Amemboa hainanica Leng, Jin & Ye sp. nov. Figs 1, 2 A, B, 3 A, 4 A, B, E, F, 5, 6 A, 7 A, 8 A, 9 A, 10 A, 11 A, 12 A, B, 15 A, 16, 18 Material examined. Holotype: ♂ (apterous), China, Hainan Province, Bai-sha County, Luo-shuai Village, Xian-nv-xi; 19 ° 5 ' 58.4 " N, 109 ° 32 ' 46.2 " E; 324 m a. s. l.; 26 Jul. 2017; Zhen Ye & Juan-juan Yuan leg. (NKUM). Paratypes: 3 ♂♂, 3 ♀♀ (apterous), same data as holotype (NKUM) • 3 ♂♂, 3 ♀♀ (apterous), China, Hainan Province, Wan-ning City, Xing-long County, Ai-qing-gu; 18 ° 47 ' 54.3 " N, 110 ° 8 ' 19.8 " E; 148 m a. s. l.; 11 Aug. 2017; Juan-juan Yuan leg. (NKUM) • 1 ♂, 1 ♀ (apterous), China, Hainan Province, Bao-ting County, Qi-xian-ling National Forest Park; 18 ° 42 ' 12.2 " N, 109 ° 41 ' 44.5 " E; 318 m a. s. l.; 4 Aug. 2017; Zhen Ye leg. (NKUM) • 1 ♂, 1 ♀ (apterous), China, Hainan Province, Le-dong County, Jian-feng-ling, Wu-fen-he, Pool 3; 18 ° 43 ' 58.0 " N, 108 ° 53 ' 9.6 " E; 859 m a. s. l.; 15 Aug. 2017; Juan-juan Yuan leg. (NKUM) • 1 ♂, 1 ♀ (apterous), China, Hainan Province, Qiong-zhong County, Li-mu-shan; 19 ° 11 ' 11.1 " N, 109 ° 44 ' 21.4 " E; 631 m a. s. l.; 25 Jul. 2017; Zhen Ye leg. (NKUM) • 1 ♂, 1 ♀ (apterous), China, Hainan Province, Bai-sha County, Luo-shuai Village, Xian-nv-xi; 19 ° 5 ' 58.4 " N, 109 ° 32 ′ 46.2 " E; 324 m a. s. l.; 26 Jul. 2017; Zhen Ye & Juan-juan Yuan leg. (NKUM) • 1 ♂, 1 ♀ (apterous), China, Hainan Province, Wan-ning City, Jian-feng-ling Nature Reserve, Yu-lin-gu; 18 ° 42 ' 30.9 " N, 108 ° 49 ' 20.2 " E; 1 Aug. 2017; Zhen Ye leg. (NKUM) • 1 ♂, 1 ♀ (apterous), China, Hainan Province, Qiong-zhong County, Beng-ling Village; 18 ° 46 ' 42.7 " N, 109 ° 50 ' 29.3 " E; 253 m a. s. l.; 9 Aug. 2017; Zhen Ye leg. (NKUM) • 1 ♂, 1 ♀ (apterous), China, Hainan Province, Wan-ning City, Xing-long County, Ai-qing-gu; 18 ° 47 ' 54.3 " N, 110 ° 8 ' 19.8 " E; 148 m a. s. l.; 11 Aug. 2017; Juan-juan Yuan leg. (NKUM). Non-type materials: 1 ♂ (apterous), China, Hainan Province, Chang-jiang County, Ba-wang-ling Nature Reserve; 19 ° 7 ' 16.8 " N, 109 ° 9 ' 38.2 " E; 650 m a. s. l.; 6 Apr. 2008; Bo Cai leg. (NKUM) • 1 ♂ (apterous), China, Hainan Province, Bao-ting County, Xian-an-shi-lin; 18 ° 36 ' 5.8 " N, 109 ° 25 ' 59.5 " E; 571 m a. s. l.; 7 Aug. 2017; Kun Jiang & Si-ying Fu leg. (NKUM) • 2 ♂♂, 1 ♀ (apterous), China, Hainan Province, Bai-sha County, Shi-cai Village, Ying-ge-ling Nature Reserve, Nan-kai Branch Station; 19 ° 4 ' 23.0 " N, 109 ° 22 ' 34.0 " E; 310 m a. s. l.; 20 Jul. 2013; Yan-hui Wang leg. (NKUM) • 3 ♂♂ (apterous), China, Hainan Province, Dan-zhou City, Lu-mu-wan Waterfall; 19 ° 13 ' 54.6 " N, 109 ° 41 ' 16.5 " E; 202 m a. s. l.; 22 Jul. 2017; Zhen Ye leg. (NKUM) • 3 ♂♂, 8 ♀♀ (apterous), China, Hainan Province, Tun-chang County, Nan-lv-ling; 19 ° 13 ' 49.0 " N, 110 ° 10 ' 20.8 " E; 172 m a. s. l.; 24 Jul. 2017; Zhen Ye leg. (NKUM) • 1 ♂ (apterous), China, Hainan Province, Wu-zhi-shan City, Shui-man Township, Shi-ling-rui Bridge; 18 ° 54 ' 10.9 " N, 109 ° 39 ' 23.7 " E; 3 Jul. 2014; Qiang Xie leg. (NKUM) • 3 ♂♂, 6 ♀♀ (apterous), China, Hainan Province, Bai-sha County, Ying-ge-ling Nature Reserve, Nan-kai Branch Station; 19 ° 2 ' 1.7 " N, 109 ° 24 ' 14.5 " E; 20 Jul. 2013; Hao-yang Wu leg. (NKUM). Diagnosis. Color pattern as shown in Figs 1, 2 A, B, 3 A, 4 A, B, E, F, 5 A – F, 12 A, B. Males: profemur moderately incrassate (Figs 5 G, 6 A); ventral side of the profemur with two tufts of dark setae on apical 1 / 2 (Figs 5 G, 6 A); protibia slightly curved and with an indistinct tumescence on basal 1 / 3 (Figs 5 G, 6 A); abdominal segment VIII relatively short (Fig. 8 A); pygophore posteriorly with a digitate median process, also with a pair of distinct blunt processes on both sides of the median process (Figs 5 H, I, 8 A, 9 A); median process of pygophore relatively broad in lateral view (Figs 5 J, K, 10 A, 11 A); lateral arm of proctiger relatively slender in ventral view (Figs 5 H, 8 A), with a distinct subapical process in lateral view, forming a distinct subapical notch on dorsal margin (Figs 5 J, 10 A). Comparative notes. Amemboa hainanica sp. nov. is most similar to A. cambodiana D. Polhemus, 2017. In males of both species, the lateral arm of the proctiger in lateral view exhibits a distinct subapical notch on its dorsal margin, isolating a small, slightly recurved apical process, which gives the lateral arm a hooked appearance (Fig. 10 A; also see Polhemus 2017: fig. 22). These are the only two known Amemboa species that share this morphological characteristic. Besides, the ventral side of the profemur bears two tufts of dark setae in the males of both species (Fig. 6 A; also see Polhemus 2017: fig. 19). Some color patterns of both species are also similar (Figs 2 A, 12 A; also see Polhemus 2017: figs 14, 15). However, these two species can be distinguished by the following characteristics. The apical hook of lateral arm is more acutely pointed in A. cambodiana (see Polhemus 2017: fig. 22), while it is blunter in A. hainanica sp. nov. (Fig. 10 A). The subapical process is weakly developed in A. cambodiana, while it is more distinct in A. hainanica sp. nov. (Fig. 10 A; also see Polhemus 2017: fig. 22). The two species can also be separated by the shape of their pygophores, which is campanulate in A. cambodiana (see Polhemus 2017: fig. 21) and lacks the pair of lateral blunt processes seen in A. hainanica sp. nov. (Fig. 9 A). Amemboa hainanica sp. nov. is also similar to A. fumi Esaki, 1925. In males of both species, the ventral side of the profemur bears two tufts of dark setae on apical 1 / 2, and protibia exhibits an indistinct tumescence on the basal 1 / 3 (Fig. 6 A, G); abdominal segment VIII relatively short (Fig. 7 A, F); pygophore has a digitate median process posteromedially and a pair of distinct blunt processes to either side of the median process (Fig. 9 A, F). However, A. hainanica sp. nov. differs from A. fumi in the following characteristics. In males of A. hainanica sp. nov., the lateral arm of proctiger bears a distinct subapical process in lateral view (Fig. 10 A), while in A. fumi, the lateral arm of proctiger lacks a process in lateral view (Fig. 10 F). Additionally, although color characteristics are quite variable within Amemboa species, some generalizations can still be made based on the current specimens. In both sexes of A. hainanica sp. nov., the black marks and stripes on head, pronotum and mesonotum are more slender and weaker (Figs 2 A, 4 A, E, 5 A, D, 12 A), or nearly absent (Figs 2 B, 4 B, F, 12 B), while they are broader and more prominent in A. fumi (Figs 2 G, 12 G). Moreover, the metanotum of A. hainanica sp. nov. exhibits brownish-yellow spots (Figs 2 A, 4 A, E, 5 A, D, 12 A) or is predominantly brownish-yellow (Figs 2 B, 4 B, F, 12 B), whereas it is entirely black in A. fumi (Figs 2 G, 12 G). Description of apterous male. Measurements. Body length 3.68–3.96 (holotype 3.76), width 1.39–1.49 (holotype 1.39), head width 0.92–0.98, interocular width 0.43–0.44, eye length (in dorsal view) 0.39–0.43; lengths of antennal segments I – IV: 0.86–0.93: 0.78–0.82: 0.83–0.89: 1.32–1.51; pronotum: length 0.53–0.55, width 0.99–1.11; mesonotum: length 1.25–1.30, width 1.39–1.49; metanotum: length 0.44–0.48, width 1.11–1.17; lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 1.24–1.30: 1.17–1.21: 0.28–0.29: 0.16–0.18, middle leg: 3.47–3.56: 2.19–2.25: 0.81–0.87: 0.40–0.43, hind leg: 3.05–3.28: 1.22–1.33: 0.48–0.53: 0.35–0.38. Color. Body dorsally brownish yellow with black stripes (Figs 1 A, 2 A, B, 5 A). Color pattern as shown in Figs 2 A, B, 3 A, 4 A, B, 5 A – C. Head dorsally with several tiny, discontinuous, black spots (Figs 2 A, B, 5 A); rostrum mainly yellow, with dorsomedian line and segment IV black (Fig. 4 A, B). Pronotum with two pairs of black stripes in dorsal view (Figs 2 A, 5 A), sometimes the pair of lateral stripes nearly absent (Fig. 2 B); proacetabulum with a pair of black or brown marks laterally, coxal cleft brown (Figs 3 A, 5 B). Mesonotum with broad, black stripes medially and slender, black stripes laterally (Figs 2 A, 4 A, 5 B, C), sometimes stripes nearly absent (Figs 2 B, 4 B); mesopleuron with a relatively broad, black stripe medially on each side, covered by silvery setae (Figs 4 A, B, 5 C); mesacetabulum with broad, black mark dorsally, covered by silvery setae (Figs 2 A, B, 4 A, B), basal part of coxal cleft black, other part brownish-black (Figs 3 A, 4 A) or pale brown (Fig. 4 B); mesosternum with a pair of elongate, black stripes anterolaterally, a broad, black stripe medially, and a pair of black spots posterolaterally (Figs 3 A, 5 B). Metanotum mainly black, with a pair of dark brown spots (Figs 2 A, 5 A) or mainly brownish-yellow (Fig. 2 B); metapleuron dark brown or yellowish-brown (Fig. 4 A, B); metacetabulum with broad, black mark dorsally, covered by silvery setae (Figs 2 A, B, 4 A, B); metasternum mainly black (Figs 3 A, 5 E). Abdominal tergites I – V black (Figs 2 A, 5 A) or brownish-yellow (Fig. 2 B); mediotergites IV – VIII with brownish-yellow spots medially (Figs 2 A, B, 5 A); abdominal sterna II – VI completely black, sternite VII mainly black with a pair of yellowish-brown stripes on posterior margin (Figs 3 A, 5 B); abdominal segment VIII mainly yellow, dorsal part black (Figs 2 A, 5 A) or with brown spots (Fig. 2 B), ventral part with a pair of black spots medially (Figs 3 A, 5 B). Structure. Head: elongate, deflected anteriorly; antennal segment I slightly curved, stouter than other segments, with apical part slightly incrassate, antennal tubercles protruded, visible in dorsal view (Fig. 1 A); compound eyes large, globular; rostrum stout, reaching anterior part of mesosternum (Fig. 2 A, B). Thorax: prothorax and metathorax short, mesothorax prolonged; proacetabulum oblique, mesoacetabulum and metacetabulum almost horizontal (Figs 4 A, B, 5 C); profemur moderately incrassate (Figs 5 G, 6 A); ventral side of the profemur with two tufts of dark setae on apical 1 / 2 (Figs 5 G, 6 A); protibia slightly curved, with an indistinct tumescence on basal 1 / 3 (Figs 5 G, 6 A); protarsus stout, with large claws (Figs 5 G, 6 A); meso- and metafemora relatively long, stouter than meso- and metatibia (Fig. 1 A); meso- and metatarsi slender (Fig. 1 A); claws of middle and hind legs shorter than claw of fore leg (Fig. 1 A). Abdomen: mediotergites declined, connexiva raised and convergent (Fig. 2 A, B); abdominal segment VII short; abdominal segment VIII cylindriform, protruding from pregenital segments, relatively short and stout (Fig. 7 A). Genitalia: pygophore posteriorly with a digitate median process (Figs 5 H, I, 8 A, 9 A), also with a pair of distinct blunt processes on both sides of median process in ventral view (Figs 5 H, I, 8 A, 9 A); median process of pygophore relatively broad in lateral view (Figs 5 J, K, 10 A, 11 A); lateral arms of proctiger relatively slender in ventral view (Figs 5 H, 8 A), with a distinct subapical process in lateral view, forming a distinct subapical notch on the dorsal margin (Figs 5 J, 10 A). Description of apterous female. Measurements. Body length 4.19–4.52, width 1.76–1.78, head width 1.00–1.02, interocular width 0.45–0.49, eye length (dorsal view) 0.44–0.48; lengths of antennal segments I – IV: 0.93–0.99: 0.80–0.88: 0.91–1.00: 1.41–1.54; pronotum: length 0.50–0.55, width 1.01–1.24; mesonotum: length 1.52–1.58, width 1.75–1.78; metanotum: length 0.50–0.56, width 1.32–1.40; lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 1.29–1.44: 1.33–1.38: 0.33–0.34: 0.20–0.21, middle leg: 3.88–4.10: 2.50–2.75: 1.02–1.06: 0.46–0.48, hind leg: 3.40–3.53: 1.48–1.56: 0.56–0.64: 0.43–0.46. Color. Color pattern as shown in Figs 1 B, 5 D – F, 12 A, B. Similar to apterous male with the following exceptions: mesosternum lacking a pair of black spots posterolaterally (Fig. 5 E); metasternum mainly yellow with median part black (Fig. 5 E); metasternum yellow, with a median black mark (Fig. 5 E); abdominal sternites II – VII mainly yellow with median black marks, the marks on sternites III – VII with brown spots in the center (Fig. 5 E). Structure. Similar to apterous male with some exceptions: body stouter than male; profemur slightly incrassate, without special modifications (Fig. 1 B); protibia straight without special modifications (Fig. 1 B). Abdominal segment VII relatively long, genital segments completely withdrawn into segment VII (Figs 5 D – F, 12 A, B). Proctiger simple, hind margin rounded. Macropterous forms. Unknown. Etymology. The specific epithet hainanica refers to the island of Hainan, China, the only area in which this species has so far been collected. Distribution. China: Hainan (Fig. 18). Habitats. Amemboa hainanica sp. nov. is found in rivers and pools below waterfalls (Fig. 15 A), actively moving on the water surface (Fig. 16 A, B) and resting at the edges of still water puddles (Fig. 16 C).

Published as part of Leng, Zhaoqi, Zhang, Beichen, Jin, Zezhong & Ye, Zhen, 2024, Taxonomic review of Amemboa Esaki, 1925 from China, with description of a new species (Hemiptera, Heteroptera, Gerridae), pp. 1-28 in ZooKeys 1210 on pages 1-28, DOI: 10.3897/zookeys.1210.125611