Bombus (Alpigenobombus) mastrucatus Gerstaecker, 1869

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 : 31-33

2. Bombus (Alpigenobombus) mastrucatus Gerstaecker, 1869 stat. rev.

Figs 1 , 26‒34 , 107

Bombus mastrucatus Gerstaecker, 1869: 326 .

Bombus brevigena Thomson, 1870: 255 .

Bombus mastrucatus var. [subsp.] flavicante Pérez, 1890b: 475 .

Bombus lefebvrei [subsp.] pyenaicus Vogt, 1909: 50 .

Bombus mastrucatus var. [subsp.] collaris Friese, 1909: 673 (not of Scopoli 1763: 306 = B. pratorum (Linnaeus)) .

Bombus mastrucatus var. [subsp.] transitorius Friese, 1909: 673 .

Bombus mastrucatus var. [subsp.] lutescens Friese, 1909: 673 (not of Pérez 1890a: 154 = B. flavidus Eversmann ).

Bombus mastrucatus var. [subsp.] luteus Friese, 1909: 673 .

Bombus mastrucatus var. [subsp.] tirolensis Friese, 1911b: 684 , replacement name for B. mastrucatus [subsp.] collaris Friese, 1909 .

Alpigenobombus wurfleini [subsp.] apfelbecki Reing in Reinig & Rasmont, 1988: 48.

Alpigenobombus wurfleini [subsp.] knechteli Reing in Reinig & Rasmont, 1988: 49.

Bombus mastrucatus morpha [not subsp.] kriechbaumeri ‒ Pittioni 1938: 66, infrasubspecific.

Bombus (Alpigenobombus) wurflenii [subsp.] balcaniensis ‒ Rasmont et al. 2021: 155, unjustified replacement name. Note 1.

NOTE 1. The earlier name B. helferanus f.[orma] apfelbecki Pittioni, 1939: 87 (= B. humilis Illiger ) was given infrasubspecific status ( Pittioni 1939: 51), so that the name apfelbecki Reinig, 1988 remains available and a replacement name is unjustified.

Species-taxon concept and variation

The taxon concept of the species B. mastrucatus is revised here from the widely-cited interpretation (since Tkalců 1969), to distinguish B. mastrucatus from the separate taxon concept of the species B. wurflenii (see the comments above on B. wurflenii ), 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).

Bombus mastrucatus is a widespread European species that had long been well-known by the use of this name by many authors (e.g., von Dalla Torre 1896; Friese & von Wagner 1912; Skorikov 1923; Reinig 1935; Pittioni 1937; aside from occasional confusion with B. lefebvrei Lepeletier de Saint-Fargeau, [1835] (= B. pomorum (Panzer, 1805)) by Strand 1901).

Then Tkalců (1969) reduced the taxon mastrucatus to the status of a subspecies within Alpigenobombus wurfleini [sic], although without a detailed justification. Subsequently, the name B. wurflenii (in various spellings) has been used in most publications for this bumblebee species in Europe (e.g., in influential keys by Løken 1973; Hagen & Aichhorn 2003; Ornosa & Ortiz-Sanchez 2004; Rasmont et al. 2021). Nonetheless, the name mastrucatus remains familiar to European bee workers from these same publications, even if only as what has often been interpreted as a subspecies.

The PTP and morphological results ( Fig. 12 , keys) both support the interpretation that B. mastrucatus and B. wurflenii are separate species. The available COI-barcode-like sequences may all be low-divergence neonumts ( Fig. 11 ). The PTP and morphological analysis results ( Fig. 12 , keys) also support the interpretation that the divergent colour patterns of the taxa mastrucatus s. str. (Alps: Figs 28–29, 32–33) and flavicante (Pyrenees: Figs 26–27, 31–32), as well as the disjunct population of the taxon brevigena (Scandinavia: Figs 30, 33–34) are conspecific (no fresh samples were available from eastern Europe for sequencing). No diagnostic characters published for the other named taxa for this group in Europe provide any reason to consider them as candidates for separate species.

Variation in the colour-pattern diagrams of B. mastrucatus in Figs 26‒34 is arranged approximately from south-west (Pyrenees) to north-east ( Norway). Bombus mastrucatus , with its unbanded red-tailed colour pattern in northern Europe and its yellow-banded red-tailed colour pattern especially in south-western Europe, appears to mimic the local colour patterns of the abundant B. (Melanobombus) lapidarius (Linnaeus, 1758) and similar species ( Williams 2007: fig. 5e, j).

Type material

Bombus mastrucatus Gerstaecker, 1869: 326 . Type not seen (not found by Tkalců 1969: 892), but identity not in doubt.

Morphological diagnosis

Female

Wings nearly clear with veins dark brown, hair long, oculo-malar area shorter than broad, clypeus adjacent to the labrum not raised in the centre but flat so that the shallow transverse anterior groove is not interrupted, this central area uniformly with many small punctures and not shining, ocello-ocular area with the punctures anteriorly to the unpunctured area in the outer half less dense than posterior to it (cf. B. wurflenii ); hair of the thoracic dorsum either entirely black or sometimes with bands anteriorly and posteriorly yellow.

Male

Wings nearly clear with veins dark brown, hair long, oculo-malar area shorter than broad; genitalia ( Fig. 107 ) with the gonostylus long and distally near its midline axis convexly rounded, length on its outer side about a quarter as long as on its inner side with the two inner corners of the distal lobe rounded, the margin between them nearly straight, penis-valve head strongly recurved, the recurved hook much longer than broad and distally at the end of the hook weakly pointed (cf. B. wurflenii ); hair of the thoracic dorsum between the wing bases predominantly black, usually with few or no yellow hairs.

Material sequenced in Fig. 12

AUSTRIA • 2 ♀♀ (queens); Carinthia, Innere Eben ; 46.978° N, 12.759° E; 26 Jul. 2019; W. Wallner leg.; BOLD seq: ABOL19-1511 ABOL19-1512; HNS: AG#164 , AG#165 • 1 ♀ (worker); Tyrol, Hohe Tauern ; 47.023° N, 12.238° E; 20 Jul. 2020; S. Schoder leg.; BOLD seq:ABOLHT20-S038; SS:AG#166 .

FRANCE • 1 ♀ (queen); Roussillon , Prats de Mollo; [42.400° N, 2.483° E]; 25 Aug. 1993; GenBank seq: AY181174; AG#066 • 1 ♀ (queen); Alpes Maritimes , Col Turini; 43.999° N, 7.429° E; 11 Jul. 2010; C. Schmid-Egger leg.; BOLD seq: BCZSMHYM07560; SNSB: AG#169 • 1 ♀ (queen); Alpes Maritimes , Trende; 44.105° N, 7.448° E; 9 Jul. 2010; C. Schmid-Egger leg.; BOLD seq: BCZSMHYM07561; SNSB: AG#170 .

NORWAY • 1 ♀ (queen); Buskerud, Mörkedalen ; [60.9° N, 8.3° E]; 2 Jul. 1994; GenBank seq: AY181175; AG#067 .

Additional sequences in Fig. 10 and haplotype duplicates

FRANCE • 1 ♀ (queen); Alpes Maritimes , Col Turini; 43.999° N, 7.429° E; 11 Jul. 2010; C. Schmid-Egger leg.; BOLD seq: BCZSMHYM07559; SNSB: AG#168 .

GERMANY • 1 ♀ (worker); Saxony, Carlsfeld ; 50.435° N, 12.585° E; 16 Jul. 2004; F. Burger leg.; BOLD seq: BCZSMHYM08976; SNSB: AG#171 • 1 ♁; Thuringia, Orlamünde ; 50.775° N, 11.541° E; 19 Sep. 2001; F. Burger leg.; BOLD seq: BCZSMHYM08978; SNSB: AG#172 • 1 ♁; Saxony, Carlsfeld ; 50.435° N, 12.585° E; 16 Jul. 2004; F. Burger leg.; BOLD seq: BCZSMHYM08979; SNSB: AG#173 .

Global distribution

Europe: Spain, France, Belgium, Italy, Bosnia and Herzegovina, Montenegro, Serbia, Macedonia, Greece, Germany, Switzerland, Austria, Czechia, Slovakia, Poland, Bulgaria, Romania, Moldova, Ukraine, Norway, Sweden, Russia (Murmansk): HNS, NHMUK, PW, RMNH, SNSB, SS, ZMHB.

This species is recorded at elevations of 1740–2740 in the Eyne Pyrenees ( Iserbyt et al. 2008), at 1000‒2450 m in Languedoc-Roussillon, France ( Rasmont 1988), and at 1500‒2600 m in the Alps ( Pittioni 1937; Neumayer 1998; Neumayer & Paulus 1999). It has been associated in general with the mountain-forest zone ( Løken 1973; Rasmont et al. 2021).

Behaviour

Male eye not obviously enlarged relative to female eye: males show ‘patrolling’ behaviour when searching for mates in Austria ( Williams 1991).

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.