South Korea: Gyeongnam Province, Namhaedo Island, Mangunsan Mountain, 34°51'52"N, 127°51'47"E.

Holotype: male (DBET), KOREA: Gyeongnam Province, Namhaedo Island, Mangunsan Mountain, 34°51'52"N, 127°51'47"E 280 m, 7.IV.2006, H.-W. Cho. Paratypes: 2 males and 6 females (DBET), same data as holotype; 10 males and 10 females (HWC), same data as holotype except for 13.VI.2007, H.-Y. Kwon; 1 male (HWC), KOREA: Gyeongnam Province, Miryang, Gajisan Mountain, 35°35'46"N, 128°59'38"E 500 m, 17.VIII.2001, T.-H. Ahn; 1 female (HWC), same data as preceding paratype except for 25.V.2001, G.-S. Jung.

42 larvae collected or obtained from adults, same data as holotype except for 23.IV.–15.V.2006.

(Figs 1–7, 19).

Diagnosis. The new species is very similar in coloration to Ambrostoma leigongshana Wang, but can be distinguished by the following characters: antennomere 3 much longer than 4 (equal in length in Ambrostoma leigongshana); pronotum with moderately dense punctures in lateral depression (dense and coarse punctures in Ambrostoma leigongshana); aedeagus widest at apical 1/5, thence narrowed with trapezoidal apex (elongate apically with rounded apex in Ambrostoma leigongshana); spermatheca almost straight, curved at apex (strongly curved in Ambrostoma leigongshana).

Description. Holotype (Figs 1–2). Body length 11.7 mm, width 5.7 mm, strongly convex dorsally. Head emerald green to ultramarine with 2 pairs of small orange yellow markings on central part. Mouthparts midnight blue. Antennomeres 1–7 ultramarine, 8–11 black. Pronotum emerald green to ultramarine with a pair of large orange yellow markings. Scutellum ultramarine. Elytra ultramarine with a pair of orange yellow markings at base and 2 pairs of orange yellow longitudinal markings on central-posterior part, all markings surrounded by emerald green. Venter mainly ultramarine with greenish luster. Legs midnight blue.

Head. Width 3.4 mm, interocular distance 2.5 mm. Vertex and frons with sparse and small punctures. Clypeus and labrum with small punctures bearing long setae. Mandibles with moderately dense punctures bearing setae on outer surface. Maxillary palp 4-segmented with apical palpomere distinctly widened and truncate. Antennae (Fig. 3) reaching elytral humeri; antennomere 1 robust, longer than 3; antennomere 2 as long as 4; antennomere 3 distinctly longer than 4; antennomeres 5–10 moderately widened; antennomere 11 longest and 2.6 times as long as wide.

Pronotum. Length 2.7 mm, width 5.4 mm. Lateral sides roundly widened anteriorly, widest at anterior 1/4. Anterior margin widely emarginated. Trichobothria on anterior and posterior angles. Disc with dense and small punctures, larger than those of head; hardly confluent large punctures in lateral longitudinal depression; interspaces with spare and minute punctures. Scutellum subtriangular, slightly wider than long, impunctate.

Elytra. Length 8.8 mm, width 6.8 mm. Sides moderately widened posteriorly and widest at posterior 2/5, thence rounded at apex. Disc with double irregular rows of punctures; transverse depression with large punctures, subequal to those of side of pronotum; interspaces with spare and minute punctures. Epipleuron flat, inner margin with micro setae along an entire length. Hind wing well developed.

Venter. Hypomera impunctate; prosternum with sparse and small punctures; prosternal process strongly enlarged and slightly emarginated apically. Abdominal sternites wrinkled laterally with sparse and small punctures; last abdominal sternite deeply emarginated on both sides. Legs moderately robust; tibiae simple without preapical tooth; fore and middle legs with tarsomere 1 slightly narrower than 3; tarsal claws simple.

Aedeagus. Strongly convex at middle, curved and sinuated at apex in lateral view (Fig. 4); subparallel-sided, widest at apical 1/5, thence narrowed with trapezoidal apex, with 2 weakly sclerotized plates in dorsal view (Fig. 5); internal sac curved, shorter than median lobe with thick and long flagellum (Fig. 6).

Paratypes. Body length 10.9–12.7 mm, width 5.2–6.2 mm. Coloration similar to holotype. Female: larger than male; tarsomere 1 of fore and middle legs distinctly narrower than 3; last abdominal sternite rounded; spermatheca (Fig. 7) almost straight, curved at apex.

(Figs 15, 17).

Description. Body length 2.7–4.2 mm, width 1.2–1.7 mm, head width 0.90–0.95 mm (n = 5). Body convex dorsally on abdomen. Pale yellow with head dark brown, tubercles and legs brown (Fig. 17). Tubercles weakly developed (Fig. 15). Sclerotized platelets on dorsum dense and strong, on venter almost absent. Setae longer than in other instars, bases of setae sclerotized.

Head. Vertex and temporal side with 30–32 pairs of long setae and 15–19 pairs of short setae. Frons with 16–19 pairs of long setae. Clypeus and labrum, each with 2 pairs of long setae. Mouthparts similar in shape and chaetotaxy to those of the last instar larva, except for stipes with 3 setae and postmentum with 3 pairs of setae.

Thorax. Prothorax with D-DL-EP (53–57L 4–6S); P (1L); ES (1L) weakly sclerotized; SS represented by a short seta; sternal region with 1–2 additional setae. Meso- and metathorax with Dae (1L); Dpi (1L); dorsal region with 11–13 additional short setae; DLi (1–3L) well developed with egg burster; DLe (4–5L 8–11S); EPa (4–5L 5S) fused with spiracle; EPp (2L 3–4S); P (1L); ES (1L) weakly sclerotized; SS represented by a short seta; sternal region with 2–3 additional setae.

Abdomen. Dorsal and dorsolateral regions with 31–35 short setae; Dpi (1L); Dpe (1L); DLp (1L); EP (9–10L 8–10S); P (3S) divided; PS-SS represented by 4–5 short setae; ES (1S); segment 8 with D-DL (3–4L 11–12S) fused; segment 9 with D-DL-EP (3L 11–12S) fused; segment 10 with pygopod developed; egg burster on segment 1 much smaller than thoracic ones.

Similar to the last instar larva except for following characters: body length 4.2–5.7 mm, width 1.8–2.4 mm, head width 1.25–1.35 mm (n = 4); black markings on head and dark patterns on dorsum much larger than those of the last instar larva; pronotum with black markings partly connected.

Description. Similar to the last instar larva except for following characters: body length 7.2–8.1 mm, width 2.8–3.8 mm, head width 1.90–2.05 mm (n = 3); dark patterns on dorsum much larger than those of the last instar larva.

(Figs 8–14, 16, 18).

The last instar larva is easily distinguished from larva of Ambrostoma superbum (Thunberg) in the following characters: pronotum with 3 black markings (2 black markings in Ambrostoma superbum); dorsolateral posterior region of each abdominal segment without dark patterns (with dark patterns in Ambrostoma superbum); width of peritreme less than half width of abdominal segment (equal to half width in Ambrostoma superbum).

Body length 11.6–12.8 mm, width 4.7–5.3 mm, head width 2.60–2.65 mm (n = 5). Body strongly convex dorsally on abdomen (Fig. 8). Yellowish white in alcohol specimens, creamy white with orange stripes in live specimens (Fig. 18). Head yellowish brown with a pair of large black markings. Pronotum with 3 black markings. Tubercles, spiracles and legs dark brown. Dorsum with dark patterns consisting of dense and strong sclerotized platelets, sparsely covered with micro setae (Fig. 10). Tubercles undeveloped (Fig. 16). Venter covered with short and moderately long setae, bases of setae not sclerotized.

Head. Hypognathous, rounded, well sclerotized, covered with dark spots (Fig. 9). Vertex and temporal side with 10–11 pairs of long setae and 77–82 pairs of short setae. Epicranial suture Y-shaped; coronal suture distinct along an entire length; frontal suture indistinct for lateral 2/5. Frons slightly depressed medially with 14–15 pairs of long setae and 17–22 pairs of short setae. Endocarina distinct; epistomal suture developed. Six stemmata on each side. Antenna 3-segmented; antennomere 1 without seta; antennomere 2 with a sensory papilla and 4 setae; antennomere 3 with 5 setae. Clypeus trapezoid with 2 pairs of setae. Labrum (Fig. 11) deeply emarginate anteriorly with 2 pairs of setae; epipharynx with 2 pairs of setae. Mandibles (Fig. 13) symmetrical, 5-toothed with 2 setae. Maxillary palp (Fig. 14) 3-segmented; palpomere 1 without seta; palpomere 2 with 3 setae; palpomere 3 conical with a seta; palpiger with 2 setae; mala with 13–14 setae; stipes with 10–13 setae; cardo without seta. Labial palp 2-segmented; prementum with 4–5 pairs of setae; postmentum with 4 pairs of setae.

Thorax. Prothorax with D-DL-EP scattered with micro setae, not sclerotized; P (6–7S); ES and SS, each represented by a short seta; sternal region with 14–16 additional setae. Meso- and metathorax with DLe (27–30M); P (8–10S); EPa and EPp, each represented by 23–27 short setae; ES and SS, each represented by a long seta; sternal region with 20–35 additional setae; mesothoracic spiracle annuliform with large peritreme; metathoracic spiracle vestigial. Legs rather stout; tibia with 28–30 setae; tarsungulus strongly curved; basal tooth weakly developed with a seta (Fig. 12).

Abdomen. Tubercles absent on segments 1–7 except for P represented by 3–4 short setae arising from sclerotized bases; epipleural to sternal regions with a lot of short setae. Segment 8 with D-DL (10–12S); segment 9 with D-DL-EP (12–14L 1–2M); segment 10 with pygopod well developed; spiracle with large peritreme similar to mesothoracic one, but smaller; eversible glands absent.

This endemic species is named after the type locality, Korea.

Specimens were collected in the southeastern part of the Korean Peninsula and on adjacent Namhaedo Island.

Overwintered adults were observed under bark or in fallen leaves near the base of trees in early April (Fig. 19). Adults and larvae fed on leaves of Zelkova serrata Makino (Ulmaceae) which is quite a common tree in Korea. Ulmus pumila Linnaeus (also Ulmaceae) was the only known host plant for three other Ambrostoma species (Yu et al. 1996). On 7 May 2006, a female laid 4 eggs that contained fully developed embryos in the laboratory. Four females were dissected shortly afterward, and 17–79 enclosed larvae were found in abdomen (Fig. 20). About 50 ovoviviparious species are actually known in 7 genera of Chrysomelinae (Bontems 1988, Bontems and Lee 2008). Ovoviviparity is reported for the first time in the genus Ambrostoma.