Bombus (Alpigenobombus) genalis Friese, 1918

Williams, Paul H., An, Jiandong, Dorji, Phurpa, Huang, Jiaxing, Jaffar, Saleem, Japoshvili, George, Narah, Jaya, Ren, Zongxin, Streinzer, Martin, Thanoosing, Chawatat, Tian, Li & Orr, Michael C., 2023, Bumblebees with big teeth: revising the subgenus Alpigenobombus with the good, the bad and the ugly of numts (Hymenoptera: Apidae), European Journal of Taxonomy 892 (1), pp. 1-65 : 41-42

8. Bombus (Alpigenobombus) genalis Friese, 1918

Figs 6 , 74‒75 , 113

Bombus genalis Friese, 1918: 84 .

Species-taxon concept and variation

The taxon concept of the species B. genalis here agrees with the long-standing interpretation (Williams 2022a) that it is separate from the taxon concepts of other species in the subgenus Alpigenobombus , based on: (1) our PTP analysis supports independent species-level coalescents in the COI gene ( Fig. 12 ); corroborated by (2) diagnostic morphological character states (see the keys).

The PTP and morphological results ( Fig. 12 , keys) support the interpretation that B. genalis and B. breviceps are separate species. The available COI-barcode-like sequences may all be low-divergence neonumts ( Fig. 11 ).

No substantial colour-pattern variation is known for B. genalis (Figs 74‒75). Bombus genalis , with its black with orange-legged colour pattern, appears to mimic the common B. (Pyrobombus) flavescens Smith, 1852 , and B. (Melanobombus) eximius Smith, 1852 ( Williams 2007: fig. 5a).

Type material

Bombus genalis Friese, 1918: 84 . Syntypes: ♀♀ (queen and worker) Sikkim, India ( ZMHB). Examined .

Morphological diagnosis

Female

Wings pale yellow with the veins light orange (unique within the subgenus Alpigenobombus ), hair short, oculo-malar area shorter than broad, clypeus in its central area shining with only a few small and large widely-spaced punctures (cf. B. breviceps ); mid and hind tibiae exoskeleton and hair bright orange, hair of the thoracic dorsum and T1 black.

Male

Wings pale yellow with the veins light orange (unique within the subgenus Alpigenobombus ), hair short, oculo-malar area shorter than broad; genitalia ( Fig. 113 ) with the gonostylus nearly equally short on both its outer side and its inner side but with the distal lobe projecting inwards as a long broadly triangular acutely pointed process, triangular in section (cf. B. breviceps , B. grahami ); mid and hind tibiae exoskeleton and hair bright orange, the hair of the scutellum and T1 predominantly black.

Material sequenced in Fig. 12

CHINA • 1 ♀ (worker); Xizang, Linzhi ; 29.5710° N, 95.4633° E; 29 Aug. 2015; Q.-T. Wu leg.; IOZ seq: FPW12; IOZ: AG#184 .

Additional sequences in Fig. 10 and haplotype duplicates

CHINA • 1 ♀ (worker); Yunnan, Guanshizhai ; 25.9334° N, 98.8008° E; 18 Aug. 2011; PW seq: PWB9; IAR: AG#040 • 1 ♀ (worker); Xizang, Miyuecun ; 29.4065° N, 95.3721° E; 18 Aug. 2015; Q.-T. Wu leg.; IOZ seq: FPW13; IOZ: AG#185 .

INDIA • 2 ♀♀ (workers); Arunachal Pradesh, Salaya ; 27.5969° N, 93.851° E; 22 Jun. 2018; J. Narah leg.; NCBS seq: BG463 BG471; NCBS: AG#200 , AG#201 • 1 ♀ (worker); Arunachal Pradesh, Hari ; 27.5838° N, 93.8446° E; 27 Sep. 2015; NCBS seq: BE637; NCBS: AG#202 .

Global distribution

Himalaya and borders of southern Hengduan: India (Sikkim, Arunachal Pradesh), China (Xizang, Yunnan), Myanmar: IAR, IOZ, NCBS, NHMUK, PW, ZMHB.

This is an uncommon species and few individuals have been recorded. This species is recorded at elevations of 1561‒1852 m in the Himalaya in the middle forest zone ( Streinzer et al. 2019).

Behaviour

Male eye very slightly enlarged relative to female eye, male mate-searching behaviour unknown.

Figures

Figs 1‒9. Individuals of the subgenus Alpigenobombus Skorikov, 1914 (with photo credits). 1. Bombus mastrucatus Gerstaecker, 1869, worker Norway robbing (P. Haringsma). 2. B. kashmirensis Friese, 1909 s. str., worker China-Sichuan robbing (PW). 3. B. kashmirensis (taxon meinertzhageni Richards, 1928) worker India-Kashmir-Zanskar (PW).4. B. sikkimiFriese, 1918, worker India-Arunachal (MS). 5. B. nobilis Friese, 1905 s. str., worker China-Yunnan (ZR). 6. B. genalis Friese, 1918, worker India-Arunachal (MS). 7. B. breviceps Smith, 1852 (taxon dentatus Handlirsch, 1888) worker China- Yunnan (PW). 8. B. breviceps (taxon channicus Gribodo, 1892) worker Thailand (CT). 9. B. grahami (Frison, 1933) worker India-Arunachal (MS). Some images reversed.

Figs 19–105 (see pages 28–29). Simplified diagrams for the colour patterns of the hair on the dorsum for particular female (f) and male (m) specimens of the species from Fig. 12. The dorsum is divided into regions, each of which shows only the predominant or most apparent colour for that region, using a simplified colour palette, with olive indicating a mixture of black and yellow hair, and grey indicating a mixture of black and white hair.

Figs 106–115. Morphology of the male genitalia for species of the subgenus Alpigenobombus Skorikov, 1914, from the dorsal aspect, anterior at the bottom of the image, posterior at the top. 106. Bombus wurflenii Radoszkowski, 1860, Turkey. 107. B mastrucatus Gerstaecker, 1869, Austria. 108. B. kashmirensis Friese, 1909, India-Kashmir. 109. B. rainai Williams, 2022, India-Kashmir. 110. B. sikkimi Friese, 1918, Nepal. 111. B. nobilis Friese, 1905, China-Sichuan. 112. B. validus Friese, 1905, China-Gansu. 113. B. genalis Friese, 1918, China-Yunnan. 114. B. breviceps Smith, 1852, ChinaSichuan. 115. B. grahami (Frison, 1933) China-Sichuan (left penis-valve recurved hook missing). Scale bars = 1 mm.

Fig. 12. Interpretation of filtered MrBayes estimate of phylogeny as a metric tree (outgroup B. festivus Smith, 1861, not shown) for the subgenus Alpigenobombus Skorikov, 1914, from COI-like sequences from the sequences identified in black and orange in Fig. 11 together with Bayesian Poisson-tree-process (PTP) models re-applied for assessing support for species’ gene coalescents by maximum likelihood (for the 11 most likely candidate species). The scale bar is calibrated in substitutions per nucleotide site. Sequence labels and branch colours as in Fig. 10. Numbers above nodes are the Bayesian support values that all daughter haplotypes are parts of a single species. Grey spots show likely mitochondrial-to-nuclear transfers of the low-divergence numts accepted for estimating this tree. Asterisks mark sequences used as informal proxies for the type specimens of each of the taxon names in Table 2. To the right in grey are shown the interpretations of the PTP results as candidate species using the oldest available names for the species.

Fig. 11. Re-interpretation of sequences from Fig. 10, re-drawn with the percentage of nucleotides A and T at codon position 3 (AT3%) for each sequence given after the sequence label. Sequences are classified: (a) in purple – earlier-diverging groups of sequences without unique morphology that often have lower AT3% and shorter sequences that appear to duplicate species as pseudospecies in Fig. 10 – these sequences are interpreted as older, more divergent numts; (b) red – remaining sequences with low AT3% (<95%) – these are interpreted as younger, less divergent numts; (c) orange – sequences from the red group but with the highest AT3% available for some taxa, selected to retain these taxa in the analysis; (d) grey and brown – sequences that are duplicate haplotypes for the black and orange sequences above and often shorter; (e) black – likely orthologous sequences with high AT3% (≥ 95%) and unique haplotypes.

Fig. 10. Default interpretation of MrBayes estimate of phylogeny as a metric tree (outgroup B. festivus Smith, 1861, not shown) for the subgenus Alpigenobombus Skorikov, 1914, from COI-like sequences from GenBank and BOLD databases with additions from the authors, analysed with Bayesian Poissontree-process (PTP) models for assessing support for species’ gene coalescents by maximum likelihood (PTP scores are shown above branches: scores approaching 1, and where branches change from blue to red, indicates where the most likely species’ gene coalescents are identified for 17 candidate species). The scale bar is calibrated in substitutions per nucleotide site. Each sequence is labelled with: sequence length; a morphological taxon name; a code consisting of a sequence identifier from the project database and a specimen identifier from the online database; its country and (for larger countries) state or province of origin.