New and little-known bees of the genus Sphecodes Latreille, 1804 (Hymenoptera: Apoidea: Halictidae) from the Himalayas

Abstract. An annotated list of twenty species of rarely collected and little known bees of the genus Sphecodes Latreille, 1804 (Hymenoptera: Apoidea: Halictidae) from the Himalayas is given. Sphecodes bluethgeni sp. nov. is described from Bhutan. Three species are newly recorded from the Himalayas: S. binghami Blüthgen, 1924, S. kershawi Perkins, 1921 and S. laticeps Meyer, 1920. Based on type specimens, new synonymies have been proposed for Sphecodes cameronii (Bingham, 1897) = S. armeniacus Warncke, 1992 syn. nov.; S. gibbus (Linnaeus, 1758) = S. indicus Bingham, 1898 syn. nov.; and S. invidus (Cameron, 1897) = S. nigrobasalis Meyer, 1922 syn. nov. A lectotype is designated for Sphecodes sikkimensis Blüthgen, 1927. Illustrated keys to males and females of all species known from the Himalayas and an updated checklist of the 26 Himalayan species of Sphecodes are provided. Additionally, one new species from neighboring Uttar Pradesh (India), Sphecodes uttaricus sp. nov., is here described as new and included due to its close relationship to the Himalayan S. sikkimensis Blüthgen, 1927.


Introduction
The cleptoparasitic genus Sphecodes Latreille, 1804, numbering 70 species in the Palaearctic Region and 50 species in the Oriental Region, has long been one of the least studied groups in the family Halictidae Thomson, 1869. Previous reviews of some regional faunas (Central and Southeast Asia, Mongolia, China, Turkey, Iran, Caucasus, Near East, Central Europe, etc.) have significantly improved our knowledge of these bees, helping bridge the gaps in our knowledge of Sphecodes in these territories. The species composition of these faunas has been greatly clarified, twelve new species have been described, seventeen new synonymies have been proposed, and the taxonomical status of some species has been revised (Bogusch & Straka 2012;Astafurova & Proshchalykin 2014, 2015a, 2015b, 2015c, 2016a, 2016b, 2017a, 2017bAstafurova et al. 2015Astafurova et al. , 2018aAstafurova et al. , 2018bAstafurova et al. , 2018cAstafurova et al. , 2018dAstafurova et al. , 2019Astafurova et al. , 2020bÖzbek et al. 2015).
However, the territories located in the transitional zone between the Palaearctic and the Oriental regions remain insufficiently studied. The Himalayas are the perfect example of this situation. Geographically, the Himalayas are located in the Indian subcontinent. The countries and territories included are: India (Arunachal Pradesh, Himachal Pradesh, Jammu and Kashmir, Meghalaya, Mizoram, Nagaland, Sikkim, Tripura, Uttarakhand, Darjeeling district of West Bengal), Tajikistan (Gorno-Badakhshan Province), Afghanistan (Badakhshan Province), Bhutan, Nepal, China (Aksai Chin, Xizang), Myanmar (Kachin State), and Pakistan (Azad Jammu and Kashmir, Gilgit-Baltistan, Khyber Pakhtunkhwa) (Fig. 1). The bee fauna of the Himalayas is generally under-recorded and, given the enormous size and ecological diversity of the area, the discovery of large numbers of undescribed species including endemics is very likely. Thus, the goal of this paper is to improve our knowledge of the taxonomy and distribution of Himalayan Sphecodes bees as an essential foundation for more advanced biogeographical investigations.
The first information on the genus Sphecodes from the Himalayas was published by Smith (1853), who described S. fumipennis from "N. India". This species has since only been recorded from Sikkim (Blüthgen 1924(Blüthgen , 1927Saini & Rathor 2012;Rajkumar & Dey 2016). A total of nineteen species have been described since from the Himalayas (Blüthgen -6 species, Nurse -4 species, Smith -3 species, Cameron -2 species, , with fourteen of them still valid (see section on taxonomy for details). In total, twenty three species of Sphecodes have been recorded from the Himalayas so far (Table 1).
In the present paper, based on a comprehensive study of specimens (including types) deposited in various collections, we report additional records of 20 species from this area. Further, one species is described as new and three species are recorded from the Himalayas for the first time, resulting in a total number of 26 species of Sphecodes known from this region ( Table 1). The genus Sphecodes has not yet been documented from the Badakhshan Province of Afghanistan, Kachin State of Myanmar or Chinese Aksai Chin and Xizang, but it is probable that this cosmopolitan genus is present in these territories and it is only a matter of time before their faunas are sampled and recorded. A key to all species occurring in the Himalayas is also presented.

Etymology
This species is dedicated to famous German entomologist Paul Blüthgen (1880Blüthgen ( -1967, in recognition of his significant contributions to the study of bees and wasps.   Description Female (Fig. 6, holotype) MeasureMents. Total body length 7.0-7.5 mm; forewing length (without tegula) 5.8-6.0 mm.

Holotype
Head. Black (Fig. 7A); transverse, ca 1.25 times as wide as long; preoccipital carina absent; vertex weakly elevated, distance from top of head to upper margin of a lateral ocellus approximately a lateral ocellar diameter as seen in frontal view and ca 2.5 diameters as seen in dorsal view; mandible bi-dentate; labrum semi-oval, 0.5 times as long as basal width; F1 0.7 times as long as wide; F2 0.8-0.9 times as long as wide; F3 0.9-1.0 times as long as wide; gena wide, 1.1 times as wide as eye; supraclypeal area weakly bulging; clypeus with punctures separated by at most a half puncture diameter; frons, paraocular and supraclypeal areas with confluent punctures (20-25 μm); ocello-ocular area with punctures separated by 0.5-2 puncture diameters (Fig. 7A), vertex behind ocelli shiny with sparse punctures; gena shiny, with dense setal pores; face (below antennal sockets) and gena with sparse and thin setae.

Male
Unknown.

Diagnosis
The male of this species is similar to S. invidus owing to a similar shape of antennal tyloids (well developed, covering entire lateral flagellar surface and a part of ventral one), sculpture and coloration of the body, including hyaline wings, the areolate mesoscutum, the densely punctate T1 on the disc and the marginal zone. The species clearly differs from S. invidus by the weaker elevated vertex as seen in frontal view, with distance from top of head to upper margin of lateral ocellus ca 1.5 lateral ocellar diameter (vs 2 in S. invidus) and the finer punctate metasoma (10-20 μm vs 15-25 μm).

Descriptive notes
Wings hyaline, without darkening; hind wing with the angle between basal (M) and cubital (Cu) veins ca 80°, costal margin with seven hamuli. Lateral preoccipital carina present.

Female
Unknown.

Descriptive notes
Wings hyaline, with weak yellowish darkening; hind wing with the angle between basal (M) and cubital (Cu) veins ca 80°, costal margin with eight or nine hamuli. Lateral preoccipital carina present.

Female
Unknown.

Diagnosis
This species is close to the S. simlaensis owing to a similar structure, sculpture of the body and the fact that the females morphologically are difficult to distinguish, but S. iridipennis has a slightly less transverse head (1.1 times as wide as long vs 1.2) and entirely red legs (at least femora black or brownish in S. simlaensis).

Descriptive notes
Wings with weak yellowish or brownish darkening; hind wing with basal vein strongly curved with the angle between basal (M) and cubital (Cu) veins ca 90°, costal margin with five hamuli. Preoccipital carina absent.

Male
Unknown.

Remarks
Since we could not clearly differentiate between females of S. iridipennis and S. simlaensis, except by their relative head length and coloration, more specimens should be studied (including the male finding) to make a decision on their synonymy.
The specimens recorded as S. iridipennis from Chapra (India) by Rajkumar & Dey (2016: 1847 3) belong to another species. Unlike the holotype this specimen, re-described as S. iridipennis, has more transverse head (1.3 times as wide as long) and possibly belongs to the undescribed female of S. chaprensis Blüthgen, 1927. Perkins, 1921 Figs 2G, 5D

Diagnosis
The female is closest to that of S. gibbus by the shape of the head and sculpture of the body, but differs from this species by the less elevated vertex with distance from top of head to upper margin of lateral ocellus approximately two lateral ocellar diameters as seen in frontal view (vs ca 3), the sparser punctate metasoma with almost impunctate marginal zones on T1 and T2 (distinctly punctate in S. gibbus) and on average smaller body length 7.5-10 mm (vs 7-15 mm). We have not studied the male, but according to the description of Blüthgen (1927) it is similar to that of the Palaearctic S. alternatus Smith, 1853 and S. reticulatus Thomson, 1870 owing to similar sculpture, shapes of antennal tyloid area and gonostylus (tyloids of S. lasimensis are more developed and semicircular across basal 1/5-⅓ of ventral flagellar surface vs 1/7-1/5 in S. alternatus and S. reticulatus).

Descriptive notes
Wings with brownish darkening; hind wing with the angle between basal (M) and cubital (Cu) veins ca 70°, costal margin with eight, nine or ten hamuli.
Male (according to Blüthgen 1927) Head weakly transverse, ca 1.15 times as wide as long; vertex elevated with distance from top of head to upper margin of lateral ocellus approximately two lateral ocellar diameters as seen in frontal view. Tyloids (from F4 onward) weakly developed, semicircular across basal 1/5-⅓ of ventral surface of flagellomeres.

Diagnosis
The female of this species is similar to that of S. tantalus Nurse, 1903 owing to a similar structure, sculpture and coloration of the body, but it differs from this species by having a more densely punctate  mesoscutum, with the punctures separated by 1-2 puncture diameters (vs 2-5), and the pygidial plate as wide as the metabasitarsus (vs 0.8). Both these species are close to S. crassus Thomson, 1870 by the strongly enlarged metafemur, but it differs by the entirely red metasoma.

Descriptive notes
Wings hyaline, without darkening; hind wing with the angle between basal (M) and cubital (Cu) veins ca 80°, costal margin with five hamuli.

Female
Total body length 6.5 mm (Fig. 14). Head (Fig. 15A) strongly transverse, ca 1.3 times as wide as long; vertex weakly elevated as seen in frontal view (distance from top of head to upper margin of lateral ocellus at most a lateral ocellar diameter), but wide as seen in dorsal view (approximately three ocellar diameters); F1 and F2 strongly transverse, ca 0.6 times as long as wide, F3 weakly transverse, 0.8 times as long as wide; labrum semi-oval, 0.6 times as long as wide; clypeus and ocello-ocular area with dense punctures separated by 0.5-1 puncture diameter; paraocular and supracypeal areas with dense plumose pubescence, but not obscuring integument. Mesoscutum (Fig. 15C-D) with sparse punctures (20-25 μm) separated by one or two puncture diameters; hypoepimeral area reticulate; metafemur strongly enlarged in proximal half, maximum width 0.5 times its length; tibia and tarsi red-yellowish. Metasomal T1 impunctate (Fig. 15B), T2 on an anterior half with fine and relatively dense punctures; marginal zones impunctate; pygidial plate as wide as metabasitarsus; T1-T5 red.

Male
Unknown.

Descriptive notes
Wings hyaline, without darkening; hind wing with basal vein strongly curved with the angle between basal (M) and cubital (Cu) veins almost 90°, costal margin with five hamuli.

Male
Unknown.

Remarks
Since we could not clearly differentiate between females of S. setiger and S. puncticeps, except by relative flagellar length, more specimens from the type locality including the male are needed to be studied to make a decision on their synonymy. Blüthgen, 1927 Fig

Diagnosis
This species is similar to S. chaprensis and S. simlaensis, sharing similar shape and sculpture of the body, including weakly developed antennal tyloids, a densely punctate mesoscutum and scarcely punctate metasomal terga, but differs from these species by having longer antennae with flagellomeres (from F3 onward) ca 1.3 times as long as wide (vs 1.1-1.2) and the shape of the gonostylus without a membranous part.

Descriptive notes
Wings hyaline; hind wing with the angle between basal (M) and cubital (Cu) veins almost 90°, costal margin with five hamuli. Preoccipital carina absent.

Female
Unknown.

Diagnosis
The female of this species is similar to that of S. perplexus (refer to Diagnosis of S. perplexus above).

Female
Total body length 8 mm (Fig. 19). Head strongly transverse, ca 1.3 times as wide as long (Fig. 20A); vertex weakly elevated as seen in frontal view (distance from top of head to upper margin of lateral ocellus at most a lateral ocellar diameter), but wide as seen in dorsal view (approximately three ocellar diameters); F1 and F2 strongly transverse, 0.6-0.7 times as long as wide, F3 almost square; labrum semi-oval, 0.6 times as long as wide; clypeus and ocello-ocular area with dense punctures separated by at most a half puncture diameter; paraocular and supracypeal areas with relatively dense, but thin plumose pubescence, not obscuring integument. Mesoscutum with sparse punctures (20-25 μm) separated by 2-5 puncture diameters (Fig. 20C); hypoepimeral area reticulate; metafemur strongly enlarged in proximal half, maximum width 0.4 times its length; legs red. Metasomal T1 impunctate, T2-T4 with a few fine setal pores, marginal zones impunctate; pygidial plate dull, 0.8 times as wide as metabasitarsus; T1-T5 red (Fig. 20B).

Male
Unknown.

Diagnosis
This species is closest to S. sikkimensis and S. formosanus Cockerell, 1911 by a combination of large body size (more than 9 mm), costal margin with at least nine hamuli and the presence of a lateral preocipital carina. The new species differs from S. sikkimensis by having fewer hamuli (9-10 vs 12-15) and a smaller body size (10.5 mm vs 12-15 mm) and from S. formosanus it differs by having sparse and mixed punctation of T1 with coarse (15-25 μm / 0.5-3) and microscopical punctures (5 μm) (vs dense and coarse punctures separated by 0.5-1 puncture diameter).

Etymology
The specific epithet is named after the Indian state Uttar Pradesh, the type locality of this species. Head ( Fig. 22B-C). Black; transverse, ca 1.25 times as wide as long; lateral preoccipital carina present, well-developed; vertex elevated, distance from top of head to upper margin of lateral ocellus ca 1.5 ocellar diameter as seen in frontal view and ca two diameters as seen in dorsal view; mandibles bi-dentate; F1 0.5 times as long as wide; F2 0.7 times as long as wide; F3 1.1 times as long as wide; supraclypeal area bulging; frons and paraocular area mostly with confluent punctures; ocello-ocular area densely punctate with confluent punctures and punctures separated by at most a half puncture diameter (30-50 μm); clypeus sparser punctate with shiny, smooth interspaces equal to at most a puncture diameter; paraocular area and gena with dense plumose setae, obscuring integument.

Male
Unknown.

Distribution
Only known from the holotype.

Discussion
In total, 26 species of Sphecodes are now recorded from the Himalayas (Table 1), and 16 of these are distributed beyond the studied region. The Himalayan mountain system is traditionally considered to be the boundary between the Palaearctic and the Oriental regions. This feature is reflected in the mixed composition of the fauna of the genus in this region: the Sphecodes fauna of the Himalayas includes eight Palaearctic, eight Oriental and ten endemic species.
The Himalayan fauna of Sphecodes has a high degree of endemicity (38%), but this phenomenon may be in part due to an incomplete knowledge of the distribution of the Sphecodes fauna. Illustrating this, one half of these endemic species (S. almoransis, S. dissimilandus, S. setiger, S. shillongensis, S. perplexus) are known only from their type localities.
The majority of the Palaearctic Himalayan Sphecodes assemblage is composed of widespread Trans-Palaearctic or Eurasian species. Only the range of S. hakkariensis is otherwise small, limited to mountainous areas of Turkey and Tajikistan. Interestingly, Sphecodes cameronii is an inter-realm species, distributed from Turkey and Central Asia to India (Pali) and Sri Lanka. All Palaearctic Himalayan species occur in the western to central parts of the Himalayas; moreover, three of them (S. alternatus, S. intermedius, S. hakkariensis) in the studied territory are known from Tajikistan (Gorno-Badakhshan Province) only.
The Oriental Himalayan species of Sphecodes are distributed from the Himalayas to Southeast Asia and China, where they are mainly distributed in mountainous areas. In the Himalayas, these species occur in the central and eastern parts. The ranges of Sphecodes kershawi and S. binghami, which are distributed all the way to Malaysia, are the most widespread among Oriental species occurring in the Himalayas.