The phylogenetic placement of the enigmatic subtribe Stenolamina is investigated based on the analysis of four molecular loci (CAD, wg, 28S, 12S). Historically, the position of Stenolamina remained unfixed, and was listed as incertae sedis within the darkling beetle subfamily Blaptinae. Molecular data render Stenolamina as a separate lineage within the tribe Opatrini. The morphology and distribution of Stenolamina are reexamined. Scanning electron microscopy revealed that Stenolamina shares the synapomorphic Opatrini protrochanter structure seen in all other members of the tribe. Furthermore, unique antennal sensoria (placoid / stenolamoid) are reported for Stenolamina – this feature is distinct from all other Blaptinae. This paper presents the first morphological definition of Stenolamina. Finally, Stenolamus borowieci sp. nov. is described from the surroundings of Port Nolloth (South Africa). The material examined for this species displayed a striking type of sexual dimorphism, which is omnipresent within Stenolamina (females with acute basal angles of the pronotum).