Colletes perplexus sp. nov. Fig. 1 A – F Type material (3 specimens). Holotype: ♂. Azerbaijan. • “ Azerbaijan, Nakhchivan AR, Ordubad, Kotam, 700 m, 38°53'25"N, 46°03'14"E, 19. V. 2025, leg. Proshchalykin, Maharramov ” (ZISP). Paratypes. Azerbaijan. • “ Azerbaijan, Nakhchivan AR, Ordubad, Bilav, 1050 m, 39°02'43"N, 45°49'07"E, 22. V. 2025, 2 ♂ Proshchalykin, Maharramov ” (FSCV / RCMK). Diagnosis. The new species belongs to the C. nanus species group that is characterised in the male sex by overall small size (maximum body length ~ 9.0 mm), malar area elongate, mesoscutal disc polished, either impunctate or sparsely punctate, anterior declivorous part of T 1 densely covered with short appressed and long erect hair, T 1 – T 5 and S 2 – S 5 with dense and broad white apical hair bands (Noskiewicz 1936). This group is particularly speciose in deserts and semi-deserts of North Africa and the Middle East. Far fewer species occur in the Caucasus region and Middle Asia, namely C. popovi Noskiewicz, 1936, C. schwarzi Kuhlmann, 2002 and the enigmatic C. penulatus Noskiewicz, 1936. The latter species is known only from the single female holotype and, thus, is not considered here (but see comment below under Remarks). In neighbouring Iran, C. sirjanensis Kuhlmann, 2023 was described based on males but its oval-shaped S 7 (Kuhlmann et al. 2023) differs significantly from the ± round S 7 of C. perplexus, C. schwarzi and C. popovi, hence, it is also not included here. Therefore, the diagnosis is limited to these three closely related species, which are the only others of the C. nanus species group found in the region and share a very similar morphology. They are extensively illustrated in this paper to facilitate their identification. The recently described C. storozhenkoi Kuhlmann & Proshchalykin, 2025 (Proshchalykin and Kuhlmann 2025) is also not considered here. The species is also known only from females collected at a single site in Dagestan in the coastal lowlands of the Caspian Sea and the following morphological features suggests that C. storozhenkoi and C. perplexus very likely represent two separate taxa. In C. storozhenkoi punctation on the mesoscutal disc unusually dense for a species in this group (much more dispersed in C. perplexus), hair on mesoscutum in particular posteriorly short and thickly plumose (C. perplexus: disproportionately longer, more slender, and less plumose), horizontal part of propodeum shorter (C. perplexus: disproportionately longer) and depressions of apical tergal margins differ disproportionally for sexes of the same species. However, this can only be clarified ultimately if the unknown sex of at least one of the two species is found or through genetic analysis (e. g. DNA barcoding), which was not feasible within the context of this study. The male of C. perplexus differs from C. popovi and C. schwarzi by the following character combination: Apical tergal hair bands narrower (Fig. 1 C) than in the other species (Fig. 1 G, K), appressed hair on the sloping base of T 1 sparser and more restricted, barely reaching the disc (Fig. 1 D) (appressed hair denser and more extensive in C. schwarzi and C. popovi as in Fig. 1 H, L), punctation on discs of T 1 and T 2 fine and dense (i

Published as part of Kuhlmann, Michael, Proshchalykin, Maxim Yu. & Maharramov, Mahir M., 2026, New and little-known bees of the genus Colletes Latreille, 1802 (Hymenoptera, Colletidae) from the Nakhchivan Autonomous Republic of Azerbaijan, with descriptions of two new species, pp. 95-112 in ZooKeys 1268 on pages 95-112, DOI: 10.3897/zookeys.1268.174008