Previously regarded as a variety of Ponera coarctata (Latreille, 1802), P. testacea was raised to species status by Csösz & Seifert (2003), on good morphological and ecological evidence. It is also a senior synonym of P. coarctata var. crassisquama (Emery, 1916), (Scupola, 2006).
Fewer than 20 records have been confirmed so far, all from coastal sites in southern England, with nearly half from Dungeness, E. Kent, where it was first recognized as a British species from pitfall trap specimens (Attewell et. al., 2010). It has since been confirmed as widespread at Dungeness and also from a scatter of coastal sites in six vice-counties of S. England from E. Cornwall to E. Suffolk, (Jarman, 2010; Alexander, 2012; Paul, 2011). Many records are from specimens originally identified as P. coarctata and re-determined following publication of the Dungeness finds. A record from Orford Ness, E. Suffolk (Telfer, 2013), is significant in being at the same latitude as the northernmost continental record, which is in Berlin (B. Seifert, pers. comm. to P. Attewell). It is possible that some of the Channel Island records for coarctata may be determined as testacea.
Elsewhere, it is abundant in the Mediterranean region, Iberia, S. France and Italy, and ranges sporadically into northwest (Belgium and Netherlands), central and eastern Europe, and the Balkans, to 52ºN.