Bombus (Sibiricobombus) tescorum Williams & An & Byvaltsev & Jonghe & Huang & Mei & Monfared & Orr & Raina & Streinzer 2026, nom. nov. et stat. rev.

8. Bombus (Sibiricobombus) tescorum Williams nom. nov. et stat. rev. urn:lsid:zoobank.org:act: E2A94219-04F9-43C9-9F8A-EF80E36FFF78 Figs 1, 7, 9, 49‒51, 97 Bombus (Sibiricobombus) regeli [?Forma] [= subsp.] miniatocaudatus Vogt, 1911: 61, not of Vogt, 1909: 56 (= B. soroeensis (Fabricius, 1777)). Bombus (Sibiricobombus) regeli Ab. miniatocaudatus ‒ Vogt 1909: 50 footnote 1, infrasubspecific. Bombus (Sibiricobombus) asiaticus ‒ Williams 1991: 87, (in part) misidentification. 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 T2 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, T4‒5 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 A3 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) T6 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 T1‒2 yellow, T2 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, T4‒6 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; S6 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). 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.: 6880A07 (COI); DA, SB094 • 1 ♀ (queen); Bayan Ölgiy, Bulgan River; 46.5833° N, 91.3667° E; 26 Jul. 1992; A. Culverwell leg.; BOLD no.: 6880D05 (COI); PW, SB066. RUSSIA ‒ Tuva • 1 ♀ (queen); Kaa-Khem, Mt Apedek; 51.7090° N, 94.7869° E; 16‒17 Aug. 2010; Y. Danilov leg.; BOLD no.: 6880E03 (COI); PW, SB076. Distribution North Asian montane species ‒ North Asia: RUSSIA: Tuva, Altai (Republic); MONGOLIA. (AB, Naturalis, NHMUK, PW.) 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). 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, SB076) 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 T2.