The supposed monotypy of the trapdoor spider genus Amblyocarenum Simon, 1892 is reassessed and rejected. Qualitative and quantitative morphological differences in both males and females are distinguished in samples collected on Sardinia and Sicily, respectively, indicating the existence of at least two distinct Amblyocarenum species in these two regions. The study of smaller, less representative samples from southwest Italy, Algeria, and Spain also suggest the existence of distinct, although morphologically difficult to distinguish, Amblyocarenum species in other geographical regions of the western Mediterranean. Here, we describe a new species, A. nuragicus n. sp., from Sardinia. Detailed field observations and photographic work provide additional new information about this new species. More intensive sampling and the use of more inclusive research methods (molecular, geographic, ecological and ethological) are advocated in order to clarify the extant species diversity of the genus Amblyocarenum.