Halictidae Thomson, 1869 is one of the largest families in the Hymenoptera, with approximately 4,400 species worldwide, and includes four subfamilies: Halictinae, Rophitinae, Nomiinae, Nomioidinae (Richards and Packer, 2020). In many faunas, Halictidae is the most common bee and is known as very important pollinator of wildflowers and crops (Dikmen, 2007).

The genus Lasioglossum Curtis, 1833, belonging to the Halictinae, is a cosmopolitan bee group comprising about 1,750 species worldwide (Gibbs et al., 2012). On the Korean Peninsula, 52 species of Lasioglossum in 6 subgenera (Acanthalictus, Dialictus, Hemihalictus, Lasioglossum, Leuchalictus, Sphecodogastra) are recorded, of which 13 species are included in the subgenus Hemihalictus. (Murao, 2017;2021). The subgenus HemihalictusCockerell, 1897 includes approximately 260 species worldwide (Ascher and Pickering 2023). The main morphological characteristics of Hemihalictus are weak or absent second submarginal vein (1rs-m) of female, black head and mesosoma, and posterior surface of propodeum with weak and short lateral carina not reaching to dorsal surface (Gibbs et al., 2013;Murao, 2021).

In this study, we recognized new distributional record of halictid bee Lasioglossum (Hemihalictus) sphecodicolor Sakagami and Tadauchi 1995 from South Korea. We present diagnosis, description, and photographs for diagnostic characters of newly recorded species. Also, key to species of subgenus Hemihalictus from South Korea provided.

Materials and Methods

All samples for this study were collected by sweeping in Jeju Island from 2016 to 2022. All 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). 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).

Systematic Accounts

Family Halictidae Thomson, 1869

Subfamily Halictinae Thomson, 1869

Genus Lasioglossum Curtis, 1833

Subgenus HemihalictusCockerell, 1897

HemihalictusCockerell, 1897: 288. Type species: Panurgus lustransCockerell, 1897, by original designation.

SudilaCameron, 1898: 52. Type species: Sudila bidentataCameron, 1898, by designation of Sandhouse (1943).

ProsopalictusStrand, 1913: 26. Type species: Prosopalictus micansStrand, 1913, by original designation and monotypy.

CeylonicolaFriese, 1918: 501. Type species: Ceylonicola atraFriese, 1918 (= Sudila bidentataCameron, 1898), by designation of Sandhouse (1943).

Halictus (Microhalictus) Warncke, 1975: 85. Type species: Melitta minutissima Kirby, 1802, by original designation.

Halictus (Puncthalictus) Warncke, 1975: 87. Type species: Hylaeus punctatissimus Schenck, 1853, by original designation.

Halictus (Rostrohalictus) Warncke, 1975: 88. Type species: Halictus longirostris Morawitz, 1876, by original designation and monotypy

Halictus (Marghalictus) Warncke, 1975: 95. Type species: Hylaeus marginellus Schenck, 1853, by original designation.

Lasioglossum (Sellalictus) Pauly, 1980: 120. Type species: Halictus latesellatus Cockerell, 1937, by original designation.

Halictus (Pauphalictus) Warncke, 1981: 87. Type species: Halictus pauperatus Brullé, 1832, by original designation.

Lasioglossum (Mediocralictus) Pauly, 1984: 143. Type species: Halictus mediocris Benoist, 1962, by original designation.

Evylaeus (Limbevylaeus) Pesenko, 2007: 20. Type species: Halictus limbellus Morawitz, 1876, by original designation.

Evylaeus (Crassevylaeus) Pesenko, 2007: 20. Type species: Halictus crassepunctatus Blüthgen, 1923, by original designation and monotypy.

Evylaeus (Laevinodilaeus) Pesenko, 2007: 20. Type species: Halictus laevinodis Morawitz, 1876, by original designation and monotypy.

Evylaeus (Pallidevylaeus) Pesenko, 2007: 23. Type species: Nomioides pallida Radoszkowski, 1888, by original designation and monotypy.

Evylaeus (Nitidiusculaeus) Pesenko, 2007: 24. Type species: Melitta nitidiuscula Kirby, 1802, by original designation.

Evylaeus (Truncevylaeus) Pesenko, 2007: 24. Type species: Halictus truncaticollis Morawitz, 1877, by original designation.

Lasioglossum (Hemihalictus) sphecodicolorSakagami and Tadauchi, 1995 제주황배꼬마꽃벌(신칭) (Figs.1A-H)

Lasioglossum (Evylaeus) sphecodicolor Sakagami and Tadauchi, 1995: 191

Lasioglossum (Hemihalictus) sphecodicolor – Murao, 2021: 43

Redescription

Female.

Body: Body length 5.4-6.0 mm. Body width 1.8-2.0 mm

Coloration: Head and mesosoma black (Fig.1A); clypeus black, labrum black, mandible black base to median, reddishbrown apex; flagellum black dorsally, reddish-brown ventrally; Pronotal lobe black; legs black, base of femur and tibia reddishbrown; metatibial spur reddish-brown, tegula reddish-brown entirely, black basally, semi-transparent; wing membrane hyaline, veins reddish-brown; Metasoma reddish-brown (Fig.1A).

Pubescence: Body hair color white to pale yellow. Tomentum dense on pronotal collar and lobe; Tomentum sparse on pronotum dorsal area, genal area, posterior margin of scutum, metanotum, lateral and posterior surface of propodeum, mesepisternum and metepisterum. Mesoscutum with straight hairs. Metasomal terga with fringes of straight hairs on latero-apical margin (Fig. 1F). 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, weakly imbricate in basal, with punctures dense in basal (IS < 1 PD), irregularly sparser in apical (IS < 2 PD); supraclypeal area strongly imbricate, with punctures moderately dense (IS ≤ 2 PD); paraocular area strongly imbricate, apical margin near mandible shiny, with punctures moderately dense (IS ≤ 2 PD); frons tessellate, with punctures crowded (IS = 0 PD); vertex shiny, with punctures dense in lateral (IS ≤ 1 PD), moderately dense in medial (IS ≤ 2 PD); genal area shiny, with punctures moderately dense (IS = 1-2 PD); postgenal area punctures linate with straight ridges, without punctures; tegula imbricate basally, shiny apically, punctures absent; mesoscutum tessalate, with punctures moderately dense (IS = 1-2 PD) medially, denser (IS < 1 PD) marginally (Fig.2B); scutellum shiny medially, weakly imbricate marginally, with punctures moderately dense (IS = 1-2 PD) submedially, denser marginally and on median line (IS < 1 PD); metapostnotum imbricate, with longitudinal carina subparallelly in basal half, not reaching posterior margin; preëpisternum and hypoepimeron shiny or weakly imbricate, with punctures crowded (IS = 0 PD); mesepisternum shiny or weakly imbricate, with punctures crowded dorsally (IS = 0 PD), otherwise rugulose; metepisternum sculpture ruguloso-lineate dorsally, otherwise rugulose; propodeum lateral and 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.1D); T2 basally and on apical rim coriarious, disc shiny, with punctures moderately sparse (IS 2-4 PD), on apical rim obscure; T3 coriarious, with punctures moderately sparse (IS = 2-6 PD) and obscure.

Structure: Head length/width ratio 0.89 (± 0.01 SD); vertex slightly rounded in frontal view; upper interorbital distance/ maximum interorbital distance ratio 0.86 (± 0.01 SD), lower interorbital distance/maximum interorbital distance ratio 0.77 (± 0.01 SD); ocelloccipital distance/interocellar distance ratio 0.76 (± 0.01 SD), ocellocular distance/interocellar distance ratio 1.00 (± 0.01 SD); antennocular distance/interantennal distance ratio 1.97 (±0.03 SD); supraclypeal area slightly convex, length/width ratio 0.76 (± 0.01 SD); clypeus slightly convex, length/width ratio 0.52 (± 0.02 SD); apicolateral denticles very low rounded knobs; clypeus length/supraclypeal area length ratio 1.28 (± 0.03 SD); compound eye width/gena width ratio 1.18 (± 0.03 SD); malar space linear; forewing with 3 submarginal cells; lateral surface of pronotum without rides; pronotal angle obtuse; tegula shape oval; mesoscutum length/ width ratio 0.77 (± 0.01 SD); scutum/scutellum length ratio 3.01 (± 0.06 SD); scutellum/metanotum length ratio 2.01 (± 0.13 SD); metanotum/metapostnotum length ratio 0.84 (± 0.01 SD). Propodeum lateral carinae not reaching dorsal margin; oblique carina absent. Basitibial plate of hind leg carinate marginally. Metatibial spur with 3 narrow teeth with rounded tip. T2 depressed apical rim length less than 50% of segment. (n=3)

Distribution. South Korea (Jeju Is.) (New record), Japan (Hokkaido, Honshu, Izushotô Islands, Shikoku, Kyushu, Tsushima Is., northern Ryukyus) (Murao, 2021)

Flower records in South Korea. Anacardiaceae: Rhus javanica. Rubiaceae: Paederia foetida (New record). Asteraceae: Taraxacum officinale. Hydrangeaceae: Deutzia crenata. Hydrangea serrata Ser. var. serrata. Polygonaceae: Persicaria manshuricola. Saxifragaceae: Astilbe odontophylla (Murao, 2021).

Specimen examined. South Korea: Jeju-do: 1♀, Jocheoneup, 11.v.2016 Lee et al (NIBR), 1♀, Bukcheon-ri, Jocheoneup, on Rhus javanica, 7.ix.2021 KY Lim (SNU), 2♀, Namjoro, Jocheon-eup, on Paederia foetida, 4.viii.2022, SH Jung (SNU).

Diagnosis: Female of Lasioglossum sphecodicolor can be recognized by reddish-brown abdomen, mesepisternum reticulate- punctate on lower area, metasomal terga with distinct fringes on posterior margin from other species in subgenus Hemihalictus from Korean peninsula.

Key to species of the subgenus Hemihalictus in South Korea (modified from Murao 2017; 2021)

Female