Darkling beetles (Tenebrionidae: Coleoptera) are commonly associated with hot arid lands worldwide. In southern Africa, the number of species is reported to increase along the east-to-west gradient in aridity. The highest diversity is found in the Namib Desert, which occupies a 100 km by 2,000 km hyperarid strip along the west coast, from South Africa to the south into southern Angola. We sought to confirm this regional diversity pattern by collecting tenebrionids with pitfall traps at five SASSCAL observatories along a transect stretching from the hyperarid desert interior (MAP 25 mm, CV 130%) to semiarid conditions 260 km inland (MAP 343 mm, CV 36%). We collected tenebrionids during 11–20 month-long trapping sessions and identified species from seven tenebrionid tribes and subtribes which were previously recorded in half-degree squares across the arid western half of the southern Africa region. Even though there was a six-fold decrease in tenebrionid abundance, all diversity indices increased with increasing aridity (e.g. α-diversity inland: 1.40, desert interior 3.71). Community structure was very different in the interior highland plateau compared to the desert (ß-diversity 0.52–0.69), while adjacent sites in the desert differed less (ß-diversity 0.26–0.29). In the desert, tenebrionids were recorded most Darkling beetles (Tenebrionidae: Coleoptera) are commonly associated with hot arid lands worldwide. In southern Africa, the number of species is reported to increase along the east-to-west gradient in aridity. The highest diversity is found in the Namib Desert, which occupies a 100 km by 2,000 km hyperarid strip along the west coast, from South Africa to the south into southern Angola. We sought to confirm this regional diversity pattern by collecting tenebrionids with pitfall traps at five SASSCAL observatories along a transect stretching from the hyperarid desert interior (MAP 25 mm, CV 130%) to semiarid conditions 260 km inland (MAP 343 mm, CV 36%). We collected tenebrionids during 11–20 month-long trapping sessions and identified species from seven tenebrionid tribes and subtribes which were previously recorded in half-degree squares across the arid western half of the southern Africa region. Even though there was a six-fold decrease in tenebrionid abundance, all diversity indices increased with increasing aridity (e.g. α-diversity inland: 1.40, desert interior 3.71). Community structure was very different in the interior highland plateau compared to the desert (ß-diversity 0.52–0.69), while adjacent sites in the desert differed less (ß-diversity 0.26–0.29). In the desert, tenebrionids were recorded most