Rhyacobates elongatus Leng & Tran 2023, sp. nov.
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 elongatus

description: Rhyacobates elongatus sp. nov.
urn:lsid:zoobank.org:act: 34F2BA54-0EE7-4FF0-BE46-11B774AB7BE9
Figs 3B, 4B, 5B, 6B, 8B, 17–18
Diagnosis
Body length of apterous females 11.25–11.88, of apterous males 7.70–8.00. In both sexes, mesonotum and metanotum completely black, without median yellow stripe (Figs 3B, 4B). Female: posterior margin of mediotergite VII with a distinctly long median process (Fig. 18A, D); posterior margin of abdominal segment VII with five processes, including an elongate, tapering process terminating each connexivum, a pair of blunt processes laterally, and a semicircular median process ventrally (Fig. 18D–F). Male: middle trochanter with 4–5 small spines on distal part; middle femur with small spines along its length, with irregular distances between spines (Fig. 18I); length of middle tibia ca 1.4 times length of hind tibia; proctiger laterally with broadly rounded lobes (Figs 6B, 18J); paramere relatively stout, curved at basal fourth, distal part tapering towards slightly curved and rounded apex (Figs 8B, 18K).
Etymology
The name elongatus refers to the pair of elongate connexival processes of sternum VII and also to the elongate medial process on posterior margin of mediotergite VII of the female (Figs 2B, 18A, D–F).
Material examined
Holotype (Fig. 17A–B)
VIETNAM • ♀ (apterous); Hà Tĩnh Province, Vũ Quang National Park, Khe Nam Châm stream, site #2, downstream; 18°17′20.7″ N, 105°21′38.5″ E; 21 Apr. 2022; A.D. Tran et al. leg.; TAD2209; ZVNU.
Paratypes (Fig. 17C)
VIETNAM • 4 ♁♁, 6 ♀♀ (apterous), 7 ♁♁, 1 ♀ (macropterous); same collection data as for holotype; ZVNU • 1 ♁, 1 ♀ (apterous); same collection data as for holotype; NKUM • 2 ♁♁, 2 ♀♀ (apterous), 1 ♁ (macropterous); same collection data as for holotype; ZRC • 4 ♁♁, 1 ♀ (apterous); 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 ♁, 1 ♀ (apterous); same collection data as for preceding; NHMW.
Description
Apterous female
MEASUREMENTS. Body length 11.25–11.88 (holotype 11.38), width 2.67–2.97 (holotype 2.43), head width 1.46, interocular width 0.62, eye length (dorsal view) 0.68; relative lengths of antennal segments I–IV: 4.20: 1.17:1.26: 0.92; pronotum: length 0.82, width 1.57; mesonotum: length 2.72, width 2.43; metanotum: length 0.92, width 2.55; abdomen length (ventral view) 4.95; abdominal sternum VII: length 1.58, width 1.26; abdominal mediotergite I: length 0.36, width 1.12; relative lengths of leg segments (femur: tibia: tarsal segment I:tarsal segment II): fore leg: 4.40:3.60: 2.15: 0.90, middle leg: 11.88: 6.40: 3.28:0.41, hind leg: 11.88: 4.75:0.12: 0.17.
C OLORATION. Median black spot of head posteriorly bifurcate. Pronotum mainly black with a median brownish-yellow spot. Mesonotum and metanotum completely black, without yellow markings (Figs 3B, 18A). Connexivum dorsally blackish. Venter of female mainly light yellow, except mesosternum and mesopleuron black antero-laterally (Fig. 18B). Metasternum and abdominal venter light yellow.
ABDOMEN. Abdomen relatively long, caudal part moderately curved dorsad (Figs 5B, 18C). Connexiva erect on abdominal segments I–VI, parallel to each other above mediotergites, reflexed over terminal terga (Figs 5B, 17A, 18C). Abdominal mediotergite I not swollen, with sparse silvery pubescence laterally (Fig. 3B). Abdominal segment VII elongate, in lateral view nearly as long as three preceding abdominal segments, completely enclosing genital segments; ventral length of sternum VII nearly as long as two preceding sterna. Abdominal connexiva convergent towards abdominal apex (Figs 17B, 18A, D). Posterior margin of abdominal segment VII with five processes, including an elongate, tapering process terminating each connexivum, a pair of blunt processes laterally, and a semicircular median process ventrally (Fig. 18D–F).
Macropterous female
Similar to apterous female in general structure and coloration with following exceptions: pronotal lobe covering most of mesonotum; posterior margin of pronotal lobe broadly rounded and slightly lighter colored (dark-yellowish).
MEASUREMENTS. Body length 10.81, width 2.53, head width 1.44, interocular width 0.59, eye length (dorsal view) 0.65; relative lengths of antennal segments I–IV: 4.10: 1.08: 1.19:0.94; pronotum: length 3.23, width 2.38; mesonotum width 2.53; metanotum: length 0.67, width 2.59; length of fore wing: 7.65; abdomen length (ventral view) 4.70; abdominal sternum VII: length 1.50, width 1.17; abdominal mediotergite I: length 0.35, width 1.08; relative lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 4.20: 3.40: 2.03: 0.90, middle leg: 11.88: 6.19: 3.20: 0.44, hind leg: 11.88: 4.95: 0.14: 0.21.
Apterous male
MEASUREMENTS. Body length 7.70–8.00, width 2.08–2.22, head width 1.33, interocular width 0.54, eye length (dorsal view) 0.59; relative lengths of antennal segments I–IV: 3.78: 1.10: 1.26: 0.92; pronotum: length 0.72, width 1.35; mesonotum: length 2.25, width 1.94; metanotum: length 0.73, width 1.98; abdomen length (ventral view) 3.30; abdominal sternum VII: length 0.36, width 1.12; abdominal mediotergite I: length 0.25, width 0.72; relative lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 4.13: 3.15: 1.26: 0.72, middle leg: 11.38: 5.56: 2.75: 0.41, hind leg: 11.44: 3.93: 0.13: 0.16.
C OLORATION. Median black spot of head posteriorly bifurcate. Pronotum and mesonotum mainly black with a median brownish-yellow spot. Mesonotum and metanotum completely black, without yellow markings (Figs 4B, 17C, 18G). Connexivum dorsally blackish. Mesosternum blackish with thin yellow median stripe on anterior two-thirds and light yellow posterior third (Fig. 18H). Metasternum and abdominal venter light yellow.
LEG. Middle trochanter with 4–5 small spines on distal part; middle femur with small spines scattered along its length, not forming a distinct row (Fig. 18I).
GENITALIA. Abdominal segment VIII slightly dorso-ventrally depressed. Genitalia slightly directed ventrad. Pygophore elongate, apical end subovate. Proctiger laterally with broadly rounded lobes (Figs 6B, 18J). Paramere relatively stout, curved at basal fourth, distal part tapering towards the slightly curved and rounded apex (Figs 8B, 18K).
Macropterous male
Similar to apterous male in general structure; pronotal lobe similar to that of macropterous female.
MEASUREMENTS. Body length 8.90–9.35 (including wings), width 2.20–2.34, head width 1.32, interocular width 0.52, eye length(dorsal view) 0.63; relative lengths of antennal segments I–IV:3.80: 1.07: 1.24: 0.92; pronotum: length 2.91, width 2.08; mesonotum width 2.13; metanotum: length 0.61, width 2.01; length of fore wing: 6.40; abdomen length (ventral view) 3.20; abdominal sternum VII: length 0.50, width 1.12; abdominal mediotergite I: length 0.29, width 0.67; relative lengths of leg segments (femur:tibia: tarsal segment I: tarsal segment II): fore leg: 4.00: 3.06:1.19:0.68, middle leg: 11.00:5.50: 2.78: 0.41, hind leg: 10.94:3.83: 0.11: 0.15.
Distribution
Vietnam: Hà Tĩnh.
Comparative notes
Rhyacobates elongatus sp. nov. is probably a sister species of R. bui sp. nov.; see comparative notes under R. bui.
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 22-26, DOI: 10.5852/ejt.2023.893.2285, http://zenodo.org/record/8385630