Pleciobates herczeki, Leng & Ye, 2023

Leng, Zhaoqi & Ye, Zhen, 2023, Description of a new species of Pleciobates Esaki, 1930 (Hemiptera: Heteroptera Gerridae) from Hainan Island, China, Zootaxa 5382 (1), pp. 87-96 : 87-95

Pleciobates herczeki sp. nov.

( Figs 1–7)

Material examined. Holotype: apterous female, CHINA, Hainan Prov., Qiong-zhong County, Jia-tong Village (18°47′57.8″ N, 109°53′55.8″ E), 8 Aug. 2017, 242 m, leg. Zhen Ye and Juan-juan Yuan ( NKUM) . Paratypes: 2 apterous males and 2 apterous females, CHINA, Hainan Prov., Bai-sha County, Hong-kan Waterfall (19°4′32.9″ N, 109°29′55.7″ E), 28 Apr. 2023, 513 m, leg. Zhao-qi Leng ( NKUM) ; 2 apterous males and 2 apterous females, CHINA, Hainan Prov., Bai-sha County, Nan-mei-qiao (19°9′7.2″ N, 109°26′2.8″ E), 29 Apr. 2023, 222 m, leg. Zhaoqi Leng and Yi-chen Zhang ( NKUM) ; 1 apterous male and 2 apterous females, same collection data as for holotype ( NKUM) ; 1 apterous male and 1 apterous female, CHINA, Hainan Prov., Wan-ning City, Jian-feng-ling Nature Reserve , Yu-lin-gu (18°42′30.9″ N, 108°49′20.2″ E), 1 Aug. 2017, leg. Zhen Ye ( NKUM) ; 1 apterous male and 1 apterous female, CHINA, Hainan Prov., Qiong-zhong County, Beng-ling Village (18°46′42.7″ N, 109°50′29.3″ E), 8 Aug. 2017, 253 m, leg. Zhen Ye ( NKUM) ; 1 apterous male and 1 apterous female, CHINA, Hainan Prov., Changjiang County, Qing-song Village, Ba-wang-ling Nature Reserve , Nan-sha River (19°5′0.1″ N, 109°15′58.1″ E), 28 July. 2017, leg. Kun Jiang ( NKUM) ; 1 apterous male and 1 apterous female, CHINA, Hainan Prov., Bai-sha County, Luo-shuai Village , Xian-nv-xi (19°5′56.4″ N, 109°32′45.6″ E), 26 July. 2017, 324 m, leg. Zhen Ye and Si-ying Fu ( NKUM) ; 1 apterous male and 1 apterous female, CHINA, Hainan Prov., Dan-zhou City, Lu-mu-wan Waterfall (19°13′54.6″ N, 109°41′16.5″ E), 22 July. 2017, 202 m, leg. Zhen Ye and Juan-juan Yuan ( NKUM) ; 1 apterous male and 1 apterous female, CHINA, Hainan Prov., Wu-zhi-shan City, Xin-min Village (18°49′6.7″ N, 109°39′25.0″ E), 5 Aug. 2017, 579 m, leg. Zhen Ye ( NKUM) .

Comparative material examined. Non-type materials of Pleciobates tuberculatus Esaki, 1930 ( Fig. 2D, E): 3 apterous males and 5 apterous females, MALAYSIA, Perak State, Gerik, Kampung Kuala Bikan (5°27′50.7″ N, 101°8′10.8″ E), 14 Apr. 2019, leg. Zhen Ye ( NKUM); 7 apterous males and 6 apterous females, MALAYSIA, Pahang State (3°38′52.5″ N, 102°42′03.4″ E), 19 Apr. 2019, 40 m, leg. Zhen Ye ( NKUM) .

Diagnosis. In female, mesonotum and metanotum without distinct median longitudinal sulcus ( Figs 1A, 2A, 3A); tubercle on posterior margin of metanotum well developed ( Figs 2B, 3B–C); posterior margin of sternite VII evenly concave ( Figs 2C, 3F); genitalic segments relatively short, reaching less than one-third the length of the connexical processes on abdominal segment VI, gonapophyses processes not exposed ( Figs 2A–C, 3D–F). In male, posterior part of the mesonotum with indistinct median longitudinal sulcus, metanotum with distinct median longitudinal sulcus ( Figs 1B, 4A); pygophore with a pair of distinctly pointed lateral lobes, posterolateral corners of the basal part angular and elongate in lateral aspect ( Fig. 5A); proctiger relatively narrow on the anterior and posterior parts, gradually widened on posterior one-third, laterally with a pair of blunt lobes directed slightly downwards ( Fig. 5B).

Comparative notes. Species of Pleciobates are quite similar to each other, with the diagnostic characteristics among the different species involving modifications to abdominal segment VII in the female, and the genitalic structures of the male. The female of Pleciobates herczeki sp. nov. can be easily distinguished from all other congeneric species by having the evenly concave hind margin of abdominal sternite VII ( Figs 2C, 3F). The hind margin of sternite VII of the female is more abruptly emarginated in Pleciobates tuberculatus Esaki, 1930 ( Fig. 2 D–E) and only along a median “V” shape notch in Pleciobates vietnamensis Zettel & Chen, 1996 ; is almost straight, not concave, in the other three species (i.e., Pleciobates bengalensis Jehamalar, Basu & Zettel, 2014 , Pleciobates expositus Jehamalar, Chandra & Zettel, 2014 and Pleciobates pacholatkoi Zettel & Chen, 1996 ). Female of P. herczeki sp. nov. is mostly similar to P. pacholatkoi , however, males of the two species show differences in genitalic structures: in P. herczeki sp. nov., the paramere is not constricted on apex part ( Fig. 5D), while it is relatively constricted in P. pacholatkoi ; in P. herczeki sp. nov., endosoma has an angular ventral projection ( Fig. 5C), while the ventral projection is relatively blunt in P. pacholatkoi (see Fig. 10 in Zettel & Chen, 1996).

Description. Apterous female. Measurements. Body length 6.37–7.08, width 2.43–2.72, head width 1.19– 1.31, interocular width 0.41–0.49, eye length (dorsal view) 0.52–0.57; relative lengths of antennal segments I–IV: 2.57–2.89: 0.79–0.87: 0.95–1.04: 0.69–0.78; pronotum: length 0.66–0.75, width 1.35–1.51; mesonotum: length 2.19–2.29, width 2.43–2.55; metanotum: length 0.85–0.94, width 2.37–2.49; connexival process length 0.76–0.88; abdomen length (ventral view) 2.49–2.51; abdominal sternum VII: length 0.73–0.76, width 1.51–1.59; relative lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 2.97–3.07: 2.24–2.31: 1.02–1.06: 0.74–0.78, middle leg: 8.38–9.35: 4.49–5.23: 1.76–2.13: 0.29–0.39, hind leg: 7.81–8.92: 2.56–2.91: 0.11–0.13.

Coloration. Quite typical for the genus as described by Jehamalar et al. (2014). Median black spot of head reduced, indistinctly bifid or dissolving into smaller spots posteriorly ( Figs 1A, 2A, 3A). Rostrum I blackish on basal part, brownish-yellow on apical part; rostrum II brownish yellow; rostrum III chiefly blackish except brownish yellowish on basal part; rostrum IV blackish ( Fig. 2B). Dorsum of the body clothed with minute silvery white pubescence, midline of mesonotum and metanotum without obvious pubescence ( Fig. 2A). Pronotum mainly black with a median brownish-yellow spot, mesonotum and metanotum completely black ( Figs 1A, 2A, 3A). Posterior region of acetabula brownish-yellow. Coxa and trochanter of all legs brownish-yellow; fore femur yellowish with two blackish broad stripes fused apically; fore tibia and fore tarsus black; middle and hind legs mainly blackish except the basal area of middle femur brownish ( Fig. 1A). Connexiva dorsally blackish. Mesosternum chiefly blackish with a median subtriangular yellowish spot. Abdominal venter light yellowish ( Fig. 2C).

Body structure. Mesonotum and metanotum without distinct median longitudinal sulcus ( Figs 1A, 2A, 3A). Tubercle on posterior margin of metanotum well developed, directed upwards, blunt and with setae on apex, reaching anterior margin of abdominal mediotergite II ( Figs 2B, 3B–C); posterior margin of the sternum VII slightly curved. Posterior margin of each connexival segment VI with elongate process, also with setae on lateral and apical part and directing downwards ( Figs 2A–C, 3D–F). Posterior margin of sternite VII evenly concave, taking the shape of a curve ( Figs 2C, 3F).

Genitalia. Genitalic segments relatively short, not reaching the apex one third of the connexical process of abdominal segment VI, gonapophyses processes not exposed ( Figs 2A–C, 3D–F).

Apterous male. Measurements. Body length 6.94–6.98, width 1.93–1.94, head width 1.16–1.18, interocular width 0.42–0.47, eye length (dorsal view) 0.53–0.55; relative lengths of antennal segments I–IV: 3.08–3.09: 0.71– 0.76: 1.04–1.15: 0.75–0.81; pronotum: length 0.68–0.69, width 1.31–1.41; mesonotum: length 2.23–2.24, width 1.93–1.94; metanotum: length 0.56–0.64, width 1.84–1.9; relative lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 3.23–3.52: 2.51–2.65: 0.92–0.94: 0.55–0.58, middle leg: 9.94–10.29: 4.69– 4.72: 1.89–1.91: 0.41–0.43, hind leg: 8.79–9.35: 0.43–0.51: 0.12–0.13.

Coloration. Quite typical for the genus as described by Jehamalar et al. (2014). Median black spot of head reduced, indistinctly bifid or dissolving in smaller spots posteriorly ( Figs 1B, 4A). Rostrum I blackish on basal part, brownish-yellow on the apical part; rostrum II brownish yellow; rostrum III chiefly blackish except brownish yellowish on basal part; rostrum IV blackish. Dorsum of body clothed with minute silvery white pubescence, midline of mesonotum and metanotum without obvious pubescence ( Fig. 1B). Pronotum mainly black with a median brownish-yellow spot, mesonotum and metanotum completely black ( Figs 1B, 4A). Posterior region of the acetabula brownish-yellow. Coxa and trochanter of all legs brownish-yellow; fore femur yellowish with two blackish broad stripes fused apically; fore tibia and fore tarsus blackish; middle and hind legs mainly blackish except the basal area of middle femur brownish ( Fig. 1B). Connexiva dorsally blackish. Mesosternum chiefly blackish with a median subtriangular yellowish spot, narrower than female. Abdominal venter light yellowish ( Fig. 4B).

Body structure. Posterior part of mesonotum with indistinct median longitudinal sulcus, metanota with distinct median longitudinal sulcus ( Fig. 4A).

Genitalia. Pygophore with a pair of distinctly pointed lateral lobes, basal part angular and elongate in lateral aspect ( Fig. 5A). Proctiger relatively narrow on the anterior and posterior parts, gradually widened on posterior one-third, laterally with a pair of blunt lobes slightly directed downwards ( Fig. 5B). Endosoma structure as shown in the line drawing ( Fig. 5C), ventral projection with a distinct sharp angle. Paramere widened and curved on basal part, gradually tapering across the apex, apex of the paramere slightly curved, not constricted, with several short setae ( Fig. 5D).

Etymology. This species is named in honor of Aleksander Herczek for his contributions to the taxonomic study of Heteroptera, on the occasion of his 70 th birthday.

Biology and Ecology. Pleciobates herczeki sp. nov. typically inhabits clear, small to medium streams, living in areas with rocks protruding from the surface of the water ( Fig. 6A). The habits of this species are similar with those of Rhyacobates Esaki, 1923 , they usually climb onto the rocks when they are resting ( Fig. 6B–E), and when predators approach, they will quickly jump into the water and stride against the wave swiftly.

Distribution. China: Hainan ( Fig. 7).