Halictidae Thomson, 1869 is one of the largest families in the order Hymenoptera, with approximately 4,400 species worldwide and includes four subfamilies: Halictinae, Rophitinae, Nomiinae, and Nomioidinae (Ascher and Pickering, 2024). The genus Lasioglossum Curtis, 1833, belonging to the subfamily Halictinae, is cosmopolitan bee group comprise with about 1,800 species worldwidely (Gibbs et al., 2012). Michener (2007) divided the genus Lasioglossum into 17 subgenera. Currently, status of subgenera has changed by several phylogenetic studies (Danforth and Ji, 2001, Gibbs et al., 2013), and Ascher and Pickering (2024) summarized the current researches and revised 31 subgenera worldwide. On the Korean Peninsula, six subgenera (Acanthalictus, Dialictus, Hemihalictus, Lasioglossum, Leuchalictus, and Sphecodogastra) of the genus Lasioglossum have been recorded (Murao et al., 2015;Murao, 2017, 2021).
In this study, we recognized new records of two subgenera of Lasioglossum with two species: Lasioglossum (Ctenonomia) kumejimense (Matsumura and Uchida, 1926) and Lasioglossum (Pyghalictus) politum pekingenseBlüthgen, 1925 from South Korea. We present diagnosis, description, and photographs for diagnostic characters of newly recorded species. Also, the key to subgenera of Lasioglossum from South Korea is provided.
Materials and Methods
All samples for this study were collected by sweeping in South Korea from 2020 to 2023. Collected samples were made into dried specimens for exact identification. Observation and photographs for each species were taken by a DMC 5400 digital camera attached to a Leica Z16 APO motorized macroscope. Morphological characters were taken by Leica Application Suite X (LAS X). Images were retouched using Adobe Photoshop CS6. All examined specimens used in this study are deposited in the insect collection of the College for Agriculture and Life Sciences, Seoul National University (CALS, SNU, Seoul, Korea). Terminology used for morphological characters follows Michener (2007) and Gardner and Gibbs (2023). Morphological abbreviations used in this paper as follows: T1-Tn, metasomal terga segment 1-n; IS, the length of interspaces between punctures; PD, puncture diameters.
Systematic Accounts
Family Halictidae Thomson, 1869
Subfamily Halictinae Thomson, 1869
Genus Lasioglossum Curtis, 1833
Subgenus CtenonomiaCameron, 1903
CtenonomiaCameron, 1903: 178. (Type species: Ctenonomia carinataCameron, 1903, monobasic)
Halictus (Nesohalictus) Crawford, 1910: 120. (Type species: Halictus robbiiCrawford, 1910 = Nomia halictoides Smith, 1858, by original designation)
Halictus (Oxyhalictus) Cockerell and Ireland, 1935, in Cockerell, 1935: 91. (Type species: Halictus acuiferus Cockerell and Ireland, 1935, monobasic)
Lasioglossum (Labrohalictus) Pauly, 1981: 719. (Type species: Lasioglossum saegeriPauly, 1981, monobasic)
Lasioglossum (Ctenonomia) kumejimense (Matsumura and Uchida, 1926) 유명산줄꼬마꽃벌(신칭) (Figs. 1A-H)
Halictus kumejimensisMatsumura and Uchida, 1926: 68.
Halictus yaeyamensisMatsumura and Uchida, 1926: 68.
Lasioglossum (Ctenonomia) kumejimenseSakagami, 1989: 509.
Lasioglossum (Ctenonomia) vagans kumejimenseEbmer, 1998a: 377.
Lasioglossum (Evylaeus) miyanoiTadauchi, 1994: 216.
Diagnosis: Female of Lasioglossum kumejimense can be recognized by hair tuft on basolateral area of T1 and pectinate metatibial spur from other species of the Lasioglossum series from Korean peninsula. This species is similar to L. (C.) vagans, which distributed from Africa to Southeastern Asia; however, it can be easily distinguished by the weak or absent reticulation on the posterior surface of the mesoscutum.
Redescription
Female.
Body: Body length 5.22 mm; body width 2.00 mm; Forewing length 3.69 mm.
Coloration: Head and mesosoma black (Fig. 1A); clypeus black, labrum black, mandible black base to median, brown apex; flagellum black dorsally, brown ventrally; Pronotal lobe black; legs dark brown; metatibial spur yellow, tegula black to brown, semi-transparent; wing membrane hyaline, veins brown; Metasoma entirely black, posterior margin brown, semi-transparent.
Pubescence: Body hair color white to pale yellow. Tomentum dense on basolateral area of T1, basal area of T2~T4, pronotal collar and lobe. Mesoscutum with straight hairs. Metasomal terga with no fringes on latero-apical margin (Fig. 1F). Disc of T1 with moderately dense short hairs. Disc of T2~T4 with moderately dense short simple hairs over entire surface.
Surface sculpture: Clypeus shiny to weakly imbricate at base, with punctures dense in basal (Interspace between punctures (IS) ≤ 1 Puncture diameter (PD)), irregularly sparser in apical (IS ≤ 3 PD); supraclypeal area shiny to weakly imbricate, with punctures moderately dense (IS 1 - 2 PD); paraocular area shiny, with punctures dense (IS ≤ 1 PD); frons tessellate, with punctures crowded (IS = 0 PD); vertex shiny, with punctures moderately sparse in lateral (IS 2 - 4 PD), punctures moderately dense in medial (IS ≤ 2 PD); genal area shiny, with punctures moderately sparse (IS 2 - 4 PD); postgenal area linate with straight ridges, without punctures; tegula imbricate basally, shiny apically, punctures absent; mesoscutum anteriorly and medially tessellate, posteriorly weaker or shiny, with punctures moderately dense (IS 1 - 1.5 PD), denser (IS ≤ 1 PD) marginally (Fig. 1B); scutellum shiny, with punctures moderately sparse (IS 2 - 5 PD) submedially, denser marginally and on median line (IS ≤ 1 PD); metapostnotum shiny, with irregularly longitudinal carina subparallelly, reaching posterior margin (Fig. 1C); preepisternum, hypoepimeron and mesepisternum shiny, with no distinct punctures and rugose entirely (Fig. 1E); metepisternum ruguloso-lineate; propodeum lateral surface tessellate; posterior surface shiny to weakly tessellate; T1 entirely shiny, apical rim coriarious, with punctures moderately dense (IS 1 - 3 PD) medially, sparser (IS 4 - 9 PD) basally and on subapicolateral boss, absent on apical rim (Fig. 1D); T2 basally shiny, apically coriarious, with punctures moderately dense (IS ≤ 2 PD) basal to medially, absent on apical rim; T3 similar to T2.
Structure: Head length/width ratio 0.92 (± 0.00 SD) (Fig. 1G); vertex slightly rounded in frontal view; upper interorbital distance/maximum interorbital distance ratio 0.89 (± 0.00 SD), lower interorbital distance/maximum interorbital distance ratio 0.75 (± 0.00 SD); ocelloccipital distance/interocellar distance ratio 0.73 (± 0.00 SD), ocellocular distance / interocellar distance ratio 0.75 (± 0.00 SD); antennocular distance / interantennal distance ratio 1.36 (±0 .00 SD); supraclypeal area slightly convex, length/width ratio 0.62 (± 0.00 SD); clypeus nearly flat, length/width ratio 0.43 (± 0.00 SD); apicolateral denticles rounded obtuse points; clypeus length/supraclypeal area length ratio 1.40 (± 0.00 SD); compound eye width/gena width ratio 1.05 (± 0.00 SD); malar space linear; forewing with 3 submarginal cells; pronotal angle obtuse; tegula shape oval; mesoscutum length/width ratio 0.67 (± 0.00 SD); mesoscutum/scutellum length ratio 2.51 (± 0.00 SD); scutellum/metanotum length ratio 2.30 (± 0.00 SD); metanotum/metapostnotum length ratio 0.86 (± 0.00 SD). Propodeum lateral carina distinct and reaching to dorsal margin; oblique carina distinct, transverse carina distinct only on posterior margin fused with oblique carina and lateral carina. Basitibial plate of hind leg carinate marginally. Metatibial spur with 3 - 4 narrow teeth with round tip (Fig. 1H). T2 depressed apical rim length less than 50% of segment. (n=1).
Material examined. 1♀, Mt. Yumyeong, Yumyeongsan-gil, Seorak-myeon, Gapyeong-gun, Gyeonggi-do, Republic of Korea, on Yellow Pan Trap, 3.viii.2023, Seung-Hun Jung (SNU).
Distribution. South Korea (Gyeonggi-do - New record), Japan (Kagoshima Pref. of Kyushu, Ryukyu), Taiwan, Mariana Islands (Murao et al., 2009).
Floral host. Amaranthaceae: Celosia argentea; Apiaceae: Torilis japonica; Asteraceae: Aster sp., Bidens pilosa var. pilosa, B. pilosa var. minor, B. tripartite, Ixeris japonica, Ix. Stolonifera, Prenanthes tanakae, Youngia japonica, Ixeridium dentatum, Sonchus oleraceus, Wedelia prostrata var. robusta; Boraginaceae: Mertensia maritima subsp. asiatica; Heliotropium foertherianum; Brassicaceae: Brassica rapa var. oleifera; Commelinaceae: Tradescantia ohiensis; Euphorbiaceae: Mallotus japonicus; Fabaceae: Melilotus officinalis subsp. suaveolens, Trifolium repens; Lamiaceae: Clinopodium chinense subsp. grandiflorum var. urticifolium; Oxalidaceae: Oxalis corniculata; Rosaceae: Rubus sp., R. parvifolius, Rhaphiolepis indica var. umbellate, Rosa multiflora, Duchesnea chrysantha; Rubiaceae: Paederia scandens; Rutaceae: Murraya paniculate; Solanaceae: Solanum nigrum; Verbenaceae: Vitex rotundifolia (Murao et al., 2009).
Subgenus PyghalictusWarncke, 1975
Pyghalictus Warancke, 1975: 103. (Type species: Halictus politusSchenck, 1853, by designation of Pesenko (2007)).
Lasioglossum (Pyghalictus) politum pekingenseBlüthgen, 1925 작은고동배꼬마꽃벌(신칭) (Figs. 2A - H)
Halictus pekingensisBlüthgen, 1925: 115.
Lasioglossum (Evylaeus) politum pekingense: Ebmer, 1988b: 667; Murao and Tadauchi, 2011: 55.
Diagnosis: Female of Lasioglossum politum pekingense can be easily distinguished by its clearly tessellated mesoscutum from other subspecies, such as politum (Schenck, 1853) and atomarium (Morawitz, 1876), which have a polished or shiny mesoscutum (Blüthgen, 1925;Schenck, 1853) and recognized by small body-size and short-headed from other species of the genus Lasioglossum from Korean peninsula. This species has color variation of metasoma. Female metasoma presents black, reddish brown and intermediate type in japan. (Murao and Tadauchi, 2011).
Redescription
Female.
Body: Body length 3.5~4.0 mm; body width 1.1~1.2 mm; Forewing length 2.8~3.0 mm.
Coloration: Head and mesosoma black (Fig. 2A); clypeus black entirely, dark brown apically, labrum yellowish-brown, mandible yellowish-brown with brown base and apex; flagellum black dorsally, yellowish-brown ventrally; Pronotal lobe yellowish-brown; legs yellowish-brown entirely, coxa to femur dark brown, metatibial spur yellowish-brown; tegula yellowish-brown and transparent; wing membrane hyaline, veins yellowish-brown. Metasoma yellowish-brown entirely, darker basally.
Pubescence: Body hair color white to pale yellow. Tomentum dense on metanotum, Tomentum sparse on pronotal collar and lobe. Mesoscutum with straight hairs. Metasomal terga with no fringes on latero-apical margin (Fig. 2F). Disc of T1 without short hairs on medial area. Discs of T2~T4 with moderately dense short hairs over entire surface.
Surface sculpture: Clypeus shiny, with punctures moderately dense in basal (IS 1 - 2 PD), irregularly sparser in apical (IS < 4 PD); supraclypeal area shiny to weakly imbricate, with punctures sparse (IS < 2 PD); paraocular area shiny, with punctures moderately dense (IS ≤ 2 PD); frons tessellate, with punctures crowded (IS = 0 PD); vertex imbricate to weakly shiny, with punctures moderately dense in lateral (IS ≤ 2 PD), indistinct punctures moderately dense in medial and hind area of ocelli (IS ≤ 2 PD); genal area shiny, with punctures moderately dense (IS ≤ 2 PD); postgenal area linate with straight ridges, without punctures; tegula imbricate basally, shiny apically, punctures absent; mesoscutum tessellate, with punctures moderately sparse (IS 2 - 3 PD), denser (IS ≤ 1 PD) marginally (Fig. 2B); scutellum tessellate, with punctures moderately sparse (IS 2 - 3 PD) submedially, denser marginally and on median line (IS ≤ 2 PD); metapostnotum tessellate, with longitudinal carina subparallelly in basal half, not reaching posterior margin (Fig. 2C); preepisternum, hypoepimeron and mesepisternum tessellate, with no distinct punctures (Fig. 2E); metepisternum ruguloso-lineate dorsally, tessellate ventrally; propodeum lateral surface tessellate; posterior surface tessellate; T1 shiny, with punctures minute and sparse (IS > 4 PD), and irregularly distributed medially, absent on basal area and apical rim (Fig. 2D); T2 basally coriarious, disc and apical rim shiny, with punctures moderately sparse (IS = 2 - 4 PD) basal to medially, absent apically; T3 coriarious, with punctures moderately sparse (IS = 2 - 6 PD) and obscure.
Structure: Head length/width ratio 0.89 (± 0.01 SD) (Fig. 2G); vertex slightly rounded in frontal view; upper interorbital distance/maximum interorbital distance ratio 0.89 (± 0.02 SD), lower interorbital distance/maximum interorbital distance ratio 0.81 (± 0.01 SD); ocelloccipital distance/interocellar distance ratio 0.61 (± 0.01 SD), ocellocular distance / interocellar distance ratio 0.94 (± 0.01 SD); antennocular distance / interantennal distance ratio 2.10 (±0 .04 SD); supraclypeal area nearly flat, length/width ratio 0.54 (± 0.03 SD); clypeus nearly flat, length/ width ratio 0.36 (± 0.02 SD); apicolateral denticles flat; clypeus length/supraclypeal area length ratio 1.81 (± 0.09 SD); compound eye width/gena width ratio 0.92 (± 0.02 SD); malar space linear; forewing with 3 submarginal cells; pronotal angle nearly acute; tegula shape oval; mesoscutum length/width ratio 0.76 (± 0.04 SD); mesoscutum/scutellum length ratio 2.86 (± 0.05 SD); scutellum/metanotum length ratio 2.08 (± 0.07 SD); metanotum/metapostnotum length ratio 0.73 (± 0.04 SD). Propodeum lateral carinae not reaching dorsal margin; oblique carina and transverse carina absent. Basitibial plate of hind leg carinate marginally. Inner hind spur with 3 narrow teeth with acute tip (Fig. 2H). T2 depressed apical rim length less than 50% of segment. (n=3).
Material examined. 2♀, 203, Hwaksan-ro, Buk-myeon, Gapyeong-gun, Gyeonggi-do, Republic of Korea, on Koelreuteria paniculata, 9.vii.2020, Ka-Yun Lim (SNU); 3♀, Valley Cheonmi, Cheonmi-ri, Bangsan-myeon, Yanggu-gun, Gangwon- do, Republic of Korea, on Erigeron annuus, 5.vii.2023, Seung-Hun Jung (SNU).
Distribution. South Korea (Gangwon-do, Gyeonggi-do - New record), Japan (Hokkaido, Honshu, Shikoku, Kyushu, Tsushima), China (northeast) (Murao and Tadauchi, 2011).
Floral host. Asteraceae: Erigeron annuus; Sapindaceae: Koelreuteria paniculata (New record).
Discussion
The newly recorded subgenus Ctenonomia of the genus Lasioglossum is mainly distributed from Africa to tropical Asia (Michener, 2007). In Eastern Asia, seven species were recorded, and recently, certain species have been recorded at latitudes similar to those of Korean penninsula, indicating a broader distribution (Murao et al., 2009, 2020;Proshchalykin, 2009). In this regard, it appears that the distribution of Lasioglossum kumejimense, which has not been studied since 2009, has also expanded.
Key to subgenera of Lasioglossum in South Korea (modified from Murao, 2021)
Female
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1. 2nd submarginal crossvein of forewing strong (thick and distinct marginally), like 1st submarginal cross-vein and unlike the 3rd submarginal crossvein (The Lasioglossum series) ········································································· 2.
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- 2nd submarginal crossvein of forewing weaker (thin and obscure marginally) than the 1st submarginal cross-vein, like the 3rd submarginal crossvein (The Hemihalictus series) ········································································ 4.
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2. Inner hind tibial spur pectinate with few large teeth ······· ···························································· L. (Ctenonomia)
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- Inner hind tibial spur serrate ········································· 3.
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3. Lateral carina and oblique carina of posterior surface of propodeum well developed, lateral carina reaching dorsal surface and distinctly fused with oblique carina ············ ··························································· L. (Leuchalictus)
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- Lateral carina and oblique carina of posterior surface of propodeum usually poorly developed, lateral carina usually not reaching dorsal surface, if lateral carina reaches dorsal surface, seems like fused with oblique carina and transverse carina ·················································· L. (Lasioglossum)
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4. Mandible with two preapical teeth; labrum without basal elevation ············································ L. (Acanthalictus)
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- Mandible with one preapical tooth; labrum with basal elevation ······································································ 5.
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5. Lateral carina and oblique carina of posterior surface of propodeum well developed, lateral carina reaching dorsal surface and distinctly fused with oblique carina ············ ······················································ L. (Sphecodogastra)
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- Lateral carina and oblique carina of posterior surface of propodeum usually poorly developed, lateral carina not reaching dorsal surface ················································ 6.
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6. Head and mesosoma with green-metalic luster ·············· ································································· L. (Dialictus)
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- Head and mesosoma with black luster ·························· 7.
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7. Larger species (body 4.5 - 9.0 mm), genal area shorter than compound eye in lateral view, clypeus longer, 1.5 - 2.4 times wider than length ······················ L. (Hemihalictus)
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- Smaller species (body 3.5 - 4.0 mm), genal area wider than compound eye in lateral view, clypeus short, 2.6 - 2.9 times wider than length. ··································· L. (Pyghalictus)