Rhyacobates scorpio Andersen & Chen 1995
Creators: name: Leng, Zhaoqi
name: Tran, Anh Duc
name: Ye, Zhen
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Gerridae
Rhyacobates
Rhyacobates scorpio

description: Rhyacobates scorpio Andersen & Chen, 1995
Figs 2D, 3O, 4L, 5N, 7E, 8K, 32–33
Rhyacobates scorpio Andersen & Chen, 1995: 62–63, figs 1, 28–32 (original description).
Diagnosis
Body length of apterous females 9.22–11.95, of apterous males 8.01–8.10. Female: pronotum mainly black with a median brownish-yellow spot; mesonotum and metanotum mainly black with a median brownish-yellow stripe (Figs 2D, 3O, 32A, 33A); abdominal segments I–VI straight, with long, blackish setae on mesal margins of the connexivum; abdominal segment VII elongate, abruptly bent dorsad at an angle of about 90° (Figs 5N, 33C), dorsally with an angular process terminating each connexivum (Fig. 33D–F), posterior margin of sternum VII angularly produced in the middle (Fig. 33G). Male: middle trochanter with 3–5 spines; middle femur with spines but not in distinct row (Fig. 33J); length of middle tibia ca 1.2–1.4 times length of hind tibia; proctiger relatively large, with broadly rounded lobes laterally (Figs 7E, 33K); paramere relatively slender, strongly curved at basal fourth, distal part tapering towards hook-shaped apex (Figs 8K, 33L).
Material examined
Holotype (Fig. 32A–C)
CHINA • ♀ (apterous); Sichuan Province, Song Ch′i Hsien; Jul. 1938; D.C. Graham leg.; USNM.
Paratypes (Fig. 32D–G)
CHINA – Sichuan Province • 2 ♁♁, 1 ♀ (apterous); E-mei Mountain, Jie-yin Temple; 14 Jul. 1957; Le-yi Zheng leg.; NKUM • 1 ♀ (apterous); Song Ch′i, Kuanhsien; Aug. 1938; D.C. Graham leg.; USNM • 1 ♀ (apterous); Wenchuan City; Aug. 1938; D.C. Graham leg.; USNM.
Non-type specimens
CHINA – Sichuan Province • 1 ♁, 1 ♀ (apterous); E-mei-shan City, E-mei Mountain, Qingyin Attic; 29°34′29.7″ N, 103°24′38.3″ E; 19 Aug. 2013; Zhen Ye leg.; NKUM • 5 ♁♁, 11 ♀♀ (apterous); Le-shan City, Mu-chuan County, Hei-xiong Valley; 28°52′26.8″ N, 103°57′31.1″ E; 1090 m a.s.l.; 2 Aug. 2017; Chen-guang Zheng leg.; NKUM • 2 ♁♁, 10 ♀♀ (apterous); Ya-an City, Bi-xia Mountain; 30°4′8.9″ N, 102°59′34.6″ E; 30 Jul. 2016; Chen-guang Zheng leg.; NKUM.
Supplemental description
Apterous female
MEASUREMENTS. Body length 9.22–11.95, width 3.31–3.81, head width 1.83, interocular width 0.84, eye length (dorsal view) 0.78; relative lengths of antennal segments I–IV: 4.85: 1.51:1.83:1.29; pronotum: length 1.02,width 2.08;mesonotum: length2.97, width 3.81; metanotum:length 1.25,width 3.28;abdomen length (ventral view) 5.06; abdominal sternum VII: length 1.53, width 1.58; abdominal mediotergite I: length 0.63, width 1.63; relative lengths of leg segments (femur:tibia: tarsal segment I:tarsal segment II): fore leg: 5.15: 4.59:2.23:1.32, middle leg: 14.15:8.52: 5.32: 0.59, hind leg: 14.31:7.92:0.21:0.28.
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 2D, 3O, 32A, 33A). Connexivum dorsally brownish-yellow. Abdominal tergum I with a median yellow marking. Mesosternum chiefly blackish with two median yellowish spots, divided by a blackish line (Fig. 33B). Abdominal venter light yellow.
ABDOMEN. Abdomen relatively short, gradually tapering towards apex (Fig. 33C). Connexiva on abdominal segments I–VI erect, not meeting each other above mediotergites, reflexed upon abdominal mediotergite VII (Fig. 33A). Abdominal segment VII elongate, completely enclosing genital segments, nearly as long as two preceding abdominal segments together, abruptly turning dorsad at a maximum angle of about 90°, dorsally with an angular process terminating each connexivum (Fig. 33D–F), posterior margin of sternum VII angularly produced in the middle (Fig. 33G).
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; abdominal segment VII only weakly turned dorsad.
MEASUREMENTS. Body length 11.31, width 3.58, head width 1.64, interocular width 0.84, eye length (dorsal view) 0.73; relative lengths of antennal segments I–IV: 4.63:1.34: 1.62: 1.22; pronotum: length 4.61, width 2.81; mesonotum width 3.58; metanotum: length 0.85, width 3.23; abdomen length (ventral view) 4.68; abdominal sternum VII: length 2.15, width 1.63; abdominal mediotergite I: length 0.66, width 1.17; relative lengths of leg segments (femur:tibia: tarsal segment I:tarsal segment II): fore leg: 4.68:4.28:1.98: 1.15, middle leg: 12.70: 7.26: 3.76:0.58, hind leg: 13.56:6.78: 0.18: 0.29.
Apterous male
MEASUREMENTS. Body length 8.01–8.10, width 1.60–2.81, head width 1.66, interocular width 0.83, eye length (dorsal view) 0.64; relative lengths of antennal segments I–IV: 4.62: 1.48: 1.70: 1.18; pronotum: length 0.91, width 1.83; mesonotum: length 2.38, width 2.81; metanotum: length 0.91, width 2.41; abdomen length (ventral view) 3.72; abdominal sternum VII: length 0.54, width 1.34; abdominal mediotergite I: length 0.41, width 1.06; relative lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 5.16:4.40: 1.44: 0.70, middle leg: 13.02:7.44: 3.78: 0.59, hind leg: 13.35: 6.13: 0.19: 0.29.
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 4L, 33H). Connexivum dorsally blackish. Mesosternum chiefly blackish with median brownish spots or totally blackish (Fig. 33I). Abdominal venter dark-yellow.
LEG. Middle trochanter with 3–5 spines on distal part; middle femur with spines but not in distinct row (Fig. 33J).
GENITALIA. Abdominal segment VIII ventro-laterally impressed. Pygophore large, ovate. Proctiger relatively large, with broadly rounded lobes laterally (Figs 7E, 33K). Paramere relatively long and slender, strongly curved at basal fourth, distal part tapering towards hook-shaped apex (Figs 8K, 33L).
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 8.35, width 2.78, head width 1.57, interocular width 0.78, eye length (dorsal view) 0.61; relative lengths of antennal segments I–IV: 4.52: 1.43: 1.61:1.18; pronotum: length 3.20, width 2.51; mesonotum width 2.78; metanotum width 2.46; abdomen length (ventral view) 2.90; abdominal sternum VII: length 0.51, width 1.33; abdominal mediotergite I: length 0.44, width 1.09; relative lengths of leg segments (femur:tibia: tarsal segment I: tarsal segment II): fore leg: 4.85: 4.05: 1.38: 0.95, middle leg: 13.01: 7.55:3.98: 0.54, hind leg: 13.45:6.19: 0.15: 0.23.
Distribution
China: Sichuan (Andersen & Chen 1995).
Comparative notes
The female of R. scorpio can be distinguished from that of all other species of Rhyacobates by the unique shape of its abdomen (Figs 5N, 33C): abdominal segments I–VI are straight, with long, blackish setae on the lateral margins of the connexivum; abdominal segment VII is elongate, and abruptly turns dorsad at a maximum angle of about 90°, dorsally with an angular process terminating each connexivum (Fig. 33D–F), ventrally with a median process (Fig. 33G).
description: 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 56-60, DOI: 10.5852/ejt.2023.893.2285, http://zenodo.org/record/8385630