Eucera nigrescens Pérez, 1880

Gérard, Maxence, Fiordaliso, William, Ferrais, Louise, Fournier, Chloé, Hairault, Malo, Lheureux, Lise, Rosa, Paolo & Ghisbain, Guillaume, 2025, Wild bee diversity of the National Park of the Semois Valley (Belgium), Biodiversity Data Journal 13, pp. e 144223-e 144223 : e144223-

Eucera nigrescens Pérez, 1880

Conservation status

EN

Distribution

Its population in Belgium has declined around 50 % to 80 % between 1900-1969 and 1970-2017, with severely fragmented populations ( Drossart 2019). Few populations remain in Pays de Herve, Condroz and Plateaux Limoneux Hennuyers ( Drossart 2019). The drastic decline of leguminous crops and nutrient-poor grasslands is probably a major driver of this decline.

Notes

Eucera nigrescens primarily inhabits meadows and grasslands rich in Fabaceae , as these plants are its main foraging source ( Standfuss 2009). Females exclusively collect pollen from Fabaceae species, while males are often associated with the orchid Ophrys fuciflora ( Gaskett 2010) . The single specimen we collected was observed foraging on a Lathyrus species.

Diagnosis

One of the two Eucera species in Belgium. Compared to E. longicornis , E. nigrescens (Fig. 10 ) it has a domed and elongated clypeus, and the mesonotum weakly punctuated ( Amiet et al. 2007). In males, the mesosoma hair colour varies considerably, ranging from brown to silver, whereas, in females, the variation is more limited, primarily spanning from light to dark brown.

Figures

Figure 10. Eucera nigrescens, ♂. Habitus in lateral view and head in oblique view. Scale bar: 5 mm. Photo credit: Paolo Rosa.