Rhyacobates bui, Leng & Tran, 2023

Leng, Zhaoqi, Tran, Anh Duc & Ye, Zhen, 2023, Taxonomic review of Rhyacobates Esaki, 1923, with descriptions of three new species (Hemiptera: Heteroptera: Gerridae), European Journal of Taxonomy 893 (1), pp. 1-73 : 18-19

publication ID	https://doi.org/ 10.5852/ejt.2023.893.2285
publication LSID	lsid:zoobank.org:pub:D9DA4879-BC1D-4947-96E8-7D574DE334BA
DOI	https://doi.org/10.5281/zenodo.10064059
persistent identifier	https://treatment.plazi.org/id/8A1A2DC9-C314-4458-AF0C-752FEECA39C7
taxon LSID	lsid:zoobank.org:act:8A1A2DC9-C314-4458-AF0C-752FEECA39C7
treatment provided by	Plazi
scientific name	Rhyacobates bui
status	sp. nov.

Treatment

Rhyacobates bui sp. nov.

urn:lsid:zoobank.org:act:8A1A2DC9-C314-4458-AF0C-752FEECA39C7

Figs 3A View Fig , 4A View Fig , 5A View Fig , 6A View Fig , 8A View Fig , 15–16 View Fig View Fig

Diagnosis

Body length of apterous females 8.81–9.30, of apterous males 6.50–6.91. In both sexes, mesonotum and metanotum completely black, without median yellow stripe ( Figs 3A View Fig , 4A View Fig ). Female: posterior margin of mediotergite VII with a distinctly long, slender median process ( Fig. 16A, D View Fig ); posterior margin of abdominal segment VII with five processes, including a blunt process terminating each connexivum, a pair of blunt processes laterally, and a semicircular median process ventrally ( Fig. 16D–G View Fig ). Male: middle trochanter with 3–4 small spines; middle femur with scattered small spines arranged in a row, but with irregular distance between spines ( Fig. 16J View Fig ); length of middle tibia ca 1.6 times length of hind tibia; proctiger laterally with subtrapezoid lobes, dorsally with brownish setae ( Figs 6A View Fig , 16K View Fig ); paramere relatively slender, strongly curved at basal third, distal part tapering towards distinctly curved and narrow apex ( Figs 8A View Fig , 16L View Fig ).

Etymology

This species dedicated to Prof. Wenjun Bu (Institute of Entomology, Nankai University, China), in recognition of his contributions to the study ofthe taxonomy, phylogeny and biogeography of Heteroptera .

Material examined

Holotype ( Fig. 15A View Fig )

CHINA • ♀ (apterous); Guangxi Province, Fang-cheng-gang City , Shang-si County, Shi-wan-da-shan; 21°54′4.1″ N, 107°54′22.1″ E; 300–400 m a.s.l.; 13 Aug. 2019; Zhen Ye and Si-qi Wang leg.; NKUM. GoogleMaps

Paratypes ( Fig. 15B View Fig )

CHINA • 3 ♁♁ (apterous); same collection data as for holotype; NKUM GoogleMaps .

VIETNAM • 10 ♁♁, 3 ♀♀ (apterous); L ạng SƠn Province, L ộc Bình , M ẫu SƠn , upstream of Long Đǻu stream ; 21°48′59.3″ N, 106°59′56.3″ E; 7 Nov. 2020; A.D. Tran et al. leg.; TAD20-37; ZVNU GoogleMaps • 1 ♁, 1 ♀ (apterous); same collection data as for preceding; NHMW GoogleMaps • 1 ♁, 1 ♀ (apterous); same collection data as for preceding; NKUM GoogleMaps • 2 ♁♁, 2 ♀♀ (apterous); same collection data as for preceding; ZRC GoogleMaps .

Description

Apterous female

MEASUREMENTS. Body length 8.81–9.30 (holotype 8.81), width 2.34–2.52 (holotype 2.52), head width 1.41, interocular width 0.75, eye length (dorsal view) 0.62; relative lengths of antennal segments I–IV: 3.34: 1.02: 1.12:0.71; pronotum: length 0.72, width 1.51; mesonotum: length 2.34, width 2.52 (holotype 2.52); metanotum: length 0.84, width 2.21; abdomen length (ventral view) 4.16; abdominal sternum VII: length 1.16, width 1.15; abdominal mediotergite I: length 0.35, width 0.92; relative lengths of leg segments (femur:tibia: tarsal segment I: tarsal segment II): fore leg: 3.56: 2.84:1.46:0.78, middle leg: 10.01:5.94:2.63:0.44, hind leg: 10.16: 3.88: 0.11:0.17.

COLORATION. Median black spot of head reduced, indistinctly bifid or dissolved into smaller spots posteriorly ( Fig. 3A View Fig ). Pronotum mainly black with a median brownish-yellow spot. Mesonotum and metanotum completely black, without yellow markings ( Figs 3A View Fig , 16A View Fig ). Connexivum dorsally blackish. Venter of female mainly light yellow, except mesosternum and mesopleuron black laterally ( Fig. 16B View Fig ). Abdominal venter light yellow.

ABDOMEN. Abdomen relatively long, nearly straight, gradually tapering towards apex ( Figs 5A View Fig , 16C View Fig ). Connexiva erect on abdominal segments I–VI, parallel to each other above mediotergites, reflexed over terminal mediotergites ( Fig. 16A, D View Fig ). Abdominal mediotergite I not swollen, fully covered with silvery pubescence ( Fig. 3A View Fig ). Posterior margin of mediotergite VII with a distinctly long median process ( Fig. 16A, D View Fig ), about half the length of mediotergite VII (excluding the process). Abdominal segment VII elongate, nearly as long as three preceding abdominal segments, completely enclosing genital segments. Abdominal dorsal margin not curved in lateral view ( Figs 5A View Fig , 16C View Fig ). Posterior margin of abdominal segment VII with five processes, including a blunt process terminating each connexivum, a pair of blunt processes laterally, and a semicircular median process ventrally ( Fig. 16D–G View Fig ).

Apterous male

MEASUREMENTS. Body length 6.50–6.91, width 1.62–1.97. head width 1.21, interocular width 0.52, eye length (dorsal view) 0.54; relative lengths of antennal segments I–IV: 3.11: 0.88: 0.98: 1.08; pronotum: length 0.70, width 1.35; mesonotum: length 1.87, width 1.62; metanotum: length 0.65, width 1.60; abdomen length (ventral view) 2.72; abdominal sternum VII: length 0.38, width 0.52; abdominal mediotergite I: length 0.22, width 0.57; relative lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 3.01: 2.34: 0.78: 0.52, middle leg: 8.88: 4.65: 2.10: 0.38, hind leg: 8.56:2.97: 0.11: 0.15.

COLORATION. Median black spot of head reduced, indistinctly bifid or dissolved in smaller spots posteriorly ( Figs 4A View Fig , 16H View Fig ). Pronotum and mesonotum mainly black with a median brownish-yellow spot. Mesonotum and metanotum completely black, without yellow markings ( Figs 4A View Fig , 16H View Fig ). Connexivum dorsally blackish. Mesosternum chiefly blackish with a median subtriangular yellowish spot ( Fig. 16I View Fig ). Abdominal venter light yellow.

ABDOMEN. Abdominal mediotergite I not swollen, nearly completely covered by silvery pubescence ( Fig. 4A View Fig ).

LEG. Middle trochanter with 3–4 small spines; middle femur with a row of irregularly-spaced small spines ( Fig. 16J View Fig ).

GENITALIA. Abdominal segment VIII ventro-laterally depressed. Pygophore large, ovate. Proctiger laterally with subtrapezoid lobes, dorsally with brownish setae ( Figs 6A View Fig , 16K View Fig ). Paramere relatively slender, strongly curved basal third, distal part tapering towards distinctly curved and narrowed apex ( Figs 8A View Fig , 16L View Fig ).

Distribution

China: Guangxi. Vietnam: Lạng SƠn.

Comparative notes

This new species is closely related to R. elongatus sp. nov. in having an elongate medial process on the posterior margin of mediotergite VII and five processes on abdominal segment VII of the female, including two connexival processes, two lateral blunt processes and a semicircular median process on the ventral side ( Figs 16D–F View Fig , 18D–F View Fig ). However, the abdominal mediotergite I of R. bui sp. nov. is fully covered with silvery pubescence, which is much denser than in R. elongatus ( Fig. 3A–B View Fig ). The connexival processes of abdominal segment VII of R. bui are much shorter and blunter ( Fig. 16D View Fig ) than those of R. elongatus ( Fig. 18D View Fig ). The abdomen of the female of R. bui is almost straight ( Fig. 16C View Fig ), whereas that of R. elongatus is curved dorsad in the caudal part ( Fig. 18C View Fig ). These two species are also related to five species (i.e., R. angustus , R. lundbladi , R. svenhedini , R. takahashii , and R. zetteli ) in having the median process on the posterior margin of mediotergite VII in the female, but this structure in R. bui and R. elongatus is much longer than that of the five latter species. Furthermore, both R. bui and R. elongatus have entirely black mesonota and metanota ( Figs 3A–B View Fig , 4A–B View Fig ), without yellow stripes (in both sexes), which is a character state shared with R. constrictus . Females of R. bui and R. elongatus can be easily separated from R. constrictus by the following characteristics: (1) R. bui and R. elongatus have slender bodies ( Fig. 3A–B View Fig ), whereas R. constrictus has a wider, stouter body ( Fig. 3I View Fig ); (2) the posterior margin of mediotergite VII of R. bui and R. elongatus has a median process ( Figs 16A, D View Fig , 18A, D View Fig ), whereas that of R. constrictus lacks a median process ( Figs 3I View Fig , 26B View Fig ); (3) the posterior margin of abdominal segment VII of R. bui and R. elongatus has five processes ( Figs 16D–F View Fig , 18D–F View Fig ), whereas that of R. constrictus has only one median process ventrally ( Fig. 26A–B View Fig ; also see Tran & Nguyen 2016: figs 36–39).

NHMW	Austria, Wien, Naturhistorisches Museum Wien
ZRC	Singapore, National University of Singapore, Raffles Museum of Biodiversity Research, Zoological Reference Collection
NKUM	Nankai University
NHMW	Naturhistorisches Museum, Wien