Bremus formosellus Frison, 1934: 163 Bremus formosellus Frison, 1934: 166 Bremus formosellus Frison, 1934: 167 Bombus pyrosoma Williams 1991: 102 Morawitz, 1890: 349 Widespread polytypic species or complexes of local species? Revising bumblebees of the subgenus Melanobombus world-wide (Hymenoptera, Apidae, Bombus) Williams, Paul H. Altanchimeg, Dorjsuren Byvaltsev, Alexandr Jonghe, Roland De Jaffar, Saleem Japoshvili, George Kahono, Sih Liang, Huan Mei, Maurizio Monfared, Alireza Nidup, Tshering Raina, Rifat Ren, Zongxin Thanoosing, Chawatat Zhao, Yanhui Orr, Michael C. European Journal of Taxonomy 2020 2020-10-02 719 1 120 MFJM (Frison, 1934) Frison 1934 [582,1005,434,461] Insecta Apidae Bombus Animalia Hymenoptera 65 66 Arthropoda species formosellus   Figs 13, 98–102, 192      Bremus formosellus Frison, 1934: 163.    Bremus formosellusvar. [subsp.] derivatus  Frison, 1934: 166.    Bremus formosellusvar. [subsp.] gradatus  Frison, 1934: 167.    Bombus pyrosoma(part) –  Williams 1991: 102(non  Morawitz, 1890: 349).    Bombus formosellusis known only from Taiwan( Frison 1934; Chiu 1948; Starr 1992).  Bombus pyrosoma s. lat.has been treated as a widespread Asian species by Williams (1998), to include the taxon  formosellus. Here,  B. formosellusis recognised as separate from the north Chinese  B. pyrosoma s. str.because of their unique and strongly divergent species coalescents in the COI gene ( Fig. 10), corroborated by differences in morphology (see the Diagnosis). The morphological differences are subtle, but do appear to support the two as separate species within a morphologically more distinctive complex of  pyrosoma s. str. + formosellus. Our PTP analysis ( Fig. 10) supports relatively strongly two coalescents in the COI gene for the north Chinese  B. pyrosoma s. str., and the Taiwanese  B. formosellus. The two coalescent groups differ in COI barcode sequences for at least 12 diagnostic nucleotide positions (1.8% of the barcode region). These nucleotide differences are all synonymous, making no difference to the amino acid sequences at translation. From morphology,  B. formosellushas a paler colour pattern of the hair than  B. pyrosoma s. str.for the females and especially for the queens. The queen of  B. formosellus(below) has the hair of the thoracic dorsum with broad anterior and posterior bands strongly dominated by white, whereas for  B. pyrosoma s. str.these areas are black or usually with a small minority of white hairs intermixed. The male gonostylus inner process is also not clearly divided into two teeth as it is in  B. pyrosoma s. str. Queens of this species have not previously been described. However, S. Lu located a female (ML503) in the TFRI collection that appears to be large enough (body length 20 mm) and collected early enough in the year (July 14, by I. Sung) to be a queen. This individual has lost much of its hair so the colour pattern is not clear, but females appear to show weak size-dependent dimorphism in the colour pattern of the hair: the queen has the remaining hair of T2 extensively black but with white hair narrowly anteriorly and medially and with orange hair narrowly posteriorly, especially in the lateral corners ( Fig. 98); whereas workers (which are smaller) either have T2 chocolate-coloured anteriorly and black posteriorly or have T2 extensively dull yellow ( Figs 99–101). Recently queens of this species have been reared in laboratory colonies, from which this colour pattern is confirmed (I. Sung in litt.). Males have the thoracic bands and T1–2 yellow ( Fig. 102).    Diagnosis  Females  Queens medium-sized body length 20 mm, workers 10–15 mm. Can be distinguished within Taiwanby the hair of the thoracic dorsum with white bands (cf.  B. eximius).  Males Body length 13–14 mm. Can be distinguished within Taiwanby their combination of the hair of the thoracic dorsum with yellow bands, side of the thorax yellow, and T3–7 red. Genitalia ( Fig. 192) with the gonostylus much reduced, less than a quarter as long on its outer side as broad, with the distal edge concave and the inner distal corner with two indistinct adjacent teeth, the proximal tooth slightly shorter than the distal tooth and the two not clearly separated by an indentation (emargination) ( cf. pyrosoma s. str.); volsella with the inner distal corner produced as a narrow curved hook ( cf. rufipes-group,  B. simillimus,  lapidarius-group,  sichelii-group,  keriensis-group); eye unenlarged relative to female eye.    Material examined   Holotype   CHINA• ♂, holotypeof  Bremus formosellus Frison, 1934by original designation; Taiwan, Roeichi;  15 Sep. 1924; T. Shirakiand J. Sonanleg.; INHS(examined PW).  Material sequenced( 5 specimens)   CHINA–  Taiwan• 1 ♀(worker); Tayuling; 23.9767° N, 121.5206° E;  5 Aug. 1991; C. Starrleg.; NHMUKseq: NHMPW07; PW: ML317•  1 ♀(worker); Tahsuehshan; 24.3428° N, 121.1243° E; M. Kuoleg.; NHMUKseq: NHMPW09; PW: ML318•  1 spec.; Taiwan; 24.1806° N, 121.3101° E; GenBankseq: AF279522; SEHU: ML184•  2 ♀♀(workers); Taiwan;  15 Jun. 2019; I. Sungleg.; TFRIseq: L11 LL12; TFRI: ML573 ML574.    Global distribution (Taiwanese mountain species) East Asia: CHINA: Taiwan. (INHS, NHMUK, PW, TFRI.) The species is narrowly distributed but not rare in collections.    Behaviour Expected to be food-plant generalists. Male mate-searching behaviour is expected to resemble the patrolling of  B. eurythorax. 2867606481 1924-09-15 INHS, PW T. Shiraki & J. Sonan China Taiwan Roeichi 66 67 1 holotype 2867606620 1991-08-05 NHMUK, PW C. Starr China 23.9767 Tayuling 7 121.5206 66 67 ML317 1 1 Taiwan 2867606465 NHMUK, PW M. Kuo China 24.3428 Tahsuehshan 7 121.1243 66 67 ML318 1 1 Taiwan 2867606411 SEHU GenBank China 24.1806 Taiwan 7 121.3101 66 67 ML184 1 Taiwan 2867606308 2019-06-15 TFRI I. Sung China Taiwan 66 67 ML573, ML574 2 2 Taiwan