taxonID	type	description	language	source
FE5D87EC26156D7DDE0EFCAEFBF5F9AC.taxon	description	We associate a total of 82 published formal names with species of the subgenus Sibiricobombus (including misspellings and infrasubspecific names). Below is a list of the 11 species recognised from the integrative analysis together with the synonyms that occur most frequently in the literature (identified from morphology) with the changes since the last checklist labelled (Williams 1998). The subgenus Obertobombus (Reinig 1930) is included within the subgenus Sibiricobombus (Richards 1968), based on evidence from morphology (Richards 1968; Williams 1991) and from genes (Cameron et al. 2007; Williams et al. 2008, 2022). The species of Obertobombus are recognised here as part of the sibiricus - group of species.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26156D7DDE0EFCAEFBF5F9AC.taxon	description	Accounts of the species Accounts of the 11 species accepted after integrative assessment follow below. Square brackets [Bombus xus] are used to indicate transliterations, translations, and interpretations.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26116D72DDFBF9FFFA8CF8BC.taxon	description	Figs 1, 7 – 8, 12 ‒ 17, 90, 101	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26116D72DDFBF9FFFA8CF8BC.taxon	diagnosis	Diagnosis Females Queens body length 20 ‒ 21 mm, workers 12 ‒ 14 mm. Colour pattern of the hair with the head predominantly black, the thoracic dorsum anterior and posterior bands and metasomal T 1 ‒ 3 entirely yellow, and hair of the band between the wing bases either yellow or orange or black, and hair of T 4 ‒ 5 either orange or black, the lower side of thorax and legs black (Figs 12 ‒ 14). Morphology with hind basitarsus outer surface in the centre with short branched hairs dense, black and strongly overlapping so that reflections from the outer surface are interrupted; (in large individuals) T 6 subapically medially with a longitudinal ridge with a flattened crest. Males Body length 14 ‒ 17 mm. Colour pattern of the hair similar to the female, with the head black but with yellow on the vertex and on the clypeus, the thoracic dorsum anterior and posterior bands and metasomal T 1 ‒ 3 entirely yellow, and hair of the band between the wing bases either yellow or orange or black, and hair of T 4 ‒ 6 either orange or black, the coxae and legs predominantly black (Figs 15 ‒ 17). Morphology with the eye scarcely enlarged relative to the eye of a female bumblebee, from the dorsal aspect the eye separated from the lateral ocellus by more than 2 × the ocellar breadth; S 6 with the posterior margin in the middle with a deep concave indentation; penis-valve head with the recurved section broad, narrowing gradually towards the tip (Fig. 90).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26116D72DDFBF9FFFA8CF8BC.taxon	materials_examined	Type material Lectotype of Apis sibirica (designated here) RUSSIA • ♀ (worker); “ Sibiria ”; P. Pallas leg.; NHMUK Banks Collection (examined PW). Holotype of Bombus melinoides (by monotypy?) RUSSIA • ♀ (queen); Irkutsk; (type not seen but identity not in doubt). Syntypes of Bombus flaviventris CHINA • 2 ♀♀ (queen, worker); ZMB (examined PW). Holotype of Bombus (Subterraneobombus) flaviventris subsp. ochrobasis (by original designation) CHINA • ♀ (queen); [not] Sikkim [Xizang], “ Khamba Jong ” [Gampa Dzong]; 15 - 30 Jul. 1903; NHMUK (examined PW). Holotype of Bombus (Pyrobombus) nikiforuki (by original designation) CHINA • ♀ (worker); Qinghai, “ Hsi-li-gou ” north of Dulan; 31 Aug. 1950; C. Yang leg.; LMOB (examined PW). Material examined CHINA ‒ Gansu • 2 ♂♂; Yongden, Tongyuan; 36.6767 ° N, 103.0472 ° E; 2 Sep. 2010; P. Williams leg.; BOLD nos: 6880 C 09, 6880 C 10 (COI); PW, SB 058, SB 059. ‒ Inner Mongolia • 1 ♀ (worker), 1 ♂; Majiazi; 43.2176 ° N, 117.3153 ° E; 10 Sep. 2007; P. Williams leg.; BOLD nos: 6880 C 11, 6880 C 12 (COI); PW, SB 060, SB 061. – Qinghai • 1 ♀ (worker); Xingfucan; 35.8993 ° N, 97.8892 ° E; 10 Aug. 2013; P. Williams leg.; PW, SB 002 / NHMC 06 • 1 ♀ (worker); NW of Dulan; 36.6689 ° N, 98.1181 ° E; 14 Aug. 2013; P. Williams leg.; PW, SB 001 / NHMC 07. ‒ MONGOLIA ‒ Zavkhan • 1 ♀ (worker); Tegshiin Gol; 48.3313 ° N, 97.8645 ° E; 22 Jul. 2004; J. Gelhaus leg.; BOLD no.: 1550 G 03 (COI); KSEM, SB 044.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26116D72DDFBF9FFFA8CF8BC.taxon	distribution	Distribution Asian desert-edge and Tibetan Plateau species: Fig. 101 ‒ North Asia: KAZAKHSTAN, MONGOLIA, RUSSIA: East Siberia. ‒ East Asia: CHINA: Xinjiang, Xizang, Qinghai, Gansu, Ningxia, Shaanxi, Hebei, Inner Mongolia. One of the highest recorded bumblebee species in the world at 5640 m a. s. l., along with B. tibeticus Williams, 2020 (recorded in 2018 under the name B. keriensis Morawitz s. lat.) and B. tanguticus Morawitz, 1887 from a site beside the West Rongbuk Glacier in Tibet [= Xizang], at 28.061160 ° N, 86.847273 ° E (Williams 2018). The species is so far unrecorded from central Xizang, e. g., in collections from the Tanggu La mountains. (AB, EA, EB, IAR, IZCAS, LMOB, NHMUK, PW, RDJ, UUH, VLA, ZIN, ZMB.)	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26116D72DDFBF9FFFA8CF8BC.taxon	biology_ecology	Behaviour Because the male eye is scarcely enlarged relative to the eye of a female, as in most bumblebees, the male mate-searching behaviour is expected to be similar to the most widespread male “ patrolling ” behaviour (Awram 1970; Svensson 1979), as for B. tunicatus Smith, 1852, compared with “ racing ” behaviour (below) (Williams 1991). It is also possible, but unrecorded, that the males might seek out colonies with young females.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26116D72DDFBF9FFFA8CF8BC.taxon	discussion	Taxonomic remarks Note on the lectotype of Apis sibirica Fabricius, 1781: this would appear to be (one of?) the specimen (s) referred to by Fabricius (1781) in the original description as being in the Banks Collection (“ Dr. Pallas. Muʃ. Dom. Banks. ”). Because the number of specimens of Apis sibirica in this collection seen by Fabricius was not explicit in the original description and others may have existed, this individual which lacks the left hind tarsi and has some glue on the underside (with a later red-edged, round NHMUK label printed with “ Type / H. T. ”, a recent printed label identifying B. sibiricus: “ BMNH (E) # 668744 ”, and an old drawer label “ Apis Sibirica / Fabr. Sp. ruf. [?] No 22. ”) is designated as lectotype in order to reduce uncertainty in the identity of the taxon and in the application of the name. The taxon concept of the species B. sibiricus here agrees with the recent interpretation (Williams 1998), presenting evidence that: (1) our PTP analysis supports independent species-level coalescents in the COI gene (Fig. 1); corroborated by (2) diagnostic morphological character states (see the keys). The species-level coalescent in the COI gene (Fig. 1) also supports as conspecific the red-tailed taxon sibiricus s. str. from Mongolia and the black-tailed taxon flaviventris from the QTP. This conspecificity is corroborated by their closely similar morphology (see the key). Surprisingly, the black-tailed taxon flaviventris has had unusually widely different interpretations by previous authors: (1) as part of a “ Gruppe confusus ” (Friese 1905); (2) as part of the subgenus Subterraneobombus (Richards 1930); or (3) as part of the subgenus Sibiricobombus (Williams 1991, 1998). Individuals of the orange-tailed colour pattern vary from having a distinct orange band in the hair between the wing bases (taxon sibiricus s. str.) to having the thoracic dorsum entirely yellow (taxon melinoides).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261E6D70DDAEF8CFFB03FB39.taxon	description	Figs 1, 7 – 8, 18 ‒ 21, 91	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261E6D70DDAEF8CFFB03FB39.taxon	diagnosis	Diagnosis Females Queens body length 20 ‒ 23 mm, workers 12 ‒ 13 mm. Colour pattern of the hair with the head, lower side of the thorax and legs predominantly black, metasomal T 3 ‒ 4 either black or more or less extensively dull orange, thoracic dorsum anterior and posterior bands and T 1 ‒ 2 yellow, T 5 dull orange (Figs 18 ‒ 20). Morphology with labral furrow broad, 0.35 × the entire breadth of the labrum; antennal A 3 length 2 × greatest breadth; hind basitarsus outer surface in the centre with short branched hairs dense, black and strongly overlapping so that reflections from the outer surface are interrupted; (in large individuals) T 6 subapically medially with a deep narrow longitudinal groove. Males Body length 16 mm. Colour pattern of the hair similar to the female, with the head except the yellow vertex, legs predominantly black, thoracic dorsum anterior and posterior bands, anterior sides of the thorax, and T 1 ‒ 2 yellow, metasomal T 3 either black or more or less extensively dull orange, T 4 ‒ 6 dull orange (Fig. 21). Morphology with the eye scarcely enlarged relative to the eye of a female bumblebee, from the dorsal aspect the eye separated from the lateral ocellus by more than 2 × the ocellar breadth; S 6 with the posterior margin in the middle with a shallow narrow concave indentation; volsella with the inner distal corner as a broad but obtusely pointed hook projecting posteriorly almost as far as the outer distal corner (Fig. 91).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261E6D70DDAEF8CFFB03FB39.taxon	materials_examined	Type material Syntype of Bombus semenovi (lectotype designation by Podbolotskaya unpubl.) CHINA • ♀ (queen); Qinghai, “ im Thale des gelben Flusses ” [Yellow River, Huang He]; [1884]; N. Przhevalsky leg.; ZIN (examined PW). Holotype of Bombus (Sibiricobombus) xionglaris (by original designation) CHINA • ♂; Xizang, Nyalam; 31 May 1974; X. Zhang leg.; IZCAS (examined PW). Holotype of Bombus (Subterraneobombus) duanjiaoris (by original designation) CHINA • ♀ (worker); Xizang, Rutog; 23 Aug. 1976; F. Huang leg.; IZCAS (examined PW). Holotype of Bombus (Subterraneobombus) zhadaensis (by original designation) CHINA • ♀ (queen); Xizang, Zanda; 25 Jun. 1976; F. Huang leg.; IZCAS (examined PW). Material examined CHINA ‒ Qinghai • 1 ♀ (worker); Kunlun Shan Pass; 35.6920 ° N, 94.0520 ° E; 13 Aug. 2013; P. Williams leg.; PW, SB 003 / NHMC 08 • 2 ♀♀ (workers); Kunlun Shan; 35.9063 ° N, 94.4052 ° E; 18 Jul. 2017; IZCAS, SB 040 / MOBBT 3, SB 089 / BB 07 • 1 ♀ (worker); Kunlun Shan Pass; 35.6917 ° N, 94.0533 ° E; 19 Aug. 2013; IAR, SB 016 / JH 8. ‒ Xizang • 1 ♂; Tanggula Shan; 32.8614 ° N, 91.9174 ° E; 18 Aug. 2015; IAR, SB 004 / JH 13 • 1 ♀ (queen); Tanggula Shan; 32.8614 ° N, 91.9174 ° E; 29 Jun. 1999; K. Huber leg.; BOLD no.: 1552 A 07 (COI); LMOB, SB 041 • 1 ♂; near Zhilong; 32.8614 ° N, 91.9174 ° E; 18 Aug. 2015; IAR, SB 017 / JHNEW. INDIA ‒ Jammu & Kashmir • 1 ♀ (queen); Zanskar, Nimaling; 33.7927 ° N, 77.5881 ° E; 18 Aug. 1980; P. Williams leg.; BOLD no.: 1555 D 11 (COI); PW, SB 014.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261E6D70DDAEF8CFFB03FB39.taxon	distribution	Distribution Tibetan high montane species ‒ East Asia: INDIA: Kashmir & Jammu; CHINA: Xizang, Qinghai. (IAR, IZCAS, NHMUK, PW, ZIN.)	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261E6D70DDAEF8CFFB03FB39.taxon	biology_ecology	Behaviour Because the male eye is scarcely enlarged relative to the eye of a female, as in most bumblebees, the male mate-searching behaviour is expected to be similar to the most widespread male “ patrolling ” behaviour (Awram 1970; Svensson 1979), as for B. tunicatus, compared with “ racing ” behaviour (below) (Williams 1991). It is also possible, but unrecorded, that the males might seek out colonies with young females.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261E6D70DDAEF8CFFB03FB39.taxon	discussion	Taxonomic remarks Note 1 on the name B. semenovi Morawitz, 1887 stat. rev.: the type locality of B. semenovi is probably near the source of the Yellow River, in the river valley downstream from the Zhaling Hu in Qinghai. See the discussion of the type locality of B. (Melanobombus) tanguticus Morawitz, 1887 in Williams (2018). The taxon concept of the species B. semenovi stat. rev. here agrees with the recent interpretation of a species separate from B. oberti (Williams 2022 a), presenting evidence that: (1) our PTP analysis supports independent species-level coalescents in the COI gene (Fig. 1); corroborated by (2) diagnostic morphological character states (see the keys). Queens show some variation from T 3 black (Qinghai) to T 3 predominantly orange-red, or at least with an orange-red fringe posteriorly (Zanskar, Kashmir, India). The taxa xionglaris, duanjiaoris and zhadaensis are re-descriptions of the taxon semenovi.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261C6D76DDD0FB48FEB1FD1E.taxon	description	Figs 1, 7 – 8, 22 ‒ 25, 92	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261C6D76DDD0FB48FEB1FD1E.taxon	diagnosis	Diagnosis Females Queens body length 20 ‒ 23 mm, workers 13 mm. Colour pattern of the hair with the head, lower side of the thorax and legs predominantly black, thoracic dorsum anterior and posterior bands and T 1 ‒ 2 either yellow (workers and some queens) or grey-white (some queens), metasomal T 3 black, at most with a narrow posterior pale fringe, T 4 ‒ 5 either dull orange or dark brown or black (Figs 22 ‒ 24). Morphology with labral furrow narrow, 0.25 × the entire breadth of the labrum; antennal A 3 length 2 × greatest breadth; hind basitarsus outer surface with short branched hairs dense, black and strongly overlapping so that reflections from the outer surface are interrupted; (in large individuals) T 6 subapically medially with a deep narrow longitudinal groove. Males Body length 17 mm. Colour pattern of the hair with the head black with yellow on the vertex and on the clypeus, the legs with many pale hairs, thoracic dorsum anterior and posterior bands and T 1 ‒ 2 yellow, metasomal T 3 black, T 4 ‒ 6 dull orange (Fig. 25). Morphology with S 6 with the posterior margin in the middle with a shallow narrow indentation; volsella with the inner distal corner broadly and evenly rounded and much shorter than the outer distal corner (Fig. 92).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261C6D76DDD0FB48FEB1FD1E.taxon	materials_examined	Type material Lectotype of Bombus oberti (by designation of Williams 1991: 92) KAZAKHSTAN • ♂; “ im Hochgebirge bei Wernoye ” [Almaty]; A. Kuschakewitsch leg.; ZIN (examined PW). Holotype of Bombus melanurus var. [= subsp.] apicatus (by monotypy) KYRGYZSTAN • ♀ (queen); “ Pamir Hochland am Alai ”; ZMB (examined PW). Lectotype of Bombus (Obertobombus) oberti var. [= subsp.] griseofasciatus (designated here) TAJIKISTAN • ♀ (queen); Pamir, “ Pass Naisa-Tasch ”; 31 Jul. 1928; W. Reinig leg.; Naturalis (examined PW). Material examined TAJIKISTAN • 1 ♀ (queen); Pamir, SE Kara-Kul; 38.9537 ° N, 73.5076 ° E; 12 Jul. 1928; W. Reinig leg.; Naturalis, SB 042 / NHMK 01.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261C6D76DDD0FB48FEB1FD1E.taxon	distribution	Distribution Rare Central Asian high montane species ‒ Central Asia: KAZAKHSTAN, KYRGYZSTAN, TAJIKISTAN. (Naturalis, PW, ZIN, ZMB.)	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261C6D76DDD0FB48FEB1FD1E.taxon	biology_ecology	Behaviour Because the male eye is scarcely enlarged relative to the eye of a female, as in most bumblebees, the male mate-searching behaviour is expected to be similar to the most widespread male “ patrolling ” behaviour (Awram 1970; Svensson 1979), as for B. tunicatus, compared with “ racing ” behaviour (below) (Williams 1991). It is also possible, but unrecorded, that the males might seek out colonies with young females.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261C6D76DDD0FB48FEB1FD1E.taxon	discussion	Taxonomic remarks Note on the name B. oberti var. griseofasciatus Reinig, 1930: although Reinig used both “ subsp. ” and “ var. ’ in his 1930 publication, which would imply infrasubspecific status for taxa described as “ var. ”, he gave the taxon griseofasciatus a geographically defined distribution in the “ Pamir-Gebiet ” (p. 109) and also used the name as a simple trinomen “ Bombus oberti griseofasciatus ” (p. 73), both of which would appear to confer subspecific status. Note on the lectotype of B. oberti var. griseofasciatus Reinig, 1930: the label data matches the data for one of the specimens referred to by Reinig 1930 in the original description. Because others were listed, this individual, which lacks the right hind terminal joint of the tarsus and has a bald patch on T 2 (labels: (1) printed “ Zentral – Pamir / VII. - VIII. 28 / leg. Reinig ”; (2) hand-written “ Pass Naisa-Tasch / 4100 m 31. VI. 28 ”; (3) hand-written “ B. oberti / griseofasciatus / det. W. F. Reinig ”; (4) printed “ Collectie / C. et O. Vogt / Acq. 1960 ”; (5) red printed “ Bombus / oberti griseofasciatus / Reinig, 1930 / ZMAN type HYME. 0106.7 ”; (6) printed “ ZMA. INS. 959151 [square barcode] ”; (7) printed “ Bombus / (Sibiricobombus) / oberti / det. PH Williams 2018 ”; (8) red hand-written “ LECTOTYPE ♀ / Bombus oberti / var. [= ssp.] / griseofasciatus / Reinig, 1930 / det. PH Williams 2023 ”) is designated as lectotype in order to reduce uncertainty in the identity of the taxon and in the application of the name. The taxon concept of the species B. oberti here agrees with the recent interpretation of a species separate from B. semenovi stat. rev. (Williams 2022 a), presenting evidence that: (1) our PTP analysis supports independent species-level coalescents in the COI gene (Fig. 1); corroborated by (2) diagnostic morphological character states (see the keys). In the Tian Shan, queens, workers, and males all have yellow bands and an orange-red tail. However, in the Pamir, while workers and males retain a similar colour pattern, queens have the yellow replaced by grey-white and the tails are either black or dark brown (the colour-pattern taxon apicatus; Reinig 1930, 1932, 1934).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261A6D75DD85FD6EFEDFFAD0.taxon	description	Figs 1, 7 – 8, 26 ‒ 30, 93	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261A6D75DD85FD6EFEDFFAD0.taxon	diagnosis	Diagnosis Females Queens body length 19 ‒ 23 mm, workers 12 ‒ 18 mm. Colour pattern of the hair with the head predominantly black with only a few brown hairs intermixed on the vertex, the thoracic dorsum and metasomal T 1 ‒ 5 bright orange-red, the side of the thorax and legs predominantly black (Figs 26 ‒ 27). Morphology with the hind basitarsus outer surface in the centre with short branched hairs dense, black and strongly overlapping so that reflections from the outer surface are interrupted; (in large individuals) T 6 subapically medially with a raised boss. Males Body length 14 ‒ 18 mm. Colour pattern of the hair with the head predominantly black including the clypeus, often with orange hairs more or less intermixed on the vertex, the thoracic dorsum and metasomal T 1 ‒ 6 bright orange-red, either the side or the lower side of the thorax and the legs predominantly black (Figs 28 ‒ 30). Morphology with the eye greatly enlarged relative to the eye of a female bumblebee, from the dorsal aspect the eye separated from the lateral ocellus by 1 × the ocellar breadth; S 6 with the posterior margin in the middle nearly straight; penis-valve head recurved section narrow curved and finger-like, concave posteriorly at the base (Fig. 93).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261A6D75DD85FD6EFEDFFAD0.taxon	materials_examined	Type material Lectotype of Bombus morawitzi (by designation of Tkalců 1968: 199) UZBEKISTAN • ♀ (queen); “ Samarkand ”; ZMB (examined PW). Holotype of Bombus oppositus (by monotypy) CHINA • ♀ (queen); Xinjiang, “ Yark. Exp. ” “ No precise locality indicated ” [mountains west of Yarkant?]; F. Stoliczka leg.; NZSI (examined PW). Syntype of Bombus hydrophthalmus KAZAKHSTAN • ♂; “ im Hochgebirge bei Wernoye ” [Almaty]; A. Kuschakewitsch leg.; NHMUK (examined PW). Material examined AFGHANISTAN • 1 ♀ (worker); Wakhan, N of Borak; 37.09 ° N, 73.63 ° E; 9 Jul. 1971; GG, SB 095 / GG 002. CHINA ‒ Xinjiang • 1 ♀ (worker); Kuqa, Ku’ergan; 42.4358 ° N, 83.2538 ° E; 31 Jul. 2011; IAR, SB 015 / NHMC 06 • 1 ♀ (worker); Akqi, Sumutashi; 40.9055 ° N, 78.3568 ° E; 15 Jul. 2012; IAR, SB 019 / NHMC 01. TAJIKISTAN • 1 ♀ (worker); Pamir, Rushan; 37.9901 ° N, 71.5846 ° E; Jul. 2000; Gurko leg.; BOLD no.: 6880 F 04 (COI); MM, SB 077.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261A6D75DD85FD6EFEDFFAD0.taxon	distribution	Distribution Central Asian high montane species ‒ Central Asia: AFGHANISTAN, TAJIKISTAN, KYRGYZSTAN, KAZAKHSTAN, CHINA: Xinjiang. (AB, GG, IAR, IZCAS, Naturalis, NHMUK, NZSI, PW, UMons, ZIN, ZMB.)	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261A6D75DD85FD6EFEDFFAD0.taxon	biology_ecology	Behaviour Because the male eye is greatly enlarged relative to the eye of a female bumblebee and the male antenna is strongly elongated, the male mate-searching behaviour is expected to be similar to the “ racing ” behaviour described for “ B. asiaticus ” (actually B. longiceps stat. rev.) with these morphological characteristics by Williams (1991).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC261A6D75DD85FD6EFEDFFAD0.taxon	discussion	Taxonomic remarks The taxon concept of the species B. morawitzi here agrees with the recent interpretation as a distinctive species (Tkalců 1968; Williams 1998; Ghisbain et al. 2020). We present evidence that: (1) our PTP analysis supports independent species-level coalescents in the COI gene (Fig. 1); corroborated by (2) diagnostic morphological character states (see the keys). The colour pattern of this species shows little variation, although there is some variation in both sexes in how much black hair is intermixed on T 1 and in males in the extent of the black hair on the side of the thorax.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26196D74DDD1FAD3FCAAF9AE.taxon	description	Figs 1, 7 – 8, 31 ‒ 32, 94	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26196D74DDD1FAD3FCAAF9AE.taxon	diagnosis	Diagnosis Females Queens body length 16 ‒ 19 mm, workers 15 mm. Colour pattern of the hair with the head predominantly black, the thoracic dorsum anterior and posterior bands and metasomal T 1 ‒ 6 yellow, lower side of thorax and legs black (Fig. 31). Morphology with the clypeus in its centre with scattered large and few small punctures, so that the surface has smooth shining areas; hindleg basitarsus outer surface with short branched hairs so short and sparse that they are not overlapping and the surface is conspicuously brightly shining; (in large individuals) T 6 subapically medially slightly but irregularly raised. Males Body length 15 mm. Colour pattern of the hair with the entire body predominantly yellow, except for the thoracic dorsum with black hair between the wing bases (Fig. 32). Morphology with the eye greatly enlarged relative to the eye of a female bumblebee, from the dorsal aspect the eye separated from the lateral ocellus by 1 × the ocellar breadth; S 6 with the posterior margin in the middle with a deep concave indentation; volsella posterior to the gonostylus greatly broadened and nearly straight, penis-valve head on its inner side ventrally at the base marked by a ridge with a projecting angle, this angle also marked dorsally on a parallel dorsal ridge; penis-valve head recurved section narrowing gradually towards the tip, volsella just beyond gonostylus 3 × its breadth between its distal posterior corners (Fig. 94).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26196D74DDD1FAD3FCAAF9AE.taxon	materials_examined	Type material Type of B. vorticosus subsp. sulfureus “ Asia minor ”; (type not seen but identity not in doubt). Holotype of Bombus (Sibiricobombus) sulfureus var. [= subsp.] aureocorbicularis (by monotypy) IRAN • (worker); Alborz, “ Keredj-Mazanderan ”; Brandt leg.; 12 Aug.; (type not seen but identity not in doubt). Material examined IRAN • 1 ♀ (queen); Qazvin, Werk; 38.5488 ° N, 47.2609 ° E; 6 Jun. 2007; A. Monfared leg.; PW, SB 008 / NHMI 027 • 1 ♀ (worker); Qazvin, Bala Rouch; 36.3870 ° N, 50.6639 ° E; 19 Aug. 2012; A. Monfared leg.; PW, SB 007 / NHMI 025.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26196D74DDD1FAD3FCAAF9AE.taxon	distribution	Distribution Rare West Asian montane species ‒ West Asia: TURKEY, IRAN. (AM, NHMUK, PW, UMons.)	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26196D74DDD1FAD3FCAAF9AE.taxon	biology_ecology	Behaviour Because the male eye is greatly enlarged relative to the eye of a female bumblebee and the male antenna is strongly elongated, the male mate-searching behaviour is expected to be similar to the “ racing ” behaviour described for “ B. asiaticus ” (actually B. longiceps stat. rev.) with these morphological characteristics by Williams (1991). Similar “ racing ” behaviour has been observed in Turkey (Rasmont et al. 2021).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26196D74DDD1FAD3FCAAF9AE.taxon	discussion	Taxonomic remarks The taxon concept of the species B. sulfureus here agrees with the recent interpretation (Williams 1998; Monfared et al. 2007; Rasmont et al. 2021) of a species separate from B. niveatus, presenting evidence that: (1) our PTP analysis supports independent species-level coalescents in the COI gene (Fig. 1); corroborated by (2) diagnostic morphological character states (see the keys). This separation of B. sulfureus from B. niveatus is also supported by a difference in CLGS (Rasmont et al. 2005). The colour pattern of this species shows little variation.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26186D49DD89F9F9FE23FAF9.taxon	description	Figs 1, 7 – 8, 33 ‒ 44, 95	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26186D49DD89F9F9FE23FAF9.taxon	diagnosis	Diagnosis Females Queens body length 17 ‒ 22 mm, workers 9 ‒ 16 mm. Colour pattern of the hair with the head predominantly black, legs black, the thoracic dorsum anterior and posterior bands, side of thorax, and metasomal T 1 ‒ 2 either yellow or white, T 3 at least in part either black or yellow or white, T 4 ‒ 5 orange-red (Figs 33 ‒ 38). Morphology with the clypeus in its centre with scattered large and very many small punctures, so that the surface is uneven; hindleg basitarsus outer surface with short branched hairs long so that they are just overlapping and the shining surface is only partly obscured; (in large individuals) T 6 subapically medially slightly but irregularly raised. Males Body length 15 ‒ 17 mm. Colour pattern of the hair with the head, side of thorax, legs, thoracic dorsum anterior and posterior bands and metasomal T 1 ‒ 2 either yellow or white, T 3 at least in part either black or yellow or white, T 4 ‒ 7 orange-red (Figs 39 ‒ 44). Morphology with the eye greatly enlarged relative to the eye of a female bumblebee, from the dorsal aspect the eye separated from the lateral ocellus by 1 × the ocellar breadth; S 6 with the posterior margin in the middle with a deep concave indentation; volsella posterior to the gonostylus greatly broadened and weakly curved, penis-valve head on its inner side ventrally at the base marked by a ridge with a projecting angle, this angle also marked dorsally on a parallel dorsal ridge; penis-valve head recurved section narrowing abruptly just before the tip, volsella just beyond gonostylus 2 × its breadth between its distal posterior corners (Fig. 95).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26186D49DD89F9F9FE23FAF9.taxon	materials_examined	Type material Lectotype of Bombus niveatus (by designation of Tkalců 1969: 897) ISRAEL • ♀ (queen), “ Palaestina ”; ZSM (type not seen but identity not in doubt). Syntypes of Bombus vorticosus UNKNOWN • (syntypes of both sexes and castes); most from ” Krakau ” [locality likely in error]; Nowicki leg.; (types not found by Tkalců 1969: 897, but identity not in doubt). Syntypes of Bombus (Kallobombus) parnassius GREECE • “ Parnass ”; (types not seen but identity not in doubt). Lectotype of Bombus araraticus (by designation of Tkalců 1969: 897) TURKEY • ♂; “ Ararat ”; O. Radoszkowski leg.; ZMB (type not seen but identity not in doubt). Syntypes of Bombus (Sibiricobombus) asiaticus [subsp.] pallidofasciatus RUSSIA • “ Kaukasus ”; unknown repository (types not seen but identity not in doubt). Syntypes of Bombus (Sibiricobombus) vorticosus Forma [= subsp.] postzonatus TURKMENISTAN • 2 ♀♀ (queens); “ Krassnowodsk ” [Turkmenbashi]; unknown repository (types not seen but identity not in doubt). Lectotype of Bombus (Sibiricobombus) vorticosus morpha [= subsp.] iranensis (designated here) IRAN • ♀ (queen); Alborz, Nissa; 1 – 10 Aug. 1936; Brandt leg.; NHMUK (examined PW). Lectotype of Bombus (Sibiricobombus) niveatus morpha [= subsp.] persicus (designated here) IRAN • ♀ (queen); Alborz, Nissa; 20 Jul. – 1 Aug. 1936; Brandt leg.; NHMUK (examined PW). Material examined GEORGIA • 1 ♀ (queen); Calka, Bashdashi; 41.5891 ° N, 44.1330 ° E; 27 May 2011; BOLD no.: 1555 A 02 (COI); IEAUG, SB 053. GREECE • 3 ♀♀ (workers); N of Lamia; 38.9365 ° N, 22.4300 ° E; 8 Jun. 2016; M. Halada leg.; BOLD nos: 6880 G 01 to 6880 G 03 (COI); PW, SB 086 to SB 088. IRAN • 1 ♀ (worker); Qazvin, Vikan; 36.3754 ° N, 50.6893 ° E; 9 Aug. 2011; A. Monfared leg.; PW, SB 010 / NHMI 010 • 1 ♀ (queen); Qazvin, Wikan [Vikan]; [36.3754 ° N, 50.6893 ° E]; 30 Jul. 2006; A. Taghavi leg.; PW, SB 013 / NHMI 028 • 1 ♀ (worker); Tehran, Damavand; 35.7013 ° N, 52.0586 ° E; 14 Jun. 2015; A. Monfared leg.; PW, SB 009 / NHMI 008 • 2 ♀♀ (worker, queen); Qazvin, Vikan; 36.3754 ° N, 50.6893 ° E; 9 Aug. 2011; A. Monfared leg.; PW, SB 011 / NHMI 011, SB 012 / NHMI 009.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26186D49DD89F9F9FE23FAF9.taxon	distribution	Distribution West Asian and European montane species ‒ Europe: ALBANIA, GREECE, UKRAINE, RUSSIA: Caucasus. ‒ West Asia: TURKEY, GEORGIA, SYRIA, LEBANON, ISRAEL, IRAN, TURKMENISTAN. (AM, GG, Naturalis, NHMUK, PW, UMons, ZIN, ZMB.) Records of B. niveatus from Xizang (Wang 1982) are misidentifications of B. (Melanobombus) keriensis Morawitz, 1887 (Williams et al. 2020).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26186D49DD89F9F9FE23FAF9.taxon	biology_ecology	Behaviour Because the male eye is greatly enlarged relative to the eye of a female bumblebee and the male antenna is strongly elongated, the male mate-searching behaviour is expected to be similar to the “ racing ” behaviour described for “ B. asiaticus ” (actually B. longiceps stat. rev.) with these morphological characteristics by Williams (1991).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26186D49DD89F9F9FE23FAF9.taxon	discussion	Taxonomic remarks Note on the syntypes of B. vorticosus Gerstaecker, 1872: described as most syntypes from “ Krakau ” [locality likely in error]; Nowicki leg.; (types not found by Tkalců 1969: 897, but identity not in doubt). The given type locality is very unlikely to be either Kraków (Poland) or Krakau (Austria) as these are far too far north for this species. Note on the lectotype of B. vorticosus morpha iranensis Pittioni, 1937 designated here: the original description data from Pittioni (1937) match one of the specimens in the NHMUK collection. Because other specimens were listed, this individual, which lacks both antennae (labels: (1) printed “ IRAN: ELBURS-GEB. / NISSA, (CA. 3000 M.) / 1.8. – 10.8.1936 / LEG. BRANDT ”; (2) hand-written “ vortic. ira - / ♀ nensis Pitt / det. Pittioni ”; (3) hand-written with black border “ f. iranensis / Pitt typ. ”; (4) printed “ Pittioni Coll. / Turner Bequest / B. M. 1954 - 76 ”; (5) printed “ [barcode] / NHMUK 013380602 ”; (6) printed “ Bombus / (Sibiricobombus) / niveatus / det. PH Williams 2022 ”; (7) red hand-written “ LECTOTYPE ♀ / Bombus vorticosus / morpha [= ssp.] / iranensis / Pittioni, 1937 / det. PH Williams 2023 ”) is designated as lectotype in order to reduce uncertainty in the identity of the taxon and in the application of the name. Note on the lectotype of B. niveatus morpha persicus Pittioni, 1937 designated here: the original description data from Pittioni (1937) match one of the specimens in the NHMUK collection. Because other specimens were listed, this individual, which lacks the right antenna (labels: (1) red hand-written “ Type ”; (2) printed “ B. M. TYPE / HYM / 17 b. 1318 ”; (3) printed “ IRAN: ELBURS-GEB. / NISSA, (CA. 3000 M.) / 20.7. – 1.8.1936 / LEG. BRANDT ”; (4) hand-written “ niveatus per - / ♀ sicus Pitt / det. Pittioni ”; (5) printed “ Pittioni Coll. / Turner Bequest / B. M. 1954 - 76 ”; (6) printed “ [barcode] / NHMUK 013380602 ”; (7) printed “ Bombus / (Sibiricobombus) / niveatus / det. PH Williams 2022 ”; (8) red hand-written “ LECTOTYPE ♀ / Bombus niveatus / morpha [= ssp.] / persicus / Pittioni, 1937 / det. PH Williams 2023 ”) is designated as lectotype in order to reduce uncertainty in the identity of the taxon and in the application of the name. The taxon concept of the species B. niveatus here agrees with the recent interpretation (e. g., Williams 1998; Monfared et al. 2007; Rasmont et al. 2021) of a species separate from B. sulfureus, presenting evidence that: (1) our PTP analysis supports independent species-level coalescents in the COI gene (Fig. 1); corroborated by (2) diagnostic morphological character states (see the keys). This separation of B. niveatus from B. sulfureus is also supported by a difference in CLGS (Rasmont et al. 2005). The species-level coalescent in the COI gene (Fig. 1) also supports as conspecific the white-banded taxon niveatus s. str. and the yellow-banded taxon vorticosus. Conspecificity is corroborated by their morphology (see the keys) and by their similar male CLGS mixtures (Rasmont et al. 2005). It has been claimed that the two taxa “ differ significantly ” in habitat (Rasmont et al. 2021), although it also appears that their distributions are broadly overlapping and geographically concentric, with the white-banded colour pattern the more frequent at higher elevations (where it co-occurs with other white-banded bumblebees). This might be explained by mimetic selection in favour of different mimetic model patterns at different elevations. It is common for pale-banded mountain bumblebees to have both yellow- and white-banded colour patterns that are more frequent in different areas (Williams 2007). There are several examples of this in the subgenus Melanobombus (Williams et al. 2020). Both the yellow-banded and the white-banded colour patterns also vary in whether T 3 is entirely black (Greece, Turkey, Lebanon) or, in the Alborz mountains of northern Iran, has more extensive pale hair (yellow taxon iranensis, white taxon persiensis), varying from a posterior fringe on T 3 to covering T 3 entirely in the male (Pittioni’s infrasubspecific taxon brandti). Individuals with T 3 extensively yellow resemble B. sulfureus.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26256D4EDDEAFA08FE37FCE8.taxon	description	Figs 1, 7, 9, 45 ‒ 48, 96	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26256D4EDDEAFA08FE37FCE8.taxon	diagnosis	Diagnosis Females Queens unknown, body length workers 12 ‒ 14 mm. Colour pattern of the hair with the head and legs usually predominantly black sometimes with some yellow intermixed, the thoracic dorsum anterior and posterior bands, side of thorax, and metasomal T 1 ‒ 2 bright sulphur yellow, metasomal T 3 ‒ 4 black, T 4 at most with a few white hairs along the posterior margin, T 5 white (Figs 45 ‒ 46). Morphology with the oculo-malar area anteriorly sparsely covered with large punctures regularly spaced; antennal A 3 length 3 × greatest breadth; hind basitarsus outer surface with the short branched hairs few and very widely spaced so that they are not overlapping, with reflections from the outer surface clearly visible and brightly shining; (in large individuals) T 6 subapically medially weakly raised. Males Body length 12 ‒ 14 mm. Colour pattern of the hair similar to the female but with yellow hair on the head, more often intermixed between the wing bases, on the legs, and with metasomal T 3 ‒ 4 black, at most with a few white hairs along the posterior margins (Figs 47 ‒ 48). Morphology with the eye greatly enlarged relative to the eye of a female bumblebee, from the dorsal aspect the eye separated from the lateral ocellus by 1 × the ocellar breadth; S 6 with the posterior margin in the middle nearly straight and hardly concave; gonocoxa from the dorsal aspect distally narrower than adjacent spatha, gonostylus distal lobe approximately circular, volsella beyond gonostylus strongly inwardly curved, nearly parallel-sided, and consistently just broader than its breadth between the distal posterior corners (Fig. 96).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26256D4EDDEAFA08FE37FCE8.taxon	materials_examined	Type material Holotype of Bombus (Sibiricobombus) obtusus (by original designation) AFGHANISTAN • ♂; Koh-i-Baba, Puistagoli; 2 Aug. 1948; N. Haarløv leg.; SNM, 00240323 (photos examined PW). Material examined AFGHANISTAN • 1 ♀ (worker); Hindu Kush; [34.3824 ° N, 66.8670 ° E]; 8 Aug. 1968; M. Tong leg.; BOLD no.: 6880 D 07 (COI); NHMUK, SB 068.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26256D4EDDEAFA08FE37FCE8.taxon	distribution	Distribution Rare endemic Afghan montane species ‒ Central Asia: AFGHANISTAN. (NHMUK, UMons.)	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26256D4EDDEAFA08FE37FCE8.taxon	biology_ecology	Behaviour Because the male eye is greatly enlarged relative to the eye of a female bumblebee and the male antenna is strongly elongated, the male mate-searching behaviour is expected to be similar to the “ racing ” behaviour described for “ B. asiaticus ” (actually B. longiceps stat. rev.) with these morphological characteristics by Williams (1991).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26256D4EDDEAFA08FE37FCE8.taxon	discussion	Taxonomic remarks The taxon concept of the species B. obtusus here agrees with the recent interpretation (Tkalců 1968; Williams 1998) of a species separate from B. asiaticus, presenting evidence that: (1) our PTP analysis supports independent species-level coalescents in the COI gene (Fig. 1); corroborated by (2) diagnostic morphological character states (see the keys). Richards (1951: 198) described the females of B. obtusus as “ Structurally apparently identical with B. asiaticus F. Mor. and only differing in that all the hairs of abdominal tergite 4 are black ”. Tkalců (1968: 198) described this species only as being morphologically more closely related to B. morawitzi than to B. asiaticus. To support these groups he cites differences in the incisura of the mandible, although these differences appear to be at best subtle and inconsistent. However, Williams (1991: 90) described a character difference between B. obtusus and B. asiaticus in the hairs of the hind basitarsus that is more reliable (see the key). Richards (1951) and Tkalců (1969) appear to have been, in effect, using colour pattern alone to determine what they considered to be “ B. obtusus ”, which could explain why some of their descriptions of its colour-pattern variation may be inconsistent with those reported here based on morphology, because they may have been including some individuals considered here to be part of B. asiaticus. Variation in the colour pattern of B. obtusus has been described in three aspects. First, the black band between the wing bases varies from narrower than the yellow anterior band, but distinct with a sharp boundary, to indistinct with a mixture of yellow, to being replaced by yellow (taxon badakshanensis), especially for males (Richards 1951; Tkalců 1968). Second, one worker (collection site unspecified) was described as having the T 5 ‒ 6 pale hairs with their bases “ brownish-red ” (Richards 1951; Tkalců 1968). This has not been seen by us for B. obtusus, although we have seen this colour pattern for Afghan B. asiaticus. Third, based on a description of material from two sites identified as B. asiaticus by Reinig (1940) (prior to Richards’ description of B. obtusus), Tkalců (1969) suggested that there might also be a black-tailed colour pattern of B. obtusus, with a colour pattern resembling of B. (Subterraneobombus) melanurus Lepeletier, 1835 (thoracic dorsum and T 1 ‒ 2 yellow, T 3 ‒ 6 black). This material was described by Tkalců as most likely lost. This colour pattern has not been seen by us, although we have seen this colour pattern for Afghan B. asiaticus.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26226D43DD4CFC3BFD82F983.taxon	description	urn: lsid: zoobank. org: act: E 2 A 94219 - 04 F 9 - 43 C 9 - 9 F 8 A-EF 80 E 36 FFF 78 Figs 1, 7, 9, 49 ‒ 51, 97	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26226D43DD4CFC3BFD82F983.taxon	diagnosis	Diagnosis Females Queens body length 17 ‒ 20 mm, worker 14 mm. Colour pattern with the hair beneath the base of the hind wing black, thoracic dorsum varying from either dull yellow with a narrow black band between the wing bases to almost entirely black, metasomal T 2 varying from either dorsally with at least a few black hairs intermixed along the posterior margin and in the posterior lateral quarter with no black along the midline to predominantly black, T 4 ‒ 5 pinkish-orange (Figs 49 ‒ 50). Morphology with the oculo-malar area anteriorly only sparsely covered with small to medium punctures scattered irregularly; clypeus in the anterior lateral corners with a large patch of large punctures spaced by their own breadths with a dense patch of many small and medium punctures between them; antennal A 3 length 3 × greatest breadth; ocello-ocular area with a broad band of dense fine punctures along the inner eye margin, this band along its inner edge with a line of medium and large punctures; hind basitarsus outer surface with short branched hairs not especially dense and partly overlapping so that reflections from the outer surface are partly obscured; (in large individuals) T 6 subapically medially with a raised boss. Males Body length 16 mm. Colour pattern with the hair on the head black except on the clypeus yellow and the vertex with a few yellow hairs intermixed, side of the thorax yellow, thoracic dorsum dull yellow with a narrow black band between the wing bases, legs black with some yellow, metasomal T 1 ‒ 2 yellow, T 2 dorsally usually with at least a few black hairs along the posterior margin and in the posterior lateral quarter but no black along the midline, T 4 ‒ 6 pinkish-orange (Fig. 51). Morphology with the eye greatly enlarged relative to the eye of a female bumblebee, from the dorsal aspect the eye separated from the lateral ocellus by 1 × the ocellar breadth; S 6 with the posterior margin in the middle with a deep concave indentation; gonocoxa from the dorsal aspect distally narrower than adjacent spatha, gonostylus distal lobe approximately square, volsella posterior to the gonostylus narrowed and angled inwards towards the body midline, volsella beyond the gonostylus nearly parallel-sided and consistently just broader than its breadth between the distal posterior corners, penis-valve head on its inner side ventrally at the base without a projecting angle, this angle only marked dorsally (Fig. 97).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26226D43DD4CFC3BFD82F983.taxon	materials_examined	Type material Holotype of Bombus (Sibiricobombus) regeli [subsp.] miniatocaudatus (by monotypy: Williams 1991) MONGOLIA • ♂; “ Septentrionalis ”; Naturalis (examined PW). Material examined MONGOLIA • 1 ♂; Hovd, Tsenkher; 46.9676 ° N, 91.6496 ° E; 9 Aug. 2014; D. Altanchimeg leg.; BOLD no.: 6880 A 07 (COI); DA, SB 094 • 1 ♀ (queen); Bayan Ölgiy, Bulgan River; 46.5833 ° N, 91.3667 ° E; 26 Jul. 1992; A. Culverwell leg.; BOLD no.: 6880 D 05 (COI); PW, SB 066. RUSSIA ‒ Tuva • 1 ♀ (queen); Kaa-Khem, Mt Apedek; 51.7090 ° N, 94.7869 ° E; 16 ‒ 17 Aug. 2010; Y. Danilov leg.; BOLD no.: 6880 E 03 (COI); PW, SB 076.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26226D43DD4CFC3BFD82F983.taxon	distribution	Distribution North Asian montane species ‒ North Asia: RUSSIA: Tuva, Altai (Republic); MONGOLIA. (AB, Naturalis, NHMUK, PW.)	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26226D43DD4CFC3BFD82F983.taxon	biology_ecology	Behaviour Because the male eye is greatly enlarged relative to the eye of a female bumblebee and the male antenna is strongly elongated, the male mate-searching behaviour is expected to be similar to the “ racing ” behaviour described for “ B. asiaticus ” (actually B. longiceps stat. rev.) with these morphological characteristics by Williams (1991).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC26226D43DD4CFC3BFD82F983.taxon	discussion	Taxonomic remarks Note 1 on the name B. regeli? Forma miniatocaudatus Vogt 1911: 61. Vogt (1911) named a taxon “ Sb. regeli miniatocaudatus ”, although he gave no explicit reference connecting this name as an indication of his earlier use of a similar name that as an ‘ Ab. ’ [erration] was clearly of infrasubspecific in rank (Vogt 1909, see Note 3 below). The 1911 name can be considered as a new proposal at a new status and includes a minimal description to distinguish it from B. vorticosus (= B. niveatus): B. regeli is distinguished from B. vorticosus by its consistently longer hair and black pleurae; and B. regeli s. str. is distinguished from the taxon miniatocaudatus by the latter having the hair of the “ Kaudalsegmenten ” (tail) red rather than white. The nomenclatural rank of the taxon miniatocaudatus Vogt (1911) is not specified explicitly, although in a section on “ Neue Hummelformen ” and as a trinomen it can by default be considered to be of subspecific rank (ICZN 1999: Article 45.6). Vogt (1911) writes that red-tailed individuals (taxon miniatocaudatus) never occur in the “ Siebenstromgebiet ” [Semirechye] region of Central Asia, implying that it is geographically restricted, which is consistent with subspecific status in the sense of ICZN (see also the comments on type material below), making it an available name. However, while the name miniatocaudatus Vogt (1911) may be available, it cannot be the valid name for a bumblebee species because it is a junior homonym in Bombus of B. soroeensis var. [= subsp.] miniatocaudatus Vogt, 1909 (Vogt 1911: 50 footnote 1 states that he intends “ Varietas geographica ” to be equivalent to subspecies in rank; this “ variety ” is interpreted as having subspecific status because it is also described as regionally restricted: ICZN 1999: Article 45.6.4). Therefore, a new replacement name (not a description of a new species) is required for the taxon miniatocaudatus Vogt (1911) in the subgenus Sibiricobombus (see Note 3 and the comments on type material below). Note 2 on the replacement name for the name B. regeli? Forma miniatocaudatus Vogt, 1911: 61. Because B. regeli miniatocaudatus Vogt, 1911 is a junior homonym in the genus Bombus of B. (Kallobombus) soroeensis subsp. miniatocaudatus Vogt, 1909, the replacement name B. tescorum nom. nov. et stat. rev. is proposed here (ICZN 1999: Article 60.3) in order to reduce the confusion that is likely to follow if the name miniatocaudatus Vogt, 1911 in the subgenus Sibiricobombus were to be propagated in the literature. The replacement name ‘ tescorum ’ (from a meaning of rough or barren regions, wastes, or deserts: thanks to I. Beavis pers. com.) describes what is known of the hilly dry steppe habitat of this species. Vogt (1909) named two taxa “ miniatocaudatus ”, a name he used in both cases for red-tailed colour patterns (also in part replaced by more extensive black?). The name for a taxon in the subgenus Sibiricobombus was described in the category of ‘ Ab. ’, which is specifically given infrasubspecific status by the ICZN (1999: Article 45.6.2). Note 3 on the type of B. regeli? Forma miniatocaudatus Vogt 1911: 61: Vogt (1911) did not designate a holotype or a series of syntypes. However, Vogt (1909) specified that he had a single male with the colour pattern of the taxon miniatocaudatus in the subgenus Sibiricobombus from Central Asia. Williams (1991) examined a single male in the Vogt collection at the Naturalis, Leiden, that agrees with Vogt’s descriptions of the taxon miniatocaudatus in the subgenus Sibiricobombus from 1911 and carries a hand-written red label “ regeli = Gruppe / miniatocaudatus / Type ” and a label Mongolia “ Septentrionalis ”. This specimen is regarded as a syntype of miniatocaudatus Vogt, 1911. The taxon concept of the species B. tescorum nom. nov. et stat. rev. here supports it as a species separate from B. asiaticus, B. falsificus stat. rev., B. longiceps stat. rev., and B. obtusus, presenting evidence that: (1) our PTP analysis supports independent species-level coalescents in the COI gene (Fig. 1); corroborated by (2) diagnostic morphological character states (see the keys). That the asiaticus - group might consist of a series of species has been anticipated by Reinig (1940). Our concept of the species B. tescorum nom. nov. et stat. rev. is considerably narrower than the application of the name miniatocaudatus Vogt, 1911 by some authors, which has included yellow-banded and orange-tailed individuals belonging to other species of the asiaticus - group, especially of B. falsificus stat. rev. (Richards 1930; Wang 1982) and of some B. asiaticus (Richards 1930). Reinig (1934) distinguished “ dem mongolischen miniatocaudatus Vogt ” from his taxon “ B. regeli rufocaudatus ” in the Pamir (= B. asiaticus) by the lighter (yellow) bands of the latter. A queen of B. tescorum nom. nov. et stat. rev. from Tuva (Russia, SB 076) shows almost complete replacement of the yellow hair with black, with only some dull yellow hair remaining intermixed in a transverse band in the middle of T 2.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262F6D40DD85F98DFA96FE51.taxon	description	Figs 1, 7, 9, 52 ‒ 71, 98	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262F6D40DD85F98DFA96FE51.taxon	diagnosis	Diagnosis Females Queens body length 17 ‒ 20 mm, workers 11 ‒ 15 mm. Colour pattern with the hair of the head and legs black, beneath the base of the hind wing bases either usually yellow or white or rarely black, thoracic dorsum either bright yellow or bright yellow with a black band between the wing bases or white with a black band between the wing bases, metasomal T 2 either part yellow or part white, with black at least intermixed along the midline, T 3 black, T 4 ‒ 5 either usually predominantly orange or rarely white or black (Figs 52 ‒ 61). Morphology with the oculo-malar area anteriorly only sparsely covered with small to medium punctures scattered irregularly; clypeus with the anterior lateral corners with a large patch of large punctures spaced by their own breadths with a dense patch of many small and medium punctures between them; antennal A 3 length 3 × greatest breadth; ocello-ocular area with a broad band of dense fine punctures along the inner eye margin, this band along its inner edge without medium and large punctures; hind tibia outer corbicular surface in its upper proximal half coarsely sculptured and matt, so that reflections are much interrupted by the prominent sculpturing; hind basitarsus outer surface with short branched hairs not especially dense and partly overlapping so that reflections from the outer surface are partly obscured; (in large individuals) T 6 subapically medially with a raised boss. Males Body length 13 ‒ 17 mm Colour pattern with the hair on the head black except on the clypeus either yellow or white, hair of the side of the thorax either yellow or white, thoracic dorsum either bright yellow or bright yellow with a black band between the wing bases or white with a black band between the wing bases, hair of the legs predominantly black, metasomal T 2 in part either yellow or white or black, T 4 ‒ 6 either usually predominantly orange or rarely black (Figs 62 ‒ 71). Morphology with the eye greatly enlarged relative to the eye of a female bumblebee, from the dorsal aspect the eye separated from the lateral ocellus by 1 × the ocellar breadth; S 6 with the posterior margin in the middle with a deep concave indentation; gonocoxa from the dorsal aspect distally as broad as adjacent spatha, gonostylus distal lobe approximately square, volsella posterior to the gonostylus narrowed and angled inwards towards the body midline, volsella beyond the gonostylus narrowing to less than its breadth between the distal posterior corners, penis-valve head on its inner side ventrally at the base without a projecting angle, this angle only marked dorsally, penis-valve shaft at its proximal base on its outer side with a deeply marked ‘ S’ - shaped step, penis-valve head recurved section nearly straight posteriorly at the base (Fig. 98).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262F6D40DD85F98DFA96FE51.taxon	materials_examined	Type material Lectotype of Bombus longiceps (by designation of Frison 1935: 340) INDIA • ♀ (large worker, not a queen); Kashmir, Ladakh Leh; [Aug. to Sep.]; F. Stoliczka leg.; NZSI (examined PW). Syntypes of Sibiricobombus flavodorsalis INDIA • ♀♀ (queens), Kashmir, Ladakh, Suru valley; ZIN (type not seen but identity not in doubt). Syntypes of Sibiricobombus oshanini INDIA • ♀♀ (queens), 1 ♂, Kashmir; Ladakh, Nubra valley; ZIN (type not seen but identity not in doubt). Holotype of Bombus (Sibiricobombus) huangcens (by original designation) CHINA • ♀ (queen); Xizang, Zanda; 28 Jun. 1976; F. Huang leg.; IZCAS (examined PW). Material examined CHINA ‒ Xizang • 2 ♀♀ (workers); Burang, Lalongba; 30.2060 ° N, 81.2523 ° E; 22 Jul. 2018; IZCAS, SB 093 / BB 24, SB 090 / BB 02. INDIA ‒ Himachal Pradesh • 1 ♀ (queen), 2 ♂♂; Saichu Nalla; 31.6000 ° N, 78.2670 ° E; 8 Sep. 1986; A. Hutchings leg.; BOLD nos.: 6880 D 12, 6880 E 01, 6880 E 02 (COI); PW, SB 073 to SB 075. – Kashmir & Jammu • 1 ♀ (queen); Zanskar, Padum; 33.4746 ° N, 76.8871 ° E; 30 Jul. 2007; R. Raina leg.; BOLD no.: 1552 D 10 (COI); RR, SB 050 • 1 ♀ (queen); Kashmir, Kazalwan; 34.6464 ° N, 74.7171 ° E; 19 Jun. 2007; R. Raina leg.; BOLD no.: 1552 E 03 (COI); RR, SB 046 • 2 ♀♀ (queens); Kashmir, Shah Pora; 34.6552 ° N, 74.8942 ° E; 28 Jun. 2009; R. Raina leg.; BOLD nos: 1552 D 07, 1552 D 09 (COI); RR, SB 047, SB 051 • 1 ♀ (queen); Kashmir, Baltal; 34.2648 ° N, 75.4366 ° E; 14 Jul. 2008; R. Raina leg.; BOLD no.: 1552 D 06 (COI); RR, SB 048 • 1 ♀ (worker); Kashmir, Gulmarg; 34.0548 ° N, 74.3856 ° E; Aug. 1985; P. Williams leg.; BOLD no.: 6880 C 05 (COI); PW, SB 054. PAKISTAN • 1 ♀ (worker); Skardu; 35.2903 ° N, 75.6444 ° E; 31 Aug. 2017; S. Jaffar leg.; BOLD no.: 1552 E 12 (COI); SJ, SB 049 • 1 ♀ (worker); Hindu Kush, Shanduz Pass; 36.0756 ° N, 72.5200 ° E; 5 Jul. 2004; V. Gurko leg.; BOLD no.: 6880 F 07 (COI); MM, SB 080.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262F6D40DD85F98DFA96FE51.taxon	distribution	Distribution West Himalayan species ‒ East Asia: AFGHANISTAN; PAKISTAN; INDIA: Kashmir & Jammu, Himachal Pradesh, Uttarakhand, Sikkim; NEPAL; CHINA: Xizang. (IZCAS, NHMUK, NKME, PW, SMF, ZIN, ZSI.)	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262F6D40DD85F98DFA96FE51.taxon	biology_ecology	Behaviour The male eye is greatly enlarged relative to the eye of a female bumblebee and the male antenna is strongly elongated, which is related to the male mate-searching behaviour described for this species (under the misidentified name of B. asiaticus) as “ racing behaviour ” by Williams (1991). Uniquely (as far as is known), males of this species were found to congregate in groups of up to 10 individuals among grass roots to spend the night torpid, with individually numbered males switching between clusters on successive nights (although this could be the result of disturbance) (Williams 1991: 23).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262F6D40DD85F98DFA96FE51.taxon	discussion	Taxonomic remarks The taxon concept of the species B. longiceps stat. rev. here agrees with the recent interpretation of a species separate from B. asiaticus, B. falsificus stat. rev., B. obtusus, and B. tescorum nom. nov. et stat. rev. (Williams 2022 a), presenting the details of evidence that: (1) our PTP analysis supports independent species-level coalescents in the COI gene (Fig. 1); corroborated by (2) diagnostic morphological character states (see the keys). That the asiaticus - group might consist of a series of species has been anticipated by Reinig (1940). The taxa flavodorsalis and oshanini are re-descriptions of the taxon (yellow unbanded colour pattern) longiceps stat. rev. The species-level coalescent in the COI gene (Fig. 1) also supports as conspecific the yellow-unbanded taxon longiceps s. str., the yellow-banded taxon huangcens, and the white-banded taxon (callophenax of authors other than Cockerell (1917) (= B. avinoviellus Skorikov, 1914, see Williams et al. 2016 )). Sculpturing of the female hind tibia is slightly more coarse and the wings are darker in Kashmir white-banded bees than in yellow unbanded Ladakh bees. Conspecificity is corroborated by their clypeal sculpturing (see the keys). Williams (1991: 115 – 118) also described how in high mountain passes (near Nigagar and Lal Pani) of the Great Himalaya in Kashmir, where “ white-banded ” (Kashmir valley) and “ yellow-unbanded ” (Ladakh) populations meet and produce apparent intermediate colour patterns (and also show some black-tailed colour patterns), the frequencies of states for two out of three colour-pattern characters (for presence / absence of a black thoracic band; and tail red / black) in the haploid males predicted the frequencies in the diploid females (the prediction failed for white / yellow bands). These predictions would be expected to hold if there were simple bi-allelic coding with simple dominance. Crucially, this is consistent with the two regional populations interbreeding as parts of a single species.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262C6D47DDAFFE51FE6CFA66.taxon	description	Figs 1, 7, 9, 72 ‒ 74, 99	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262C6D47DDAFFE51FE6CFA66.taxon	diagnosis	Diagnosis Females Queens body length 17 ‒ 18 mm, workers 12 ‒ 15 mm. Colour pattern with the hair beneath the base of the hind wing black, thoracic dorsum yellow with a narrow black band between the wing bases, lower side of the thorax and legs black, metasomal T 1 ‒ 2 dorsally entirely yellow without black hairs even in the posterior lateral quarter, T 4 ‒ 5 orange (Fig. 72). Morphology with the oculo-malar area anteriorly only sparsely covered with small to medium punctures scattered irregularly; clypeus with the anterior lateral corners with a small patch of large punctures spaced by their own breadths with only a very few scattered small punctures between them; antennal A 3 length 3 × greatest breadth; hind basitarsus outer surface with short branched hairs not especially dense, but partly overlapping so that reflections from the outer surface are partly obscured; (in large individuals) T 6 subapically medially with a raised boss.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262C6D47DDAFFE51FE6CFA66.taxon	description	Males Body length 15 ‒ 16 mm. Colour pattern with the hair on the head black except on the clypeus yellow, thoracic dorsum yellow with a narrow black band between the wing bases, metasomal T 2 dorsally entirely yellow without black hairs even in the posterior lateral quarter, T 4 ‒ 6 orange (Figs 73 ‒ 74). Morphology with the eye greatly enlarged relative to the eye of a female bumblebee, from the dorsal aspect the eye separated from the lateral ocellus by 1 × the ocellar breadth; S 6 with the posterior margin in the middle with a deep concave indentation; gonocoxa from the dorsal aspect distally as broad as adjacent spatha, gonostylus distal lobe approximately square, volsella posterior to the gonostylus narrowed and angled inwards towards the body midline, beyond the gonostylus narrowing to less than its breadth between the distal posterior corners, penis-valve head on its inner side ventrally at the base without a projecting angle, this angle only marked dorsally, penis-valve shaft at its proximal base on its outer side with only a shallowly marked ‘ S’ - shaped step (Fig. 99).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262C6D47DDAFFE51FE6CFA66.taxon	materials_examined	Type material Holotype of Bombus (Sibiricobombus) miniatocaudatus race [= subsp.] falsificus (by original designation) CHINA • ♀ (queen); Xizang, Tingri; 4 Jul. 1924; R. Hingston leg.; NHMUK (examined PW). Holotype of Bombus (Sibiricobombus) heicens (by original designation) CHINA • ♀ (queen), Xizang, Rutog; 26 Aug. 1976; F. Huang leg.; IZCAS (examined PW). Material examined CHINA ‒ Qinghai • 1 ♂; Yakou, Nangguanxiu; 36.6821 ° N, 98.7751 ° E; 30 Aug. 2010; P. Williams leg.; BOLD no.: 6876 C 02 (COI); PW, SB 052 • 2 ♀♀ (workers); ridge S of Caka; 36.6671 ° N, 98.7737 ° E; 9 Aug. 2013; P. Williams leg.; BOLD nos.: 6880 D 01, 6880 D 02 (COI); PW, SB 062, SB 063 • 2 ♀♀ (workers); Kunlun Shan pass; 35.6920 ° N, 94.0520 ° E; 13 Aug. 2013; P. Williams leg.; BOLD nos.: 6880 D 03, 6880 D 04; PW, SB 064, SB 065. – Xizang • 1 ♀ (queen); Mapang Yongcuo, Sere; 30.7151 ° N, 81.3662 ° E; 23 Jul. 2018; IZCAS, SB 091 / BB 20 • 1 ♀ (worker); Xindisang; 32.3551 ° N, 80.4848 ° E; 29 Jul. 2018; IZCAS, SB 092 / BB 21	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262C6D47DDAFFE51FE6CFA66.taxon	distribution	Distribution East Tibetan Plateau species ‒ East Asia: CHINA: Xizang, Qinghai, Gansu. (IAR, IZCAS, NHMUK, PW.)	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262C6D47DDAFFE51FE6CFA66.taxon	biology_ecology	Behaviour Because the male eye is greatly enlarged relative to the eye of a female bumblebee and the male antenna is strongly elongated, the male mate-searching behaviour is expected to be similar to the “ racing ” behaviour described for “ B. asiaticus ” (actually B. longiceps stat. rev.) with these morphological characteristics by Williams (1991). Male perching and “ racing ” behaviour has been observed on one occasion in Qinghai (PW).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262C6D47DDAFFE51FE6CFA66.taxon	discussion	Taxonomic remarks Note on the name B. miniatocaudatus race falsificus Richards, 1930: 652: although Richards (1930) uses the term “ Subsp. ” as well as “ var. ” and “ race ”, he states that the taxon falsificus is characteristic of a particular geographical area, so this nominal taxon is therefore deemed to be of subspecific rank (ICZN 1999: Article 45.6.4) (Williams 1991). The taxon concept of the species B. falsificus stat. rev. here agrees with the recent interpretation of a species separate from B. asiaticus, B. longiceps stat. rev., B. obtusus, and B. tescorum nom. nov. et stat. rev. (Williams 2022 a), presenting evidence that: (1) our PTP analysis supports independent species-level coalescents in the COI gene (Fig. 1); corroborated by (2) diagnostic morphological character states (see the keys). That the asiaticus - group might consist of a series of species was anticipated by Reinig (1940). The colour pattern of this species shows little variation. The taxon heicens is a re-description of the taxon falsificus stat. rev.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262B6D44DDF8F9A1FAF1FE73.taxon	description	Figs 1, 7, 9, 75 ‒ 89, 100	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262B6D44DDF8F9A1FAF1FE73.taxon	diagnosis	Diagnosis Females Queens body length 16 ‒ 21 mm, workers 9 ‒ 18 mm. Colour pattern with the hair of the head black and the legs predominantly black, beneath the base of the hind wing either usually yellow or rarely black, thoracic dorsum bright yellow usually with a narrow black band between the wing bases, metasomal T 2 either usually nearly entirely yellow without black hairs intermixed along the midline or rarely extensively black, T 3 black, T 4 either white or buff or orange or black, T 5 either white or buff or orange (Figs 75 ‒ 82). Morphology with the oculo-malar area anteriorly only sparsely covered with small to medium punctures scattered irregularly; clypeus with the anterior lateral corners with a large patch of large punctures spaced by their own breadths with a dense patch of many small and medium punctures between them; antennal A 3 length 3 × greatest breadth; ocello-ocular area with a broad band of dense fine punctures along the inner eye margin, this band along its inner edge without medium and large punctures; hind tibia outer corbicular surface in its upper proximal half weakly sculptured and smooth, so that the shining reflections are scarcely interrupted by the sculpturing; hind basitarsus outer surface with short branched hairs not especially dense but partly overlapping so that reflections from the outer surface are partly obscured; (in large individuals) T 6 subapically medially with a raised boss. Males Body length 13 ‒ 18 mm. Colour pattern with the hair of the head and the legs either yellow or black, the hair beneath the base of the hind wing either usually yellow or rarely black, thoracic dorsum either bright yellow or bright yellow with a black band between the wing bases or predominantly black with a yellow anterior band, metasomal T 1 ‒ 2 either usually nearly entirely yellow without black hairs intermixed along the midline or rarely extensively or entirely black, T 3 black, T 4 ‒ 6 either white or orange or black (Figs 83 ‒ 89). Morphology with the eye greatly enlarged relative to the eye of a female bumblebee, from the dorsal aspect the eye separated from the lateral ocellus by 1 × the ocellar breadth; S 6 with the posterior margin in the middle with a deep concave indentation; gonocoxa from the dorsal aspect distally as broad as adjacent spatha, gonostylus distal lobe approximately square, volsella posterior to the gonostylus narrowed and angled inwards towards the body midline, beyond the gonostylus narrowing to less than its breadth between the distal posterior corners, penis-valve shaft at its proximal base on its outer side with a deeply marked ‘ S’ - shaped step, penis-valve head on its inner side ventrally at the base without a projecting angle, this angle only marked dorsally, penis-valve head recurved section nearly straight posteriorly at the base (Fig. 100).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262B6D44DDF8F9A1FAF1FE73.taxon	materials_examined	Type material Lectotype of Bombus hortorum var. [= subsp.] asiaticus (by designation of Williams, 1991) TAJIKISTAN • ♀ (worker); “ Tschiburgan ”; 26 Jun. 1871; ZMMU (examined PW). Holotype of Bombus bizonatus (by monotypy) CHINA • ♀ (queen); Xinjiang, “ No locality indicated ” [mountains west of Yarkant?]; F. Stoliczka leg.; NZSI (examined PW). Syntype of Bombus regeli (lectotype designation by Podbolotskaya unpubl.) CHINA • 1 ♀ (queen); Xinjiang, near “ Kuldsha ” [Yining]; E. Regel leg.; ZIN (examined PW). Holotype of Bombus regeli var. [= subsp.] pamirensis (by monotypy) TAJIKISTAN • ♂; “ Pamir-Hochlande ”; O. Staudinger leg.; unknown repository (type not seen but identity not in doubt). Syntypes of Bombus (Sibiricobombus) regeli subsp. diversocaudatus TAJIKISTAN • 13 ♀♀; ‘ Pamir-darja-Gebiet’; Aug. 1928; W. Reinig leg.; unknown repository (types not seen but identity not in doubt). Holotype of Bombus (Sibiricobombus) flavicollis (by original designation) CHINA • ♀ (queen); Xinjiang, Zhaosu; 24 Jul. 1978; Y. Han leg.; IZCAS (examined PW). Holotype of Bombus (Sibiricobombus) asiaticus [subsp.] baichengensis (by original designation) CHINA • ♀ (queen); Xinjiang, Baicheng; 19 May 1978; X. Zhang leg.; IZCAS (examined PW). Material examined KAZAKHSTAN • 1 ♀ (worker); Korday; 43.01 ° N, 74.01 ° E; 18 Jun. 2003; BOLD no.: 1549 F 06 (COI); KUK, SB 045 • 1 ♂; Ketmen Mts; [43.3309 ° N, 80.2188 ° E]; 14 Jun. 1998; V. Gurko leg.; BOLD no.: 6880 F 11 (COI); MM, SB 084. KYRGYZSTAN • 1 ♂; Ketmen Mts, Tujuk; [41.4532 ° N, 71.9314 ° E]; 6 Jul. 1999; V. Gurko leg.; BOLD no.: 6880 F 08 (COI); PW, SB 081 • 1 ♀ (queen); Sari-Tzelek; [42.10 ° N, 72.00 ° E]; 4 Jun. 1995; BOLD no.: 6880 F 09 (COI); MM, SB 082. TAJIKISTAN • 2 ♀♀ (queens); E of Khorog; 37.4814 ° N, 71.5938 ° E; 3 Jun. 2009; L. Best leg.; BOLD nos: 1552 H 01, 1552 H 02 (COI); PW, SB 005, SB 006 • 1 ♀ (worker); E of Khorog; 37.4814 ° N, 71.5938 ° E; 16 Jun. 2009; L. Best leg.; BOLD no.: 6880 D 10 (COI); PW, SB 071 • 1 ♀ (queen); E of Khorog; 37.4814 ° N, 71.5938 ° E; 17 Jun. 2009; L. Best leg.; BOLD no.: 6880 D 09 (COI); PW, SB 070 • 1 ♀ (queen); Okmamad; 37.6968 ° N, 72.6968 ° E; 25 Jun. 2009; L. Best leg.; BOLD no.: 6880 D 11 (COI); PW, SB 072.	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262B6D44DDF8F9A1FAF1FE73.taxon	distribution	Distribution Central Asian montane species ‒ Central Asia: KAZAKHSTAN, KYRGYZSTAN, TAJIKISTAN, AFGHANISTAN, CHINA: Xinjiang. (IAR, IZCAS, NHMUK, NZSI, PW, UMons, ZIN, ZMMU.)	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262B6D44DDF8F9A1FAF1FE73.taxon	biology_ecology	Behaviour Because the male eye is greatly enlarged relative to the eye of a female bumblebee and the male antenna is strongly elongated, the male mate-searching behaviour is expected to be similar to the “ racing ” behaviour described for “ B. asiaticus ” (actually B. longiceps stat. rev.) with these morphological characteristics by Williams (1991).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
FE5D87EC262B6D44DDF8F9A1FAF1FE73.taxon	discussion	Taxonomic remarks Note on the name B. hortorum var. asiatica Morawitz in Fedtschenko 1875: 4: mandatory change in an incorrect original spelling to asiaticus (Williams 1991). The taxon concept of the species B. asiaticus here agrees with the recent interpretation of a species separate from B. falsificus stat. rev., B. longiceps stat. rev., B. obtusus, and B. tescorum nom. nov. et stat. rev. (Williams 2022 a), presenting evidence that: (1) our PTP analysis supports independent species-level coalescents in the COI gene (Fig. 1); corroborated by (2) diagnostic morphological character states (see the keys). That the asiaticus - group might consist of a series of species has been anticipated by Reinig (1940). The species-level coalescent in the COI gene (Fig. 1) also supports as conspecific the white-tailed taxon asiaticus s. str. and the orange-tailed taxon pamirensis. Conspecificity of these taxa is corroborated by their morphology (see the keys). In addition, (1) some individuals (especially from Afghanistan) have the black band between the wing bases (‘ inter-alar’ band) much reduced or replaced by yellow; (2) some have the pale tail colour replaced by black; and (3) some (especially from Kyrgyzstan and Kazakhstan) have the yellow bands reduced by replacement of yellow hair with black. Colour-pattern variation in Afghanistan and the Pamir is described in more detail by Reinig (1930, 1932, 1940). The taxon flavicollis is a re-description of the taxon (colour pattern) pamirensis and the taxon baichengensis is a re-description of the taxon (colour pattern) asiaticus s. str. (Williams 1998).	en	Williams, Paul H., An, Jiandong, Byvaltsev, Alexandr, Jonghe, Guillaume Ghisbain Roland De, Huang, Jiaxing, Mei, Maurizio, Monfared, Alireza, Orr, Michael C., Raina, Rifat, Streinzer, Martin (2026): The steppe bumblebees of the subgenus Sibiricobombus revised world-wide from species’ gene coalescents and morphology despite numts (Hymenoptera, Apidae, genus Bombus). European Journal of Taxonomy 1041: 1-59, DOI: 10.5852/ejt.2026.1041.3199, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3199/14203
