Gonioctena (Gonioctena) koryeoensis, Cho, Hee Wook & Lee, Jong Eun, 2010

Cho, Hee Wook & Lee, Jong Eun, 2010, Gonioctena koryeoensis (Coleoptera: Chrysomelidae: Chrysomelinae), a new species from Korea, with a description of immature stages, Zootaxa 2438, pp. 52-60 : 53-58

Gonioctena (Gonioctena) koryeoensis sp. nov.

Type material. Holotype: male, Mt. Cheonseongsan, Yangsan-si, Gyeongsangnam-do, KOREA, N35°25’9.7” E129°7’ 36.6”, 9.V.2006, HW Cho. Paratypes: 1 male and 2 females, same data as holotype; 1 male, same data as holotype except for 13.V.2005; 1 female, Mt. Jaeyaksan, Milyang-si, Gyeongsangnam-do, KOREA, N35°32’44.5” E128°58’ 48.7”, 5.V.1992, SS Kwon; 3 females, Mt. Gajisan, Ulju-gun, Ulsan, Gyeongsangnam-do, KOREA, N35°37’11.2” E129°0’ 10.7”, 19.V.2001, HJ Kim; 1 male, Dalseong-gun, Daegu, Gyeongsangbuk-do, KOREA, N35°43’36.8” E128°30’ 8.7”, 4.VI.2001, MH Kim; 1 female, Mt. Palgongsan, Daegu, Gyeongsangbuk-do, KOREA, N36°0’58.1” E128°41’36.6”, 23.V.1993, MH Kim.

Additional material. 34 larvae fixed, 7 larvae reared to pupae, 22 larvae reared to adults, same data as holotype; 17 larvae fixed, same data as holotype except for 13.V.2005.

Etymology. This endemic species is named "Koryeo," for the ancient kingdom of Korea from which the current name " Korea " originated.

Adult ( Figs. 1–8)

Diagnosis. This new species is similar in coloration to G. laeta Medvedev and G. japonica Chûjô et Kimoto , but can be distinguished by the following characters: small body length 4.9–5.6 mm (6.5–8.0 mm in G. japonica , 5.0–6.0 mm in G. laeta ); second antennal segment nearly as long as third (same in G. japonica , distinctly shorter than third in G. laeta ); pronotum with three small obscure spots (a pair of triangular basal black markings in the other species); ventral surfaces reddish brown (same in G. japonica , black in G. l a e t a); apical prolongation of aedeagus short and broad in dorsal view (extremely long and narrow in G. japonica , short and narrow in G. laeta ).

Description. Holotype male ( Fig. 1). Body convex and oblong, length 5.3 mm, width 3.4 mm. Head reddish brown anteriorly, black posteriorly; mandibles reddish brown with apex black; maxillary palp reddish brown; antennae yellowish brown; pronotum reddish brown with three small obscure spots; scutellum piceous; elytra reddish brown with five pairs of black spots; elytral suture black except for basal 1/3; ventral surfaces reddish brown; legs entirely reddish brown.

Head finely punctate with Y-shaped suture between eyes; interstices finely granulate. Mandibles threetoothed with excavation for reception of palpus at lateral side. Maxillary palp four-segmented with apical segment distinctly widened and apically truncate, 1.4 times wider than third segment. Antennae ( Fig. 2 ) eleven-segmented, nearly reaching the base of pronotum, first segment curved, 1.8 times as long as second, second as long as third, third slightly longer than fourth, seventh to tenth distinctly widened, each slightly longer than wide, eleventh longest, 1.8 times as long as wide, gently pointed at apex.

Pronotum twice as wide as long, widest at 1/5 of its length from basal corner, thence roundly narrowed anteriorly, slightly so posteriorly; anterior margin deeply emarginate; surface finely punctate medianly and strongly so laterally; interstices finely granuate; posterior angles with setigerous pores. Scutellum subtriangular, rounded at apex, nearly as long as wide, impunctate.

Elytra subparallel-sided, rounded at apex; humeri raised; surface with eleven regular rows of punctures; interstices finely punctate; elytral epipleura slanted downwards from outer edge, visible in lateral view.

Tibiae ( Fig. 3 ) armed with preapical tooth followed by coarsely setose emargination; fore-legs with first tarsal segment distinctly widened, slightly narrower than third segment; tarsal claws appendiculate.

Aedeagus ( Fig. 4 ) slightly widened, then suddenly and strongly narrowed with short and broad prolongation in dorsal view, sinuate with short prolongation in lateral view.

Female. Body length 5.6 mm, width 3.6 mm, larger than in male. Apical segment of maxillary palp smaller and more narrowly truncate than in male, 1.3 times wider than third segment. Spermatheca absent.

Variation. 14 males and 18 females (paratypes and reared adults) measured. Body length 4.9–5.6 mm, width 3.2–3.6 mm. The color variation as in Figs. 5–8.

First instar larva ( Fig. 18 )

Diagnosis. The first instar larva of this species is easily distinguished from the other known Gonioctena species by the following characters: dorsal region of meso- and metathorax with five tubercles Dai-Dae, DLai, Dpi, Dpe-DLpi and DLe; dorsal region of first six abdominal segments with six tubercles Dai-Dae, DLai, DLae, Dpi, Dpe-DLpi and DLpe.

Description. Similar to mature larva except for following characters. Body length 2.0– 2.4 mm, width 0.7– 0.8 mm, head width 0.55–0.57 mm.

Thorax. Prothorax with three tubercles D-DL-EP (dorsal, dorsolateral and epipleural fused, 12L 4–5S), P (pleural, 1S 1M) and ES-SS (eusternal and sternellar fused, 1L 1S). Meso- and metathorax with ten tubercles Dai-Dae (dorsal anterior interior and dorsal anterior exterior fused, 4L 1M), DLai (dorsolateral anterior interior, without seta), Dpi (dorsal posterior interior, 2L), Dpe-DLpi (dorsal posterior exterior and dorsolateral posterior interior fused, 1L 2M, egg bursters on DLpi), DLe (dorsolateral exterior, 3–4L 1–2S 2M), EPa (epipleural anterior, 3S), EPp (epipleural posterior, 3–5L), P (1S 1M), SS (1S) and ES (1L 3S).

Abdomen. First six segments with ten tubercles Dai-Dae (4L 1M), DLai (1L), DLae (dorsolateral anterior exterior, 2M), Dpi (2L), Dpe-DLpi (1L), DLpe (dorsolateral posterior exterior, 1L 1M), EP (4–5L 1S), P (2S 1M), PS-SS (parasternal and sternellar fused, 3S) and ES (1L). Seventh segment with dorsal and dorso-lateral tubercles fused (6L 4M). Eighth segment with five tubercles D-DL (8–10L 5M), EP (3–4S), P (2S 1M), PS- SS (2–3S) and ES (1S). Ninth segment with two tubercles D-DL-EP (7L 2S) and ES-PS-SS (4S). Tenth segment with ventral tubercles fused (4–5M).

Last instar larva ( Figs. 9–17 , 19 )

Diagnosis. The last instar larva of this species is easily distinguished from the other known Gonioctena species by the following characters: dorsal region of meso- and metathorax with six tubercles Dai-Dae, DLai, Dpi, Dpe-DLpi, DLe and ad1; dorsal region of first six abdominal segments with five tubercles Dai-Dae, DLai, DLae, Dpi-Dpe-DLpi and DLpe ( Fig. 19 ).

Description. Body length 7.5–8.6 mm, width 2.1–2.4 mm, head width 1.3–1.4 mm. Body yellowish white, slightly convexed dorso-ventrally ( Fig. 9 ). Head blackish brown with clypeus yellowish brown anteriorly. Tubercles on dorsum dark brown and very large, on venter pale brown and very weak. Chitinous platelets on dorsum dense and strong, on venter very weak. Sac-like eversible glands dorsally present between seventh and eighth abdominal segments. Legs dark brown to brown with yellowish white on inside.

Head ( Fig. 10 ). Hypognathous, rounded, strongly sclerotized. Epicranial suture Y-shaped. Epicranium covered with obscure dark spots with seventeen pairs of setae. Frons slightly depressed medially with five pairs of setae. Endocarina distinct; epistomal suture developed. Six stemmata present on each side. Antenna ( Fig. 14 ) three-segmented, first segment with two sensilla, second segment with a sensory papilla and four setae, third segment with six setae. Clypeus ( Fig. 13 ) with three pairs of setae. Labrum deeply notched at anterior margin with two pairs of setae; epipharynx with five pairs of setae. Mandible ( Fig. 11 ) five-toothed with two setae. Maxillary palp ( Fig. 15 ) three-segmented; palpifer with two setae; stipes with three setae; cardo with a seta; mala with fourteen setae. Labial palp two-segmented; prementum with four pairs of setae; postmentum covered with spinules antero-laterally with three pairs of setae.

Thorax. Dorsum with a narrow longitudinal line. Dorsal and epipleural regions of prothorax with a large tubercle D-DL-EP (17–19L 30–33S, Fig. 16 ); pleural region with a tubercle P (1L 3–4S); sternal region with a tubercle ES-SS (1L 3S). Dorsal region of meso- and metathorax with six tubercles Dai-Dae (2L 6S), DLai (2– 3S), Dpi (1L 3–4S), Dpe-DLpi (1L 5–6S), DLe (4L 12S 2–3M) and ad1 (secondary tubercle on dorsal region, 1S); epipleural region with two tubercles EPa (10S) and EPp (2L 5S); pleural region with a tubercle P (1L 2– 3S); sternal region with two tubercles SS (1S), ES (1L, 3S) and six additional setae. Mesothoracic spiracles annuliform, fused with tubercle EPa. All pairs of legs similar in size, shape and chaetotaxy; tibia ( Fig. 12 ) with nine setae; tarsus strongly curved with pointed tip, enlarged basally with a seta; pulvillus absent.

Abdomen. Dorsal region of first six segments with five tubercles Dai-Dae (10S), DLai (3–4S), DLae (3S), Dpi-Dpe-DLpi (2L 8S) and DLpe (1L 3–4S 1M); epipleural region with a tubercle EP (4L 11–12S); pleural region with a tubercle P (2L 5–7S); sternal region with four tubercles PS-SS (reduced to three small tubercles, 3S), ES (3S), as1 (secondary tubercle on sternal region, 1S), as2 (1S) and three additional setae. Seventh segment with dorsal and dorso-lateral tubercles fused (3L 15S 4M). Eighth segment with five tubercles D-DL (3L 12S 7M), EP (2L 8S), P (3S 1M), PS-SS (2S) and ES (1S). Ninth segment with two tubercles D-DL-EP (3L 12S 2M) and ES-PS-SS (3S 1M). Tenth segment with ventral tubercles fused (5M), pygopod developed. Spiracles ( Fig. 17 ) present on first eight segments, similar to mesothoracic spiracles but smaller.

Pupa ( Figs. 20–22 )

Diagnosis. The pupa is very similar to other species of Gonioctena , but can be distinguished by the shape and chaetotaxy of apical processes of ninth abdominal segment.

Description. Body length 5.2–5.5 mm, width 2.9–3.2 mm. Body orange ground color.

Head ( Fig. 21 ). Rounded with seven pairs of setae, not visible in dorsal view. Labrum slightly notched at anterior margin with two pairs of setae. Mandible with a seta.

Thorax. Pronotum with forty-two to fifty-one pairs of setae; mesonotum with two to three pairs of setae; metanotum with three to four pairs of setae ( Fig. 20 ). Femur with three setae apically; tibia with a seta preapically; last tarsal segment with a seta apically.

Abdomen. Each abdominal segment with ten to eighteen pairs of setae. Lateral projections present on first six abdominal segments. Apical processes of ninth abdominal segment ( Fig. 22 ) strongly pointed with seven pairs of setae. Spiracles present on first eight abdominal segments, but small and inconspicuous on sixth to eighth abdominal segments.

Distribution. Specimens were collected from mountainous areas in the southeastern part of the Korean Peninsula.

Host plants. The species feeds on leaves of Alnus spp. ( Betulaceae ), which are common trees on the Korean Peninsula.

Remarks. On 14 May 2006, a female in the laboratory laid 17 eggs that contained advanced embryos ( Fig. 23). The eggs hatched within a day. Ovoviviparity is rather common in Gonioctena , and females tend to lose spermatheca ( Bontems 1988). Gonioctena koryeoensis is reported here as an ovoviviparous species for the first time.

Figures

FIGURES 2 – 4. Gonioctena koryeoensis. 2. Antenna; 3. Fore tibia; 4. Aedeagus. Scale bars = 0.5 mm.

FIGURES 18 – 19. Schematics of larval tubercle pattern (above: prothorax, middle: mesothorax, below: second abdominal segment). 18. First instar larva; 19. Last instar larva.

FIGURES 9 – 17. Last instar larva of Gonioctena koryeoensis. 9. Habitus; 10. Head; 11. Mandible; 12. Tibia and tarsus; 13. Clypeus and labrum; 14. Antenna; 15. Lower mouth parts; 16. Pronotum (D-DL-EP); 17. Spiracle. Scale bars = 1 mm (9), 0.5 mm (10, 16), 0.1 mm (11 – 15, 17).

FIGURES 20 – 22. Pupa of Gonioctena koryeoensis. 20. Habitus; 21. Head; 22. Ninth abdominal segment. Scale bars = 1 mm (20), 0.5 mm (21, 22).