Rhyacobates turgidus sp. nov. urn:lsid:zoobank.org:act: A61745D8-0A50-4E9C-89CA-B557C637ED2E Figs 3C–D, 4C, 5C, 6C, 8C, 19–20 Diagnosis Body length of apterous females 7.82–8.50, of apterous males 5.90–6.31. In both sexes, abdominal mediotergite I distinctly swollen and large, about as long as the three subsequent abdominal terga together (Figs 3C–D, 4C, 20A–B, H). Female: pronotum mainly black with a median brownish-yellow spot; mesonotum and metanotum mainly black with a median brownish-yellow stripe (Figs 3C, 19A, 20A); abdominal mediotergite I with a median brownish-yellow stripe; abdominal terga II–VI distinctly short (Figs 3C–D, 20A–B); abdominal mediotergite II medially hidden beneath the abdominal mediotergite I but not laterally (Figs 3C, 20A); laterosternites of connexivum VII expanded dorsad, folded mesad, but not meeting in middle of abdominal dorsum; posterior margin of sternum VII with a short and pointed median process (Fig. 20E–G). Male: middle trochanter with one spine; middle femur with scattered small spines, not arranged in distinct row (Fig. 20J); length of middle tibia ca 1.4 times length of hind tibia; proctiger with angular lobes laterally (Figs 6C, 20K); paramere relatively slender, strongly curved at basal third, distal part tapering towards hook-shaped apex (Figs 8C, 20L). Etymology The species epithet is derived from the Latin adjective ʻturgidusʼ, meaning ʻswollenʼ and refers to the extremely large abdominal mediotergite I. Material examined Holotype (Fig. 19A) CHINA • ♀ (apterous); Sichuan Province, Lu-zhou City, He-jiang County, Tian-tang-ba; 106°15′09.5″ N, 28°35′3.6″ E; 741 m a.s.l.; 9 Aug. 2016; Chen-guang Zheng leg.; NKUM. Paratypes (Fig. 19B) CHINA • 3 ♁♁, 3 ♀♀ (apterous), 1 ♀ (dealated macropterous); same collection data as for holotype; NKUM • 3 ♀♀ (apterous); Chongqing City, 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 • 1 ♁, 4 ♀♀ (apterous); Sichuan Province, Lu-zhou City, Xu-yong County, Hua-gao-xi National Nature Reserve; 28°16′19.4″ N, 105°32′27.6″ E; 741 m a.s.l.; 15 Aug. 2013; Yang Liu and Zhen Ye leg.; NKUM. Description Apterous female MEASUREMENTS. Body length 7.82–8.50 (holotype 8.20), width 3.01–3.60 (holotype 3.48), head width 1.48, interocular width 0.71, eye length (dorsal view) 0.43; relative lengths of antennal segments I– IV: 3.89:1.02: 1.18: 0.92; pronotum: length 0.81, width 1.65; mesonotum: length 3.78, width 3.25; metanotum: length 0.84, width 2.84; abdomen length (ventral view) 2.94; abdominal sternum VII: length 1.56, width 1.05; abdominal mediotergite I: length 0.86, width 1.71; relative lengths of leg segments (femur: tibia: tarsal segment I:tarsal segment II): fore leg: 3.94:3.38: 1.93: 0.88, middle leg: 11.12: 6.88: 4.25:0.45, hind leg: 11.35: 5.41:0.16: 0.24. 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 3C, 19A, 20A). Connexivum dorsally brownish-yellow. Abdominal mediotergite I with a median yellow stripe. Mesosternum chiefly blackish with a median subtriangular yellowish spot (Fig. 20C). Abdominal venter light yellow. ABDOMEN. Abdomen relatively short, almost straight (Fig. 5C, 20D). Connexiva erect on abdominal segments I–VI, parallel to each other above mediotergites, reflexed over terminal mediotergites (Fig. 20A–B).Abdominal mediotergite I distinctly swollen, nearly as long as three subsequent abdominal terga together, sparsely covered with silvery pubescence on each side; abdominal terga II–VI distinctly short in length (Figs 3C–D, 20A–B). Abdominal mediotergite II medially hidden beneath abdominal mediotergite I, but laterally exposed (Figs 3C–D, 20A). Abdominal segment VII elongate, nearly as long as two preceding abdominal segments together, length of ventral margin distinctly longer than that of dorsal margin in lateral view (Figs 5C, 20D); laterosternites of connexivum VII expanded dorsad, folded mesad, not meeting in middle of abdominal dorsum (Fig. 20E). Abdominal sternum VII tapering caudad, posterior margin with a short and pointed median process (Fig. 20E–F). 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 (Figs 3D, 20B). MEASUREMENTS. Body length 7.81, width 2.90, head width 1.45, interocular width 0.66, eye length (dorsal view) 0.53; pronotum: length 2.97, width 2.41; mesonotum width 2.90; metanotum: length 0.67, width 2.51; abdominal sternum VII: length 1.05, width 1.49; abdominal mediotergite I: length 0.67, width 1.19. Apterous male MEASUREMENTS. Body length 5.90–6.31, width 2.14–2.20, head width 1.32, interocular width 0.60, eye length (dorsal view) 0.42; relative lengths of antennal segments I–IV: 3.28: 0.92: 1.03: 0.87; pronotum: length 0.71, width 1.41; mesonotum: length 1.30, width 2.14; metanotum: length 0.71, width 1.82; abdomen length (ventral view) 1.98; abdominal sternum VII: length 0.46, width 0.83; abdominal mediotergite I: length 0.46, width 0.85; relative lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 3.33: 2.88: 1.02: 0.63, middle leg: 8.72: 5.41: 2.66: 0.43, hind leg: 8.95:3.78: 0.16: 0.23. COLORATION. 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 black, without yellow markings (Figs 4C, 19B, 20H). Connexivum dorsally blackish (Figs 4C, 19B). Mesosternum chiefly blackish with a median subtriangular yellowish spot (Fig. 20I). Abdominal venter dark-yellow. ABDOMEN. Abdomen relatively short. Abdominal mediotergite I extremely swollen (Figs 4C, 20H), nearly as long as three subsequent abdominal terga together. LEG. Middle trochanter with one spine; middle femur with scattered small spines, not arranged in distinct row (Fig. 20J). GENITALIA. Abdominal segment VIII ventro-laterally impressed. Pygophore large, ovate. Proctiger with angular lobes laterally (Figs 6C, 20K). Paramere relatively slender, strongly curved at basal third, distal part tapering towards hook-shaped apex (Figs 8C, 20L). Distribution China: Chongqing, Sichuan. Comparative notes Rhyacobates turgidus sp. nov. is closely related to R. recurvus and R. constrictus. These three species possess a robust body and similar outline of abdominal segment VII (Fig. 3C, I, N). Rhyacobates turgidus can be distinguished from R. constrictus by median yellowish stripes on the mesonotum, metanotum and abdominal mediotergite I (Figs 3C, 20A), which are absent in R. constrictus. Rhyacobates turgidus can be distinguished from R. recurvus by the following characteristics: (1) in lateral view, R. turgidus has a nearly straight abdomen (Fig. 5C, 20D), whereas R. recurvus has its abdomen curved dorsad (Figs 5M, 31C); (2) R. turgidus has an extremely swollen abdominal mediotergite I, which is nearly as long as the three subsequent abdominal tergites, and distinctly short abdominal terga II–VI (Figs 3C–D, 20A–B), whereas abdominal terga I–VI of R. recurvus are relatively normal-sized (Figs 3N, 31A).

Published as part of Leng, Zhaoqi, Tran, Anh Duc & Ye, Zhen, 2023, Taxonomic review of Rhyacobates Esaki, 1923, with descriptions of three new species (Hemiptera: Heteroptera: Gerridae), pp. 1-73 in European Journal of Taxonomy 893 (1) on pages 26-30, DOI: 10.5852/ejt.2023.893.2285, http://zenodo.org/record/8385630