Euroleon coreanus Okamoto, 1926

Kim, Jiseung, Ahn, Neung-Ho & Kim, Sora, 2025, A taxonomic review of the family Myrmeleontidae Latreille (Neuroptera, Myrmeleontiformia) from the Korean peninsula, highlighting the conservation value of this family, ZooKeys 1262, pp. 97-174 : 97-174

Euroleon coreanus Okamoto, 1926

Figs 7 , 8 , 32 B , 35 C , 36 B , 37 F

Euroleon coreanus Okamoto, 1926: 19. Type locality: Korea.

Euroleon sjostedti Navás, 1928: 30. Type locality: China: Gansu: Sanchowfu.

Teula sinica Navás, 1930 b: 6 . Type locality. China: Hebei: Chengde.

Euroloen alienus Navás, 1932: 111. Type locality: China: Shaanxi: Tapaischan: Tsinling-schan mont.

Euroleon sinuosus Navás, 1935: 42. Type locality: China: Shaanxi: Tapaischan: Tsinling-schan mont.

Euroleon sinicus (Navás, 1930 b): Hölzel 1970 a: 128.

Euroleon sanxianus Yang, 1997: 618. Type locality: China: Hubei: Yichang: Zigui: Jiulingtou.

Euroleon flavicorpus Wang, 2009: 53 . Type locality: China: Shanxi: Jincheng: Yangcheng.

Specimens examined.

[ JBNU] • 1 ♂ 3 ♀ (reared from larva), Yulji-ri , Susan-myeon, Jecheon-si, Chungcheongbuk-do, Korea, 15. VI. 2023, J. I. Shim ; • 4 ♂ 4 ♀ (reared from larva), Changwon-ri , Nam-myeon, Yeongwol-gun, Gangwon-do, Korea, 25. VI. 2023, J. S. Kim ; • 6 ♂, Yulji-ri , Susan-myeon, Jecheon-si, Chungcheongbuk-do, Korea, 30. VII. 2024, J. S. Kim ; • 2 larvae (3 rd instar), Changwon-ri , Nam-myeon, Yeongwol-gun, Gangwon-do, Korea, 25. VI. 2023, J. S. Kim ; 1 larva (3 rd instar), Changwon-ri , Nam-myeon, Yeongwol-gun, Gangwon-do, Korea, 18. V. 2024, J. S. Kim .

Diagnosis.

Compared to other species in the genus Euroleon , E. coreanus has the morphological characteristics of a dark brown thorax and abdomen, a pair of brownish spots and a middle stripe on the pronotum, few dark brown markings on the wings, a small axillary plate, and a black marking on the clypeus. In larvae, the hind coxae are unmarked, abdominal sternite IX has an anterior row of four digging setae, a paired rastra each with three digging setae.

Description.

Male, adult. Head (Fig. 7 B, C ). Vertex wide, strongly raised, dark brown. Frons Yellow, broad dark brown band extending from below vertex to below base of antenna, with short yellow hairs; clypeus yellow, with black marking at middle. Antenna dark brown, short, with slightly defined club, densely covered with short black hairs; flagellum comprising ~ 30 flagellomeres. Mouthparts reddish brown; labrum yellow, with hyaline black hairs; maxillary palpus dark brown; labial palpus dark brown, much longer than maxillary palpus, spindle-shaped.

Thorax (Fig. 7 C ). Pronotum broad, length shorter than width, dark brown, yellow longitudinal midline, with long black hairs. Mesonotum dark brown, darker anteriorly, with long yellow hairs. Metanotum dark brown, with pair of yellow marking in the middle, with yellow hairs.

Legs. Coxae yellow, moderately covered with long brown hairs. Femora yellowish brown, moderately covered with black setae. Tibiae yellowish brown, moderately covered with black setae. Tibial spurs reddish brown, short, almost straight, approximately as long as combined lengths of tarsomeres 1–3. Tarsi reddish brown, tarsomere 5 approximately as long as combined lengtsh of tarsomeres 1–4; claws reddish brown.

Wings (Fig. 7 A ). With dark brown markings. Forewings veins and crossveins mostly brown; presectoral area with seven or eight crossveins; RP arising beyond CuA fork; CuP supporting one cell before fusing with 1 A; 3 A fused with 2 A; pterostigma white; anterior Banksian line absent, posterior Banksian line distinct. Hindwings approximately as long as forewings; narrower than forewing; presectoral area with 3–5 crossveins; RP arising beyond MP fork; pterostigma white; anterior Banksian line indistinct, posterior Banksian line distinct; male with pilula axillaris.

Abdomen (Fig. 7 A ). Shorter than hindwing, dark brown, densely covered with brown hairs.

Genitalia (Fig. 7 D, E, H – K ). Ectoproct rectangular, covered with long black setae. Sternite IX narrow, covered with long black setae. Gonarcus brown, arched, with long lateral arms. Mediuncus lightly sclerotized, dark brown, moderately raised. Parameres well sclerotized, dark brown, rectangular in ventral view.

Size. BL: 24.3–28.6 mm; FWL: 26.8–29.5 mm; HWL: 25.0– 27.6 mm.

Female, adult. Except terminalia, generally similar to male. Pilula axillaris absent. Terminalia (Fig. 7 F, G ): tergite VIII wider than tergite IX; tergite IX narrow, triangular in lateral view; ectoproct semicircular in lateral view; lateral gonapophyses semicircular in lateral view; smaller than ectoproct; posterior gonapophyses short, with long black setae; anterior gonapophyses small, with long black setae; pregenital plate distinct, triangular, presented on membrane below tergite VIII.

Size. BL: 24.8–25.9 mm; FWL: 27.4–31.2 mm; HWL: 25.6–29.8 mm.

Larva, 3 rd instar. General color pale brown, with dark brown markings (Fig. 8 A – C ). Head longer than wide, with an anterior pair of spots and a V-shaped dark brown marking on dorsal side, with two pairs of dark brown spots on ventral side; with a pair of spots in lateral side; mandibles reddish brown; interdental mandibular setae (6–7) (3) (2–3) (2); external setae long (Fig. 8 D, E ). Abdominal sternite VIII with long black setae. Abdominal sternite IX with an anterior row of four digging setae, a paired rastra each with three digging setae (Fig. 8 F ).

Size. BL: 8.9 mm; HL: 2.3 mm, HW: 1.6 mm, ML: 2.6 mm.

Biological notes.

Euroleon coreanus is observed very locally in calcareous grasslands of Chungcheongbuk-do and Gangwon-do in South Korea (Fig. 37 F ). Adults emerge from late June in South Korea. Larvae are pit builders. They were collected from dry, fine soils in calcareous grasslands with open surroundings (Fig. 36 B ).

Distribution.

Korea, China, Russia, Kazakhstan, Mongolia ( Bao and Wang 2006).

Remarks.

Euroleon coreanus was recorded as new species by Okamoto (1926) based on specimens from Korea. In contrast, Okamoto (1926) described E. coreanus seems to be common in Korea, whereas we affirm that this species is distributed very locally in calcareous grasslands in Chungcheongbuk-do and Gangwon-do.

Figures

Figure 7. Euroleon coreanus Okamoto, 1926, adult. A. Dorsal habitus, male; B. Head, frontal view; C. Head and thorax, dorsal view; D, E. Male terminalia: D. Lateral view; E. Ventral view; F, G. Female terminalia: F. Lateral view; G. Ventral view; H – K. Male genitalia: H. Dorsal view; I. Ventral view; J. Lateral view; K. Caudal view.

Figure 8. Euroleon coreanus Okamoto, 1926, third instar larva. A – C. Habitus: A. Dorsal view; B. Ventral view; C. Lateral view; D, E. Head: D. Dorsal view; E. Ventral view; F. Abdominal sternite IX.

Figure 32. Photographs of adults in the field, A. Deutoleon lineatus lineatus; B. Euroleon coreanus.

Figure 35. Living third instar larvae. A. Synclisis japonica; B. Baliga micans; C. Euroleon coreanus; D. Myrmeleon bore; E. Myrmeleon formicarius; F. Myrmeleon immanis; G. Nepsalus jezoensis; H. Distoleon littoralis; I. Ascalohybris subjacens; J. Libelloides sibiricus.

Figure 36. Habitats of the Myrmeleontidae larvae, with arrows indicating the positions where the larvae were collected. A. Under a dead tree trunk (Baliga micans); B. Calcareous grassland in limestone area (Euroleon coreanus); C. Sandy riverbank (Myrmeleon bore); D. Cut slope beside trail (Myrmeleon formicarius); E. Foredune (Myrmeleon immanis); F. Rock wall covered with lichen (Nepsalus jezoensis); G. Natural coastal dune (Synclisis japonica and Distoleon littoralis); H. Rocky hill (Ascalohybris subjacens and Libelloides sibiricus).

Figure 37. Distribution maps. A. Synclisis japonica and Baliga micans; B. Genus Myrmeleon (Myrmeleon bore, Myrmeleon fomicarius, and Myrmeleon immanis); C. Dendroleon pupillaris and Nepsalus jezoensis; D. Genus Distoleon (Distoleon littoralis and Distoleon nigricans); E. Genus Paraglenurus (Paraglenurus albiventris, Paraglenurus japonicus, and Paraglenurus melanostictus); F. Euroleon coreanus and Deutoleon lineatus lineatus; H. Ascalohybris subjacens and Libelloides sibiricus.