Rhyacobates anderseni Tran & Yang 2006
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 anderseni

description: Rhyacobates anderseni Tran & Yang, 2006
Figs 3F, 4E, 5E, 6E, 8E, 23
Rhyacobates anderseni Tran & Yang, 2006: 14–16, figs 7–16, 27 (original description).
Rhyacobates anderseni – Tran & Nguyen 2016: 513 (with remarks).
Diagnosis
Body length of females 6.79–7.30, of males 6.00–6.20. Both sexes: mesonotum mainly black with a median brownish-yellow stripe (broader in female, narrower in male); metanotum chiefly blackish, without yellow markings (Figs 3F, 23A). Female: hind margin of metanotum with a pointed median process extending over abdominal tergum I (Fig. 23C–D); pronotum mainly black with a median brownish-yellow spot; posterior margin of abdominal segment VII with four processes, dorsally with a long process terminating each connexivum (Fig. 23F–G), laterally with a pair of pointed processes (Fig. 23F, H), ventrally almost truncate, without median process (Fig. 23H). Male: middle trochanter without spines; middle femur with scattered small spines, not arranged in distinct row (Fig. 23K); length of middle tibia ca 1.8–1.9 times length of hind tibia; proctiger with rounded lobes laterally (Figs 6E, 23L); paramere relatively stout and evenly curved, middle part thickened, distal part tapering towards rounded apex (Figs 8E, 23M).
Material examined
Type specimens
See Tran & Yang (2006).
Non-type specimens
CHINA • 5 ♁♁, 3 ♀♀ (apterous); Yunnan Province, Jing-hong City, Cai-yang River; 22°33′4.1″ N, 101°5′14.6″ E; 879 m a.s.l.; 30 Jul. 2016; Zhen Ye leg.; NKUM.
VIETNAM • 1 ♁ (apterous), 1 ♁ (macropterous); Hà Tĩnh Province, Vũ Quang National Park, Khe Nam Châm stream, site #1, upstream; 18°17′31.5″ N, 105°21′18.7″ E; 21 Apr. 2022; A.D. Tran et al. leg.; TAD2208; ZVNU • 1 ♀ (macropterous); same collection data as for preceding; NKUM.
GPS data of previous records: see Tran & Yang (2006).
Supplemental description
Apterous female
MEASUREMENTS. Body length 6.79–7.30, width 2.00–2.60, head width 1.32, interocular width 0.58, eye length (dorsal view) 0.59; relative lengths of antennal segments I–IV: 3:0.86: 1.21: 0.74; pronotum: length 0.73, width 1.47; mesonotum: length 2.36, width 2.54; metanotum: length 0.88, width 1.98; abdomen length (ventral view) 2.88; abdominal sternum VII: length 1.23, width 1.18; abdominal mediotergite I: length 0.15, width 0.96; relative lengths of leg segments (femur:tibia: tarsal segment I:tarsal segment II): fore leg: 3.03: 2.35:1.17:0.83, middle leg: 8.75: 5.35:2.63:0.45, hind leg: 8.85:3.08:0.15: 0.21.
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 blackish, without yellow markings (Figs 3F, 23A). Connexivum dorsally blackish. Venter of female chiefly blackish with a median yellowish spot (Fig. 23B). Abdominal venter light yellow.
ABDOMEN. Hind margin of metanotum produced as a median protuberance over abdominal tergum I (Fig. 23C–D). Abdomen relatively short, nearly straight, moderately curved dorsad posteriorly (Figs 5E, 23E). Connexivum on abdominal segments I–VI dorsally blackish, forming a straight line in dorsal view (Figs 3F, 23A). Abdominal segment VII elongate, nearly as long as three preceding abdominal segments together (Fig. 23E), completely enclosing genital segments (Figs 3F, 23G). Posterior margin of abdominal segment VII with four processes, dorsally with a long, slender process terminating each connexivum (Fig. 23G), laterally with a pair of pointed processes (Fig. 23F, H), ventrally almost truncate, without a median process (Fig. 23H).
Apterous male
MEASUREMENTS. Body length 6.00–6.20, width 1.70–1.90, head width 1.21, interocular width 0.55, eye length (dorsal view) 0.53; relative lengths of antennal segments I–IV: 2.84: 0.89:1.14:0.78; pronotum: length 0.68, width 1.31; mesonotum: length2.13,width 1.85; metanotum:length 0.64, width 1.65;abdomen length (ventral view) 1.94; abdominal sternum VII: length 0.38, width 0.59; abdominal mediotergite I: length 0.19, width 0.68; relative lengths of leg segments (femur:tibia: tarsal segment I:tarsal segment II): fore leg: 3.04: 2.44:0.89:0.54, middle leg: 8.80: 4.86:2.38:0.36, hind leg: 8.75:2.62:0.11: 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 4E, 23I). Connexivum dorsally blackish. Metasternum anteriorly blackish and posteriorly light yellow (Fig. 23J). Abdominal venter anteriorly blackish and posteriorly light yellow or completely light yellow.
LEG. Middle trochanter without spines; middle femur with scattered small spines, not arranged in distinct row (Fig. 23K).
GENITALIA. Abdominal segment VIII ventro-laterally impressed. Pygophore large, ovate. Proctiger with rounded lobes laterally (Figs 6E, 23L). Paramere relatively stout and evenly curved, middle part thickened, distal part tapering towards rounded apex (Figs 8E, 23M).
Distribution
China: Yunnan; Vietnam: Hà Tĩnh (Tran & Yang 2006).
Comparative notes
Rhyacobates anderseni is distinct from all congeners in having a median process on the posterior margin of the metanotum in the female (Fig. 23D), which is present in three other ptilomerine genera, i.e., Andersenius, Pleciobates and Jucundus Distant, 1910. However, this species matches all other characteristics of Rhyacobates defined by Andersen & Chen (1995), as discussed by Tran & Yang (2006: 16). Future phylogenetic studies using molecular data may help to resolve the taxonomic position of this species.
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 34-36, DOI: 10.5852/ejt.2023.893.2285, http://zenodo.org/record/8385630