Lindenius marsianus Mokrousov & Proshchalykin, sp. nov. http://zoobank.org/ urn:lsid:zoobank.org:act: 7A684A4D-5158-4FF5-9F0F-746EFA8EA68D (Figs 8–16) Type material (1 ♀, 5 ♂). Holotype — ♂, Altai, “ Mars ”, / 50.0639°N, 88.3125°E / 22.VI 2022 / Proshchalykin, Fateryga // Holotype ♂ Lindenius / marsianus Mokrousov / et Proshchalykin [ZISP]. Paratypes: ibid., 22.VI.2022, 1 ♀, Proshchalykin, Fateryga [CMMN]: ibid., 17.VI.2022, 1 ♂, Proshchalykin [CMMN]; Altai, 15 km SE of Kuray, 50.1861°N, 88.1178°E, 17.VI.2022, 1 ♂, Proshchalykin, Fateryga [1 ♂ CMMN, 2 ♂ ZISP]. Diagnosis. Lindenius marsianus belongs to the L. albilabris species group, characterized by the absence of the hypersternaulus, the lateral angle of the clypeal middle lobe inconspicuously separated, the lateral notches of the clypeus not large, not reaching the lower eye margin. It differs from the other species of the group by the following character combination: body completely black, except for yellow pattern on legs; frontal groove slightly deepened; vertex completely punctate, without large interspases; orbital fovea small and indistinct; distance between antennal socket and eye less than half socket diameter; mesopleuron irregularly punctured, interspaces 1–3 puncture diameters; femoral setae shorter than midocellus diameter; propodeal enclosure predominantly and adjacent areas nearly smooth or microsculptured; female S 3–5 with irregular punctation, medially nearly impunctate, with matt microsculpture; male F 1–9 slightly convex ventrally, midbasitarsus not curved, without long setae, longest femoral setae shorter than midocellus diameter. Description. Head rounded; frontal groove slightly deepened; vertex completely punctate without large interspases; orbital foveae small and indistinct; distance between antennal socket and eye less than half socket diameter; interantennal elevation lacking; scapal basin without medial tubercle near antennal sockets; gena without spine. Median clypeal lobe slightly sinuate laterally, lateral angles nearly rectangular (more acute in males); lateral notch not large but distinct; lateral tooth acute, directed forward. Mandibular inner margin with triangular tooth near middle. Apressed silver pubescence well developed along inner eye edge and on clypeus (except triangular apical median part). Mesosoma. Pronotal collar slightly raised, anterior border laterally sharpened, medial furrow narrow and not deep. Mesonotum and scutellum irregulary punctate, punctures slightly smaller than on mesopleuron. Mesopleuron irregularly punctate, interspaces 1–3 puncture diameters apart. Propodeal enclosure predominantly and lateral surface nearly smooth or microsculptured. Femoral setae shorter than midocellus diameter. Legs. Not specifically modified in both sexes. Length of longest femoral setae shorter than midocellus diameter. Wings. Typical for genus. Coloration. Completely black with the following parts yellow: apical femoral rim, anterior surface of fore- and midtibiae, base of hindtibia and tarsal base (basitarsi completely or predominantly yellow). Male (Figs 8–13). Body length 4.9–6.7 mm (holotype 6.7 mm). Head (Figs 11–12) ratio H:W = 0.93; ratio POL:OOL = 1.41. F1–9 slightly convex ventrally, central flagellomeres nearly cubical (Fig. 10). Metasoma. S 6 posterior margin notched medially; T 1–6 and S 2–6 minutely punctate, with short, white, not dense setae. Pygidial plate wide, with distinct punctures, arcuate apically. Female (Figs 14–16). Body length 7.7 mm. Head (Figs 15–16) ratio H:W = 0.87; ratio POL:OOL = 1.60. Central flagellomeres nearly cubelike. Metasoma. S3–5 with irregular punctation, medially nearly impunctate, with matt microsculpture. Pygidial plate punctate, with slightly concave lateral sides. Etymology. Toponym, derived from the popular tourist place name “Mars” in Altai Mountains—the type locality of the species. Distribution. Russia (Altai Republic).

Published as part of Mokrousov, Mikhail V. & Proshchalykin, Maxim Yu., 2025, Corrections and additions to the catalogue of the digger wasps (Hymenoptera: Ampulicidae, Sphecidae, Crabronidae) of Russia, pp. 401-450 in Zootaxa 5728 (3) on pages 411-412, DOI: 10.11646/zootaxa.5728.3.1, http://zenodo.org/record/17895037