Rhyacobates lundbladi
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 lundbladi

description: Rhyacobates lundbladi (Hungerford, 1957)
Figs 2C, 3L, 4I, 5K, 7B, 8H, 29
Esakobates lundbladi Hungerford, 1957: 33–36 (original description).
Rhyacobates lundbladi – Hungerford & Matsuda 1959: 69–72. — Matsuda 1960: 273–276, figs 659, 661, 665, 667, 669–672, 677, 679–680. — Andersen & Chen 1995: 61–62, figs 26–27 (with remarks).
Diagnosis
Body length of apterous females 11.62–12.21, of apterous males 8.02–8.41. Female: pronotum mainly black with a median brownish-yellow spot; mesonotum and metanotum mainly black with a median brownish-yellow stripe (Figs 3L, 29A); yellowish subtriangular marking on metanotum similar to the marking on pronotum (Figs 3L, 29A); posterior margin of abdominal mediotergite VII with a short median process (Fig. 29A, D); abdominal segment VII with four distinct processes, including two lobe-like processes on each connexival corner, consisting of one broader, posteriorly directed outer process and a narrower inner process (Fig. 29D–F); posterior margin of sternum VII with a small, rounded median process (Fig. 29E). Male: middle trochanter without spines; middle femur with scattered small spines, not arranged in distinct row (Fig. 29J); length of middle tibia ca 1.5–1.6 times length of hind tibia; proctiger relatively large, with angular lobes laterally (Figs 7B, 29K); paramere relatively slender and sinuate, middle part thickened, distal part tapering towards narrowly rounded apex (Figs 8H, 29L).
Material examined
Non-type specimens
CHINA – Hunan Province • 10 ♁♁, 7 ♀♀ (apterous); Shao-yang City, Dong-kou County, Luo-xi; 27°2′19.4″ N, 110°13′48.6″ E; 500 m a.s.l.; 27 Jul. 2016; Yan-chen Li and Chen-guang Zheng leg.; NKUM. – Jiangxi Province • 1 ♀ (apterous); Lu-shan City, Gu-ling County; 16 Jul. 1935; O. Piel leg.; IZAS • 1 ♁ (dealated macropterous); Lu-shan City, Gu-ling County; 16 Jul. 1935; O. Piel leg.; IZAS.
Supplemental description
Apterous female
MEASUREMENTS. Body length 11.62–12.21, width 2.60–3.08, head width 1.67, interocular width 0.81, eye length (dorsal view) 0.66; relative lengths of antennal segments I–IV: 5.11: 1.24: 1.67: 1.10; pronotum: length 0.91, width 1.78; mesonotum: length 2.94, width 3.34; metanotum: length 0.81, width 3.08; abdomen length (ventral view) 5.68; abdominal sternum VII: length 1.95, width 1.53; abdominal mediotergite I: length 0.52, width 1.41; relative lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 5.28:4.51: 3.05: 1.10, middle leg: 13.71:7.95: 3.68: 0.51, hind leg: 14.10: 6.73: 0.17: 0.21.
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 3L, 29A). Yellowish subtriangular marking on metanotum similar with the one on pronotum. Connexivum dorsally brownish-yellow.Abdominal tergum I with a median yellow marking.Mesosternum chiefly blackish with a median subtriangular yellowish spot (Fig. 29B). Abdominal venter light yellow.
ABDOMEN. Abdomen relatively long, sightly curved dorsad towards end (Fig. 29C). Connexiva erect on abdominal segments I–VI, subparallel to each other above mediotergites, reflexed over terminal mediotergites, nearly meeting each other above mediotergite VII (Fig. 29D). Posterior margin of abdominal mediotergite VII with a short median process. Abdominal segment VII elongate, moderately curved dorsad towards end or nearly straight, about as long as two preceding abdominal segments together (Figs 5K, 29C). Posterior margin of abdominal segment VII with four distinct processes, including two lobe-like processes on each connexival corner (Fig. 29D–F), one broader, posteriorly-directed outer lobe and the other narrower pointed inner lobe, ventrally with a small, median process (Fig. 29E).
Apterous male
MEASUREMENTS. Body length 8.02–8.41, width 2.00–2.60, head width 1.54, interocular width 0.83, eye length (dorsal view) 0.60; relative lengths of antennal segments I–IV: 4.12: 1.02: 1.35: 0.94; pronotum: length 0.75, width 1.66; mesonotum: length 2.33, width 2.41; metanotum: length 0.61, width 2.06; abdomen length (ventral view) 3.08; abdominal sternum VII: length 0.59, width 1.22; abdominal mediotergite I: length 0.40, width 0.87; relative lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 4.15: 3.41: 1.38: 0.70, middle leg: 11.32: 6.44: 2.63: 0.43, hind leg: 10.71: 4.08: 0.14: 0.20.
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 with two color forms: one without (Fig. 29G) and the other with (Figs 4I, 29H) yellow marking on metanotum and abdominal tergum I. Individuals of the two types were found mixed in the same population. Connexivum dorsally blackish. Mesosternum chiefly blackish with a median subtriangular yellowish spot, narrower than that of female (Fig. 29I). Abdominal venter light yellow.
LEG. Middle trochanter without spines; middle femur with scattered small spines, not arranged in distinct row (Fig. 29J).
GENITALIA. Abdominal segment VIII ventro-laterally impressed. Pygophore large, ovate. Proctiger relatively large, with angular lobes laterally (Figs 7B, 29K). Paramere relatively slender and sinuate, middle part thickened, distal part tapering towards narrowly rounded apex (Figs 8H, 29L).
Distribution
China: Hunan (first record); Zhejiang (Andersen & Chen 1995).
Comparative notes
Rhyacobates lundbladi is closely related to R. svenhedini due to their large body sizes, the bilobate processes on the connexival corners of abdominal segment VII and the median process on posterior margin of abdominal mediotergite VII (Figs 3L, P, 29D, 34D). However, R. lundbladi differs from R. svenhedini by the combination of following characteristics of the female: (1) in R. lundbladi, the subtriangular yellowish marking on metanotum is wide, with larger apex angle (Figs 3L, 29D), whereas in R. svenhedini, the subtriangular yellowish marking on metanotum is relatively thin, with sharp apex angle (Figs 3P, 34D); (2) in R. lundbladi the inner processes on the connexivum of abdominal segment VII are elongate (Fig. 29D), whereas that in R. svenhedini is very small (Fig. 34D).
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 48-51, DOI: 10.5852/ejt.2023.893.2285, http://zenodo.org/record/8385630