Taxonomic review of Rhyacobates Esaki, 1923, with descriptions of three new species (Hemiptera: Heteroptera: Gerridae) Author Leng, Zhaoqi 89B546A1-5B53-4C03-9098-FBB36BC9EC85 Institute of Entomology, College of Life Sciences, Nankai University, Tianjin, 300071, China. zhaoqileng0712@gmail.com Author Tran, Anh Duc 3CB36F17-D917-4600-B888-C33B1C04259F Faculty of Biology, VNU University of Science, Vietnam National University, Hanoi, Nguyen Trai, Thanh Xuan, Hanoi, Vietnam. tran.anhduc@hus.edu.vn Author Ye, Zhen B095C7FB-E95B-4D0D-A61F-09B0B223571F Institute of Entomology, College of Life Sciences, Nankai University, Tianjin, 300071, China. yezhen1987331@nankai.edu.cn text European Journal of Taxonomy 2023 2023-09-28 893 1 1 73 https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2285/9863 journal article 274285 10.5852/ejt.2023.893.2285 e441bc9d-bb44-4ee6-b29f-a6724b96592b 2118-9773 8385630 D9DA4879-BC1D-4947-96E8-7D574DE334BA Rhyacobates takahashii Esaki, 1923 Figs 2F , 3Q , 4O , 5P , 7G , 8M , 35 Rhyacobates takahashii Esaki, 1923: 388 , pl. 1 (original description). Rhyacobates takahashii – Esaki 1925: 60 . — Matsuda 1960: 273–276 , figs 656–658, 660, 663, 674–676, 678. — Andersen & Chen 1995: 55 , figs 2–5 (with remarks). Diagnosis Body length of apterous females 8.60–10.88, of apterous males 6.20–7.32. Female: pronotum mainly black with a median brownish-yellow spot; mesonotum and metanotum mainly black with a median brownish-yellow stripe ( Fig. 35A ); posterior margin of abdominal mediotergite VII with a short median process ( Fig. 35E ); posterior margin of abdominal segment VII with three processes, including a relatively slender, angular process terminating each connexivum, and a pointed median process ventrally ( Fig. 35F–G ). Male: middle trochanter with one spine; middle femur with scattered small spines, not arranged in distinct row ( Fig. 35L ); length of middle tibia ca 1.5–1.8 times length of hind tibia; proctiger with angular lobes laterally ( Figs 7G , 35M ); paramere relatively slender, strongly curved at basal fourth, distal part tapering towards hook-shaped apex ( Figs 8M , 35N ). Material examined Non-type specimens CHINA – Guangxi Province • 5 ♁♁, 2 ♀♀ (apterous); Lai-bin City , Jin-xiu County ; 23°55′51.6″ N , 110°10′46.6″ E ; 524 m a.s.l. ; 26 Jul. 2019 ; Ze-zhong Jin leg.; NKUM . – Taiwan Island • 1 ♁ (apterous); Taitung , Xinwulixi , Xinwuli bridge; 2 Dec. 2001 ; H.H. Tan , K. Lim and Y.M. Ju leg.; THH0199; ZRC • 1 ♀ (apterous); Taipei County , Wulai , Fusan ; 24°46.973′ N , 121°30.106′ E ; 336 m a.s.l. ; 6 Apr. 2004 ; A.D. Tran leg.; TAD0402; ZRC • 3 ♁♁, 7 ♀♀ (apterous); Pingtung County , Henchun , Wangsha stream; 22°02.351′ N , 120°45.852′ E ; 39 m a.s.l. ; 8 Apr. 2004 ; A.D. Tran leg.; TAD0406; ZRC • 4 ♁♁, 2 ♀♀ (apterous), 2 ♁♁, 1 ♀ (macropterous); Yilan County , Yuanshan , Dahu stream; 24°45.218′ N , 121°39.777′ E ; 147 m a.s.l. ; 12 Apr. 2004 ; A.D. Tran leg.; TAD0412; ZRC • 7 ♁♁, 9 ♀♀ (dealated macropterous); Taizhong City , Ba-xian Mountain ; 24°17′55.1″ N , 120°45′41.5″ E ; 5 Jun. 2011 ; Qiang Xie leg.; NKUM . Supplemental description Apterous female MEASUREMENTS . Body length 8.60–10.88, width 2.59–2.90, head width 1.84, interocular width 0.85, eye length (dorsal view) 0.68; relative lengths of antennal segments I–IV: 4.10: 1.05:1.22:0.81; pronotum: length 0.90, width 1.84;mesonotum: length3.05,width 2.94; metanotum:length 0.92, width 2.65;abdomen length (ventral view) 4.66; abdominal sternum VII: length 1.87, width 1.29; abdominal mediotergite I: length 0.35, width 1.11; relative lengths of leg segments (femur:tibia:tarsal segment I:tarsal segment II): fore leg: 4.46: 3.62: 2.01:0.90, middle leg: 12.40:6.86: 2.98: 0.38, hind leg: 12.73: 4.57:0.11:0.14. 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 ( Fig. 35A ). Abdominal tergum I with a median yellow marking. Connexivum dorsally brownish-yellow. Mesosternum chiefly blackish with a median subtriangular yellowish spot ( Fig. 35B ). Abdominal venter light yellow. ABDOMEN . Abdomen relatively short, curved dorsad towards end ( Fig. 35D ) or nearly straight. Connexiva erect on abdominal segments I–II, converging along dorsal midline of IV–VI segments, meeting erectly above terminal mediotergites ( Fig. 35A ). Abdominal segment VII elongate, nearly as long as three preceding abdominal segments together ( Figs 5P , 35D ). Posterior margin of abdominal mediotergite VII with a short median process ( Fig. 35E ). Posterior margin of abdominal segment VII with three processes, dorsally above terminating each connexivum with a relatively slender process directing ventrad, ventrally with a pointed median process ( Fig. 35E–G ). 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; posterior margin broadly rounded and brownish ( Fig. 3Q ). MEASUREMENTS . Body length 10.01, width 2.86, head width 1.51, interocular width 0.60, eye length (dorsal view) 0.58; relative lengths of antennal segments I–IV: 3.98: 1.08:1.22:0.98; pronotum: length 3.12, width 2.41; mesonotum width 2.86; metanotum: length 0.73, width 2.62; abdomen length (ventral view) 4.80; abdominal sternum VII: length 1.46, width 1.79; abdominal mediotergite I: length 0.39, width 1.15; relative lengths of leg segments (femur:tibia: tarsal segment I:tarsal segment II): fore leg: 4.68:3.85:1.91: 0.97, middle leg: 12.47: 6.77: 3.32:0.33, hind leg: 13.31:5.13: 0.17: 0.23. Apterous male MEASUREMENTS . Body length 6.20–7.32, width 1.80–2.09, head width 1.43, interocular width 0.59, eye length (dorsal view) 0.60; relative lengths of antennal segments I–IV: 3.58: 1.04:1.07:0.84; pronotum: length0.76, width 1.55; mesonotum:length 2.16, width 2.09;metanotum:length0.69, width 1.88; abdomen length (ventral view) 2.69; abdominal sternum VII: length 0.53, width 1.22; abdominal mediotergite I: length 0.34, width 0.70; relative lengths of leg segments (femur:tibia: tarsal segment I:tarsal segment II): fore leg: 3.49: 2.91:1.06:0.62, middle leg: 10.02: 5.11: 2.17: 0.35, hind leg: 10.04: 2.79:0.11:0.13. Fig. 35. Morphological features of Rhyacobates takahashii Esaki, 1923 . A . Body of female, dorsal view. B–C . Body of female, excluding head and prothorax, ventral view. D . Body of female, lateral view. E . Abdominal end of female, dorsal view. F . Abdominal end of female, ventral view. Abdominal end of female, lateral view. H . Body of male, dealated macropterous form, lateral view. I–J . Body of male, apterous form (I) and dealated macropterous form (J), dorsal view. K . Body of male, 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. 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 ( Fig. 35I ). Connexivum dorsally blackish. Mesosternum chiefly blackish with a median subtriangular yellowish spot, narrower than that of female ( Fig. 35K ). Abdominal venter light yellow. LEG . Middle trochanter with one spine; middle femur with scattered small spines, not arranged in distinct row ( Fig. 35L ). GENITALIA . Abdominal segment VIII ventro-laterally impressed. Pygophore large, ovate. Proctiger with rounded lobes laterally ( Figs 7G , 35I ). Paramere relatively slender, strongly curved at basal fourth, distal part tapering towards hook-shaped apex ( Figs 8M , 35J ). 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 ( Figs 5P , 35J ). MEASUREMENTS . Body length 6.39, width 1.85, head width 1.22, interocular width 0.47, eye length (dorsal view) 0.49; relative lengths of antennal segments I–IV: 3.24:0.93: 0.90: 0.79; pronotum: length 2.40, width 1.81; mesonotum width 1.85; metanotum: length 0.49, width 1.68; abdomen length (ventral view) 2.29; abdominal sternum VII: length 0.53, width 0.97; abdominal mediotergite I: length 0.25, width 0.69; relative lengths of leg segments (femur:tibia: tarsal segment I:tarsal segment II): fore leg: 3.66:3.11:1.34: 0.60, middle leg: 10.48: 5.32:2.26:0.33, hind leg: 11.02: 3.56: 0.13: 0.18. Distribution China : Guangxi (first record); Taiwan ( Andersen & Chen 1995 ). Comparative notes The female of R. takahashii can be distinguished from all other species of Rhyacobates by the combination of following characters: in the females, the posterior margin of abdominal segment VII has three processes, including an erect, elongate and angular process terminating each connexivum, which is directed ventrad, and a pointed, slender median process ventrally ( Fig. 35F–G ).