The genus Stizus Latreille, 1802 (Hym., Bembicidae) in Uzbekistan

Introduction

According to Sann et al. (2018), Spheciformes constitute a large and taxonomically diverse assemblage that includes ten families: Ammoplanidae, Ampulicidae, Astatidae, Bembicidae, Crabronidae, Mellinidae, Pemphredonidae, Philanthidae, Psenidae and Sphecidae. All these families belong to the superfamily Apoidea within the order Hymenoptera. The genus Stizus Latreille, 1802 belongs to the family Bembicidae and is distributed worldwide, except in Southeast Asia, Australia, and South America (Nemkov, 2012). Currently, the genus comprises 108 recognized species (Pulawski, 2025). To date, no targeted research has been conducted on the genus Stizus within the territory of Uzbekistan. However, information on its representatives can be found in the works of Radoszkowski (1877), Gussakovskij (1928, 1935), Davletshina et al. (1979), Islamov (1986), Kazenas (2001, 2002), and Nemkov (2012, 2015). Based on the analysis of available literature, 16 species of this genus are known to occur in Uzbekistan (Pulawski, 2025). The aim of the present study is to provide a detailed assessment of the species composition of the genus Stizus in the territory of Uzbekistan.

Materials and methods

Field investigations were conducted from 2021 to 2024 across various geographical regions of Uzbekistan, including the northwestern, northeastern, eastern, central, and southern parts of the country. The geographic coordinates of the sampling sites were recorded using the Maps.me application, and cartographic visualization was performed using ArcGIS Pro. Standard methods described by Golub et al. (2012) were employed for material collection, including the use of an entomological net and yellow plastic pan traps of the Moericke type (Moericke, 1951). Most digger wasps encountered on flowering plants in the studied regions were collected using an entomological net. Captured specimens were removed with forceps and preserved either in 15 ml plastic vials containing 96% ethanol or stored in cotton-stoppered containers.

The collected material was delivered to the Entomology Laboratory of the Institute of Zoology. For specimen preparation, wings were softened in a humid chamber, after which the specimens were mounted on special plates and spread for further identification. Subsequently, the samples were labeled and added to the collection. Species identification of Stizus was performed using an SMZ-161-TL stereomicroscope. Identifications were based on keys and taxonomic literature by Pulawski (1978, 2025), Nemkov (2012), and Kazenas (1978, 2013), and confirmed by comparison with reference specimens housed in the Zoological Institute of the Academy of Sciences of the Republic of Uzbekistan. Additionally, international electronic catalogues and atlases were also consulted. Family-level classification follows the latest Apoidea taxonomy proposed by Sann et al. (2018). Species nomenclature and general distribution were adopted from Pulawski (2025). All specimens were deposited in the scientific collection of the Institute of Zoology of the Academy of Sciences of the Republic of Uzbekistan.

Results

Family Bembicidae Latreille, 1802

Genus Stizus Latreille, 1802

Stizus annulatus (Klug, 1845)

Material examined: 3♀, 1♂, Republic of Karakalpakstan, Kyzylkum Desert [42.483087, 60.567972], 30.05.2023; 1♀, [42.497556, 59.816574], 15.05.2024. 2♀, 1♂, Kungrad District, Ustyurt Plateau [43.861025, 57.596561], 08.06.2024; 3♀, 2♂, Republic of Karakalpakstan, Nukus, vicinity of Lake Ashshikol [42.507836, 59.640728], 13.05.2024.

General distribution: Algeria, Azerbaijan, Egypt, Greece, Iran, Israel, Kazakhstan, Libya, Mongolia, Palestine, Syria, Tajikistan, Turkey, Turkmenistan, Uzbekistan (Pulawski, 2025).

Stizus bizonatus Spinola, 1839

Material examined: 1♀, Republic of Karakalpakstan, Kyzylkum Desert [42.436481, 60.525503], 30.05.2023; 1♂, Jizzakh Region, vicinity of Lake Tuzkan [40.631567, 67.32672], 29.06.2024

Distribution: Egypt, Ethiopia, Iran, Iraq, Saudi Arabia, Syria, Tajikistan, Turkmenistan, UAE, Uzbekistan (Pulawski, 2025).

Stizus dispar F. Morawitz, 1888

Material examined: 1♂, Republic of Karakalpakstan, Kyzylkum Desert [42.436277, 60.524797], 30.05.2023; 1♀, Kungrad District, Ustyurt Plateau [43.902589, 57.549738], 13.06.2023; 4♀, [44.233284, 57.908559], 07.06.2024.

Distribution: Iran, Kazakhstan, Tajikistan, Turkmenistan, Uzbekistan (Pulawski, 2025).

Stizus eximius F. Morawitz, 1894 (Fig. 1)

Diagnosis: Body length 22–28 mm. General coloration reddish to yellowish; mesosoma and anterior abdominal segments reddish, with yellow markings on pronotum and scutellum. Wings hyaline. Female antennae 12-segmented, male antennae 13-segmented. Inner margins of eyes subparallel, without emargination. Abdomen sessile; first sternite entirely situated beneath the tergite. Fore wing with three cubital cells (Nemkov, 2009).

Material examined: 1♀, Republic of Karakalpakstan, Takhtakupyr District, vicinity of Lake Korateren [43.226152, 60.395658], 22.06.2023; 1♂, Jizzakh Region, vicinity of Lake Aydar [41.016939, 65.968675], 25.06.2023 (Fig. 2). The species was identified on Tamarix sp.

Distribution: Kazakhstan, Turkmenistan (Pulawski, 2025) and Uzbekistan (new record).

Fig. 1. Stizus eximius F. Morawitz, 1894, male from Uzbekistan. a) Habitus, lateral view; b) Head, frontal view; c) Habitus, dorsal view; [Photos by D. Musaev].

Remarks: In Uzbekistan, this species occurs exclusively in arid regions and is active during the summer months (June–July). Females excavate burrows 10–30 cm deep in the ground, where they lay eggs and provision the cells with paralyzed but still living prey for the developing larvae. Our observations indicate that the larvae feed on orthopteran insects such as locusts and grasshoppers (Orthoptera), as well as on representatives of the order Dermaptera (earwigs).

Stizus euchromus Handlirsch, 1892

Material examined: 1♀, Navoi Region, Kyzylkum Desert [41.677925, 64.318019], 24.06.2023; 1♂, Kashkadarya Region, Talimarjan District [38.394713, 65.476927], 19.04.2024; 1♂, Republic of Karakalpakstan, Kungrad District, Ustyurt Plateau [44.275504, 57.580816], 07.06.2024.

Distribution: Georgia, Iran, Turkmenistan, Uzbekistan (Pulawski, 2025).

Fig. 2. Collection habitats Stizus eximius F. Morawitz, 1894. Lake Aydar (a) and Lake Korateren (b), [photos by SH. Nazarov and M. Embergenov].

Stizus handlirschi Radoszkowski, 1893

Material examined: 6♀, 1♂, Republic of Karakalpakstan, Karauzyak District [43.047164, 60.047678], 08.08.2023; 2♀, Republic of Karakalpakstan, Karauzyak District [42.868567, 59.968772], 11.08.2023.

Distribution: Iran, Pakistan, Tajikistan, Turkey, Turkmenistan, Uzbekistan (Pulawski, 2025).

Stizus koenigi F. Morawitz, 1888

Material examined: 2♂, Republic of Karakalpakstan, vicinity of the Aral Sea [44.699282, 58.101533], 18.05.2022; 1♀, Shomanay District, desert zone [42.806675, 58.669285], 22.07.2022; 1♀, Republic of Karakalpakstan, Kyzylkum Desert [43.228551, 60.693162], 28.07.2022; 6♀, 7♂, Republic of Karakalpakstan, Kungrad District, Ustyurt Plateau [44.402748, 57.675034], 17.06.2023.

Distribution: Afghanistan, Iran, Kazakhstan, Libya, Tajikistan, Tunisia, Turkmenistan, Uzbekistan (Pulawski, 2025).

Stizus praestans F. Morawitz, 1893

Material examined: 1♀, Republic of Karakalpakstan, Kungrad District, Ustyurt Plateau [44.393150, 57.670481], 17.06.2023.

Distribution: Azerbaijan, Iran, Kazakhstan, Tajikistan, Uzbekistan (Pulawski, 2025).

Stizus ruficornis (J. Forster, 1771)

Material examined: 8♀, 4♂, Republic of Karakalpakstan, Nukus, Ashshikol vicinity [42.507814, 59.640686], 07.05.2021; 7♀, 6♂, Republic of Karakalpakstan, Chimbay District, desert zone [43.124719, 59.769114], 11.05.2021; 4♀, 5♂, Republic of Karakalpakstan, Turtkul District [41.981767, 61.193300], 02.06.2021; 9♀, 5♂, Republic of Karakalpakstan, Lower Amudarya State Biosphere Reserve, Tallik zone [41.936636, 60.469533], 12.07.2021; 19♀, 7♂, Republic of Karakalpakstan, Shumanay District, desert zone [42.816317, 58.659989], 22.07.2022; 1♀, Republic of Karakalpakstan, Turtkul District [41.939621, 61.167003], 29.08.2022; 3♀, Fergana Region, Yazyavan District [40.682028, 71.396960], 16.05.2023; 2♂, Khorezm Region, Yangiaryk District [41.317406, 60.448196], 30.05.2023; 11♀, Republic of Karakalpakstan, Kyzylkum Desert [43.274074, 60.543351], 31.05.2023; 8♂, Republic of Karakalpakstan, Kungrad District, Ustyurt Plateau [44.393150, 57.670481], 17.06.2023; 5♂, Navoi Region, Kyzylkum Desert [41.676928, 64.317959], 24.06.2023; 2♀, 4♂, Republic of Karakalpakstan, Karaozek District [43.033869, 60.039803]; 8♀, [43.047722, 60.047997], 08.08.2023; 1♂, Khorezm Region, Kyzylkum Desert [41.056866, 62.027392], 28.04.2024; 2♂, Samarkand Region, Jomboy District [39.462748, 66.379740], 07.05.2024; 9♀, 6♂, Republic of Karakalpakstan, Nukus, Ashshikol vicinity [42.507836, 59.640728], 15.05.2024.

Distribution: Algeria, Angola, Azerbaijan, China, Egypt, Ethiopia, France, Gambia, Ghana, Greece, Iran, Israel, Italy, Jordan, Kazakhstan, Libya, Madagascar, Malta, Morocco, Namibia, Nigeria, Oman, Palestine, Portugal, Romania, Russia, Saudi Arabia, Spain, Syria, Tajikistan, Tunisia, Turkey, Turkmenistan, UAE, Ukraine, Uzbekistan, West Africa, Yemen (Pulawski, 2025).

Stizus rufiventris Radoszkowski, 1877

Material examined: 2♀, 6♂, Republic of Karakalpakstan, Kungrad District, vicinity of the Aral Sea [44.721289, 58.046893], 18.05.2022; 4♂; Republic of Karakalpakstan, Nukus, vicinity of Lake Ashshikol [42.507418, 59.640398], 07.06.2022; 3♂, Jizzakh Region, Gallyaaral District [40.128447, 67.522141], 30.05.2023; 3♀, Republic of Karakalpakstan, Kyzylkum Desert [42.735786, 59.991375], 01.06.2023; 5♂, Republic of Karakalpakstan, Kungrad District, Ustyurt Plateau [44.393150, 57.670481], 17.06.2023; 2♀, 3♂, Navoi Region, Kyzylkum Desert [41.676529, 64.317872], 24.06.2023; 5♀, Republic of Karakalpakstan, Nukus [42.642756, 59.314453], 20.08.2023.

Distribution: Algeria, Azerbaijan, Egypt, Georgia, Iran, Kazakhstan, Mongolia, Russia, Tajikistan, Turkey, Turkmenistan, UAE, Ukraine, Uzbekistan (Pulawski, 2025).

Discussion

Specimen collection conducted in various regions of the Republic of Uzbekistan from 2021 to 2024 provides new insights into the genus Stizus. Two species, S. ruficornis and S. rufiventris, are the most widespread and frequently encountered across all surveyed areas. Additionally, S. eximius was recorded for the first time in Uzbekistan. This species was found in the northwestern and central parts of the country, particularly in habitats associated with Tamarix vegetation near lakes. The new records of species belonging to the genus Stizus (Hymenoptera: Bembicidae) significantly contribute to the understanding of the genus’s biodiversity in Uzbekistan. The data substantially expand the current knowledge of Stizus species in the region. Notably, S. eximius, previously known from Turkmenistan, and Kazakhstan, is now confirmed within Uzbekistan’s fauna. This finding underscores the insufficient and uneven study of Bembicidae diversity in the country and highlights the need for continued comprehensive faunistic surveys. The genus Stizus is represented in Uzbekistan by 17 species, indicating a relatively high diversity compared with neighboring Central Asian countries. Uzbekistan hosts the largest number of Stizus species (17), followed by Turkmenistan (15), while both Tajikistan and Kazakhstan have 12 species each, and only two species was found in Kyrgyzstan (Antropov et al., 2017; Pulawski, 2025)(Table 1).

Within Uzbekistan, the distribution of Stizus species shows a strong concentration in the western and northwestern regions, particularly Republic of Karakalpakstan, Khorezm and Navoi regions (Fig. 3). These areas include extensive sandy zones of the Kyzylkum Desert and deltaic zones near the Aral Sea, which represent typical habitats for the genus. Multiple species, including S. annulatus, S. ruficornis, S. koenigi, and S. rufiventris, were recorded sympatrically in these regions. Diversity decreases eastward, with only a few species such as S. eximius and S. handlirschi recorded from the foothill and mountain areas of Navoi Region. This gradient corresponds to changes in soil type and vegetation: Stizus species prefer loose, sandy substrates suitable for burrow construction, which are less common in elevated zones. In terms of abundance, S. ruficornis clearly dominates the wasp fauna of Uzbekistan, accounting for 61.26 % of all collected specimens (Table 2). This species exhibits broad ecological tolerance and occurs in all surveyed regions, confirming its adaptability to diverse desert environments. The second most frequent species, S. rufiventris (14.86 %), also shows wide distribution across arid and semi-arid landscapes. In contrast, S. praestans, S. bizonatus, and S. euchromus are rare and localized, representing less than 2% of the total material. Their limited occurrence may be related to microhabitat specificity, as indicated by the small number of records from neighboring countries, or to restricted sampling in certain ecological zones.

Comparative analysis across Central Asia reveals that ten species (S. annulatus, S. dispar, S. fasciatus, S. histrio, S. koenigi, S. ruficornis, S. rufiventris, S. praestans, S. handlirschi, and S. euchromus) are shared between Uzbekistan and Turkmenistan, indicating strong faunal affinity between these two countries. This similarity can be attributed to the comparable desert ecosystems and climatic conditions along their common border. Conversely, Kyrgyzstan hosts only two species (S. bipunctatus and S. perrisi), both of which are also widespread in Uzbekistan, suggesting that the Kyrgyzstan’s mountainous terrain is less favorable for Stizus species. From a zoogeographical perspective, the Stizus fauna of Uzbekistan is predominantly Turanian, closely linked with the desert complex of the Turan lowlands. The presence of widely distributed species such as S. ruficornis and S. rufiventris reflects stable populations adapted to continental arid conditions. Meanwhile, species shared with southern Kazakhstan and Tajikistan suggests faunal continuity along the desert-steppe and piedmont transitions of Central Asia. Overall, the western deserts of Uzbekistan represent a key center of diversity for the genus Stizus in Central Asia. The combination of climatic aridity, open sandy habitats, and xerophytic vegetation provides optimal ecological conditions for nesting and foraging activities. Further surveys in the less-studied eastern and southern regions of the country are expected to reveal additional species and clarify the biogeographical relationships of Stizus within the Central Asia. Ongoing research on invertebrate biodiversity in Uzbekistan, including the present study, will contribute valuable data to enhance national biodiversity management and support the protection of vulnerable arid-land ecosystems.

Fig. 3. Distribution of species of the genus Stizus in Uzbekistan