Rhyacobates chinensis Hungerford & Matsuda, 1959

Leng, Zhaoqi, Tran, Anh Duc & Ye, Zhen, 2023, Taxonomic review of Rhyacobates Esaki, 1923, with descriptions of three new species (Hemiptera: Heteroptera: Gerridae), European Journal of Taxonomy 893 (1), pp. 1-73 : 37-42

Rhyacobates chinensis Hungerford & Matsuda, 1959

Figs 2B , 3H , 4F , 5G , 6G , 8F , 11–13 , 25

Rhyacobates chinensis Hungerford & Matsuda, 1959: 69 (original description).

Rhyacobates esakii Miyamoto & Lee, 1963: 43 (synonymized with Rhyacobates chinensis ).

Rhyacobates chinensis – Andersen & Chen 1995: 57, figs 6–11 (with remarks).

Diagnosis

Body length of apterous females 8.01–9.45, of apterous males 6.20–6.81. Female: pronotum mainly black with a median brownish-yellow spot; mesonotum and metanotum mainly black with a median brownish-yellow stripe ( Figs 3H , 25A ); posterior margin of abdominal segment VII with five processes, including a short, angular process terminating each connexivum, a pair of pointed processes laterally, which are as long as or longer than connexival process, ventrally with a pointed, median process ( Figs 5G , 25G–I ). Male: middle trochanter with 3–6 spines; middle femur with spines but not in distinct row ( Fig. 25L ); length of middle tibia ca 1.5–1.7 times length of hind tibia; proctiger with angular lobes laterally ( Figs 6G , 25M ); paramere relatively slender and sinuate, basal and middle parts thickened, distal part tapering towards hook-shaped apex ( Figs 8F , 25N ).

Material examined

Non-type specimens

CHINA – Chongqing City • 13 ♁♁, 15 ♀♀ (apterous); Si-mian Mountain ; 28°36′30.4″ N, 106°22′19.2″E; 895 m a.s.l.; 10 Aug. 2016; Yan-fei Li leg.; NKUM . – Hebei Province • 10 ♁♁, 11 ♀♀ (apterous); Cheng-de City, Wei-chang County, Yu-dao-kou; 42°13′8.7″ N, 117°1′33.6″ E; 1200 m a.s.l.; 30 Aug. 2016; Ya-hui Zhen leg.; NKUM • 4 ♁♁, 26 ♀♀ (apterous); Cheng-de City, Xing-long County, Wu-ling Mountain ; 29 Aug. 1973; Sheng-li Liu leg.; NKUM . – Henan Province • 15 ♁♁, 31 ♀♀ (apterous); Xin-xiang City, Hui County, Bo-bi Village ; 35°34′47.2″ N, 113°35′47.6″ E; 1200 m a.s.l.; 21 Jul. 2016; Ye Zhen leg.; NKUM . – Hubei Province • 2 ♁♁, 2 ♀♀ (apterous); Shi-yan City, Zhu-xi Village ; 32°16′36.1″ N, 109°41′59.7″ E; 600 m a.s.l.; 11 Aug. 2015; Zhen Ye leg.; NKUM • 8 ♁♁, 12 ♀♀ (apterous); Jinchun County, Wen-quan Bridge ; 30°14′35.2″ N, 115°43′5.2″ E; 56 m a.s.l.; 12 Jul. 2022; Zhao-qi Leng leg.; NKUM • 11 ♁♁, 10 ♀♀ (apterous); Sui-zhou City , Hei-long-tan; 31°47′21.1″ N, 114°5′16.1″ E; 225 m a.s.l.; 14 Jul. 2022; Zhao-qi Leng, Chen Liu and Zi-he Li leg.; NKUM • 27 ♁♁, 29 ♀♀ (apterous); Huang-gang City , Ying-shan County, Tao-hua-chong; 30°58′5.2″ N, 116°1′29.3″ E; 719 m a.s.l.; 13 Jul. 2022; Zhao-qi Leng and Zhen Ye leg.; NKUM . – Hunan Province • 5 ♁♁, 5 ♀♀ (apterous); Zhangjia-jie City , Jin-bian-xi; 14 Oct. 1985; Huan-guang Zou leg.; NKUM . – Liaoning Province • 12 ♁♁, 13 ♀♀ (apterous); Dan-dong City , Kuan-dian County; 41°0′5.7″ N, 125°11′26.1″ E; 222 m a.s.l.; 6 Jul. 2016; Juan-juan Yuan leg.; NKUM . – Neimenggu Province • 7 ♁♁, 4 ♀♀ (apterous); Xi-lin-guo-le League , Zhong-li-fang; Aug. 1974; Zhong-ming Jiang leg.; NKUM . – Shaanxi Province • 1 ♁, 1 ♀ (apterous); Chang-zhi City, Tai-hang Mountain ; 35°53′52.3″ N, 113°28′57.9″ E; 1070 m a.s.l.; 9 Aug. 2018; Hua-xi Liu and Xue Dong leg.; NKUM • 8 ♁♁, 9 ♀♀ (apterous); Hua County, Gao-tang Village ; 34°24′23.3″ N, 109°39′1.6″ E; 1070 m a.s.l.; 7 Jul. 2014; Huan-huan Yang leg.; NKUM . – Sichuan Province • 2 ♁♁, 3 ♀♀ (apterous); Guang-yuan City , Shui-mo-gou; 32°48′3.4″ N, 106°3′33.7″ E; 1002 m a.s.l.; 19 Jul. 2016; Yan-chen Li leg.; NKUM • 6 ♁♁, 7 ♀♀ (dealated macropterous); Guang-yuan City , Shui-mo-gou; 32°48′3.4″ N, 106°3′33.7″ E; 1002 m a.s.l.; 19 Jul. 2016; Yan-chen Li leg.; NKUM • 2 ♁♁, 3 ♀♀ (apterous); Wan-yuan City, Yu-quan Mountain ; 32°9′35.6″ N, 108°8′19.4″ E; 580 m a.s.l.; 25 Aug. 2017; Chen-guang Zheng leg.; NKUM. – Tian-jin City • 2 ♀♀ (apterous); Ji-zhou District, Xia-ying Village ; 29 Jul. 1985; Liu leg.; NKUM .

Supplemental description

Apterous female

MEASUREMENTS. Body length 8.01–9.45, width 2.60–3.20, head width 1.42, interocular width 0.74, eye length (dorsal view) 0.65; relative lengths of antennal segments I–IV: 4.31: 1.04:1.18:0.86; pronotum: length 0.74, width 1.66;mesonotum: length2.42, width 3.03; metanotum:length 0.62, width 2.75;abdomen length (ventral view) 4.69; abdominal sternum VII: length 1.82, width 1.75; abdominal mediotergite I: length 0.54, width 1.36; relative lengths of leg segments (femur:tibia: tarsal segment I:tarsal segment II): fore leg: 4.36: 3.84:1.96:0.88, middle leg: 12.51:6.85: 3.32: 0.48, hind leg: 14.21:5.45:0.15:0.25.

C OLORATION. Median black spot of head posteriorly bifurcate. Pronotum mainly black with a median brownish-yellow spot. Mesonotum and metanotum mainly black with a median brownish-yellow stripe ( Figs 3H , 25A ). Connexivum dorsally brownish-yellow. Abdominal tergum I completely yellow or with a median yellow marking. Mesosternum chiefly blackish with a median subtriangular yellowish spot ( Fig. 25B ). Abdominal venter light yellow.

ABDOMEN. Abdomen relatively short, curved dorsad towards end at different angles. Connexiva convergent along dorsal midline of abdominal segments IV–VI, meeting erectly above terminal mediotergites ( Fig. 25A ). Abdominal segment VII elongate, nearly as long as three preceding abdominal segments together ( Fig. 25E ). Posterior margin of abdominal segment VII with five processes, dorsally with a short, angular process terminating each connexivum, laterally with a pair of pointed processes, as long as or longer than connexival process, ventrally with a pointed median process ( Fig. 25C–D ). Processes of abdominal segment VII variable among populations ( Fig. 25G–I ).

Dealated macropterous female

Similar to apterous female in general structure and coloration with following exceptions: thorax with a pronotal lobe, anterior part with a subrhombic yellow marking, posterior part elongate, covering most of mesonotum ( Fig. 25F ); posterior margin broadly rounded and brownish; abdominal segment VII wider than that of apterous form.

MEASUREMENTS. Body length 9.19, width 3.48, head width 1.89, interocular width 0.86, eye length (dorsal view) 0.67; relative lengths of antennal segments I–IV: 4.38:1.64: 1.62: 1.03; pronotum: length 3.43, width 2.89; mesonotum width 3.48; metanotum: length 0.73, width 3.06; abdomen length (ventral view) 4.04; abdominal sternum VII: length 1.89, width 2.03; abdominal mediotergite I: length 0.49, width 1.31; relative lengths of leg segments (femur:tibia: tarsal segment I: tarsal segment II): fore leg: 4.44: 4.08: 2.26: 0.92, middle leg: 13.11:7.72: 3.88: 0.61, hind leg: 13.49:5.88: 0.19: 0.25.

Apterous male

MEASUREMENTS. Body length 6.20–6.81, width 1.80–2.10, head width 1.36, interocular width 0.76, eye length (dorsal view) 0.54; relative lengths of antennal segments I–IV: 3.94: 1.01: 1.04: 0.94; pronotum: length 0.74, width 1.58; mesonotum: length 2.19, width 2.18; metanotum: length 0.68, width 2.03; abdomen length (ventral view) 2.53; abdominal sternum VII: length 0.45, width 1.08; abdominal mediotergite I: length 0.34, width 0.79; relative lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 3.84: 3.28: 1.16: 0.58, middle leg: 10.90:6.11: 2.63: 0.41, hind leg: 11.57: 3.52: 0.14: 0.20.

C OLORATION. Median black spot of head posteriorly bifurcate. Pronotum mainly black with a median brownish-yellow spot. Mesonotum mainly black with a median brownish-yellow stripe. Metanotum chiefly blackish, without yellow markings ( Figs 4F , 25J ). Connexivum dorsally blackish. Mesosternum chiefly blackish with a median subtriangular yellowish spot, narrower than that of female ( Fig. 25K ). Abdominal venter light yellow.

LEG. Middle trochanter with 3–6 spines on distal part; middle femur with spines but not in distinct row ( Fig. 25L ).

GENITALIA. Abdominal segment VIII ventro-laterally impressed. Pygophore large, ovate. Proctiger with angular lobes laterally ( Figs 6G , 25M ). Paramere relatively slender and sinuate, middle part thickened, distal part tapering towards hook-shaped apex ( Figs 8F , 25N ).

Dealated macropterous male

Similar to apterous female in general structure and coloration with following exceptions: thorax with a pronotal lobe, anterior part with a subrhombic yellow marking, posterior part elongate, covering most of mesonotum; posterior margin broadly rounded and brownish.

MEASUREMENTS. Body length 7.48, width 2.64, head width 1.46, interocular width 0.76, eye length (dorsal view) 0.59; relative lengths of antennal segments I–IV: 3.86:1.12: 1.16: 0.90; pronotum: length 2.84, width 2.42; mesonotum width 2.64; metanotum: length 0.59, width 2.35; abdomen length (ventral view) 2.84; abdominal sternum VII: length 0.55, width 1.25; abdominal mediotergite I: length 0.29, width 0.89; relative lengths of leg segments (femur:tibia: tarsal segment I: tarsal segment II): fore leg: 4.06: 3.47: 1.06: 0.67, middle leg: 11.69:6.16: 2.76: 0.44, hind leg: 11.81: 4.16: 0.15: 0.21.

Distribution

China: Chongqing, Liaoning, Shaanxi, Shanxi, Sichuan (first records); Hebei, Henan, Hubei, Hunan, Inner Mongolia, Tianjin; Korea: Nam Te Cheon ( Andersen & Chen 1995).

Comparative notes

Rhyacobates chinensis is most similar to R. abdominalis ; see comparative notes under R. abdominalis .

Figures

Fig. 2. Habitus of Rhyacobates spp. in dorsal view (females), apterous form if not stated otherwise. A. R. abdominalisAndersen & Chen, 1995.B. R. chinensis Hungerford & Matsuda, 1959.C. R. lundbladi (Hungerford, 1957). D. R. scorpio Andersen & Chen, 1995. E. R. svenhedini (Lundblad, 1934). F. R. takahashii Esaki, 1923, dealated macropterous female. Scale bar = 3 mm.

Fig. 3. Photographs of bodies of Rhyacobates spp. in dorsal view (females), apterous form if not stated otherwise.A. R. bui sp. nov. B. R. elongatus sp. nov. C. R. turgidus sp. nov., apterous form.D. R. turgidus sp. nov., dealated macropterous form.E. R. abdominalis Andersen & Chen, 1995. F. R. anderseni Tran & Yang, 2006. G. R. angustus Tran & Nguyen, 2016, holotype (ZVNU). H. R. chinensis Hungerford & Matsuda, 1959. I. R. constrictus Tran & Nguyen, 2016. J. R. edentatus Andersen & Chen, 1995. K. R. gongvo Tran & Yang, 2006. L. R. lundbladi (Hungerford, 1957). M. R. malaisei Andersen & Chen, 1995. N. R. recurvus Andersen & Chen, 1995. O. R. scorpio Andersen & Chen, 1995. P. R. svenhedini (Lundblad, 1934). Q. R. takahashii Esaki, 1923, dealated macropterous form. R. R. zetteli Tran & Nguyen, 2016. Scale bar = 3 mm.

Fig. 4. Photographs of bodies of Rhyacobates spp. in dorsal view (males), apterous form if not stated otherwise.A. R. bui sp. nov.B. R. elongatus sp. nov.C. R. turgidus sp. nov.D. R. abdominalisAndersen & Chen, 1995. E. R. anderseni Tran & Yang, 2006. F. R. chinensis Hungerford & Matsuda, 1959. G. R. edentatus Andersen & Chen, 1995. H. R. gongvo Tran & Yang, 2006. I. R. lundbladi (Hungerford, 1957). J. R. malaisei Andersen & Chen, 1995. K. R. recurvus Andersen & Chen, 1995. L. R. scorpio Andersen & Chen, 1995. M. R. svenhedini (Lundblad, 1934), apterous form. N. R. svenhedini, macropterous form. O. R. takahashii Esaki, 1923, dealated macropterous form. Scale bar = 3 mm.

Fig. 5. Photographs of bodies of Rhyacobates spp. in lateral view (apterous females). A. R. bui sp. nov. B. R. elongatus sp. nov.C. R. turgidus sp. nov.D. R. abdominalisAndersen & Chen, 1995.E. R. anderseni Tran & Yang, 2006. F. R. angustus Tran & Nguyen, 2016, holotype (ZVNU). G. R. chinensis Hungerford & Matsuda, 1959. H. R. constrictus Tran & Nguyen, 2016. I. R. edentatus Andersen & Chen, 1995. J. R. gongvo Tran & Yang, 2006. K. R. lundbladi (Hungerford, 1957). L. R. malaisei Andersen & Chen, 1995. M. R. recurvus Andersen & Chen, 1995. N. R. scorpio Andersen & Chen, 1995. O. R. svenhedini (Lundblad, 1934). P. R. takahashii Esaki, 1923. Q. R. zetteli Tran & Nguyen, 2016. Scale bar = 3 mm.

Fig. 6. Proctiger of Rhyacobates spp. in dorsal view (males). A. R. bui sp. nov. B. R. elongatus sp. nov. C. R. turgidus sp. nov. D. R. abdominalis Andersen & Chen, 1995. E. R. anderseni Tran & Yang, 2006. F. R. angustus Tran & Nguyen, 2016. G. R. chinensis Hungerford & Matsuda, 1959. H. R. constrictus Tran & Nguyen, 2016. I. R. edentatus Andersen & Chen, 1995. Scale bar = 0.2 mm.

Fig. 8. Paramere of Rhyacobates spp. in lateral view. A. R. bui sp. nov. B. R. elongatus sp. nov. C. R. turgidus sp. nov. D. R. abdominalis Andersen & Chen, 1995. E. R. anderseni Tran & Yang, 2006. F. R. chinensis Hungerford & Matsuda, 1959. G. R. edentatus Andersen & Chen, 1995. H. R. lundbladi (Hungerford, 1957). I. R. malaisei Andersen & Chen, 1995. J. R. recurvus Andersen & Chen, 1995. K. R. scorpio Andersen & Chen, 1995. L. R. svenhedini (Lundblad, 1934). M. R. takahashii Esaki, 1923. Scale bar = 0.2 mm.

Fig. 11. Rhyacobates chinensis Hungerford & Matsuda, 1959, live habitus in situ. A. A group of nymphs and adults resting on a riverside rock. B. Individual of apterous female resting on rock. C. Individual of apterous male striding on the water surface. D. A group of nymphs and adults shifting on the water surface when disturbed. E. Nymphs resting on rock. Images not to scale.

Fig. 12. Rhyacobates chinensis Hungerford & Matsuda, 1959, in copulation. A. Dealated macropterous male mating with apterous female, lateral view. B. Dealated macropterous male mating with dealated macropterous female, dorsal view. C. Dealated macropterous male mating with apterous female, dorsal view. D. Apterous male mating with apterous female on the water surface, dorsal view. Images not to scale.

Fig. 13. Rhyacobates chinensis Hungerford & Matsuda, 1959, in copulation. Apterous male mating and seizing the dealated macropterous female using its fore leg on a riverside rock, while the female is feeding on its prey.

Fig. 25. Morphological features of Rhyacobates chinensis Hungerford & Matsuda, 1959. A. Body of female, dorsal view. B. Body of female, excluding head and prothorax, ventral view. C–D. Abdominal end of female, ventral view. E–F. Body of female, apterous form (E, excluding head and prothorax) and dealated macropterous form (F), lateral view. G–I. Abdominal end of female, lateral view. J. Body of male, dorsal view. K. Body of female, excluding head and prothorax, ventral view. L. Basal part of right middle leg of male, ventral view. M. Proctiger of male, dorsal view. N. Left paramere, lateral aspect, two different views. Scale bars: A–L = 1 mm; M–N = 0.2 mm.