﻿The genus Epeolus Latreille, 1802 (Hymenoptera, Apidae) in Central Asia

﻿Abstract Available information about bees of the genus Epeolus in Central Asia is summarized. Twenty species are currently known from this area. Two new species are described: E.albus Astafurova & Proshchalykin, sp. nov. and E.pesenkoi Astafurova, sp. nov. Two species are newly recorded from Central Asia: E.asiaticus Astafurova & Proshchalykin, 2022 and E.nudiventris Bischoff, 1930. The hitherto unknown male of E.mikhailovi Astafurova & Proshchalykin, 2021 is described, and lectotypes are designated for E.ruficornis Morawitz, 1875 and E.vinogradovi Popov, 1952.


Introduction
Central Asia as understood here covers the territories of Kazakhstan, Uzbekistan, Kyrgyzstan, Turkmenistan, and Tajikistan and has an area of about 4 million square kilometres, roughly half the size of Europe (Fig. 1).It comprises the arid to semi-arid regions of the Turanian Basin at its centre and the mountain ranges of the Tien Shan and Pamir in the east.Climatically and orographically the region is highly diverse, ranging from the lowland deserts of the Caspian Depression to the 7,495 m high Ismoil Somoni Peak in the Pamir.Aside from the Mediterranean Basin, Central Asia is the most important centre of bee diversity in the Palaearctic Region (Michener 1979).However, the bee fauna of Central Asia is underrecorded and, given the enormous size and ecological diversity of the area, the discovery of large numbers of undescribed species, including endemics, is highly likely (Kuhlmann and Proshchalykin 2013;Astafurova and Proshchalykin 2017;Dathe and Proshchalykin 2018;Astafurova et al. 2018;Wood 2023).Popov (1967) recorded about 1,200 bee species in 70 genera from this region and Ascher and Pickering (2023) list 1,360 species for this region, but the true number almost certainly is much higher.
The genus Epeolus Latreille, 1802 includes more 120 species spread across much of the globe; they occur throughout the Holarctic region, from the west coast of the United States and from Japan to Europe and North Africa (Michener 2007).A total of 59 species are known from the Americas (Onuferko 2018(Onuferko , 2019;;Onuferko and Sheffield 2022) and about 50 from the Palaearctic region, of which 18 species are found in Europe (Bogusch and Hadrava 2018;Bogusch 2018Bogusch , 2021;;Astafurova and Proshchalykin 2021a, 2021b, 2021c, 2022a, 2022b).Unlike other Epeolini, all Epeolus species are so far known to be cleptoparasites of species of Colletes Latreille, 1802 (Colletidae).
Epeolus transitorius was the first species of the genus described from Central Asia (Eversmann 1852), and eight species have been described since from this area (Astafurova and Proshchalykin -four species; Morawitz -one species; Eversmann -one species; Radoszkowski -one species; Popov -one species), all of them still valid.Sixteen Epeolus species have been recorded from Central Asia so far (Astafurova and Proshchalykin 2021a, 2021c, 2022a, 2022b;Ascher and Pickering 2023).Based on a comprehensive study of specimens in various collections, we list here 20 species of Epeolus (Table 1) and describe as new two species from Central Asia for the first time.
A key to Central Asian Epeolus has not been included in this paper; it is forthcoming in a subsequent publication uniting this and the entire Palaearctic fauna due to their extensive sharing of species and the need for some additional work in these regions.

Materials and methods
The results presented in this paper are based on 354 Epeolus specimens currently housed in the Zoological Institute, Russian Academy of Sciences (St. Petersburg, Russia, ZISP); Zoological Museum of the Moscow State University (Moscow, Russia, ZMMU); Federal Scientific Center of the East Asia Terrestrial Biodiversity, Far Eastern Branch of Russian Academy of Sciences (Vladivostok, Russia, FSCV); and Oberösterreichisches Landesmuseum, Biologiezentrum (Linz, Austria, OLBL).
Abbreviations T and S are used for metasomal tergum and metasomal sternum, respectively.
Specimens were studied with an Olympus SZ51 stereomicroscope, and photographs were taken with a combination of stereomicroscope (Olympus SZX10) and digital camera (Olympus OM-D).Final images are stacked composites generated using Helicon Focus v. 7.7.4Pro.All images were post-processed for contrast and brightness using Adobe Photoshop.New distributional records are noted with an asterisk (*).Morawitz, 1875, E. subrufescens Saunders, 1908, and E. warnckei Bogusch, 2018 in sharing the axillae with a pair of long, acute, curved teeth (free portion of axilla), reaching posterior margin of mesoscutellum or longer.Of them, the new species is most similar to E. subrufescens (Northern Africa, Middle East, and Turkey), with which it shares a pair of well-developed posteriorly directed processes (tubercles) between medial depression of the mesoscutellum (Fig. 2H) and has a male pygidial plate that is slightly bilobed apically (Fig. 2F) [vs weak developed mesoscutellar tubercles (Fig. 7D) and male pygidial plate rounded in E. flavociliatus, E. warnckei, and E. ruficornis)], but it can be separated from it by the well-developed pale pubescence of the metasomal terga that covers both the marginal zones (apical impressed area) and visible part of the discs (vs developed only as apical bands in E. subrufescens).In addition, E. albus has the labral teeth positioned more apically, while in E. subrufescens the labral teeth are positioned submedially.
In E. vinogradovi axillar teeth are more elongate and strongly curved; the mesoscutellum is with a pair of long, truncate teeth (Fig. 8D).
Pubescence: body with well-developed, snow-white tomentum of thick, plumose setae covering mostly of integument (Fig. 2A-C).Labrum almost glabrous, with few simple setae.Face and gena with dense tomentum of long, appressed setae obscuring underlying integument; vertex with sparser, short semi-erect setae.Mesosoma with dense, short, semi-erect setae obscured integument but little sparser than on mesoscutellum and axillae.Hind basitarsus bordered by a dense fringe of yellow long setae.Metasomal terga covered by white tomentum both on marginal zones and most of the visible part of discs (a little sparser on discs).S1-S3 with dense, white tomentum, especially on marginal zones of S2 and S3 (apical bands); S4 and S5 with long, golden setae.
Female.Structure, sculpture, and pubescence are similar to those of male (Fig. 3A-C).Antennae short, F1 1.25 times as long as wide; remaining flagellomeres slightly longer than wide.Sterna entirely covered by tomentum.Pseudopygidial area short, linear.Pygidial plate trapezoidal, apically truncate.Processes on sides of S6 normal, with short projections.S5 straight, as seen in lateral view.Integument coloration: reddish pattern of integument more developed than in male.Head mostly black, but mandibles (excluding dark apex), labrum, and clypeus yellowish; antennae reddish.Mesosoma black, except pronotal lobe, tegulae, axilla, mesoscutellum, and legs (with pale spurs) yellow to reddish; wings slightly infuscate, stigma light brown, veins from yellow to brown.Metasomal terga and sterna reddish with yellow marginal zones on S2-S4.Pygidial plate reddish.
Etymology.The specific name "albus" (from Latin, meaning white) is associated with the extremely well-developed white pubescence of the body in the new species.
Distribution.Desert areas in Kazakhstan, Uzbekistan, and Turkmenistan.
Distribution.Mountains of *Uzbekistan, Kyrgyzstan, and Tajikistan.Diagnosis.This species belongs to the E. variegatus species group [E. compar Alfken, 1938, E. eriwanensis Bischoff, 1930, E. intermedius Pérez, 1884, E. turcicus Bogusch, 2018, E. productulus Bischoff, 1930, E. productuloides Bogusch, 2018, and E. variegatus (Linnaeus, 1758)] in sharing the presence of labral tubercles positioned close to the middle of labrum (as opposed to apically or subapically) and the curved (as opposed to straight) S5 of the female.From other species of the group, the new species can be distinguished by the uninterrupted albeit medially narrowed apical bands of the metasomal terga and usually bright yellow tomentum on the body of the female.
Pubescence: pale tomentum mostly golden-yellow (Fig. 5A, E).Labrum with long simple setae near median teeth.Paraocular and supraclypeal areas with dense tomentum obscuring integument, clypeus with sparse pubescence.Upper half of frons with relatively long erect simple setae mixed with sparse appressed plumose setae.Vertex with sparse short and plumose setae.Gena with thick plumose setae on upper half (almost obscured integument) and with thin setae below.Pronotum dorsally with tomentum obscuring integument.Mesoscutum with paramedian strips of tomentum connected with lateral spots along pronotal lobe, pair small spots of tomentum posterolaterally and narrow strip along posterior margin (Fig. 5A).Mesepisternum with dense tomentum obscuring underlying integument on upper half, otherwise glabrous or with sparse setae.T1 with wide basal band of tomentum interrupted medially and connected with apical band laterally; marginal zones on T1-T4 with uninterrupted bands of tomentum.Setae on tergal discs dark brown; sparser than those comprising apical bands.Pseudopygidial area with silvery pubescence.Sterna with weak pubescence; S2 with simple short setae, S3-S5 with plumose short setae; marginal zones of T3-T4 with white tomentum laterally.
Variability.Female.Total body length 5.5-7.5 mm.Coloration of clypeus varies from entirely amber to dark brown/black along upper margin.The supraclypeal area is sometimes reddish on lower frontal keel.The metasomal terga are usually black (except amber on posterior half of T5) but may be reddish or brownish laterally along the marginal zones and on the posterior part of T1.The pubescence of the mesoscutum is usually as described in the holotype but sometimes has dense tomentum obscuring much of the anterior part instead of the usual distinct paramedian strips.Two specimens from the type locality have narrowly interrupted apical bands of tomentum.Male.Total body length 5.0-7.0 mm.The labrum varies from black to reddish.The basal band of tomentum on T1 is usually uninterrupted and is often almost merged with the apical band (except a small central area), rarely interrupted medially.Coloration of pale tomentum is usually less bright than in the female, from yellow to whitish.
Etymology.The specific epithet is dedicated to Yuri Andreevich Pesenko , a renowned melittologist and, during his lifetime, one of the leading experts on the systematics of halictid bees.
Distribution.Mountains of Kazakhstan, Uzbekistan, and Kyrgyzstan.

Figure 1 .
Figure 1.Map of Central Asia.

Table 1 .
Records of Central Asian Epeolus species by countries.