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A preliminary survey of the bumblebees of the Val Malenco
(Lombardy, Italy)
(preliminary version - 24 October 2010)

Maurizio Cornalba

The following is an account of observations of bumblebees made in the Val Malenco between 22 and 28 August 2010. The Val Malenco is a side valley of Valtellina (map), bounded by two major mountain groups, the Bernina range to the north and the Disgrazia-Masino-Bregaglia range to the west, and by lesser mountains to the east. About midway, the valley divides into two forks, the one of the river Mallero to the west, and the one of the river Lanterna to the east. Most of the localities visited lie in the drainage of the Lanterna. In the literature, there seem to be very few records of bumblebees for the valley; the only ones I am aware of are a record of Bombus pascuorum, one of B. soroeensis, one of B. sylvarum [2], and one of B. rupestris [6]. On the other hand, given the high diversity of the valley in elevation (from a few hundred metres to over 4000 m asl), terrain and vegetation, it was reasonable to expect that it might host an equally diverse bumblebee community. This has indeed turned out to be the case.

Altogether, I have observed 23 different species of bumblebees, as detailed in the list below.
Of the species found, Bombus alpinus, B. mucidus and B. subterraneus appear to be new for Lombardy.

Species number of localities number of individuals altitudinal range
alpinus (Linné, 1758) 1 1 2612
barbutellus (Kirby, 1802) 1 1 1501
bohemicus Seidl,1837 1 1
1650
hortorum (Linné, 1761) 1 1
943
humilis Illiger, 1806 2
7
943-1501
hypnorum (Linné, 1758) 1 2
1915
inexspectatus (Tkalcu, 1963) 1 1
1501
lapidarius (Linné, 1758) 5 26 943-2612
lucorum (Linné, 1761) 4 6 1650-2760
mendax Gerstaecker, 1869 2 2
2690-2760
mesomelas Gerstaecker, 1869 4 7 943-2515
monticola Smith, 1849 5 8
1600-2760
mucidus Gerstaecker, 1869 6
11
2005-2612
pascuorum (Scopoli, 1763) 3 19 943-1650
pratorum (Linné, 1761) 1 3
1650
pyrenaeus Pérez, 1880 7 14 1980-2760
ruderarius (Müller, 1776) 1 1 2410
rupestris (Fabricius, 1793) 2 2
943-2612
sichelii Radoszkowski, 1860 2 4 1650-2690
soroeensis (Fabricius, 1777) 4 26 1600-1980
subterraneus (Linné, 1758) 1
1 2385
sylvestris (Lepeletier, 1832) 1 3 1650
wurflenii Radoszkowski, 1860 4
6 2315-2690
Allopsithyrus sp. Popov, 1931
1 1 943

It is virtually certain that this list is incomplete. Other species to be expected are B. terrestris, perhaps B. sylvarum and B. argillaceus, which has been recorded in nearby localities of the Valtellina, and probably other Psithyrus, notably B. campestris, B. quadricolor and B. flavidus. B cryptarum is also a possibility.

Perhaps the most remarkable finding of my exploration of the Val Malenco is the presence of B. alpinus, B. mucidus and B. subterraneus, none of which had been previously reported from Lombardy. On the other hand, all three have been recorded just north of the Bernina range in the upper Engadin, whose bumblebee fauna is in fact almost identical to the one encountered in the higher elevations of the Val Malenco [1]. In particular, B. mucidus has been found to be common in the latter above 2000 m. This is somewhat puzzling in view of the fact that accurate searches carried out, for instance, in the Adamello Alps [4] or in the Orobic Alps [3] have failed to reveal the presence of the species in the alpine portion of Lombardy south of the Valtellina. The other two species have been found as single specimens, B. alpinus at high elevation near the edge of the glaciated core of the Bernina massif, and B. subterraneus in the gently sloping, extensive alpine prairies of the Val Poschiavina. Near the place where the specimen of B. subterraneus, a typical worker of the subspecies latreillellus, was found, I saw a large dark bumblebee which I could not determine but that looked like a queen of the dark form of subterraneus. This form is also present in the Engadin.

B. gerstaeckeri has not been found. One reason might be that, in the localities I visited, Aconitum, on which it specializes, is very scarce and never occurs in large aggregations. On the other hand, the species is known from the Poschiavo valley immediately to the east of the area considered here [1], and hence more exhaustive searches might reveal its presence also in the Val Malenco. By contrast, B. inexspectatus has been found in the valley. This, together with the recent discovery of other localities for the species in Lombardy and Valle d'Aosta, confirms me in my impression that inexspectatus is widely distributed, and not too uncommon, in the Italian Alps.

A final remark concerns the two individuals listed above as B. barbutellus and "Allopsithirus sp.". They are both rather worn queens, quite dark, with relatively short hair and lightly infuscated wings. The first individual shows well-defined, though very narrow, light bands on collar and scutellum, and has long enough hair, particularly in the posterior fringes of the hindlegs, for me to classify it as barbutellus. The second individual appears virtually all dark, except for scattered light hairs on collar and scutellum and small yellowish lateral patches on T4 and T5, and seems to have shorter hair; nevertheless, I am inclined to consider it just a melanic specimen of barbutellus. However, it is too worn for me to risk a precise diagnosis, hence the classification just under the old subgeneric name of Allopsithyrus.


References

1. Amiet F. 1996. Hymenoptera Apidae, 1. Teil. Allgemeiner Teil, Gattungsschlüssel, die Gattungen Apis, Bombus und Psithyrus. Insecta Helvetica (Fauna) 12: 98 pp.
2. Bolchi Serini G., Marianelli P. 1994. La collezione di Bombus Latr. del Museo Civico di Storia Naturale di Milano. Boll. Zool. Agr. Bachic., Ser II, 26 (1): 1-26.
3. Cornalba M. 2010. Bumblebees of the upper Brembo valley (Lombardy, Italy). Available online at: http://www-dimat.unipv.it/cornalba/bombi/ bombremb/bombremb.html
4. Intoppa F., Moreschi I., Piazza M.G., Bolchi Serini G. 1995. Bombus Latreille e Psithyrus Lepeletier del "Parco Naturale dell'Adamello" (Hymenoptera Apidae Bombinae). Boll. Zool. Agr. Bachic., Ser II, 31 (2): 167-178.
5. Intoppa F., Piazza M.G., Ricciardelli D'Albore G. 1995. Catalogo bibliografico delle specie di Bombidae (Hymenoptera Apoidea) segnalate per l'Italia. Apicoltura 10, supplemento. pp. 135.
6. Magretti P. 1881. Sugli Imenotteri della Lombardia. Memoria I. Boll. Soc. ent. ital. XIII: 3-42; 89-123; 213-273.


Appendix
Specimens, localities and foraging plants

Species Localities and foraging plants
alpinus (Linné, 1758) Bocchetta delle Forbici, Lanzada (SO); 46.329858 N 9.901619 E; 2612 m; 28.8.2010; 1 male; on Cirsium spinosissimum
barbutellus (Kirby, 1802) Franscia, Lanzada (SO); 46.292706 N 9.912006 E; 1501 m; 24.8.2010; 1 queen; on Trifolium pratense
bohemicus Seidl,1837 Alpe Palù di Caspoggio, Lanzada (SO); 46.291533 N 9.919958 E; 1650 m; 22.8.2010; 1 male; on Centaurea sp.
hortorum (Linné, 1761) Chiesa in Valmalenco (SO); 46.269097 N 9.854375 E; 943 m; 23.8.2010; 1 worker; on Trifolium pratense
humilis Illiger, 1806 Chiesa in Valmalenco (SO); 46.269097 N 9.854375 E; 943 m; 23.8.2010; 1 worker, 1 male; on Trifolium pratense, Impatiens glandulifera
Franscia, Lanzada (SO); 46.292706 N 9.912006 E; 1501 m; 24.8.2010; 3 workers, 2 males; on Trifolium pratense
hypnorum (Linné, 1758) trail to Alpe Ventina, Chiesa in Valmalenco (SO); 46.300497 N 9.776544 E; 1915 m; 26.8.2010; 2 workers; on Epilobium angustifolium
inexspectatus (Tkalcu, 1963) Franscia, Lanzada (SO); 46.292706 N 9.912006 E; 1501 m; 24.8.2010; 1 male; on Centaurea sp.
lapidarius (Linné, 1758) Alpe Palù di Caspoggio, Lanzada (SO); 46.291533 N 9.919958 E; 1650 m; 22.8.2010; 3 workers, 2 males; on Centaurea sp.
Chiesa in Valmalenco (SO); 46.269097 N 9.854375 E; 943 m; 23.8.2010; 10 workers; on Trifolium pratense, Impatiens glandulifera
Franscia, Lanzada (SO); 46.292706 N 9.912006 E; 1501 m; 24.8.2010; 1 worker; on Centaurea sp.
val Poschiavina, Lanzada (SO); 46.299997 N 9.995067 E; 2410 m; 25.8.2010; 5 workers; on Cirsium spinosissimum
Bocchetta delle Forbici, Lanzada (SO); 46.329858 N 9.901619 E; 2612 m; 28.8.2010; 3 workers; on Cirsium spinosissimum
lucorum (Linné, 1761) Alpe Palù di Caspoggio, Lanzada (SO); 46.291533 N 9.919958 E; 1650 m; 22.8.2010; 1 male; on Centaurea sp.
Passo di Canciano, Lanzada (SO); 46.297339 N 9.991347 E; 2515 m; 25.8.2010; 3 workers; on Anthillis vulneraria
trail to Capanna Marinelli, Lanzada (SO); 46.343914 N 9.907133 E; 2760 m; 28.8.2010; 1 queen; on Cirsium spinosissimum
Bocchetta delle Forbici, Lanzada (SO); 46.329858 N 9.901619 E; 2612 m; 28.8.2010; 1 worker; on Cirsium spinosissimum
mendax Gerstaecker, 1869 trail to Capanna Marinelli, Lanzada (SO); 46.343914 N 9.907133 E; 2760 m; 28.8.2010; 1 worker; on Cirsium spinosissimum
trail to Capanna Marinelli, Lanzada (SO); 46.342750 N 9.907381 E; 2690 m; 28.8.2010; 1 worker; on Cirsium spinosissimum
mesomelas Gerstaecker, 1869 Alpe Palù di Caspoggio, Lanzada (SO); 46.291533 N 9.919958 E; 1650 m; 22.8.2010; 3 workers; on Trifolium sp., Cirsium sp.
Chiesa in Valmalenco (SO); 46.269097 N 9.854375 E; 943 m; 23.8.2010; 1 worker; on Trifolium pratense
Franscia, Lanzada (SO); 46.292706 N 9.912006 E; 1501 m; 24.8.2010; 1 worker; on Trifolium pratense
Passo di Canciano, Lanzada (SO); 46.297339 N 9.991347 E; 2515 m; 25.8.2010; 2 workers; on Anthillis vulneraria
monticola Smith, 1849 Chiareggio, Chiesa in Valmalenco (SO); 46.317539 N 9.796133 E; 1600 m; 23.8.2010; 1 worker; on Epilobium angustifolium
Alpe Ventina, Chiesa in Valmalenco (SO); 46.296267 N 9.778233 E; 1980 m; 23.8.2010; 1 male; on Epilobium angustifolium
Passo di Canciano, Lanzada (SO); 46.297339 N 9.991347 E; 2515 m; 25.8.2010; 1 queen, 3 workers; on Trifolium badium, Anthillis vulneraria
trail to Capanna Marinelli, Lanzada (SO); 46.343914 N 9.907133 E; 2760 m; 28.8.2010; 1 queen; on Cirsium spinosissimum
Bocchetta delle Forbici, Lanzada (SO); 46.329858 N 9.901619 E; 2612 m; 28.8.2010; 1 male; on Cirsium spinosissimum
mucidus Gerstaecker, 1869 Alpe Campagneda, Lanzada (SO); 46.299194 N 9.943075 E; 2156 m, 25.8.2010; 1 worker; on Carduus defloratus
Piano di Campagneda, Lanzada (SO); 46.297500 N 9.964339 E; 2315 m; 25.8.2010; 3 workers, 1 male; on Cirsium spinosissimum
lago di Alpe Gera, Lanzada (SO); 46.315261 N 9.950342 E; 2140 m; 25.8.2010; 2 workers; on Cirsium spinosissimum
lago di Campomoro, Lanzada (SO); 46.310994 N 9.943572 E; 2005 m; 25.8.2010; 1 worker; on Epilobium fleischeri
trail to Rifugio Bignami, Lanzada (SO); 46.319394 N 9.941900 E; 2170 m; 27.8.2010; 1 queen, 1 worker; on Carduus defloratus, Lotus corniculatus
Bocchetta delle Forbici, Lanzada (SO); 46.329858 N 9.901619 E; 2612 m; 28.8.2010; 1 male; on Cirsium spinosissimum
pascuorum (Scopoli, 1763) Alpe Palù di Caspoggio, Lanzada (SO); 46.291533 N 9.919958 E; 1650 m; 22.8.2010; 3 workers; on Trifolium sp.
Chiesa in Valmalenco (SO); 46.269097 N 9.854375 E; 943 m; 23.8.2010; 10 workers; on Trifolium pratense, Impatiens glandulifera
Franscia, Lanzada (SO); 46.292706 N 9.912006 E; 1501 m; 24.8.2010; 3 workers; on Trifolium pratense
pratorum (Linné, 1761) Alpe Palù di Caspoggio, Lanzada (SO); 46.291533 N 9.919958 E; 1650 m; 22.8.2010; 2 workers, 1 male; on Cirsium palustre
pyrenaeus Pérez, 1880 Alpe Ventina, Chiesa in Valmalenco (SO); 46.296267 N 9.778233 E; 1980 m; 23.8.2010; 2 workers; on Epilobium angustifolium
Piano di Campagneda, Lanzada (SO); 46.297500 N 9.964339 E; 2315 m; 25.8.2010; 1 male; on Cirsium spinosissimum
Passo di Campagneda, Lanzada (SO); 46.301850 N 9.984528 E; 2632 m; 25.8.2010; 1 male; on Campanula scheuchzeri
Alpe Fellaria, Lanzada (SO); 46.329578 N 9.947992 E; 2410 m; 27.8.2010; 2 males; on Cirsium spinosissimum
trail to Capanna Marinelli, Lanzada (SO); 46.343914 N 9.907133 E; 2760 m; 28.8.2010; 2 males; on Cirsium spinosissimum
trail to Capanna Marinelli, Lanzada (SO); 46.342750 N 9.907381 E; 2690 m; 28.8.2010; 1 worker, 1 male; on Cirsium spinosissimum
Bocchetta delle Forbici, Lanzada (SO); 46.329858 N 9.901619 E; 2612 m; 28.8.2010; 2 workers, 2 males; on Cirsium spinosissimum
ruderarius (Müller, 1776) Alpe Fellaria, Lanzada (SO); 46.329578 N 9.947992 E; 2410 m; 27.8.2010; 1 male; on Cirsium spinosissimum
rupestris (Fabricius, 1793) Chiesa in Valmalenco (SO); 46.269097 N 9.854375 E; 943 m; 23.8.2010; 1 queen; on Trifolium pratense
Bocchetta delle Forbici, Lanzada (SO); 46.329858 N 9.901619 E; 2612 m; 28.8.2010; 1 male; on Cirsium spinosissimum
sichelii Radoszkowski, 1860 Alpe Palù di Caspoggio, Lanzada (SO); 46.291533 N 9.919958 E; 1650 m; 22.8.2010; 3 workers; on Centaurea sp.
trail to Capanna Marinelli, Lanzada (SO); 46.342750 N 9.907381 E; 2690 m; 28.8.2010; 1 queen; on Cirsium spinosissimum
soroeensis (Fabricius, 1777) Alpe Palù di Caspoggio, Lanzada (SO); 46.291533 N 9.919958 E; 1650 m; 22.8.2010; ssp. proteus; 1 queen, 10 workers, 10 males; on Centaurea sp.
Chiareggio, Chiesa in Valmalenco (SO); 46.317539 N 9.796133 E; 1600 m; 23.8.2010; ssp. proteus; 1 male; on Epilobium angustifolium
Alpe Ventina, Chiesa in Valmalenco (SO); 46.296267 N 9.778233 E; 1980 m; 23.8.2010; ssp. proteus; 1 male; on Epilobium angustifolium
Franscia, Lanzada (SO); 46.292706 N 9.912006 E; 1501 m; 24.8.2010; ssp. proteus; 2 workers, 1 male; on Centaurea sp.
subterraneus (Linné, 1758) val Poschiavina, Lanzada (SO); 46.304381 N 9.992286 E; 2385 m; 25.8.2010; ssp. latreillellus; 1 worker; on Cirsium spinosissimum
sylvestris (Lepeletier, 1832) Alpe Palù di Caspoggio, Lanzada (SO); 46.291533 N 9.919958 E; 1650 m; 22.8.2010; 2 queens, 1 male; on Centaurea sp., Cirsium palustre
wurflenii Radoszkowski, 1860 Piano di Campagneda, Lanzada (SO); 46.297500 N 9.964339 E; 2315 m; 25.8.2010; 1 worker; on Cirsium spinosissimum
Passo di Canciano, Lanzada (SO); 46.297339 N 9.991347 E; 2515 m; 25.8.2010; 3 workers; on Anthillis vulneraria
val Poschiavina, Lanzada (SO); 46.299997 N 9.995067 E; 2410 m; 25.8.2010; 1 worker; on Cirsium spinosissimum
trail to Capanna Marinelli, Lanzada (SO); 46.342750 N 9.907381 E; 2690 m; 28.8.2010; 1 worker; on Cirsium spinosissimum
Allopsithyrus sp. Popov, 1931
Chiesa in Valmalenco (SO); 46.269097 N 9.854375 E; 943 m; 23.8.2010; 1 queen; on Trifolium pratense

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