and
representing almost all of the taxa that have been
regarded as separate species within Richards’ (1968)
narrower concept of the subgenus Cullumanobombus
(Table I). In the Old World, these bees are often rare,
and few recent samples are available from collections. We are able to include a sample from one of the
last known specimens (the only known recent
specimen) of B. cullumanus s. str., from France. Five
specimens of B. serrisquama from Spain were sent
for sequencing, but no sequences could be obtained
2.2. DNA barcoding
DNA was sequenced for the short 5′ barcode
region of the mitochondrial-encoded COI gene
(cytochrome c oxidase, subunit 1). The sequenced
samples were taken from specimens collected mostly
within the last 15 years. Specimens were processed at
the Biodiversity Institute of Ontario, University of
Guelph, as part of the BEE-BOL campaign to
barcode the bees of the world (Packer et al., 2009).
DNA extraction, amplification and sequencing used
the standard protocols described by Hebert et al.
(2003). Universal primers for amplifying the COIbarcode sequence for insects were used (variants
COI-barcode sequences (without primer sequences)
from samples were aligned using the ClustalW function
within BioEdit (version 7.0.9.0; www.mbio.ncsu.edu/
BioEdit/bioedit.html, accessed 2010) and trimmed to a
common frame length of 658 nucleotides that was
shared by most samples. We used MrBayes (version
3.1.2; Huelsenbeck and Ronquist 2001; Ronquist and
Huelsenbeck 2003) to search for estimates of the
phylogenetic tree, from ten million generations of the
metropolis-coupled Markov-chain Monte Carlo algorithm with four chains, chain temperature set to 0.5
and with sampling of the trees every 1,000 generations. We found the nucleotide-substitution model
that fitted our COI-barcode data best according to
jModelTest (version 0.1.1; Posada 2008) to be the
general time-reversible model with an inverse-gamma
frequency distribution of changes among sites. Burn-in
was set to 10 % of the generations, with convergence
between two separate runs of the analysis judged to
have occurred when the average standard deviation of
the split frequencies approached stationarity. Post
burn-in stability of the log likelihood of the cold chain
was confirmed using Tracer (version 1.5.0; Drummond
and Rambaut 2007), and stability of the sample groups
was confirmed using AWTY (version 0.8.1; Nylander
et al. 2008). Post burn-in sample trees from both
replicates were combined, and trees were rooted using
data for B. eximius to represent an outgroup, based on
the results of Cameron et al. (2007).
2.4. Recognising species
There is no universally accepted concept of the
nature of species, or any universally accepted method
for their recognition in practice (Mallet 1995, 1997).
All of the concepts have their counter arguments. One
possibility that has been discussed is the idea of a
124
Table I. Material examined with BOLD COI sequence numbers
Caste
Locality
Collector
BOLD specimen number
In-frame sequence
length (bp)
Depository
apollineus
apollineus
apollineus
apollineus
apollineus
apollineus
crotchii
cullumanus
eximius
morrisoni
nigrotaeniatus
nigrotaeniatus
nigrotaeniatus
rufocinctus
rufocinctus
rufocinctus
rufocinctus
rufocinctus
rufocinctus
rufocinctus
rufocinctus
rufocinctus
rufocinctus
rufocinctus
rufocinctus
rufocinctus
rufocinctus
w
m
m
m
m
m
w
m
q
q
w
w
q
q
q
q
q
q
q
q
q
q
Armenia, Sevan
Turkey, Erzurum
Turkey, Kars
Turkey, Kars
Turkey, Kars
Turkey, Kars
USA, California
France, Eyne
Thailand, Tat Tone NP
USA, Utah
Kyrgyzstan, Ak-Bulak
Kyrgyzstan, Alekseyevka
Kyrgyzstan, Krasnyj Oktyabr’
Canada, Alberta
Canada, Alberta
Canada, Alberta
Canada, Alberta
Canada, Alberta
Canada, Alberta
Canada, New Brunswick
Canada, New Brunswick
Canada, Newfoundland
Canada, Northwest Territories
Canada, Nova Scotia
Canada, Nova Scotia
Canada, Ontario
Canada, Ontario
S. Droege
P. Rasmont
P. Rasmont
P. Rasmont
P. Rasmont
P. Rasmont
S. Droege
P. Rasmont
Y. Areeluck
Andrus
L. Best
L. Best
L. Best
L. Morandin
L. Morandin
L. Morandin
L. Morandin
L. Morandin
L. Morandin
C. Sheffield
C. Sheffield
C. Sheffield
L. Morandin
C. Sheffield
C. Sheffield
S. Colla
L. Packer
1549E08
1551H03
6879D09
6879D10
6879D11
6879D12
08-CA-2051
1551H02
3261H06
01-UT-2597
1551D10
1551D11
1551D08
03-BC-0329
03-BC-0330
03-BC-0331
03-BC-0332
03-BC-0333
03-BC-0334
sheffc80
sheffc81
09-NL-3037
05-NT-0041
Bee166
sheffc79
3742E06
0289G06
594
612
658
658
658
658
644
622
624
658
622
425
658
656
656
656
656
656
656
403
393
658
658
626
609
658
658
P. Williams
P. Rasmont
P. Rasmont
P. Rasmont
P. Rasmont
P. Rasmont
L. Packer
P. Rasmont
L. Packer
L. Packer
P. Williams
P. Williams
P. Williams
L. Packer
L. Packer
L. Packer
L. Packer
L. Packer
L. Packer
L. Packer
L. Packer
L. Packer
L. Packer
L. Packer
L. Packer
L. Packer
L. Packer
q
q
q
P.H. Williams et al.
Taxon
Table I. (continued)
Taxon
Locality
Collector
BOLD specimen number
In-frame sequence
length (bp)
Depository
q
q
w
m
m
q
q
q
q
w
q
w
q
m
m
m
m
m
w
w
q
q
q
q
USA, Colorado
USA, Colorado
USA, Idaho
USA, Washington
Czech Republic, Pleše
Czech Republic, Pİsečný-vršek
Germany, Brandenburg
Latvia, Keizari
Latvia, Keizari
Russia, Novosibirsk
Russia, Novosibirsk
Kyrgyzstan, Ak-Bulak
Russia, Altai Territory
Russia, Irkutsk
Russia, Moscow
Russia, Novosibirsk
Russia, Novosibirsk
Turkey, Kars
Turkey, Kars
Turkey, Kars
Mongolia, Zavkhan
Kyrgyzstan, Alekseyevka
Kyrgyzstan, Krasnyj Oktyabr’
Russia, Amur
Russia, Amur
Russia, Amur
B. and J. Thompson
B. and J. Thompson
J. Gibbs and C. Sheffield
J. Gibbs and C. Sheffield
L. Dvořák
J. Straka
C. Saure
M. Kalniņš
M. Kalniņš
Y. Yurchenko
Y. Yurchenko
L. Best
A. Byvalysev
D. Michez
T. Levchenko
A. Byvalysev
A. Byvalysev
P. Rasmont
P. Rasmont
P. Rasmont
J. Gelhaus
L. Best
L. Best
M. Proshalykin
M. Proshalykin
M. Proshalykin
3760E09
3760E10
07-ID-1427
07-WA-1428
1549H09
1549H11
1549H10
6878A01
6878A02
1549E01
1549E02
1551D09
1549E06
6878F05
PCHELA-C03
1549E03
1549E04
6879E01
6879E02
6879E04
1550G03
1551D12
1551D07
6875A07
6875A08
6875A09
565
549
658
658
658
658
626
658
658
653
583
658
658
658
658
658
658
573
632
658
658
425
658
658
658
658
L. Packer
L. Packer
L. Packer
L. Packer
P. Williams
P. Williams
P. Williams
P. Williams
P. Williams
P. Williams
P. Williams
P. Williams
P. Williams
P. Williams
Moscow University
P. Williams
P. Williams
P. Rasmont
P. Rasmont
P. Rasmont
University of Kansas
P. Williams
P. Williams
Vladivostok Institute
Vladivostok Institute
Vladivostok Institute
125
Caste abbreviations: q queen, w worker, m male
Is Bombus cullumanus extinct?
rufocinctus
rufocinctus
rufocinctus
rufocinctus
semenoviellus
semenoviellus
semenoviellus
semenoviellus
semenoviellus
semenoviellus
semenoviellus
serrisquama
serrisquama
serrisquama
serrisquama
serrisquama
serrisquama
serrisquama
serrisquama
serrisquama
sibiricus
tenuifasciatus
tenuifasciatus
unicus
unicus
unicus
Caste
126
P.H. Williams et al.
barcoding ‘gap’ between the relative amounts of COIsequence divergence expected between and within
species. This approach has been much criticised when
reduced to a single generalised divergence-threshold
criterion (Meyer and Paulay 2005; Meier et al., 2006;
Schmidt and Sperling 2008).
Although a fixed numerical criterion for recognising species from the amount of divergence may be
unreliable, a more flexible but related approach,
focussing instead on changes in the branching pattern
near the species level (between interspecific and
intraspecific regions of the tree), has also been
discussed (e.g. Monaghan et al. 2005; Papadopoulou
et al. 2008; Pons et al. 2006). Unfortunately, fully
quantitative models of these processes are only
applicable in situations where many species are
anticipated with multiple unique haplotypes within
each (Monaghan et al. 2009), which is not the case
here. Nonetheless, the principle remains applicable
by inspection of the resulting tree and distances.
MEGA (version 4.0; Tamura et al. 2007) was used to
measure intra- and inter-group sequence divergences,
which were calculated using the Kimura twoparameter distance model (Kimura 1980).
3. RESULTS
Figure 1 shows that all Bombus rufocinctus
samples are supported as a group and that this is
the sister group to a group including the
cullumanus-group (apollineus+serrisquama+
tenuifasciatus+ nigrotaeniatus + cullumanus s.
str.) plus a large New World group (including
morrisoni+crotchii).
COI differentiation within the rufocinctusgroup is generally weak, despite the large
geographic range encompassed, with only the
New Brunswick samples showing a distinct
group. Evidence to support the monophyletic
group apollineus+serrisquama+tenuifasciatus+
nigrotaeniatus + cullumanus s. str. is strong
(Figure 1). From both the long branches between
the groups interpreted as species supported
by the many uniquely shared diagnostic
polymorphisms (minima of sequence divergence ≥6.15 %, Table II) and the distinctly
shorter branches within the groups (maxima of
sequence divergence ≤2.4 %, Table II), we
conclude that there is no evidence from the
COI-barcode analysis (Figure 1) for recognising more than the following species: B.
rufocinctus, B. semenoviellus, Bombus unicus,
and the single broadly distributed species B. cullumanus s. l. The mean intraspecific divergence
within B. cullumanus s. l. is especially small given
the number of sequences and the breadth of
geographic coverage in the sample (Table II).
4. DISCUSSION
There are many potential pitfalls in the interpretation of COI barcodes in terms of the
evolution of taxa (Rubinoff et al. 2006). Those
most likely to confound our analysis are that
patterns of evolution for mitochondrial genes do
not always correspond precisely with those of
their owner species. However, these problems
have not yet been detected in studies of
bumblebees (Bertsch 2010; Williams et al. 2011).
Our tree (Figure 1) shows a strong pattern of
a distinct separation between many short terminal branches and a few long higher branches
(with many diagnostic nucleotide changes,
Table II). Elsewhere, this kind of pattern has
been interpreted as marking the separation
between small intraspecific differences and
larger interspecific differences (Monaghan et
al. 2005, 2009; Pons et al. 2006; Papadopoulou
et al. 2008). Such a strong distinction
(corresponding to the much criticised ‘barcoding gap’) is not universal among bumblebees
(e.g. Williams et al. 2011) but is nonetheless
apparent in this case. Nonetheless, it would be
desirable to compare our COI results for these
bees with results from a highly variable nuclear
gene.
Our results agree with Franklin (1913),
Frison (1927), Milliron (1973) and Plowright
and Owen (1980) in supporting just one
variable species B. rufocinctus in North America. This has long been recognised to be the
most variable species in colour pattern within
the entire western hemisphere (Franklin 1913).
Geographic structure within this variation is
Is Bombus cullumanus extinct?
127
Figure 1 Estimate of phylogeny for 49 samples of all species of the rufocinctus-group and cullumanus-group
by Bayesian analysis of COI-barcode data (frame length 658 nucleotides, sequence data available from BOLD)
from a consensus of 18,002 sample trees after burn-in; values next to the nodes are Bayesian posterior
probabilities for groups (groups with values of less than 0.8 are considered unreliable, and figures have been
removed); the scale bar represents 0.07 expected substitutions per nucleotide site
apparently weak, as reported by Plowright and
Owen (1980).
Similarly, in the eastern hemisphere, the taxa
apollineus, serrisquama, tenuifasciatus, nigrotaeniatus and cullumanus s. str., with their
strongly contrasting colour patterns, are interpreted as being parts of just one variable
species, B. cullumanus s. l. (in agreement with
Kruseman 1959; Tkalcu 1969; Reinig 1971;
Løken 1973; Ornosa 1986; Williams 1998).
Because these taxa are diagnosable from
their colour patterns and have become of
interest to bumblebee specialists, we will
continue to refer to them as taxa at the rank
of subspecies for this paper but only as
pragmatic labels and without judging their
status as biologically separate populations.
We have found no strong evidence of
geographic structure in the COI data for this
species that correlates with the variation in
128
P.H. Williams et al.
Table II. Divergence in COI-barcode sequences among and within inferred species
Species
B.
B.
B.
B.
rufocinctus
semenoviellus
unicus
cullumanus s. l.
Number of
sequences
18
7
3
21
Number of uniquely
shared diagnostic
polymorphisms
(non-synonymous)
28
13
10
22
(28)
(12)
(10)
(22)
Minimum
interspecific
sequence
divergence (%)
Maximum
intraspecific
sequence
divergence (%)
Mean
intraspecific
sequence
divergence (%)
9.64
6.15
6.15
6.73
2.40
0.69
0.00
0.48
0.76
0.31
0.00
0.09
Sequence divergences are calculated using the Kimura two-parameter (K2P) distance model
colour pattern. The Turkish and Armenian
samples (the southern part of the global
range) all have broad pale bands, although
the bands may be either white or yellow,
without intermediates. In this particular region, the white-banded female colour pattern
(apollineus: see map in Panfilov 1951) is a
frequent convergent colour pattern (Williams
2007), and other species show a similar
yellow/white dimorphism (Williams 1998;
Rasmont et al. 2005b; De Meulemeester et al.
2010). The remaining more northern samples
either have broad yellow bands or reduced
yellow bands. In the Russian steppe and
sometimes in Central Asia, females have broad
bands (serrisquama: see map in Panfilov
1951). This is the most common colour pattern
among all bumblebees worldwide, and extensively yellow patterns are especially frequent
among steppe bumblebees (Williams 2007).
Darker female colour patterns also occur in
Central Asia, some with darker yellow bands
(e.g. tenuifasciatus) and some with very little
yellow on the metasoma (e.g. nigrotaeniatus,
probably including at least the second female
of praemarinus, described from Buryatia,
although it is just possible that the holotype
of praemarinus is not actually from Vladivostok but might also have originated from Central
Asia). The darkest female colour pattern, lacking
all of the yellow bands (cullumanus s. str.), is
confined to southern England and adjacent
parts of north-western continental Europe from
the Pyrenees to southern Sweden (Rasmont et
al. 2005a). In this region, the dark colour
pattern is especially frequent among bumblebee species (Williams 2007).
The conservation status of the cullumanusgroup in Europe has been a subject of concern
for many years. Individuals with the dark
female colour pattern, B. cullumanus cullumanus s. str., are known to be in strong decline in
Britain (Yarrow 1954; Alford 1975), in France
(Rasmont 1988; Rasmont et al. 2005a), and in
Western Europe generally (Kosior et al. 2007).
A remnant population with this colour pattern
was known in the French Pyrenees (Iserbyt et
al. 2008) at least as recently as 2001, but the
very last live individual with this colour pattern
to be seen was in the Massif Central of France
in 2004. The light yellow female colour pattern,
B. cullumanus serrisquama, is in decline in
Hungary (Sárospataki et al. 2005) and in
Western Europe generally (Kosior et al. 2007),
where it is now very rare. However, in the
steppes of the west Siberian plain, it is still the
dominant or subdominant species of bumblebee
(≥10 % of the total number of bumblebees) in
13 of the 36 localities sampled by one of us
(Table III). It is also still common in some
collections from China (Xinjiang), Kazakhstan
and Kyrgyzstan (Williams 2011), as are the
darker B. cullumanus tenuifasciatus and B.
cullumanus nigrotaeniatus in the same region.
Individuals with the white-banded colour pattern, B. cullumanus apollineus, were once very
common in Turkey, but they have become rarer,
although still present (M. Aytekin, in lit.). One
of us (PR) found abundant and apparently stable
populations of B. cullumanus apollineus in the
129
Is Bombus cullumanus extinct?
Table III. Numbers of bumblebees including B. cullumanus counted in Siberia (AB) based on the method of
Pesenko (1972) using a sweep-net along transects of 2×100 m searched for 20 min and expressed as the
number of individuals per hour
Site name
Siberia
Mikchailovskoe
Melnikovo
Kamen-na-Obi
Oktyabrskoe
Troitskoe
Mikchailovskoe
Klepechiha
Klepechiha
Novonikolskoe
Grachevo
Pokrovka
Zolotoe
Bor-Forpost
Kochki
Alexandrovskii
Alexandrovskii
Petropavlovsk
Turkey
Kars, Göldalı
GPS coordinates
Date
51°49′N
52°14′N
53°44′N
55°00′N
53°42′N
51°49′N
52°05′N
52°05′N
54°32′N
55°29′N
52°02′N
55°06′N
51°52′N
54°18′N
53°39′N
53°39′N
54°50′N
79°36′E
81°06′E
81°07′E
67°54′E
77°49′E
79°36′E
81°44′E
81°44′E
68°37′E
65°41′E
79°20′E
66°56′E
80°06′E
80°25′E
78°15′E
78°15′E
69°03′E
7/2005
7/2006
7/2007
6/2005
8/2006
7/2007
7/2006
7/2008
7/2005
6/2005
7/2007
6/2005
7/2008
8/2007
7/2007
7/2008
8/2006
40°58′N 43°18′E
8/2011
Total no.
of Bombus
individuals
per hour
No. of
Bombus
spp.
No. of B.
cullumanus
individuals
per hour
Percentage of B.
cullumanus
individuals
3.0±3.0
36.0±3.0
12.0±3.0
17.4±2.7
40.5±6.1
18±3.0
4.5±1.0
30.8±5.7
47.0±4.4
21.7±5.4
24.±6.0
16.3±2.2
9.0±0.0
70.5±8.1
11.5±3.2
29.5±5.4
51.5±4.3
1
3
2
14
16
2
5
7
12
15
4
18
2
16
10
13
8
3.0±3.0
18.0±3.0
4.5±1.5
5.3±3.2
11.5±3.5
4.5±1.5
1.0±0.9
6.8±3.3
10.0±5.6
4.5±1.8
4.5±1.5
2.8±0.7
1.5±1.5
10.0±3.0
1.5±1.5
3.5±1.4
6.0±2.9
100.0
50.0
37.5
30.5
28.4
25.0
22.2
22.1
21.3
20.7
18.7
17.2
16.7
14.2
13.0
11.9
11.7
79
9
62
78.4
The date refers to the month and year of the recording period. The last line is a sample from northeastern Turkey (PR and A.
M. Aytekin)
Kars region, where it is intermixed with
scattered B. cullumanus serrisquama.
B. semenoviellus is another species that is
rare in collections. Against the general declining
trend among many European bumblebee species, it has expanded its range westwards
recently, as evidenced by several recent papers
(van der Smissen and Rasmont 1999; Přidal and
Tkalců 2003; Přidal and Komzáková 2009;
Streinzer 2010). B. unicus is known from very
few specimens from the Russian Far East,
although no targeted surveys have been made
(M. Proshchalykin, in lit.).
All of the Old World cullumanus-group
species are very rare or potentially threat-
ened, at least in some parts of their ranges.
The dark individuals of B. cullumanus cullumanus s. str. may now be extinct, but
according to our results, other closely related
individuals of B. cullumanus serrisquama
and B. cullumanus apollineus appear to be
relatively unthreatened. Therefore, although
the apparent loss of individuals with this dark
colour pattern from Western Europe (and any
special adaptive genes it might have had) is
very unfortunate; nonetheless, the positive
view is that at least our tree would appear to
predict that the amount of unique diversity
lost in all other genes (assuming that the COI
tree is predictive because of shared inheri-
130
P.H. Williams et al.
tance) is less than might have been the case if
it had been more distantly related to the
eastern part of the population (Vane-Wright
et al. 1991). It would be useful to know
whether any special characteristics of the
dark western B. cullumanus cullumanus s.
str. are also shared by the dark individuals of
B. cullumanus (tenuifasciatus, nigrotaeniatus)
from Central Asia.
What are the consequences of our results for
conservation? In a European context, B. cullumanus cullumanus s. str., if it still exists
anywhere, would be one of the highest priorities. But in a global context, our tree would
identify the far eastern B. unicus as an even
higher priority for conservation action, because
of its greater unique genetic divergence, combined with the restricted geographic range and
low abundance of the entire species. We
urgently need surveys to document the status
of B. unicus, the principal threats and its
vulnerability.
ACKNOWLEDGEMENTS
Thanks to all of those who generously donated
or loaned specimens or sequences, especially S.
Belokobylskij, L. Best, S. Droege, M. Kalniņš, T.
Levchenko, E. Ploquin and M. Proshchalykin.
Particular thanks to L. Packer for arranging for
the barcoding as part of the BEE-BOL campaign,
to the Biodiversity Institute of Ontario for the
extractions, amplification and sequencing, and to
the Canadian Barcode of Life Network and
Natural Sciences and Engineering Research Council for funding the barcoding. The research in
Russia was carried out in part with financial
support of the project MK-5168.2012.4 of the
President Grants for State Support of Young
Scientists in the Russian Federation. Thanks to
V. Blagoderov for translation and to J. Stahlhut
and J. Stefka for discussion.
Bombus cullumanus—une espèce de bourdon
européen éteinte?
Bombus / bourdon / Europe / taxonomie /
conservation des espèces / code barre génétique
Bombus cullumanus—eine ausgestorbene
europäische Hummelart?
Hummeln / Bombus / Barcode / Taxonomie /
Naturschutz
Open Access This article is distributed under the terms
of the Creative Commons Attribution License which
permits any use, distribution, and reproduction in any
medium, provided the original author(s) and the source
are credited.
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