Bombus

B. sibiricus male visiting Cosmos.

Sibiricobombus ecology and behaviour   HABITAT: High alpine grassland, mountain-meadow, open grassland and semi-desert.   FOOD-PLANTS: Long tongue-length bumblebees visiting deep flowers.   NESTING BEHAVIOUR: Nests underground or aboveground in cavities. Nest structure undescribed.   MATE-SEARCHING BEHAVIOUR: Males of most species have strongly enlarged compound eyes. B. asiaticus males perch before racing after potential mates, but avoid contact with other males and are not truly territorial (Williams, 1991).

Subgenus SIBIRICOBOMBUS Vogt
Bombus (Sibiricobombus) Vogt, 1911:60, type-species Apis sibirica Fabricius (= Bombus sibiricus (Fabricius)) by subsequent designation of Sandhouse, 1943:599
Bombus (Obertobombus) Reinig, 1930:107, type-species Bombus oberti Morawitz by monotypy
[Obertibombus Skorikov, 1931:239, incorrect subsequent spelling]
Bombus (Obertibombus) Reinig, 1934:167, unjustified emendation
Sibiricibombus Skorikov, 1938a:145, unjustified emendation
[Bombus (Sibericobombus) Kruseman, 1952:101, incorrect subsequent spelling]

TAXONOMIC STATUS: For a discussion of why several former subgenera have been synonymised within this subgenus see Williams et al. (2008 [pdf]) .

Part of the bumblebee phylogenetic tree including available Sibiricobombus species from an analysis of DNA sequence data for five genes (Cameron et al. 2007 [pdf]). Values above branches are Bayesian posterior probabilities, values below branches are parsimony bootstrap values.

Bombus (Sb.) morawitzi Radoszkowski
Morawitzi Radoszkowski, 1876:101, examined
hydrophthalmus Morawitz, 1883:240, examined
4 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

Bombus (Sb.) semenovi Morawitz
Semenovi Morawitz, 1887:198, examined
xionglaris Wang, 1982:432, examined
duanjiaoris Wang, 1982:444, examined
zhadaensis Wang, 1982:444, examined
6 names

TAXONOMIC STATUS: B. xionglaris and B. zhadaensis are closely similar to B. semenovi in morphology and in colour pattern. These bees occur at high altitudes and are not common in collections (Williams, 1991 [pdf]). However, I know of no reason why these nominal taxa should not be considered conspecific.

DISTRIBUTION: Oriental Region.

Bombus (Sb.) oberti Morawitz
Oberti Morawitz, 1883:238, examined
[pamirus Skorikov, 1912:609, infrasubspecific]
pamirus (Skorikov, 1931:232 [Subterraneobombus]) examined, not of Skorikov, 1931:226 [= B. keriensis Morawitz]
9 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

Bombus (Sb.) sibiricus (Fabricius)
fibirica [sibirica] (Fabricius, 1781:478 [Apis]) examined
flaviventris Friese, 1905:514, examined
ochrobasis Richards, 1930:655, examined
nikiforuki Tkalcu, 1961b:354, examined
7 names

TAXONOMIC STATUS: B. sibiricus and B. flaviventris have been regarded as separate species. Females of B. flaviventris are morphologically closely similar to those of B. sibiricus, but differ in having the orange pubescence dorsally between the wing bases and on gastral terga IV-VI replaced with black. The male of B. flaviventris is also closely similar in its genitalia to B. sibiricus.

B. ochrobasis appears to differ from B. flaviventris only in the lighter hue of the yellow pubescence of B. ochrobasis.

I know of no good biological reason why these three nominal taxa should not be regarded as conspecific (Williams, 1998). More evidence is awaited.

NOMENCLATURE: The orthography of Fabricius (1781) employs a long 's' (similar to 'f' or 'f'), a common practice of the period. This convention has since changed and recent authors have consistently used 's'.

COMMENT: B. flaviventris has long been placed in the subgenus Subterraneobombus (e.g. Skorikov, 1922a; Richards, 1930, 1968), although the characters of the females (Williams, 1991 [pdf]) and the males agree with the species of the subgenus Sibiricobombus.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Oriental, Palaearctic Regions.

Bombus (Sb.) obtusus Richards
obtusus Richards, 1951:196, examined
2 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

Bombus (Sb.) asiaticus Morawitz
asiatica Morawitz in Fedtschenko, 1875:4, examined
longiceps Smith, 1878:8
Regeli Morawitz, 1880:337, examined
regelii Dalla Torre, 1896:544, unjustified emendation
[miniatocaudatus Vogt, 1909:50, infrasubspecific]
miniatocaudatus Vogt, 1911:61, examined, not of Vogt, 1909:56 (= B. soroeensis (Fabricius))
heicens Wang, 1982:430, examined
huangcens Wang, 1982:430, examined
flavicollis Wang, 1985:163, examined
baichengensis Wang, 1985:164, examined
31 names

TAXONOMIC STATUS: Several of these nominal taxa have been treated as separate species.

B. heicens, B. huangcens, B. flavicollis, and B. baichengensis are morphologically closely similar to B. asiaticus and differ only in details of the colour pattern. In the case of the yellow unbanded colour form and the grey banded colour form in Kashmir, there is evidence of interbreeding, with many recombinant individuals (Williams, 1991 [pdf]).

Aside from differences in colour pattern, these taxa are similar in morphology with a range of variation (Williams, 1991 [pdf]). Until more evidence to the contrary is available from critical studies of patterns of variation, I shall treat them as parts of a single variable species.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Oriental, Palaearctic Regions.

Bombus (Sb.) sulfureus Friese
sulfureus Friese, 1905:521, examined
2 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

Bombus (Sb.) niveatus Kriechbaumer
niveatus Kriechbaumer, 1870:158
vorticosus Gerstaecker, 1872:290, examined
18 names

TAXONOMIC STATUS: B. niveatus and B. vorticosus have been regarded both as conspecific (Schmiedeknecht, 1883; Handlirsch, 1888; Dalla Torre, 1896; Schulz, 1906; Williams, 1991 [pdf]) and as separate species (e.g. Skorikov, 1922a; Pittioni, 1938; Tkalcu, 1969; Reinig, 1981; Rasmont, 1983).

The white-banded B. niveatus occurs only within the broader distributional bounds of the yellow-banded B. vorticosus (within its 'extent of occurrence' in the sense of Gaston, 1994). Although they differ in the colour of the pale pubescence (Pittioni, 1939a), they are closely similar in morphology (Williams, 1991 [pdf]; Baker, 1996b). Pittioni (1938) and Baker (1996b) report that they occur at different altitudes, without intermediate colour forms. However, the significance of this is unclear, because Baker (1996b) notes that the white-banded B. niveatus co-occurs with other bumble bees (B apollineus (= B. cullumanus), B. simulatilis (= B. ruderarius)) that also show strong convergences in these areas towards the white-banded colour pattern (see Williams, 2007 [pdf]), while elsewhere they are more broadly distributed as yellow-banded colour forms. By analogy with other species (cf. comments on B. melanopygus, B. keriensis), the difference in colour could be the effect of a single pair of alleles at one locus for pigment. It is suspicious that both colour forms show identical variation in the extent of pale fringes to the pubescence on the posterior of tergum III. Both yellow- and white-banded forms show broad fringes at the same localities (e.g. 'Sefid Khok', Iran), either through genetic recombination or through a remarkably precise convergence.

Recent studies of the secretions of the male cephalic glands by Rasmont et al. (2005) provide strong support for the interpretation that B. niveatus and B. vorticosus are conspecific and yet separate from B. sulfureus. Studies of wing venation by Aytekin et al. (2007) reach the same conclusion. Evidence from comparisons of DNA sequences from five genes is also consistent with the two taxa being conspecific (Cameron et al., 2007 [pdf]).

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.