Distoleon littoralis Miller & Stange, 1999

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

Distoleon littoralis Miller & Stange, 1999

Fig. 19 , 20 , 35 H , 36 G , 37 D

Distoleon littoralis Miller & Stange, 1999: 53. Type locality: Taiwan: Ilan County: Hanben Beach.

Specimens examined.

[ JBNU] • 1 ♀, Gyorae-ri , Jocheon-eup, Jeju-si, Jeju-do, Korea, 23. VII. 2021, J. S. Kim ; • 4 ♀, Sindu-ri , Wonbuk-myeon, Taean-gun, Chungcheongnam-do, Korea, 20. VIII. 2022, J. S. Kim ; • 1 ♂ 5 ♀ (reared from larva), Jungtong-ri , Bogil-myeon, Wando-gun, Jeollanam-do, Korea, 3. III. 2023, J. I. Shim ; • 1 ♂ (reared from larva), Sindu-ri , Wonbuk-myeon, Taean-gun, Chungcheongnam-do, Korea, 18. VI. 2023, J. S. Kim ; • 1 ♀, Sanghyo-dong , Seogwipo-si, Jeju-do, Korea, 23. IX. 2023, J. S. Kim ; • 2 ♂ 1 ♀, Gamsan-ri , Andeok-myeon, Seogwipo-si, Jeju-do, Korea, 20. VII. 2024, Y. T. Jang ; • 1 ♀, Jungdo-ri , Wando-eup, Wando-gun, Jeollanam-do, Korea, 26. VII. 2024, J. S. Kim ; • 2 ♀, Naewol-ri , Bigeum-myeon, Sinan-gun, Jeollanam-do, Korea, 27. VII. 2024, M. K. Jeong ; • 2 ♂ 2 ♀, Sindu-ri , Wonbuk-myeon, Taean-gun, Chungcheongnam-do, Korea, 31. VII. 2024, J. S. Kim ; • 1 ♀, Naewol-ri , Bigeum-myeon, Sinan-gun, Jeollanam-do, Korea, 1. VIII. 2024, J. S. Kim ; • 2 ♀, Jungdo-ri , Wando-eup, Wando-gun, Jeollanam-do, Korea, 4. VIII. 2024, Y. T. Jang ; • 2 ♀, Seopo-ri , Deokjeok-myeon, Ongjin-gun, Incheon, Korea, 13. VIII,. 2024, J. S. Kim ; • 2 ♂, Gureom-ri , Deokjeok-myeon, Ongjin-gun, Incheon, Korea, 14. VIII,. 2024, J. S. Kim ; • 1 ♂, Gureom-ri , Deokjeok-myeon, Ongjin-gun, Incheon, Korea, 15. VIII,. 2024, J. S. Kim ; • 1 ♂, Oksan-ri , Geoje-myeon, Geoje-si, Gyeongsangnam-do, Korea, 17. VIII,. 2024, Y. T. Jang ; • 1 ♂, Gilgok-ri , Maehwa-myeon, Uljin-gun, Gyeongsangbuk-do, Korea, 28. VIII. 2024, J. S. Kim ; • 2 ♀, Sa-ri , Heuksan-myeon, Sinan-gun, Jeollanam-do, Korea, 3. IX. 2024, J. S. Kim ; • 2 larvae (3 rd instar), Jungtong-ri , Bogil-myeon, Wando-gun, Jeollanam-do, Korea, 3. III. 2023, J. I. Shim .

Diagnosis.

Distoleon littoralis has pale dark brown spots in the cubital area of the forewing and the rhegma area of the hindwing. Forewing presectoral area has eight or nine crossveins. Fore coxa has many elongate white hairs. In larvae, the head is yellowish white and has an anterior dark marking and a V-shaped small dark brown marking on the dorsal side, as well as two pairs of dark spots on the ventral side. Abdominal sternite IX has sparse short digging setae and a paired rastra each with four digging setae.

Description.

Male, adult. Head (Fig. 19 B, C ). Vertex slightly narrow, slightly raised, dark brown. Frons reddish brown, with broad dark brown band extending from below vertex to below base of antenna; clypeus yellowish brown, with long pale yellow hairs. Antenna reddish brown, long, with slightly defined club, densely covered with short black hairs; flagellum comprising ~ 50 flagellomeres, each flagellomere with distal yellow annulation. Mouthparts brown; labrum brown, with hyaline brown hairs; maxillary palpus yellowish brown; labial palpus yellowish brown.

Thorax (Fig. 19 C ). Pronotum broad, length shorter than width, dark brown, with narrow yellow longitudinal middle stripe, with long black hairs. Mesonotum and metanotum dark brown, with several yellow spots.

Legs. Coxae mostly yellow, moderately covered with long white hairs. Femora yellowish brown; moderately covered with black and white hairs. Tibiae mostly yellowish brown; partly black; densely covered with short black hairs. Tibial spurs dark brown proximally, reddish brown distally, long, curved, in forelegs and midlegs approximately as long as combined lengths of tarsomeres 1–4, in hindleg approximately as long as combined lengths of tarsomeres 1–3. Tarsi yellowish white, Tarsomere 5 as long as combined lengths of tarsomeres 1–4; claws reddish brown.

Wings (Fig. 19 A ). With dark brown markings. Forewings veins and crossveins dark brown and pale yellow; presectoral area with eight or nine crossveins; RP arising beyond CuA fork; CuP supporting one cell before fusing with 1 A; 2 A fused with 3 A; pterostigma yellowish white; cubital area with pale dark brown marking; anterior Banksian lines distinct; posterior Banksian lines distinct. Hindwing slightly shorter than forewing; presectoral area with one crossvein; RP arising before MP fork; pterostigma yellowish white; rhegma area with pale brown marking; pterostigma yellowish white; anterior Banksian lines absent; posterior Banksian lines absent; male without pilula axillaris.

Abdomen (Fig. 19 A ). Shorter than hindwing, dark brown, tergites II – VIII with variable yellow markings, densely covered with short hyaline hairs.

Genitalia (Fig. 19 D, E, H – K ). Ectoproct semicircular, covered with long black setae. Sternite IX narrow, covered with long black setae. Gonarcus white, arched. Mediuncus absent. Parameres well sclerotized, brown, with long black setae, moderately hooked in lateral view.

Size. BL: 29.9–33.3 mm; FWL: 30.5–34.8 mm; HWL: 28.0– 34.1 mm.

Female, adult. Except terminalia, generally similar to male. Terminalia (Fig. 19 F, G ): tergite VIII wider than tergite IX; tergite IX narrow, rectangular in lateral view; ectoproct semicircular in lateral view; lateral gonapophyses semicircular in lateral view, smaller than ectoproct; posterior gonapophyses long, with long black setae; anterior gonapophyses absent; pregenital plate absent.

Size. BL: 27.8–33.1 mm; FWL: 29.8–38.2 mm; HWL: 28.5–37.4 mm.

Larva, 3 rd instar. General color reddish brown, with dark brown markings (Fig. 20 A – C ). Head longer than wide, with an anterior dark marking and a V-shaped small dark brown marking on dorsal side; with two pairs of dark spots on ventral side; with a dark brown stripe in lateral side; mandibles reddish brown; interdental mandibular setae (4) (1) (1) (0); external setae short (Fig. 20 D, E ). Abdominal sternite VIII with sparse black setae and prominent odontoid processes. Abdominal sternite IX with sparse short digging setae in front of rastra; a paired rastra each with four digging setae (Fig. 20 F ).

Size. BL: 12.1 mm; HL: 3.2 mm, HW: 2.6 mm, ML: 3.1 mm.

Biological notes.

Distoleon littoralis is frequently observed in South Korea, primarily in coastal areas, though it is also occasionally observed inland (Fig. 37 D ). Adults mainly emerge from July to September in South Korea. Larvae are ambush predators, concealing themselves in the sand of dunes. They were collected in sandy areas near the roots of Pinus trees (Fig. 36 G ).

Distribution.

Korea (new record), China ( Stange et al. 2003; Wang et al. 2018).

Remarks.

The first record of Distoleon littoralis in Korea was by Okamoto (1926), who identified it as D. contubernalis ( McLachlan, 1875) . However, additional taxonomic research is needed on the species status of D. littoralis and its associated species complex.

Figures

Figure 19. Distoleon littoralis Miller & Stange, 1999, 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 20. Distoleon littoralis Miller & Stange, 1999, 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.