Stenodynerus rufescens Giordani Soika, 1977 stat. nov. (Fig. 4C) Stenodynerus fastidiosissimus rufescens Giordani Soika 1977: 168, ♀—“ Cirenaica: Wadi Kut ” (holotype female NHMUK). Diagnosis. Similar to S. fastidiosissimus, but differing in the following characters: black with ferruginous-red markings, apical bands on T1–T2 only, female clypeus with apical emargination 0.25× as deep as wide, male clypeus as long as wide with apical emargination 0.55× as deep as wide. Material examined. LIBYA: Cyrenaica, Cirene, 1.V.1924, leg. C. Krüger, 1♂ (MSNVE, OR292164); Cyrenaica, Wadi Kuf, 4–10.IV.1958, leg. K.M. Guichard, 1♀ (MSNVE, paratype, OR292163). Distribution. Libya (Giordani Soika 1977) (Fig. 6A). DNA barcoding. COI-5P gene sequences were obtained from two specimens, including a topotypical paratype. The intraspecific sequence divergence of S. rufescens is 2.39%. The species is clearly separated from the other taxa considered in this study and supported by a bootstrap value of 100 (Fig. 6B). The lowest interspecific genetic distance exists between S. rufescens and S. fastidiosissimus, with a minimum of 26.56% (mean 28.19%). Notes. Giordani Soika (1977) described this taxon as a subspecies of Stenodynerus fastidiosissimus (auct. non de Saussure, 1855), based on two females from Wadi al-Kuf. Examination of one paratype and of a male specimen from Cyrene, about 30 km NE of the type locality, showed that this taxon is closer to the true S. fastidiosissimus, sharing the same dense sculpture of S2 and similar shape of ventral lobe of aedeagus. We consider it a distinct species, due to the ferruginous-red markings, apical bands on T1–T2 only and the longer male clypeus with deeper apical emargination (0.55× as deep and wide) and longer and sharper lateral teeth. Genetic data support this treatment, with a genetic distance from S. fastidiosissimus of 26.56–32.05% (mean 28.19%).

Published as part of Selis, Marco, Cilia, Giovanni, Wood, Thomas J. & Soon, Villu, 2024, Taxonomic revision of the Stenodynerus fastidiosissimus species-group in Western Europe and North Africa (Hymenoptera: Vespidae: Eumeninae), pp. 34-56 in Zootaxa 5418 (1) on page 52, DOI: 10.11646/zootaxa.5418.1.2, http://zenodo.org/record/10717928