Why make it easy when you can make it difficult? the <i>nigritus</i> group as example of the current challenges in the traditional taxonomy of the bee genus <i>Hylaeus</i> Fabricius (Apoidea: Colletidae)

We provide a revised definition of the <i>nigritus</i> group based on morphological characters and supported by a CO1 phylogeny of the group. It now includes only eight species, including three new species described herein: <i>Hylaeus malitiosus</i> Le Divelec, <b>sp. n</b>. (France), <i>H. ludificator</i> Le Divelec, <b>sp. n</b>.

(France and Spain) and <i>H. paimoni</i> Le Divelec, <b>sp. n</b>. (Armenia and Iran). Species previously associated with the <i>nigritus</i> group s.l. but excluded here are also revised.

Two species are reinstated to species rank: <i>H. jugorum</i> Morawitz <b>stat. rev</b>. (= <i>H. mellon</i> Dathe and Proshchalykin <b>syn. n</b>.) and <i>H. peregrinus</i> Dathe <b>stat. rev</b>. In total, 11 additional new synonymies are established.

An identification key to the <i>nigritus</i> group s.str. is provided, along with redescriptions and comparative diagnoses for the 10 species previously associated with the group s.l. This revision clarifies the taxonomy of several problematic Asiatic <i>Hylaeus</i> species and illustrates how insufficiently rigorous taxonomic practices can propagate errors across species delimitation, identification, classification and biodiversity data.</p>