This is one of a number of similar, medium-sized Lasioglossum species with predominantly black colouration. Females measure around 8mm and are jet black and rather shiny, especially the abdomen which when viewed under magnification shows a scarcity of micro-punctures but the presence of minute ‘ridges’ at the posterior end of the tergites. Males are black with rather long antennae and the underside of the abdomen is lightly hairy.  Such fine details can only be appreciated under strong magnification so a specimen is needed to identify this species. It is not common in Ireland, with only a handful of records and is listed as Vulnerable.

Distribution in Ireland: Records are widely scattered; Donegal, Sligo, Down, Antrim, Armagh, Meath, Laois and Carlow the only counties from which it has been reported. It exhibits a northerly bias and is under-recorded.

Flight period: Females fly between March-September, whilst males fly between June-August.

Habitat: Primarily a species of deciduous woodlands over acidic soils. Known habitats include deciduous and mixed woodland, heathland edge and wooded grey dunes.

Flowers visited: Hawkweeds, Lesser Celandine, Wood Anemone, Bramble, buttercups and others.

Personal records: I have recorded this species at a sandy, partially-wooded brownfield site at Sprucefield in Co. Down. The specimen in question was a female observed constructing a burrow in a south-facing sandy bank. I have also recorded a single female at Milford Cutting in Co. Armagh close to a small clay bank visiting a Lesser Celandine flower and around a gravelly soil slope in Bonny Glen, Co. Donegal. I have observed a female nesting in clay soil in an upturned tree base in a woodland clearing near Edenderry, Co. Down and a male feeding on Ragwort in a sandy woodland edge in Dunfanaghy, Co. Donegal.  Lightly wooded brownfield sites, scrub and woodland clearings are worth searching for this rare bee, as it is almost certainly more widespread than current records suggest. The kleptoparasites of this species are not known in Ireland, although in Britain Sphecodes ferruginatus and Nomada fabriciana have both been suggested. Sphecodes hyalinatus is another possible cleptoparasite.