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Research Article
Four new species of Laelius Ashmead (Hymenoptera, Bethylidae) from Korea with an updated key to species in the Eastern Palaearctic region
expand article infoJongok Lim‡, Seunghwan Lee§
‡ Wonkwang University, Iksan, Republic of Korea
§ Seoul National University, Seoul, Republic of Korea

Corresponding author: Jongok Lim ( jjongok79@gmail.com )

Academic editor: Wesley Dondoni Colombo
© 2024 Jongok Lim, Seunghwan Lee.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Lim J, Lee S (2024) Four new species of Laelius Ashmead (Hymenoptera, Bethylidae) from Korea with an updated key to species in the Eastern Palaearctic region. ZooKeys 1213: 251-265. https://doi.org/10.3897/zookeys.1213.121630
ZooBank: urn:lsid:zoobank.org:pub:03EC1A44-E47F-4FF3-9F57-68568C76AEDD
Open Access

Abstract

The genus Laelius Ashmead, 1893 (Hymenoptera, Bethylidae) is a cosmopolitan bethylid genus with 68 valid species distributed across most zoogeographic regions worldwide. This taxonomic study on Korean species of Laelius has led to the description of four new species, namely L. afores sp. nov., L. atratus sp. nov., L. sulcatus sp. nov., and L. tricuspis sp. nov. Additionally, illustrations of the diagnostic characteristics of each species are provided, along with an updated key for 11 Laelius species from the Eastern Palaearctic region.

Key words

Asia, Epyrinae, flat wasps, identification key, new species, taxonomy

Introduction

The genus Laelius Ashmead, 1893 (Hymenoptera, Bethylidae) is a cosmopolitan genus belonging to the subfamily Epyrinae. Currently, it comprises 68 valid species distributed across all zoogeographic regions, except for the Oceanian region as suggested by Holt et al. (2013). Three extinct fossil species have been recorded from Baltic and Rovno amber (Azevedo et al. 2018; Colombo et al. 2021). Approximately 33% (22 species) of the species were described from the Palaearctic region, with seven species reported from Eastern Asia.

Taxonomic information on Laelius species in the European Palaearctic region, mainly from Finland and Sweden, was provided by Vikberg and Koponen (2005). Laelius sinicus Xu, He & Terayama in the Eastern Palaearctic region was described by Xu et al. (2003), and Terayama (2006) published a book on Japanese Bethylidae, which included four Laelius species from Japan. Laelius yamatonis Terayama, 2006 was later recorded from South Korea by Lim et al. (2010a), and Lim et al. (2010b) provided a key to the Eastern Palaearctic species with a description of L. jilinensis Lim & Lee, 2010 from China. Currently, only one species, L. yamatonis Terayama, 2006, has been recorded in South Korea (Lim et al. 2010a).

Laelius species can be distinguished by the presence of thick black setae on the body and wings, a projected median clypeal lobe, and complete occipital carinae (Azevedo et al. 2018). The presence and relative length of the carinae on the metapostnotum and the metapectal-propodeal disc, as well as the relative length of the 2r-rs&Rs vein of the forewings, are commonly used in taxonomic and systematic studies on Laelius (Marques Jr. et al. 2023).

Laelius species parasitize larvae of various families, including Dermestidae and Scolytinae (Coleoptera), and Glossinidae (Diptera) (Vance 1932; Mertins 1980; Azevedo et al. 2018). Furthermore, Laelius species have been utilized for biological control purposes, as documented in many reports (Barbosa and Azevedo 2011).

This manuscript describes four new species of Laelius from South Korea, providing illustrations of their diagnostic characteristics and an updated taxonomic key for 11 Laelius species from the Eastern Palaearctic region.

Materials and methods

All materials examined were collected using Malaise traps from the northern and southern regions of South Korea. The abbreviations for collection localities in Korea are as follows: GW, Gangwon-do; JN, Jeollanam-do; JJ, Jeju-do. Detailed information on provincial localities in South Korea can be found in Lim et al. (2011).

The abbreviations for biometric measurements used in the text are as follows: AOL, the minimum distance between the anterior ocellus and the posterior ocellus; DAO, the diameter of the anterior ocellus; HE, the height (maximum length) of the eye in lateral view; LFW, the maximum length of the forewing; LH, the length of the head, from the apical margin of the clypeus to the posterior margin of the head in full dorsal view; POL, the distance between the posterior ocelli in full dorsal view; VOL, the vertex-ocular line, which is the distance between the top of the eye and the vertex line; WE, the minimum width of the eye in lateral view; WF, the width of the frons, the minimum distance between the eyes in full dorsal view; WH, the maximum width of the head in full dorsal view; WOT, the width of the ocellar triangle, including the width of the posterior ocelli.

Terms describing integument sculptures followed Eady (1968) and Harris (1979). Additionally, general morphological terms followed Azevedo et al. (2018), Lanes et al. (2020), and terms regarding mesoplueral structures followed Brito et al. (2021).

The specimens were examined under a Leica M205 C stereomicroscope (Leica Microsystems, Solms, Germany), and images were captured with a Dhyana 400D camera (TUCSEN CMOS, Fujian, China) attached to a Leica M205C. Multi-stacked images were produced using the Delta Multifocus ver. 24 program (Delta, South Korea) and Helicon Focus ver. 8.2.2 software (HeliconSoft, Ukraine). The final images were edited using Adobe Photoshop 2021 (Adobe Systems, Inc., San Jose, CA, USA).

The examined specimens were deposited at the Laboratory of Insect Taxonomy and Ecology at Wonkwang University (W-LITE), Iksan, Republic of Korea.

Systematic accounts

Family Bethylidae Haliday, 1839

Subfamily Epyrinae Kieffer, 1914

Laelius Ashmead, 1893

Laelius Ashmead, 1893. Bull. U.S. Nat. Mus., 45: 50. Type-species: Laelius trogodermatis Ashmead, 1893.

Paralaelius Kieffer, 1905. Ann. Soc. Sci. Bruxelles, 29: 129. Type-species: Laelius pedatus (Say, 1836).

Allepyris Kiffer, 1905. Ann. Soc. Sci. Burxelles, 29: 106. Type-species: Allepyris microneura (Kieffer, 1905).

Prolaelius Kieffer, 1905. Type-species: Paralaelius firmipennis (Cameron, 1905).

Diagnosis

The genus Laelius can be distinguished from other genera by having the mesoscuto-scutellar suture with an evident sulcus and thick black setae on the body (Colombo et al. 2022).

Laelius afores Lim, sp. nov.

https://zoobank.org/6742C3C5-B66C-4E1C-8EDF-1F9A874FF85A
Fig. 1A–E

Description

Holotype (female). Body length 2.61 mm; LFW 1.48 mm.

Color. Head black; mandible dark castaneous except apical half-light castaneous; antenna dark castaneous except scape and pedicel light castaneous in dorsal view. Mesosoma black; legs light castaneous except basal half of procoxae and metafemora castaneous; wings hyaline, tegula light castaneous, veins pale castaneous. Metasoma black.

Morphology

Head (Fig. 1A, B). 1.1× as long as wide with broadly outcurved vertex crest in dorsal view in dorsal view (Fig. 1B). Ventral and lateral surface with suberect long setae, some setae longer than LE. Mandible with four apical teeth; two uppermost teeth small, 3rd tooth from top most thick and one ventralmost sharpened. Clypeus short, broadly rounded with one median small blunt tooth, median area longitudinally elevated (Fig. 1B). First five antennomeres in ratio of 2.5: 1.7: 2.5: 1.0: 1.0 in length; scape, pedicel and flagellomere III–V and XI 2.7, 2.4, 3.3, 1.2, 1.3 and 1.3× as long as wide, respectively. Frons coriaceous with sparse punctures; frontal line absent. Vertex slightly outcurved and round marginally. WF 1.9× LE, WF 0.7× WH. Compound eye 0.19 mm long without setae. Medioccipito-genal suture present. Occipital carina complete. LE 1.0× OOL, WF 2.3× WOT. Anterior angle of ocellar triangle obtuse, POL 1.3× AOL, OOL 1.3× WOT (Fig. 1B).

Figure 1. 

Laelius afores Lim, sp. nov., holotype (female) A habitus in lateral view B head in dorsal view C mesosoma in lateral view D ditto, in dorsal view E forewing in dorsal view. Scale bars: 0.50 mm (A); 0.20 mm (B–E).

Mesosoma (Fig. 1A, C–E). Dorsal pronotal area coriaceous as head, 0.5× as long as wide, trapezoidal, humeral angle obtuse; punctures very shallow and sparse (Fig. 1D); posterior pronotal sulcus absent. Mesoscutum coriaceous as head, pronotum with short and thin setae; notaulus absent; parapsidal signum thin, reaching posterior margin of mesoscutum (Fig. 1D). Mesoscutellar disc coriaceous; mesoscuto-scutellar ridge slightly posterad at each side (Fig. 1D). Metapectal-propodeal disc 1.1× as long as wide; metapostnotal median carina and first metapostnotal lateral carinae complete, strong, completely extending transverse posterior carina of metapectal-propodeal complex; second metapostnotal lateral carina extending one-fourth of disc; paraspiracular carina distinct, presented on distal half of disc, reaching transverse posterior carina of metapectal-propodeal complex; transverse posterior carina of metapectal-propodeal complex complete and concave in dorsal view. Propodeal declivity reticulate without median carina (Fig. 1D). Mesopleuron with mesepimeral sulcus; subalar fovea oval and closed; lower mesopleural fovea opened (Fig. 1C). Femora and tibia with long setae on outer surface, getting short to tarsomeres. Tegula without some erect setae. Subcostal vein (Sc2v), median vein (M2v) and anal vein (A2v) with long setae; second radial cross vein and radial sector vein of fore wing (2r-rs&Rs2v) 0.9 mm long, 0.8× as long as Rs+M2v. First median cell of fore wing and second median cell of fore wing with few short hairs (Fig. 1E). Hind wing with three distal hamuli.

Metasoma (Fig. 1A). Tergum I and II largely smooth, polished without distinct long erect hairs; remaining terga with microreticulation on anterior half; terga III–VI with transverse sparse setae line on dorsal surface.

Material examined

Holotype. Female. Seoul National University, Sinlim, Gwanak, Seoul, South Korea. 6.iv.2020. Deok-Young Park leg. (W-LITE).

Distribution

South Korea (Seoul).

Etymology

The specific epithet afores refers to the absence of notaulus on the mesoscutum and median carina on the propodeum declivity.

Remarks

The species is similar to L. jilinensis Lim & Lee, 2010 from China by ‘overall color of body and appendages; head as long as wide with broadly outcurved vertex in dorsal view; mandible with four teeth; clypeus short with one median small blunt tooth on anterior margin; compound eye without setae; metapectal-propodeal disc as long as wide with metapostnotal median carina and first- and second metapostnotal lateral carina’. However, L. afores Lim, sp. nov. is distinguished from L. jilinensis by ‘WF 1.9× LE (WF 1.4× LE in L. jilinensis); LE 1.0× OOL (LE 1.2× LE in L. jilinensis); dorsal pronotal area 0.5× as long wide (0.8× as long as in L. jilinensis); mesoscutum without notaulus (notaulus absent in L. jilinensis); propodeal declivity without median longitudinal carina (median longitudinal carina present in L. jilinensis)’.

Laelius atratus Lim, sp. nov.

https://zoobank.org/C90ABCF0-CAD1-4B48-98F4-0029C44130E3
Fig. 2A–E

Description

Holotype (female). Body length 3.05 mm; LFW 1.67 mm.

Color. Head black; mandible light castaneous; antenna dark castaneous except apical half of scape, pedicel and basal flagellomere I light castaneous in dorsal view. Mesosoma black; legs light castaneous except coxa and femora dark black; wings hyaline, tegula light castaneous, veins pale castaneous. Metasoma black.

Morphology

Head (Fig. 2A, B). 1.1× as long as wide with slightly outcurved vertex crest in dorsal view (Fig. 2B). Ventral and lateral surface with erect or suberect setae. Mandible with four apical teeth; two uppermost teeth small, 3rd tooth from top most thick and one ventralmost sharpened. Clypeus short, anterior margin straight with one median very minute triangle tooth; median area longitudinally elevated (Fig. 2B). First five antennomeres in ratio of 3.1: 1.3: 1.0: 1.1: 1.1 in length; scape, pedicel and flagellomere III–V and XI 2.5, 1.2, 1.4, 1.2, 1.0 and 1.5× as long as wide, respectively. Frons coriaceous with sparse punctures, polished; frontal line absent. Vertex slightly outcurved and round marginally. WF 1.4× LE. WF 0.7× WH. Compound eye 0.29 mm long without setae in lateral view. Medioccipito-genal suture present. Occipital carina complete. LE 1.4× OOL, WF 2.2× WOT. Anterior angle of ocellar triangle slightly obtuse, POL 1.2× AOL, OOL 1.1× WOT (Fig. 2B).

Figure 2. 

Laelius atratus sp. nov., holotype (female) A habitus in lateral view B head in dorsal view C mesosoma in lateral view D ditto, in dorsal view E forewing in dorsal view. Scale bars: 0.50 mm (A); 0.20 mm (B–E).

Mesosoma (Fig. 2A, C–E). Dorsal pronotal area coriaceous as head, 0.6× as long as wide, trapezoidal, humeral angle obtuse; punctures shallow and sparse as head (Fig. 2D); posterior pronotal sulcus absent. Mesoscutum coriaceous as head, pronotum with short and thin setae; notaulus distinct, short on distal half of mesoscutum; parapsidal signum deep and reaching posterior margin of mesoscutum (Fig. 2D). Mesoscutellar disc coriaceous; mesoscuto-scutellar ridge posterad at each side (Fig. 2D). Metapectal-propodeal disc 0.9× as long as wide; metapostnotal median carina and second metapostnotal lateral carinae strong, completely extending transverse posterior carina of metapectal-propodeal complex; first metapostnotal lateral carinae weak, completely extending transverse posterior carina of metapectal-propodeal complex; third metapostnotal lateral carinae extending one-third of disc; paraspiracular carinae distinct, completely reaching transverse posterior carina of metapectal-propodeal complex; transverse posterior carina of metapectal-propodeal complex complete and concave in dorsal view (Fig. 2D). Propodeal declivity reticulate with median carina (Fig. 2D). Mesopleuron with mesepimeral sulcus; subalar fovea elongated and closed; lower mesopleural fovea opened (Fig. 2C). Femora and tibia with long setae on outer surface, getting short to tarsomeres. Tegula with some erect setae. Subcostal vein (Sc2v), median vein (M2v) and anal vein (A2v) with long setae; second radial cross vein and radial sector vein of fore wing (2r-rs&Rs2v) 0.1 mm long, 0.8× as long as Rs+M2v. First median cell of fore wing and second median cell of fore wing with few short hairs (Fig. 2E). Hind wing with three distal hamuli.

Metasoma (Fig. 2A). Tergum I and II largely smooth, polished without distinct long erect hairs; remaining terga with microreticulation on anterior half; terga III–VI with transverse sparse setae line on dorsal surface.

Material examined

Holotype : Female. Aguala Hotel Dorm., 1388. Hyeopjae. Hallim, JJ, South Korea. 33°23'58.8"N, 126°14'57.0"E, Malaise trap, 17.vii–20.viii.2017, Sanghyeok Nam leg. (W-LITE); paratype: Female. same collection data as holotype (W-LITE).

Distribution

South Korea (JJ).

Etymology

The specific epithet atratus refers to the submedian carinae parallel to the median discal carinae.

Remarks

The species is similar to L. nigrofemoratus Terayama, 2006 from Japan by ‘color of head, mesosoma and metasoma; head as long as wide with convex posterior margin in dorsal view; metapectal-propodeal complex with one metapostnotal median carina and three pairs of metapostnotal lateral carinae’. However, L. atratus Lim, sp. nov. is distinguished from L. nigrofemoratus Terayama by ‘mandible with four teeth (mandible with five teeth in L. nigrofemoratus); legs reddish brown except coxa and femora black (legs reddish brown including coxa in L. nigrofemoratus); first metapostnotal lateral carinae parallel to metapostnotal median carina (first metapostnotal lateral carinae extending to metapostnotal median carina near transverse posterior carina of metapectal-propodeal complex in L. nigrofemoratus)’.

Laelius sulcatus Lim, sp. nov.

https://zoobank.org/DC81C584-C302-468B-BA97-5315024018C8
Fig. 3A–E

Description

Holotype (female). Body length 4.35 mm; LFW 2.46 mm.

Color. Head black; mandible castaneous; antenna dark castaneous except scape, pedicel, flagellomere I castaneous in dorsal view. Mesosoma black; legs castaneous except coxa dark castaneous; wings hyaline, tegula light castaneous, veins pale castaneous. Metasoma black.

Morphology

Head (Fig. 3A, B). 1.1× as long as wide with broadly outcurved vertex crest in dorsal view in dorsal view (Fig. 3B). Ventral and lateral surface with suberect long setae, each seta shorter than LE. Mandible with five apical teeth; three uppermost teeth small, 4th tooth from top most thick and one ventralmost long and sharpened. Clypeus short, broadly rounded with one median small blunt tooth, median area longitudinally elevated (Fig. 3B). First five antennomeres in ratio of 3.0: 1.4: 1.2: 1.0: 1.0 in length; scape, pedicel and flagellomere III–V and XI 2.5, 1.7, 1.3, 1.0, 1.0 and 1.8× as long as wide, respectively. Frons coriaceous with sparse big punctures; frontal line absent. Vertex slightly outcurved and round marginally. WF 1.3× LE, WF 0.7× WH. Compound eye 0.40 mm long without setae. Medioccipito-genal suture present. Occipital carina complete. LE 1.7× OOL, WF 2.1× WOT. Anterior angle of ocellar triangle obtuse, POL 1.4× AOL, OOL 0.9× WOT (Fig. 3B).

Figure 3. 

Laelius sulcatus sp. nov., holotype (female) A habitus in lateral view B head in dorsal view C mesosoma in lateral view D ditto, in dorsal view E forewing in dorsal view. Scale bars: 0.50 mm (A); 0.20 mm (B–E).

Mesosoma (Fig. 3A, 3C–E). Dorsal pronotal area coriaceous as head, 0.5× as long as wide, trapezoidal, humeral angle obtuse; punctures shallower and smaller than punctures on head (Fig. 3D); posterior pronotal sulcus absent. Mesoscutum coriaceous as head, pronotum with short and thin setae; notaulus long, distinct; parapsidal signum thick, present distal half, reaching posterior margin of mesoscutum (Fig. 3D). Mesoscutellar disc coriaceous; mesoscuto-scutellar ridge wide and deep, posterad at each side (Fig. 3D). Metapectal-propodeal disc 0.7× as long as wide; metapostnotal median carina and second metapostnotal lateral carinae distinct, strong, extending transverse posterior carina of metapectal-propodeal complex; second metapostnotal lateral carinae extending distal one fifth of disc; paraspiracular carinae distinct, reaching transverse posterior carina of metapectal-propodeal complex; transverse posterior carina of metapectal-propodeal complex complete and concave in dorsal view (Fig. 3D). Propodeal declivity reticulate with distinct median carina (Fig. 3D). Mesopleuron with mesepimeral sulcus; subalar fovea oval and closed; lower mesopleural fovea opened (Fig. 3C). Femora and tibia with long setae on outer surface, getting short to tarsomeres. Tegula with some erect setae. Subcostal vein (Sc2v), median vein (M2v) and anal vein (A2v) with long setae; second radial cross vein and radial sector vein of fore wing (2r-rs&Rs2v) 0.3 mm long, 1.0× as long as Rs+M2v. First median cell of fore wing and second median cell of fore wing with few short hairs (Fig. 3E). Hind wing with three distal hamuli.

Metasoma (Fig. 3A). Tergum I and II largely smooth, polished without distinct long erect hairs; remaining terga with microreticulation on anterior half; terga III–VI with transverse sparse setae on dorsal surface.

Material examined

Holotype : Female. 854 Hangye-ri, Buk-myeon, Inje-gun, GW, South Korea. 38°08'46.5"N, 128°15'47.5"E, Malaise trap, 11–29.vi.2017, Sanghyeok Nam leg. (W-LITE); paratypes: 2 Females, Forahn House, 703 Ongpo-ri, Hanlim-eub, JJ, South Korea. 33°12'51.1"N, 126°15'04.0"E, Malaise trap, 16.v.2018, Sanghyeok Nam leg. (W-LITE); Female, Aguala Hotel Dorm., 1388. Hyeopjae. Hallim, Jeju, South Korea. 33°23'58.8"N, 126°14'57.0"E, Malaise trap, 17.vii–20.viii.2017, Sanghyeok Nam leg. (W-LITE).

Distribution

South Korea (GW, JJ).

Etymology

The specific epithet sulcatus refers to the distinctly developed notaulus on the mesoscutum.

Remarks

The species is similar to L. yamatonis Terayama, 2006 from Korea and Japan by ‘head slight longer than wide with convex posterior margin in dorsal view; mandible with five teeth; clypeus broadly rounded; pedicel about 1.7–1.8 times as long as wide; dorsal pronotal area 0.5× as long as wide; metapectal-propodeal complex with one metapostnotal median carina and two pairs of metapostnotal lateral carinae ‘. However, L. sulcatus Lim, sp. nov. is distinguished from L. yamatonis Terayama by ‘ LE 1.7× OOL (LE 1.3× OOL in L. yamatonis; mesoscutum with distinct notalulus (mesoscutum without notaulus in L. yamatonis); second metapostnotal lateral carinae reaching basal three fourth of metapostnotal-propodeal disc (second metapostnotal lateral carinae reaching basal one-fourth of metapostnotal-propodeal disc in L. yamatonis)’.

Laelius tricuspis Lim, sp. nov.

https://zoobank.org/7D6FE7CC-CB2A-47A3-8D3E-E6723B42DA01
Fig. 4A–E

Description

Holotype (female). Body length 2.57 mm; LFW 1.61 mm.

Color. Head black; basal half of mandible dark castaneous and apical half-light castaneous; antenna castaneous except basal two thirds dark castaneous in dorsal view. Mesosoma black; legs castaneous except coxa and femora dark castaneous; wings hyaline, tegula light castaneous, veins pale castaneous. Metasoma black.

Morphology

Head (Fig. 4A, B). 1.0× as long as wide with slightly convex posterior margin in dorsal view (Fig. 4B). Ventral and lateral surface with suberect long setae, some setae as long as LE. Mandible with four apical teeth; two uppermost teeth small, 3rd tooth from top most thick and one ventralmost sharpened. Clypeus short, anterior margin straight with one median small blunt tooth, median area weakly elevated (Fig. 4B). First five antennomeres in ratio of 3.5: 1.6: 1.1: 1.1: 1.0 in length; scape, pedicel and flagellomere III–V and XI 3.3, 2.0, 1.2, 1.0, 1.0 and 1.5× as long as wide, respectively. Frons coriaceous with sparse punctures; frontal line absent. Vertex slightly outcurved and round marginally. WF 1.6× LE, WF 0.7× WH. Compound eye 0.24 mm long without setae. Medioccipito-genal suture present. Occipital carina complete. LE 1.3× OOL, WF 2.4× WOT. Anterior angle of ocellar triangle obtuse, POL 1.4× AOL, OOL 1.1× WOT (Fig. 4B).

Figure 4. 

Laelius tricuspis sp. nov., holotype (female) A habitus in lateral view B head in dorsal view C mesosoma in lateral view D ditto, in dorsal view E forewing in dorsal view. Scale bars: 0.50 mm (A); 0.20 mm (B–E).

Mesosoma (Fig. 4A, C–E). Dorsal pronotal area coriaceous as head, 0.5× as long as wide, trapezoidal, humeral angle obtuse; punctures very shallow and sparse (Fig. 4D); posterior pronotal sulcus present. Mesoscutum coriaceous as head, pronotum with short and thin setae; notaulus weak, present on distal half of mesoscutum; parapsidal signum short, present on distal one third of mesoscutum (Fig. 4D). Mesoscutellar disc coriaceous; mesoscuto-scutellar ridge slightly posterad at each side (Fig. 4D). Metapectal-propodeal complex 1.0× as long as wide; metapostnotal median carina and first metapostnotal lateral carinae distinct, completely extending transverse posterior carina of metapectal-propodeal complex; median area rugulose; submedian area strigate; paraspiracular carinae distinct, reaching transverse posterior carina of metapectal-propodeal complex; transverse posterior carina of metapectal-propodeal complex complete and concave in dorsal view (Fig. 4D). Propodeal declivity reticulate with median carina (Fig. 4D). Mesopleuron with mesepimeral sulcus; subalar fovea oval and closed; lower mesopleural fovea opened (Fig. 4C). Femora and tibia with long setae on outer surface, getting short to tarsomeres. Tegula without some erect setae. Subcostal vein (Sc2v), median vein (M2v) and anal vein (A2v) with long setae; second radial cross vein and radial sector vein of fore wing (2r-rs&Rs2v) 0.2 mm long, 1.0× as long as Rs+M2v. First median cell of fore wing and second median cell of fore wing with few short hairs (Fig. 4E). Hind wing with three distal hamuli.

Metasoma (Fig. 4A). Tergum I and II largely smooth, polished without distinct long erect hairs; remaining terga with microreticulation on anterior half; terga III–VI with transverse sparse setae line on dorsal surface.

Material examined

Holotype . Female. Is. Geumho, Sani-myeon, Haenam-gun, JN, South Korea. 34°41'19"N, 126°21'19"E, Malaise trap, 1–27.vi.2023, Jongok Lim leg. (W-LITE).

Distribution

South Korea (JN).

Etymology

The specific epithet tricuspis refers to the long and distinct three metapectal-propodeal carinae (one metapostnotal median carina and one pair of metapostnotal lateral carinae).

Remarks

The species is similar to L. jilinensis Lim & Lee, 2010 from China by ‘overall color of body and appendages; head as long as wide with convex posterior margin in dorsal view; mandible with four teeth; clypeus short with one median small tooth medially on straight anterior margin; compound eye without setae’. However, L. tricuspis Lim, sp. nov. is distinguished from L. jilinensis by ‘scape 3.5× as long as flagellomere III (scape 2.8× as long as flagellomere III in L. jilinensis); WF 2.4× WOT (WF 2.2× WOT in L. jilinensis); pronotal disc 0.5× as long as wide (0.8× as long as wide in L. jilinensis); metapectal-propodeal complex with three metapostnotal lateral carinae (five metapostnotal lateral carinae present in L. jilinensis)’.

Key to the Laelius species from the Eastern Palaearctic region

1 POL wider than OOL L. antropovi Gorbatovsky, 1995 (Far Eastern Russia)
– POL narrower than OOL 2
2 Metapectal-propodeal disc with one metapostnotal median carina and one pair of first metapostnotal lateral carinae Laelius tricuspis sp. nov. (Korea)
– Metapectal-propodeal disc with more than five metapostnotal carinae 3
3 Metapectal-propodeal disc with five metapostnotal carinae 4
– Metapectal-propodeal disc with seven metapostnotal carinae 8
4 Mandible with four teeth; metapectal-propodeal disc longer than wide 5
– Mandible with five teeth; metapectal-propodeal disc wider than long 7
5 First metapostnotal lateral carinae on metapectal-propodeal disc not reaching transverse posterior carina of metapectal-propodeal complex Laelius sinicus Xu et al., 2003 (China)
– First metapostnotal lateral carinae on metapectal-propodeal disc reaching transverse posterior carina of metapectal-propodeal complex 6
6 WF less than 1.5× LE; mesoscutum with notaulus; propodeal declivity with median carina Laelius jilinensis Lim & Lee, 2010 (China, S. Korea)
– WF more than 1.5× LE; mesoscutum without notaulus; propodeal declivity without median carina Laelius afores sp. nov. (Korea)
7 Mesoscutum without notaulus; second metapostnotal lateral carinae reaching basal one fourth of metapectal-propodeal disc Laelius yamatonis Terayama, 2006 (Japan, Korea)
– Mesoscutum with distinct notaulus; second metapostnotal lateral carinae reaching basal three fourth of metapectal-propodeal disc Laelius sulcatus sp. nov. (Korea)
8 Head distinctly wider than long; pedicel 2.0× as long as wide Laelius naniwaensis Terayama, 2006 (Japan)
– Head as long as wide; pedicel less than 1.5× as long as wide 9
9 Metapectal-propodeal disc with one metapostnotal median carina and three pairs of metapostnotal lateral carinae 10
– Metapectal-propodeal disc with one metapostnotal median carina and four pairs of metapostnotal lateral carinae Laelius yokohamensis Terayama, 2006 (Japan)
10 Legs reddish brown including coxa; first metapostnotal lateral carinae on metapectal-propodeal disc connected to metapostnotal median carina near transverse posterior carina of metapectal-propodeal complex Laelius nigrofemoratus Terayama, 2006 (Japan)
– Legs reddish brown except coxa and femora black; first metapostnotal lateral carinae parallel to metapostnotal median carinae Laelius atratus sp. nov. (Korea)

Discussion

Since Ashmead established the genus Laelius in 1893, a total of 68 species have been described. Notably, 50% of the valid species (33 species) have been reported since 2000, reflecting recent discoveries facilitated by the exploration of diverse diagnostic characteristics (Vikberg and Koponen 2005; Barbosa and Azevedo 2009, 2011, 2014; Lim et al. 2010b; Marques Jr. et al. 2023).

The presence and relative ratio or length of the 2r-rs&Rs vein of the forewing stand out as the most useful characteristics in the taxonomy of Laelius (Marques Jr. et al. 2023). However, in the case of the four new species in the present study, they commonly exhibit relatively similar lengths of the 2r-rs and Rs veins.

Barbosa and Azevedo (2011) conducted cladistic analyses based on 108 female structural characters, revealing that the genus is supported by six autapomorphies: a body with thick setae present; a straight profile of the median clypeal carina; an incomplete anterior extension of the median clypeal carina; an angled anterior corner of the pronotal disc; three distal hamuli on the hindwing; and tergum II longer than the others. The four new species from the present paper, namely L. afores sp. nov., L. atratus sp. nov., L. tricuspis sp. nov., and L. sulcatus sp. nov., commonly exhibit these autapomorphies suggested by Barbosa and Azevedo (2011). Additionally, the ratios of POL, OOL, WF, LE, antennal segments, number of median discal carinae, number of mandibular teeth, and the presence of a median carina on the propodeal declivity are useful characteristics for the delimitation of new species.

In Colombo et al. (2022), a more recent study of the phylogenetic relationships of Epyrinae, a clade of six genera, including Laelius, was found to be monophyletic. Furthermore, a clade of four genera, namely Anisepyris, Austrepyris, Chlorepyris, and Laelius, which commonly share the characteristic of the mesoscuto-scutellar sulcus being well impressed and incurved medially, is sister to the remaining Epyrinae.

Laelius species exhibit weak sexual dimorphisms and share many common characteristics except for genitalia structures (Azevedo et al. 2018). Since most species of Laelius worldwide were described based on females and do not include enough species for cladistic studies on male genitalia, it is necessary to obtain many male samples for studies on the genus. Additionally, Colombo et al. (2022) analyzed nine species of Laelius, mostly from the Nearctic and Neotropical regions, except for one species from the Palaearctic region (Israel), for constructing Epyrinae phylogeny. Indeed, a clade including Laelius was supported as the sister group against the other genera of Epyrinae, necessitating further exploration of the phylogenetic relationships among the genera in the clade containing Laelius with more diverse species from various zoogeographic regions, including Eastern Asia.

In the present paper, four additional Laelius species from the Korean Peninsula, part of Far Eastern Asia, were described. Consequently, five Laelius species have been recorded in the nation, which represents higher species diversity compared to neighboring countries such as Japan (4), China (1), and Far Eastern Russia (1). This leads us to speculate that there are more unknown species in the Eastern Palaearctic region.

Acknowledgements

The authors would like to express their gratitude to Mr. Deok-Young Park (Seoul National University) for his assistance with sample collection, management, and for providing valuable bethylid samples.

Additional information

Conflict of interest

The authors have declared that no competing interests exist.

Ethical statement

No ethical statement was reported.

Funding

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education (RS-2023-00238017, NRF2020R1I1A2069484), and the Honam National Institute of Biological Resources (HNIBR), funded by the Ministry of Environment (MOE) of the Republic of Korea (Grant number: HNIBR202101101), and the Korea Forest Service.

Author contributions

Writing - original draft: JL. Writing - review and editing: SL.

Author ORCIDs

Jongok Lim https://orcid.org/0000-0001-5700-3024

Seunghwan Lee https://orcid.org/0000-0003-3026-5328

Data availability

All of the data that support the findings of this study are available in the main text.

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