Rhyacobates svenhedini
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 svenhedini

description: Rhyacobates svenhedini (Lundblad, 1934)
Figs 2E, 3P, 4M–N, 5O, 7F, 8L, 34
Esakobates svenhedini Lundblad, 1934: 23–25, pl. 2 fig. 10 (original description).
Rhyacobates svenhedini – Hungerford & Matsuda 1959: 69–72. — Matsuda 1960: 273–276. — Andersen & Chen 1995: 61, figs 24–25 (with remarks).
Diagnosis
Body length of apterous females 10.30–11.59, of apterous males 7.21–7.90. Female: pronotum mainly black with a median brownish-yellow spot, mesonotum with a median brownish-yellow stripe, metanotum medially with a subtriangular yellow marking and with a sharp apex angle (Figs 2E, 3P, 34A); posterior margin of abdominal mediotergite VII with a short median process; posterior margin of abdominal segment VII with four distinct processes dorsally, including two lobe-like processes on each connexival corner (Fig. 34D–F): one long, posteriorly directed outer process and a smaller, shorter, pointed inner process (in some individuals, the inner process is very small or indistinct); posterior margin of sternum VII with a small angular median process (Fig. 34E). Male: middle trochanter without spines; middle femur with scattered small spines, not arranged in distinct row (Fig. 34J); length of middle tibia ca 1.3 times length of hind tibia; proctiger relatively large, with angular lobes laterally (Figs 7F, 34K); paramere strongly curved at basal third, distal part slender, with hook-shaped apex (Figs 8L, 34L).
Material examined
Non-type specimens
CHINA – Sichuan Province • 31 ♁♁, 52 ♀♀ (apterous); Guang-yuan City, Qing-chuan County, Tang-jia-he; 32°31′25.1″ N, 104°49′23.7″ E; 1077 m a.s.l.; 16 Jul. 2016; Chen-guang Zheng leg.; NKUM • 2 ♁♁ (macropterous); Guang-yuan City, Qing-chuan County, Tang-jia-he; 32°31′25.1″ N, 104°49′23.7″ E; 1077 m a.s.l.; 16 Jul. 2016; Chen-guang Zheng leg.; NKUM.
Supplemental description
Apterous female
MEASUREMENTS. Body length 10.30–11.59, width 2.70–3.22, head width 1.56, interocular width 0.76, eye length (dorsal view) 0.61; relative lengths of antennal segments I–IV: 5.02: 1.22:1.34:1.23; pronotum: length 0.91,width 1.94;mesonotum: length2.59, width 3.16; metanotum:length 0.82, width 2.68;abdomen length (ventral view) 6.80; abdominal sternum VII: length 2.03, width 1.41; abdominal mediotergite I: length 0.54, width 1.36; relative lengths of leg segments (femur:tibia: tarsal segment I:tarsal segment II): fore leg: 5.19: 4.63:2.48:1.04, middle leg: 13.91:7.10: 3.32: 0.51, hind leg: 13.61:5.56:0.15:0.24.
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 medially with a subtriangular yellow marking and with a sharp apex angle (Figs 2E, 3P, 34A). Connexivum dorsally brownish-yellow. Abdominal tergum I with a median yellow marking. Mesosternum chiefly blackish with a median subtriangular yellowish spot (Fig. 34B). Abdominal venter light yellow.
ABDOMEN. Abdomen relatively long, caudal part moderately curved dorsad (Fig. 34C). Connexival margin of abdominal segments I–II erect, of III–VII reflexed (Fig. 34A), meeting each other above terminal mediotergites (Fig. 34A, D). Posterior margin of abdominal mediotergite VII with a short median process. Abdominal segment VII elongate, about as long as two preceding abdominal segments together (Figs 5O, 34C). Posterior margin of abdominal segment VII with four distinct processes, including two lobe-like processes on each connexival corner (Fig. 34D–F): one long, posteriorly-directed outer process and a smaller pointed inner process (in some individuals, the inner process very small or indistinct), posterior margin of sternum VII with a small median process (Fig. 34E).
Apterous male
MEASUREMENTS. Body length 7.21–7.90, width 1.70–2.22, head width 1.36, interocular width 0.72, eye length (dorsal view) 0.51; relative lengths of antennal segments I–IV: 3.42: 1.08:1.23:0.93; pronotum: length 0.69, width 1.45;mesonotum: length2.22, width 2.22; metanotum:length 0.66, width 2.09;abdomen length (ventral view) 3.53; abdominal sternum VII: length 0.54, width 1.04; abdominal mediotergite I: length 0.27, width 0.98; relative lengths of leg segments (femur:tibia: tarsal segment I:tarsal segment II): fore leg: 4.44: 3.84:1.29:0.78, middle leg: 12.90:6.85: 2.83: 0.51, hind leg: 13.3: 4.23: 0.21: 0.15.
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 4M, 34G). Connexivum dorsally blackish. Mesosternum chiefly blackish with a median subtriangular yellowish spot, narrower than that of female (Fig. 34I). Abdominal venter light yellow.
LEG. Middle trochanter without spines; middle femur with scattered small spines, not arranged in distinct row (Fig. 34J).
GENITALIA. Abdominal segment VIII ventro-laterally impressed. Pygophore large, ovate. Proctiger relatively large, with angular lobes laterally (Figs 7F, 34K). Paramere strongly curved at basal third, distal part slender, with hook-shaped apex (Figs 8L, 34L).
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 4N, 34H).
MEASUREMENTS. Body length 7.35, width 2.11, head width 1.30, interocular width 0.62, eye length (dorsal view) 0.51;relative lengths of antennal segments I–IV: 3.88:1.05: 1.18: 0.99; pronotum: length2.71,width 2.14; mesonotum width 2.11; metanotum width 1.80; relative lengths of leg segments (femur:tibia: tarsal segment I: tarsal segment II): fore leg: 3.96: 3.04:1.23:0.61, middle leg: 11.36:6.31: 3.05: 0.75, hind leg: 11.67: 4.99: 0.25: 0.21.
Distribution
China: Fujian, Sichuan (Andersen & Chen 1995).
Comparative notes
Rhyacobates svenhedini is most similar to R. lundbladi; see comparative notes under R. lundbladi.
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 60-63, DOI: 10.5852/ejt.2023.893.2285, http://zenodo.org/record/8385630