Megachile (Xanthosarus) nigriventris (Schenck, 1868)

Vertommen, Win, Vanormelingen, Pieter, D’Haeseleer, Jens, Wood, Thomas J., Baugnée, Jean-Yves, Blanck, Tim De, Grave, David De, Rycke, Samuel De, Deschepper, Chantal, Devalez, Jelle, Feys, Simon, Foubert, Olivier, Jacobs, Maarten, Janssen, Kobe, Legrain, Benjamin, Molenberg, Jean-Marc, Pauly, Alain, Pasau, Bernard, Reynaerts, Annie, Verheyen, Stefan, Wallays, Henk, Wielandts, Maarten & Vereecken, Nicolas J., 2024, New and confirmed wild bee species (Hymenoptera: Apoidea: Apiformes) for the fauna of Belgium, with notes on the rediscovery of regionally extinct species, Belgian Journal of Entomology 149, pp. 1-64 : 31-32

publication ID	https://doi.org/10.5281/zenodo.16958242
publication LSID	lsid:zoobank.org:pub:387AD02A-54C0-4D7E-BF1F-FA0F748217F7
persistent identifier	https://treatment.plazi.org/id/1B4187C4-FFFE-FFFC-FB7C-FBF7FB0B9817
treatment provided by	Felipe
scientific name	Megachile (Xanthosarus) nigriventris (Schenck, 1868)
status

Treatment

Megachile (Xanthosarus) nigriventris (Schenck, 1868) View in CoL – Belg. sp. nov.

Figs 5 View Fig , 11 B View Fig

SHORT DESCRIPTION: A medium to large-sized (13–17 mm) species establishing its nests in rotten wood with cut leaf fragments ( WESTRICH, 2018; DUBITZKY, 2000; REICHHOLF, 2002) and with a strong preference (oligolecty) for host plants in the family Fabaceae ( WESTRICH, 2018; AMIET & KREBS, 2019). Females and males superficially resemble M. willughbiella (Kirby 1802) with which females share a typical, broad mandible with tooth 1 larger than other teeth, without an apical brush of hairs in the grooves around the base of tooth 1 ( SCHEUCHL, 2006; PRAZ, 2017). However, females of M. nigriventris can be discriminated from M. willughbiella by their comparatively larger body size, their all-black ventral scopa, and their bicolor hair pattern particularly visible in freshly emerged individuals, with brown-reddish hairs on the thorax and the first two tergites, followed by mostly black hairs on the rest of the abdomen. Males can be distinguished based on the tarsi of the foreleg, which have relatively short hairs while the first segment is not parallel-sided.

DISTRIBUTION IN EUROPE: found throughout Europe from Spain to Scandinavia, particularly at higher elevations (up to 2000m a.s.l.) ( SCHEUCHL & WILLNER, 2016). No record from the Grand Duchy of Luxembourg ( HERRERA MESÍAS & WEIGAND, 2021) or the United Kingdom ( ELSE & EDWARDS, 2018), but it was found in the Netherlands (VAN ‘T BOSCH & RAEMAKERS, 2020, approved observations on https://waarneming.nl/species/178530/), France and Germany ( SCHEUCHL & WILLNER, 2016).

EU RED LIST STATUS: Data deficient (DD) ( NIETO et al., 2014)

ORIGIN OF RECORDS:

- NAMUR PROVINCE. Rochefort; 1♀; 21.vi.2019; leg./coll./det. N.J. Vereecken - Fig. 11 B View Fig . Gedinne; 3♀♀; 31.v.2020; leg./det. J. Preud’Homme. 1♀; 13.vi.2021; leg./det. J .

Preud’Homme. Bièvre; 1♂; 10.vi.2021; leg. J. Turelinckx; det. J. Devalez. Gedinne; 1♀; 13.vi.2021; leg./det. J. Preud’homme.

- LIÈGE PROVINCE. BÜllingen; 1♂; 31.v.2020; leg./coll./det. W. Tamsyn. 1♂; 2.vii.2022; leg./coll. D. De Grave; det. D. De Grave, W. Vertommen. Aywaille; 1♀; 1.vi.2020; leg . R. Gailly; det. J. Devalez.

- LUXEMBOURG PROVINCE. Vielsalm ; 1♀; 20.vi.2020; leg./det. K. Janssen. Léglise; 1♀; 7.vii.2021; leg./det. D. Sevrin, H. Baltus. 1♀; 11.vii.2021; leg./det. W. Tamsyn.

- FLEMISH BRABANT PROVINCE. Lubbeek; 1♀; 23.vi.2020; leg. G. Van Hoovels; det. P. Vanormelingen.

- LIMBURG PROVINCE. Nieuwerkerken ; 1♀; 14.vi.2021; leg./coll. J. D’Haeseleer; det. J. D’Haeseleer, T. De Blanck .

COMMENTS:

- Unlike other bee species in this group, this species is not specifically expanding northward. Strangely enough, it seems to be descending from higher elevations ( SCHEUCHL & WILLNER, 2016) with recent discoveries in Wallonia in 2019 and both Flanders and the Netherlands in 2020 (VAN ‘T BOSCH & RAEMAKERS, 2020; D’HAESELEER & VERTOMMEN, 2021). It is unclear why the species has suddenly been found at lower elevations, but it is clear that the species is on the move because of climate change. One possible explanation is that it is adapting to different habitats in response to climate change.