Myrmeleon bore ( Tjeder, 1941 )

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

Myrmeleon bore ( Tjeder, 1941)

Figs 9 , 10 , 35 D , 36 C , 37 B

Grocus bore Tjeder, 1941: 74. Type locality: Sweden: Kalmar: Öland: Byrum.

Enza otiosus Navás, 1912: 114 . Type locality: Japan.

Myrmeleon bore ( Tjeder, 1941): Meinander 1962: 71.

Morter bore ( Tjeder, 1941): Friheden 1973: 32.

Myrmeleon exigus Yang, 1999: 148. Type locality: China: Fujian: Dongshan.

Myrmeleon tschernovi Krivokhatsky, Shapoval & Shapoval, 2014: 173. Type locality: Russia: Kaliningrad: Curonian Spit: field station “ Fringilla ”.

Specimens examined.

[ JBNU] • 1 ♂, Oeseonmi-ri , Onjeong-myeon, Uljin-gun, Gyeongsangbuk-do, Korea, 9. VII. 2022, J. S. Kim ; • 4 ♀, Sindu-ri , Wonbuk-myeon, Taean-gun, Chungcheongnam-do, 20. VIII. 2022, J. S. Kim ; • 1 ♀, Sindu-ri , Wonbuk-myeon, Taean-gun, Chungcheongnam-do, 17. VI. 2023, J. S. Kim ; • 1 ♂ (reared from larva), Sindu-ri , Wonbuk-myeon, Taean-gun, Chungcheongnam-do, 18. VI. 2023, J. S. Kim ; • 1 ♀, Yulji-ri , Susan-myeon, Jecheon-si, Chungcheongbuk-do, Korea, 24. VI. 2023, J. S. Kim ; • 2 ♂ 1 ♀, Oeseonmi-ri , Onjeong-myeon, Uljin-gun, Gyeongsangbuk-do, Korea, 13. VII. 2024, J. S. Kim ; • 1 ♂, Naewol-ri , Bigeum-myeon, Sinan-gun, 26. VII. 2024, M. K. Jeong ;; • 1 ♂, Sindu-ri , Wonbuk-myeon, Taean-gun, Chungcheongnam-do, 31. VII. 2024, J. S. Kim ; • 1 ♂, Gorangpo-ri , Jangnam-myeon, Yeoncheon-gun, Gyeonggi-do, 9. VIII. 2024, Y. T. Jang ; • 1 ♀, Samgot-ri , Jung-myeon, Yeoncheon-gun, Gyeonggi-do, 10. VIII. 2024, Y. T. Jang ; • 1 ♂ 3 ♀, Seopo-ri , Deokjeok-myeon, Ongjin-gun, Incheon, Korea, 13. VIII. 2024, J. S. Kim ; • 1 ♂ 1 ♀, Gureom-ri , Deokjeok-myeon, Ongjin-gun, Incheon, Korea, 14. VIII. 2024, J. S. Kim ; • 2 ♂ 4 ♀, Gureom-ri , Deokjeok-myeon, Ongjin-gun, Incheon, Korea, 15. VIII. 2024, J. S. Kim ; • 2 ♂, Gilgok-ri , Maehwa-myeon, Uljin-gun, Gyeongsangbuk-do, Korea, 7. IX. 2024, J. S. Kim ; • 3 larvae (3 rd instar), Sindu-ri , Wonbuk-myeon, Taean-gun, Chungcheongnam-do, 18. VI. 2023, J. S. Kim ; • 2 larvae (3 rd instar), Samgeum-ri , Geumgangsong-myeon, Uljin-gun, Gyeongsangbuk-do, Korea, 5. VI. 2024, J. S. Kim ; • 2 larvae (3 rd instar), Seopo-ri , Deokjeok-myeon, Ongjin-gun, Incheon, Korea, 13. VIII. 2024, J. S. Kim ; 1 larva (3 rd instar), Gureom-ri , Deokjeok-myeon, Ongjin-gun, Incheon, Korea, 15. VIII. 2024, J. S. Kim ; • 2 larvae (2 nd and 3 rd instar), Goeok-ri , Yongjin-eup, Wanju-gun, Jeonbuk-do, Korea, 8. III. 2025, Y. T. Jang .

Diagnosis.

Myrmeleon bore is similar to M. formicarius in general appearance. The two species can be distinguished by differences in the Banksian line, the pilula axillaris, and the larval hind coxa. In M. bore , the posterior Banksian lines in the forewings are distinct, while they are indistinct in M. formicarius . Myrmeleon bore has a pilula axillaris in males, whereas it is absent in M. formicarius . Unlike the larvae of M. formicarius , which have some dark markings on the hind coxa, the larvae of M. bore have no such markings.

Description.

Male, adult. Head (Fig. 9 B, C ). Vertex wide, strongly raised, black, moderately covered with short black hairs, with sparse long hyaline hairs anteriorly. Frons black; clypeus yellow, with black marking extending from frons. Antenna black, short, with slightly defined club, densely covered with short black hairs; flagellum comprising ~ 30 flagellomeres. Mouthparts yellowish brown; labrum yellowish brown, with several black hairs; maxillary palpus mostly dark brown; labial palpus mostly dark brown, spindle-shaped.

Thorax (Fig. 9 C ). Pronotum broad, length shorter than width, dark brown, with yellow anterior corners, with hyaline hairs and long black hairs. Mesonotum dark brown, darker anteriorly, with yellowish white hairs. Metanotum dark brown, with pair of yellow spots at the middle, with yellowish white hairs.

Legs. Coxae dark brown, moderately covered with long brown hairs. Femora yellow, moderately covered with black setae. Tibiae yellow; moderately covered with black setae; foretibia largely dark brown; midtibia dark brown at distal end; hind tibia dark brown at distal end and ventral surface. Tibial spurs reddish brown, short, almost straight, approximately as long as length of tarsomere 1. Tarsi dark brown, tarsomere 5 shorter than combined lengths of tarsomeres 1–4; claws reddish brown; short; curved.

Wings (Fig. 9 A ). Without marking. Forewing veins and crossveins mostly dark brown; presectoral area with 6–8 crossveins; RP arising beyond CuA fork; CuP supporting one cell before fusing with 1 A; 3 A fused with 2 A; pterostigma yellowish white; anterior Banksian line indistinct, posterior Banksian line distinct. Hindwings shorter and narrower than forewings; presectoral area with five crossveins; RP arising beyond MP fork; pterostigma yellowish white; anterior Banksian line absent, posterior Banksian line distinct; male with pilula axillaris.

Abdomen (Fig. 9 A ). Shorter than hindwing, dark brown, densely covered with hyaline hairs.

Genitalia (Fig. 9 D, E, H – K ). Ectoproct rectangular in lateral view, covered with long black setae. Sternite IX narrow, covered with long black setae. Gonarcus brown, arched, with long lateral arms. Mediuncus well sclerotized, black, waterdrop-shaped in lateral view. Parameres well sclerotized, dark brown, triangular in ventral view.

Size. BL: 21.1–28.7 mm; FWL: 22.8–30.2 mm; HWL: 21.0– 28.6 mm.

Female, adult. Except terminalia, generally similar to male. Pilula axillaris absent. Terminalia (Fig. 9 F, G ): tergite VIII wider than tergite IX; tergite IX narrow, semicircular 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, semicircular, presented on posterior margin of sternite VII.

Size. BL: 24.5–27.3 mm; FWL: 26.8–32.9 mm; HWL: 24.2–30.6 mm.

Larva, 3 rd instar. General color yellowish brown, with dark brown markings (Fig. 10 A – C ). Head triangular, longer than wide, with an anterior large dark marking and a V-shaped dark brown marking on dorsal side, with a pair of dark brown spots on ventral side; with a pair of dark brown spots in lateral side; mandibles yellowish brown; interdental mandibular setae (5) (2–3) (1–3) (1); external setae long (Fig. 10 D, E ). Abdominal sternite VIII with long black setae. Abdominal sternite IX with sparse ventral digging setae and four short digging setae in front of rastra; a paired rastra each with four digging setae (Fig. 10 F ).

Size. BL: 8.7 mm; HL: 2.1 mm, HW: 1.5 mm, ML: 2.3 mm.

Biological notes.

Myrmeleon bore is a species that is frequently observed around sandy environments throughout South Korea (Fig. 37 B ) with adults emerging from June. Larvae are pit builders. They were collected in various sandy environments such as coastal dunes, riverbanks, and dried-up valleys (Fig. 36 C ).

Distribution.

Korea, Japan, China, Russia, Uzbekistan, Europe ( Stange 2004; Sekimoto 2014).

Remarks.

Myrmeleon bore was first reported from Korea by Kuwayama (1959). Enza otiosus Navás, 1912 has been considered a synonym of M. bore by Stange (2004), Sekimoto (2014), and Wang et al. (2018). However, based on the priority of the nomenclature of the International Code of Zoological Nomenclature ( ICZN 1999), M. bore should be treated as a synonym of M. otiosus . The relationship between both species needs further research because the type localities of E. otiosus ( holotype in Japan) and M. bore ( syntypes in Sweden and Norway) are a great distance apart ( Hassan et al. 2022).

Figures

Figure 9. Myrmeleon bore Tjeder, 1941, 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 10. Myrmeleon bore Tjeder, 1941, 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 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.