A new species of the genus Ranatra Fabricius, 1790 and supplementary data on Ranatra varipes Stål, 1861 (Hemiptera: Nepidae: Ranatrinae) from Vietnam

ABSTRACT

The genus Ranatra Fabricius, 1790 is currently represented in Vietnam by nine previously recorded species. Based on specimens collected from Vietnam and detailed morphological examinations, a new species, Ranatra uminhensis sp. nov. (belonging to the Ranatra malayana group), is described, illustrated, and discussed. Additional morphological data for Ranatra varipes Stål, 1861 are provided, and DNA barcode (COI) sequences for both species are presented for future reference.

Keywords:
Morphology; molecular phylogeny; taxonomy; morphometric analyses; water bug

Introduction

Members of the water bugs genus Ranatra Fabricius, 1790 (Hemiptera: Nepidae: Ranatrinae) are commonly recognized by their elongate, slender, almost cylindrical bodies, elongated and slender legs, and a yellowish-brown coloration. They are usually found along the margins of still-water environments, nestled among tangles of submerged sticks and vegetation, which they closely resemble.

The species of the genus Ranatra are found worldwide, comprising 123 valid species (excluding subspecies), with 69 species recorded in the New World and 54 species in the Old World. No species are shared between the two hemispheres, and nearly half of the global diversity is concentrated in Southeast Asia (Polhemus and Polhemus, 2008, 2013).

The most comprehensive revision of the Oriental Ranatra was conducted by Lansbury (1972), who recognized 26 species classified into six species groups (R. gracilis, R. elongata, R. malayana, R. varipes, R. filiformis, and R. biroi groups), along with a preliminary classification based on species groups. Subsequently, Tran and Zettel (2021a) provided diagnoses for six species groups sensu Lansbury, 1972 and proposed the seventh species group of the genus Ranatra, named as the Ranatra bilobata group.

Subsequent descriptions of new species and subspecies of the genus Ranatra from Southeast Asia have been published by several authors, including Nieser and Chen (1991, 1996), Nieser (1996, 1997), Zettel (1999), Chen et al. (2004), Nieser et al. (2005), Tran and Polhemus (2012), Polhemus and Polhemus (2012, 2013), Tran and Nguyen (2016), Tran and Poggi (2019), and Tran and Zettel (2021a, 2021b), Zettel et al. (2017), all of whom followed the species group framework proposed by Lansbury (1972).

Prior to the present study, nine species of the genus Ranatra had been recorded from Vietnam: Ranatra chinensis Mayr, 1865 (Ranatra elongata group), Ranatra varipes Stål, 1861, Ranatra falloui Montandon, 1907 (Ranatra varipes group), Ranatra filiformis Fabricius, 1790 (Ranatra filiformis group), Ranatra gracilis Dallas, 1850, Ranatra parmata Mayr, 1865 (Ranatra gracilis group),Ranatra thai Lansbury, 1972,Ranatra nieseri Tran & Nguyen, 2016 (Ranatra biroi group), and Ranatra bilobata Tran & Nguyen, 2016 (Ranatra bilobata group). These included taxa described or reported by Lansbury (1972), such as R. chinensis Mayr, 1865 (R. elongata group), R. varipes Stål, 1861; R. falloui Montandon, 1907 (R. varipes group), and R. filiformis Fabricius, 1790 (R. filiformis group). Also, Polhemus and Polhemus (2013) also reported distribution data for R. gracilis Dallas, 1850 (R. gracilis group). Furthermore, Tran and Polhemus (2012) elevated R. longipes thai to full species status, recognizing it as R. thai Lansbury, 1972. More recently, Tran and Nguyen (2016) described two new species, R. nieseri Tran and Nguyen, 2016 (R. biroi group) and R. bilobata Tran and Nguyen, 2016 (R. bilobata group), and provided first records of R. parmata Mayr, 1865 from Vietnam.

This study presents the description of a new species of genus Ranatra, along with supplementary data on R. varipes Stål, 1861, based on specimens collected in Vietnam and deposited in the Institute of Biology (IB). DNA barcode data (COI) for both species are also provided for future reference.

Materials and methods

Material examined and specimen depository: Ranatra specimens were collected using a pond net a 0.5 mm mesh and a 0.5 m² net area, attached to a 180 cm extension rod. At each sampling site, the net was swept across various microhabitats to ensure comprehensive coverage, including different vegetation zones, substrate types, pond and stream banks, and open water areas. Sampling was conducted in both flowing and still waters, typically near the shoreline, around aquatic vegetation, and across diverse bottom substrates. Particular attention was given to sweeping through areas containing submerged plant material, fallen branches, roots, and leaf litter to increase the likelihood of encountering target specimens.

A collection of adult specimens of Ranatra from Vietnam was deposited at the Institute of Biology (IB) (Table 1). Each specimen was labeled with identification details and locality data and individually preserved in vials containing 99% ethanol. The right hind leg or right middle leg of each specimen was severed for DNA extraction (which was subsequently used for molecular phylogenetic analysis and DNA barcoding). The remaining body parts were utilized for morphological assessment.

Table 1
The data of specimens used in this study. Abbreviations and symbols: n/a: no data; IB, Institute of Biology, Vietnam Academy of Science and Technology, Vietnam; VinhU, Vinh University, Vietnam; *, tentatively held by the corresponding author, Truong Xuan Lam.

Morphospecies	Specimen code	Collecting date	Locality	Sex	Accession numbers	Depository
					COI
Ranatra uminhensis Truong and Nguyen sp. nov. [Holotype]	TXL53	16.x.2023	Vietnam, Kien Giang	♂	PV263141	IB*
Ranatra uminhensis Truong and Nguyen sp. nov. [Paratype]	TXL53A01	19.x.2023	Vietnam, Kien Giang	♂	n/a	IB*
Ranatra uminhensis Truong and Nguyen sp. nov. [Paratype]	TXL53A02	20.xi.2023	Vietnam, Kien Giang	♂	n/a	IB*
Ranatra uminhensis Truong and Nguyen sp. nov. [Paratype]	TXL53A03	22.x.2024	Vietnam, Kien Giang	♀	n/a	IB*
Ranatra uminhensis Truong and Nguyen sp. nov. [Paratype]	TXL53A04	23.x.2024	Vietnam, Kien Giang	♂	n/a	IB*
Ranatra varipes Stål, 1861	TXL54	16.viii.2023	Vietnam, Ha Tinh	♂	PV263140	IB*
Ranatra varipes Stål, 1861	TXL54B01	16.viii.2023	Vietnam, Ha Tinh	♂	n/a	IB*
Ranatra varipes Stål, 1861	TXL54B02	6.iii.2024	Vietnam, Ha Tinh	♂	n/a	VinhU

Morphological examination and imaging. The external morphological characteristics of dry-mounted specimens were analyzed using a Nikon SMZ800N stereomicroscope. Examination of the genitalia was prepared as follows. Initially, each male specimen underwent relaxation by being immersed for three days in 70% ethanol. The male genitalia were then separated from the body and immersed in hot 10% KOH solution for five minutes until the fat and musculature were cleared. The endosoma was extracted from the phallosoma using fine tweezers after the phallus was taken out of the pygophore. All parts of the male genitalia were preserved in a genitalia vial filled with propylene glycol and subsequently associated with the pinned specimens. The female genitalia were examined in-situ, without dissection. A Nikon SMZ800N stereomicroscope was employed to investigate genital morphology. Focus stacking was performed with Helicon Focus Pro 8.2.0 (Helicon Soft Ltd., Ukraine), using a sequence of images captured with a Canon EOS Kiss X10 digital camera mounted on a Nikon SMZ 800N stereomicroscope. Image artifacts were removed using the software’s retouch function (Kumar et al., 2018).

Morphological terminology, measurement and indices. Morphological terminology followed that of Lansbury (1972), Chen et al. (2004), Polhemus and Polhemus (2013), Tran and Nguyen (2016). The following parts of the bodies were measured for Ranatra specimens (Fig. 1), using the software Image-J (http://imageJ.nih.gov/ij/) based on the direct stacking pictures designed as stated above. The assessment features are stated below, and all dimensions were given in millimeters (List of abbreviations).

Figure 1
Measurement characters of Ranatra species. Drawing based on Ranatra uminhensis Truong and Nguyen sp. nov., holotype, ♂, TXL53.

Molecular data preparation. DNA was isolated from each specimen’s right hind leg or right mid leg by the Chelex-TE-ProK protocol (Satria et al., 2015). The mitochondrial COI gene fragments were examined using the primer set LCO1490 and HCO2180. Polymerase chain reaction (PCR) amplification, cycle sequencing reaction, sequencing using ABI PRISM 3130xl (Applied Biosystems), and sequence assembly using ChromasPro 1.7.6 (Technelysium Pty Ltd., Australia) were executed using the methods of Satria et al. (2015). The PCR thermal situation for the COI gene fragment, comprised of initial denaturation at 94 °C (2 min), denaturation at 94 °C (30 s), annealing at 48.5 °C (30 s), and extension at 72 °C (45 s) for 35 cycles, with final extension at 72 °C (7 min) (Forero and Weirauch, 2012). COI sequences were effectively obtained from 5 samples of R. uminhensis Truong and Nguyen sp. nov. and 3 samples of R. varipes Stål, 1861.

List of abbreviations

AL: length of anterior lobe of pronotum

AW: anterior width of pronotum

BL: body length

HW: humeral width of pronotum

IW: interocular width

LaI: length of antennal segment I

LaII: length of antennal segment II

LaIII: length of antennal segment III

LCF: length of coxa of fore leg

LFF: length of femur of fore leg

LFH: length of femur of hind leg

LFM: length of femur of middle leg

LH: length of head

LM: length of metasternum

LO: length of operculum

LPo: length of posternum

LPr: length of prosternum

LS: length of scutellum

LTaF: length of tarsi fore leg

LTaH: length of tarsi hind leg

LTaM: length of tarsi middle leg

LTF: length of tibia fore leg

LTH: length of tibia hind leg

LTM: length of tibia middle leg

PA: posterior width of abdomen

PL: pronotal length

PLm: length of posterior lobe

PW: posterior pronotal width

RS: length of respiratory siphon

WB: width of body

WE: maximal width of eye

WFal: femur width across larger tooth (including tuft of setae)

WFb: femur width at basal half

WFl: width of larger tooth

WFs: width of smaller tooth

WFt: femur width at base of larger tooth

WH: width of head

WHE: Width across eyes

WS: width of scutellum

Results and discussion

Taxonomy

Family Nepidae Latreille, 1802

Subfamily Ranatrinae Douglas & Scott, 1865

Genus Ranatra Fabricius, 1790

Ranatra uminhensis Truong & Nguyen sp. nov.

urn:lsid:zoobank.org:act:181C6F5F-3B4D-4EDA-BD69-9548F8243A16

(Figs. 3, 4, 5)

Figure 3
Ranatra uminhensis Truong & Nguyen sp. nov., holotype, ♂, TXL53. A. antenna; B. head and prothorax dorsal view; C. head and prothorax lateral view; D. Meso and metasternum; E. left foreleg and femoral teeth, inner view. Scale bar: 0.5 mm for A; 0.3 mm for D, E; 0.2 mm for B, C.

Figure 4
Ranatra uminhensis Truong & Nguyen sp. nov. (male, holotype, ♂, TXL53; female, paratype, TXL53A03). A. apex of abdomen of male, dorsal view; B. apex of abdomen of female, dorsal view; C. apex of abdomen of male, lateral view; D. male phallotheca, dorsal view; E. male phallotheca, lateral view; F. paramere; G. apex of paramere. Scale bar: 1 mm for c; 0.6 mm for A, B; 0.5 mm for D, E; 0.3 mm for F.

Figure 5
Ranatra uminhensis Truong & Nguyen sp. nov., holotype ♂, TXL53. K. habitus, A. antenna, B. head and prothorax dorsal view, C. head and prothorax lateral view, D. Meso and metasternum, E. left foreleg and femoral teeth, inner view, G. apex of abdomen of male, lateral view, H. male phallotheca, lateral view, J. paramere, Q apex of paramere. Scale bar: 10 mm for K; 3 mm for B, C; 2 mm for E; 1 mm for D; 0.5 mm for H; 0.3 mm for J.

Material examined. Holotype. 1♂; TXL53; Vietnam, Kien Giang Province, U Minh Thuong National Park; 9°33.124' N; 105°05.214' E; 16.x.2023; XL Truong leg.; IB. Paratypes. 1♂; TXL53A01; Kien Giang Province, U Minh Thuong National Park; 9°33.184' N; 105°05.318' E; 19.x.2023; XL Truong leg.; IB. 1♂; TXL53A02; Kien Giang Province, U Minh Thuong National Park; 9°36.224' N; 105°05.511' E; 20.xi.2023; DD Nguyen leg.; IB. 1♀; TXL53A03; Kien Giang Province, U Minh Thuong National Park; 22.x.2024; XL Truong leg.; IB. 1♂; TXL53A04; Kien Giang Province, U Minh Thuong National Park; 9°35.528' N; 105°05.616'E; 23.x.2024; XL Truong leg.; IB.

Description.

General colouration: dorsum of body dark brown and darker than legs and abdomen, except ventral side of fore coxa brown.

Size: Males: body length 34.05–35.87 mm, length of respiratory siphon 27.12–28.71 mm, ratio of siphon length/body length 0.76–0.78. Female: body length 37.27 mm, length of respiratory siphon 30.08 mm; ratio of siphon length / body length: 0.81.

Structural characteristics (male) (Figs. 2A, B, 3, 4, 5):

Figure 2
Habitus images of morphospecies Ranatra uminhensis Truong & Nguyen sp. nov. and Ranatra varipes Stål, 1861. A. dorsal view, B. ventral view (Ranatra uminhensis Truong & Nguyen sp. nov., ♂, TXL53); C. dorsal view, D. ventral view (Ranatra varipes Stål, 1861, ♂, TXL54). Scale bar: 10 mm for A, B; 5 mm for C, D.

Head (Figs. 2A, B; 3B, C; 5B, C, K): in lateral view, vertex slightly higher than eye, conical tubercle with a small tubercle at the top; eyes dark brown, with red ventral side; maximal width of eye subequal to interocular width (1: 1.05–1.07); lora swollen but not raised above clypeus; width across eyes more than 1.5 times head length (1.62–1.66: 1); clypeus surpassing lora, bears short, stout, long setae along midline longitudinal, long setae present apex of tylus; lateral sides of vertex with long setae.

Antenna (Figs. 3A; 5A): The length of antennal segment I short; the antennal segment II and III with many short setae; antennal segment II with finger-like projection; length of antennal segment II shorter than length antennal segment III; ratio of length of LaI: LaII: LaIII=1.00: 1.44–1.59: 1.68–1.83.

Thorax (Figs. 3B, C; 5B, C): Length of anterior lobe of pronotum approximately 1.70–1.76 times length of posterior lobe when measured along midline; in lateral view, anterior margin slightly raised; ratio of humeral width / anterior width: 1.40–1.49; posterior lobe with humeri broadly rounded; dorsum of the posterior lobe with many coarse punctures. Scutellum with length twice its width (1.00: 1.93–2.13), holotype: length 2.13 times width, with two transverse depressions towards apex.

Legs (Figs. 2A, B, 3E, 5E): Legs slender and long, anterior femur with some irregular small black spots. Fore femur with two teeth, larger tooth on outer face, smaller tooth situating immediately anterior of flexor side of femur (Figs. 3E, 5E); the edges of the larger tooth and smaller tooth covered short, thick hairs with forming a mane; tooth apex covered with longer setae; ratio of femur width at basal half / femur width at base of larger tooth: 1.74–1.84 (holotype 1.79); ratio of femur width across larger tooth (including tuft of setae) / femur width at basal half: 1.40–1.42 (holotype 1.40); ratio of femur width across larger tooth (including tuft of setae)/ femur width at base of larger tooth: 2.47–2.63 (holotype 2.51); ratio of width of smaller tooth (WFs)/ femur width at basal half: 0.37–0.39 (holotype 0.39); ratio of length of fore femur: length of fore tibia: length of fore tarsi: 10.96–11.32: 3.88–4.03: 1.00; flexor side of fore femur bearing two teeth located at distal 0.35–0.42 (holotype 0.42). Middle femur subequal in length to hind femur (1.00: 1.02–1.03); in both sexes, hind femur when folded back along body not reaching both tip of operculum and tip of abdomen (excluding siphon). Middle tibia shorter than middle femur (1.00: 1.10–1.11), hind tibia longer than hind femur (1.11–1.12: 1.00); middle and hind femora with sparsely distributed long, thin, pale setae on posterior margins along their entire length; middle and hind tibiae with dense fringe of long setae on posterior margins along their entire length. Ratio of length of middle femur: length of middle tibia: length of middle tarsi: 5.97–5.99: 6.09–6.14: 1.00. Ratio of length of hind femur: length of hind tibia: length of hind tarsi: 6.00–6.07: 6.72–6.74: 1.00.

Meso and metasternum (Figs. 3D, 5D): Mesosternum with carina oblong in shape, rounded anterior margin, broad in the medially, projection between middle and hind coxae with deep transverse groove, narrow along mesosternum; metasternum with strongly raised longitudinal, anterior margin with a short groove, posterior margin convex, truncate; middle coxae equal to hind coxae; ratio of length of LPo: LM: LPr = 1.00: 1.98–2.13: 3.63–3.87. Space between middle coxae narrower than that between hind coxae. Membrane not reaching posterior margin of tergite 6 (Fig. 2A).

Abdomen long and narrow, apex narrowly round (Fig. 2B). Male operculum slightly shorter than connexivum (Figs. 4A, C; 5G). Distal margin of connexivum of female acutely produced; female operculum (Fig. 4B) reaching end of connexivum and base of respiratory siphon.

Male genitalia: Paramere (Figs. 4F-G, 5J-Q) elongate, tapering in distal third; apical hook of paramere open and strongly curved, with a large tooth-like projection on inner margin of hook (Figs. 4G, 5Q); apex of hook pointed; dorsal surface of paramere almost straight. Phallotheca as in Figs. 4D-E, 5H.

Measurements (mm) (Suppl. material 1): Males, BL: 34.05 –35.87 (holotype: 35.87); RS: 27.12–28.71 (holotype: 27.12); WB: 2.95–2.96 (holotype: 2.95); WB: 2.95–2.96 (holotype: 2.95); PL: 9.05–9.85 (holotype: 9.05); PW: 3.35–3.49 (holotype: 3.35); WH: 1.24–1.36 (holotype: 1.24); LH: 1.75–1.90 (holotype: 1.75); WHE: 2.84–3.11 (holotype: 2.84); WE: 1.01–1.07 (holotype: 1.01); IW: 1.06–1.14 (holotype: 1.06); LaI: 0.22–0.24 (holotype: 0.22); LaII: 0.35–0.36 (holotype: 0.35); LaIII: 0.39–0.41 (holotype: 0.39); AW: 2.01–2.13 (holotype: 2.01); HW: 2.82–3.09 (holotype: 2.82); AL: 5.08–5.16 (holotype: 5.08); PLm: 2.89–2.98 (holotype: 2.89); LCF: 8.43–8.15 (holotype: 8.43); LFF: 11.89–12.35 (holotype: 11.89); LTF: 4.07–4.10 (holotype: 4.07); LTaF: 1.05–1.11 (holotype: 1.05); LFM: 20.18–19.12 (holotype: 20.18); LTM: 20.09–21.19 (holotype: 21.19); LTaM: 2.71–3.37 (holotype: 3.37); LFH: 19.13–19.86 (holotype: 19.86); LTH: 20.50–21.69 (holotype: 21.69); LTaH: 3.09–3.27 (holotype: 3.27); LS: 2.69–2.76 (holotype: 2.69); WS: 1.26–1.36 (holotype: 1.26); PA: 2.19–2.95 (holotype: 2.19); LPr: 2.63–3.19 (holotype: 2.63); LM: 1.45–1.74 (holotype: 1.45); LPo: 0.68–0.88 (holotype: 0.68); LO: 2.83–3.00 (holotype: 2.83); WFal: 1.43–1.56 (holotype: 1.43); WFl: 1.11–1.23 (holotype: 1.11); WFs: 0.40–0.42 (holotype: 0.40); WFb: 0.99–1.18 (holotype: 0.99); WFt: 0.57–0.67 (holotype: 0.57).

Female: BL: 37.27; RS: 30.08; WH: 1.47; WE: 1.13; IW: 1.22; AW: 2.25; HW: 3.36; AL: 5.23; PLm: 3.07; fore leg: LCF: 9.73, LFF: 4.59; middle leg: LFM: 20.66, LTM: 22.39, LTaM: 3.46; hind leg: LFH: 21.23, LTH: 23.15, LTaH: 3.54.

The classification of seven species groups within the genus Ranatra Fabricius, 1790 was initially proposed by Lansbury (1972) and later revised by Tran and Zettel (2021a). However, Ranatra uminhensis sp. nov. cannot be assigned to the R. gracilis group, R. elongata group, R. varipes group, R. filiformis group, R. bilobata group and R. biroi group due to distinct differences in the structure of the apical hook of male paramere is characterized by a strongly curved, with large tooth-like projection on the inner margin just before the hook (Figs. 4G, 5Q) (Suppl. material 2). These distinctive morphological characteristics support the exclusion of Ranatra uminhensis sp. nov. from the aforementioned groups and justify its placement within the R. malayana group.

Ranatra uminhensis sp. nov. differs distinctly from R. katsara, which is known from Thailand (see Nieser, 1997: figs. 1–8). The most evident differences are observed in body size, the ratio between the lengths of the anterior and posterior lobes of the pronotum, the distance between the middle and hind coxae, and the structure of the male parameres.

Ranatra uminhensis sp. nov. also clearly differs from R. malayana, which is known from Sulawesi and Borneo (see Lansbury, 1972: figs. 142–152). According to Lansbury (1972), in R. malayana, male body length is 26–29 mm and is female body length 30 mm; siphon length is approximately 23 mm; the eye is narrower than interocular distance; the anterior lobe of pronotum is twice as long as the posterior lobe; the scutellum is twice as long as broad; the mesosternum is evenly rounded; the metasternum is flat; the space between the middle coxae is broader than that between the hind coxae (see Lansbury, 1972: fig. 144); the female operculum is not reaching the apex of the connexivum (Lansbury, 1972: fig. 147); male operculum is nearly as long as the connexivum (Lansbury, 1972: fig. 148); the paramere has a short, blunt apical hook; and the phallotheca has a long membranous posterior diverticulum (Lansbury, 1972: figs. 150–152). In contrast, in R. uminhensis, male body length is 34.05–35.87 mm and female body length is 37.27 mm; siphon length is 27.12–28.71 mm in males and 30.08 mm in the female; the eye width is subequal to the interocular distance (ratio ~1.00:1.05–1.07); the anterior lobe of the pronotum approximately is 1.70–1.76 times the length of the posterior lobe; the scutellum is more than twice as long as broad; the mesosternum has an oblong carina; the area between middle and hind coxae has a distinct transverse groove; the metasternum has a sharply raised longitudinal ridge; the distances between middle coxae and between hind coxae are approximately equal; the female operculum is reaching the apex of the connexivum; and male operculum is slightly shorter than the connexivum; the paramere is elongated, with a strongly curved apical hook terminating in a pointed apex and with a prominent, high tooth-like projection is present on the inner margin at base of the hook (Figs. 4F, G; 5J, Q)

Etymology. The specific epithet refers to its occurrence in U Minh Thuong National Park; an adjective.

DNA barcode. A partial sequence of the mitochondrial gene of cytochrome oxidase subunit I (COI) of the holotype was uploaded to GenBank with accession number PV263141 (Table 1).

Distribution. Vietnam: U Minh Thuong National Park, Tien Giang Province

Ranatra varipes Stål, 1861

(Figs. 6, 7)

Figure 6
Ranatra varipes Stål, 1861, ♂, TXL54. A. antenna; B. head and prothorax dorsal view; C. head and prothorax lateral view; D. Meso and metasternum; E. left foreleg and femoral teeth, inner view. Scale bar: 1 mm for B, C, F; 0.5 mm for D; 0.2 mm for A.

Figure 7
Ranatra varipes Stål, 1861, ♂, TXL54. A. apex of abdomen of male, dorsal view; B. apex of abdomen of female, dorsal view; C. apex of abdomen of male, lateral view; D. male phallotheca, dorsal view; E. male phallotheca, lateral view; F. paramere; G. apex of paramere. Scale bar: 0.5 mm for A, B, C, D; 0.2 mm for F.

Material examined. Vietnam: 1♂; TXL54; Ha Tinh Province, Vu Quang Natural Park; 21^o26’18” N, 105^o33’24” E; 16.viii.2023, XL Truong leg.; IB. 1♂; TXL54B01; Ha Tinh Province, Vu Quang Natural Park; 21^o26’18” N, 105^o33’24” E; 16.viii.2023; XL Truong leg.; IB. 1♂; TXL54B02; Ha Tinh Province, Vu Quang Natural Park; 21^o33’28” N, 105^o33’54” E; 6.iii.2024; TG Phan leg.; VinhU.

Supplementary description.

The body length: 20.36 –21.64 mm, length of respiratory siphon 15.78–17.09 mm, ratio of siphon length/body length (0.78–0.80)

Head (Figs. 2C, D, 6B, C): maximal width of eye longer than interocular width (1.00: 0.76–0.84); width across eyes longer than almost twice times length of head (1.82–1.96: 1.00)

Antenna (Fig. 6A): Ratio of length of LaI: LaII: LaIII = 1.00: 1.61–1.68: 1.88–2.16. Thorax (Figs. 6B, C): The length of anterior lobe about one-third greater than length of posterior lobe when measured along longitudinal midline (1.13-1.20: 1.00); humeral width one-fifth less than anterior width (1.00: 1.03-1.08); ratio of humeral width of pronotum: anterior width of pronotum (1.19–1.21: 1.00). Scutellum (Fig. 6B) with length shorter than twice times its width (1.82–1.88: 1.00). Legs (Figs. 2C, D, 6E): Fore femur relatively broad with a larger tooth at the middle and a smaller tooth at distal, pre-apical teeth absent (Fig. 6E); ratio of femur width across larger tooth (including tuft of setae) / femur width at basal half: 1.02–1.04; ratio of length of fore femur: length of fore tibia: length of fore tarsi: 11.02–13.25: 4.52–5.17:1.00. Middle femur subequal in length to hind femur (1.00: 1.01–1.02); length of tibia middle leg longer than length of femur of middle leg: 1.12–1.13: 1.00; ratio of length of middle femur: length of middle tibia: length of middle tarsi: 4.57–4.80: 5.09–5.41: 1.00. Length of tibia hind leg longer than length of femur of hind leg: 1.11–1.12: 1.00; ratio of length of hind femur: length of hind tibia: length of hind tarsi: 4.41–4.85: 4.90–5.39: 1.00.

Meso and metasternum (Fig. 6D): Ratio of length of posternum: length of metasternum: length of prosternum: 1.00: 2.40–2.54: 4.32–4.63. Abdomen long and narrow, apex narrowly round (Fig. 2D). Male operculum slightly shorter than the connexivum, slender, keeled and with pointed apex (Figs. 7A-B).

The paramere (Figs. 7E, G): slender, slightly tapering in the distal fourth near the apex, underside of apex of paramere with a large tilde-shape, with an expanded mushroom-shaped distal process, slight round subapical lobe, without pre-apical before hook. Phallotheca weakly sclerotized as in Figs. 7C, D.

Measurements (mm) (Suppl. material 1): Males, BL: 20.36–21.64; RS: 15.78–17.09; WB: 1.81–2.02; PL: 7.09–7.42; PW: 2.05–2.59; WH: 1.09–1.14; LH: 1.33–1.62; WHE: 2.56–3.01; WE: 10.90–1.08; IW: 0.76–0.82; LaI: 0.16–0.19; LaII: 0.26–0.32; LaIII: 0.30–0.41; AW: 1.50–1.68; HW: 1.86–2.06; AL: 3.16–3.52; PLm: 2.36–2.56; LCF: 5.14–5.44; LFF: 6.89–7.05; LTF: 2.69–2.89; LTaF: 0.52–0.64; LFM: 11.43–11.71; LTM: 12.88–13.02; LTaM: 2.38–2.56; LFH: 11.68–11.82; LTH: 12.98–13.14; LTaH: 2.41–2.68; LS: 1.73–1.84; WS: 0.89–1.01; PA: 1.78–1.89; LPr: 2.03–2.41; LM: 1.13–1.32; LPo: 0.47–0.52; LO: 2.10–2.22; WFal: 0.77–1.82; WFl: 0.31–0.34; WFs: 0.25–0.27; WFb: 0.73–0.74; WFt: 0.64– 0.68.

Distribution. Vietnam: Vu Quang National Park, Ha Tinh Province (this study); Dong Nai (Polhemus and Polhemus, 2013), Phuc Son, Annam (Lansbury, 1973), Quang Binh, Quang Tri (Tran and Nguyen, 2016). Java, Singapore, Malaysia, Sumatra, Burma, India, Ceylon, China, Thailand, Sarawak, Sumatra, Philippines (Lansbury, 1972, 1973; Fernando and Cheng, 1974; Chen et al., 2004; Tran and Nguyen, 2016).

DNA barcode. A partial sequence of the mitochondrial gene of cytochrome oxidase subunit I (COI) of the R. varipes Stål, 1861 was uploaded to GenBank with accession number PV263140 (Table 1)

Comments. The specimens listed above are generally consistent with the descriptions of R. varipes by Lansbury (1972) and Polhemus and Polhemus (2013). R. varipes is supplementary description herein based on newly collected material from Ha Tinh Province, Vu Quang Natural Park, which provides additional morphological data and DNA barcode (COI) sequences, which have been submitted to GenBank (Accession No.: PV263140).

The specimens of R. varipes from Ha Tinh Province exhibit slight morphological differences compared with descriptions by Lansbury (1972) and Polhemus and Polhemus (2013) in the previously described populations: the anterior lobe of pronotum is approximately one-fourth longer than the posterior lobe, and the humeral width is about one-third greater than the anterior width; the paramere is characterized by a slender and shallow incision just below the subapex, a blade-like distal process arising from a small, obtusely angulate subapical lobe (see Lansbury, 1972: figs. 131, 141; Polhemus and Polhemus, 2013: figs. 17–18). In the specimens from Ha Tinh Province, the anterior lobe of pronotum is approximately one-third longer than the posterior lobe (ratio 1.13–1.20: 1.00), and a humeral width of pronotum about one-fifth narrower than the anterior width of pronotum (ratio 1.03–1.08: 1.00); the paramere lacks the slender and shallow incision below the subapex, instead, the apex exhibits a large tilde-shaped structure and a mushroom-shaped distal process, with a slightly rounded subapical lobe (Figs. 7E-G).

Supplementary material

The following online material is available for this article:

Table S1

The measurement of the species Ranatra uminhensis sp. nov. and Ranatra varipes Stål, 1861 in Vietnam.

Table S2

The synthesize comparative notes between Ranatra uminhensis sp. nov. and species of group in genus Ranatra.

Acknowledgments

The authors would like to thank the directors and staff in Vu Quang National Park (Ha Tinh Province) and U Minh Thuong National Park (Kien Giang Province) for their kind assistance during our field activities. Moreover, we would like to send many thanks to our colleagues in the Institute of Biology, Vinh University, for their kind help and for sharing specimens. This research was supported by a grant from the Vietnam Academy of Science and Technology Code: KHCBSS.02/23-25 to Truong Xuan Lam.

• urn:lsid:zoobank.org:pub:E9E32833-55AE-4AA1-AC83-4BF174A97F44

References

• Chen, P. P., Nieser, N., Ho, J., 2004. Review of Chinese Ranatrinae (Hemiptera: Nepidae), with descriptions of four new species of Ranatra Fabricius. Tijdschr. Entomol. 147 (1), 81-102. http://doi.org/10.1163/22119434-900000142
  » http://doi.org/10.1163/22119434-900000142
• Fernando, C. H., Cheng, L., 1974. A preliminary study of the fauna and distribution of aquatic Hemiptera in Malaya and Singapore. Fed. Mus. J. 19, 21-44.
• Forero, D., Weirauch, C., 2012. Comparative genitalic morphology in the New World resin bugs Apiomerini (Hemiptera, Heteroptera, Reduviidae, Harpactorinae). Dtsch. Entomol. Z. 59 (1), 5-41.
• Kumar, S., Stecher, G., Li, M., Knyaz, C., Tamura, K., 2018. MEGA X: Molecular Evolutionary Genetics Analysis across Computing Platforms. Mol. Biol. Evol. 35 (6), 1547-1549. http://doi.org/10.1093/molbev/msy096
  » http://doi.org/10.1093/molbev/msy096
• Lansbury, I., 1972. A review of the Oriental species of Ranatra Fabricius (Hemiptera-Heteroptera: nepidae). Trans. R. Entomol. Soc. Lond. 124 (3), 287-341. http://doi.org/10.1111/j.1365-2311.1972.tb00367.x
  » http://doi.org/10.1111/j.1365-2311.1972.tb00367.x
• Lansbury, I., 1973. A review of the genus Cercotmetus Amyot & Serville, 1843 (Hemiptera-Heteroptera: nepidae). –. Tijdschr. Entomol. 116, 83-106.
• Nieser, N., Chen, P. P., 1991. Naucoridae, Nepidae and Notonectidae, mainly from Sulawesi and Pulau Buton (Indonesia), I. Tijdschr. Entomol. 134, 47-67.
• Nieser, N., 1996. Two new species of Ranatra Fabricius from Southeast Asia (Insecta: Heteroptera: Nepidae). Ann. Naturhistorischen Mus. Wien Ser. B 98, 347-351.
• Nieser, N., 1997. A new species of Ranatra from Thailand (Insecta: Heteroptera: Nepidae). Ann. Naturhistorischen Mus. Wien Ser. B 99, 79-82.
• Nieser, N., Chen, P. P., 1996. Six new taxa of Nepomorpha from Sulawesi and Mindanao. Notes on Malesian aquatic and semiaquatic bugs (Heteroptera), VI. Tijdschr. Entomol. 139 (2), 161-174.
• Nieser, N., Chen, P.-P., Yang, C. M., 2005. A new subgenus and six new species of Nepomorpha (Insecta: Heteroptera) from Yunnan, China. Raffles Bull. Zool. 53, 189-209.
• Polhemus, J. T., Polhemus, D. A., 2008. Global diversity of true bugs (Heteroptera: Insecta) in freshwater. Hydrobiologia 595 (1), 379-391. http://doi.org/10.1007/s10750-007-9033-1
  » http://doi.org/10.1007/s10750-007-9033-1
• Polhemus, D. A., Polhemus, J. T., 2012. Notes on Ranatra (Heteroptera: Nepidae) from Burma and the Andaman Isla with description of a new species. Entomol. Am. (New York) 118 (1), 242-251. http://doi.org/10.1664/12-RA-028.1
  » http://doi.org/10.1664/12-RA-028.1
• Polhemus, D. A., Polhemus, J. T., 2013. Guide to the aquatic Heteroptera of Singapore and Peninsular Malaysia. X. Infraorder Nepomorpha – Families Belostomatidae and Nepidae. Raffles Bull. Zool. 61 (1), 25-45.
• Satria, R., Kurushima, H., Herwina, H., Yamane, S., Eguchi, K., 2015. The trap-jaw ant genus Odontomachus Latreille from Sumatra, with a new species description. Zootaxa 4048 (1), 1-36. http://doi.org/10.11646/zootaxa.4048.1.1
  » http://doi.org/10.11646/zootaxa.4048.1.1
• Tran, A. D., Polhemus, D. A., 2012. Notes on Southeast Asian Ranatra (Heteroptera: Nepidae), with description of a new species from Singapore and neighbouring Indonesian islands. Raffles Bull. Zool. 60 (1), 101-107.
• Tran, A. D., Nguyen, V. V., 2016. Notes on the subfamily Ranatrinae (Hemiptera: Nepidae) from Vietnam, with two new species of Ranatra Fabricius, 1790. J. Asia Pac. Entomol. 19 (2), 515-523. http://doi.org/10.1016/j.aspen.2016.05.006
  » http://doi.org/10.1016/j.aspen.2016.05.006
• Tran, A. D., Poggi, R., 2019. The genus Ranatra Fabricius (Heteroptera: Nepidae) in Borneo, with a redescription of Ranatra spinifrons Montandon and the description of a new species. Zootaxa 4555 (2), 236-246. http://doi.org/10.11646/zootaxa.4555.2.4
  » http://doi.org/10.11646/zootaxa.4555.2.4
• Tran, A. D., Zettel, H., 2021a. Taxonomic review of the Ranatra gracilis group sensu Lansbury, 1972 (Nepomorpha: Nepidae), with descriptions of four new species. Raffles Bull. Zool. 69, 45-70. http://doi.org/10.26107/RBZ-2021-0005
  » http://doi.org/10.26107/RBZ-2021-0005
• Tran, A. D., Zettel, H., 2021b. Taxonomy of the Ranatra biroi group sensu Lansbury, 1972 (Nepomorpha: Nepidae), with descriptions of two new specie. Raffles Bull. Zool. 69, 507-521. http://doi.org/10.26107/RBZ-2021-0068
  » http://doi.org/10.26107/RBZ-2021-0068
• Zettel, H., Phauk, S., Kheam, S., Freitag, H., 2017. Checklist of the aquatic Hemiptera (Heteroptera: Gerromorpha and Nepomorpha) of Cambodia, with descriptions of new species of Microvelia Westwood, 1834 and Ranatra Fabricius, 1790. Aquat. Insects 38 (1-2), 21-48. http://doi.org/10.1080/01650424.2017.1332372
  » http://doi.org/10.1080/01650424.2017.1332372
• Zettel, H., 1999. Ranatra libera sp.n. (Heteroptera: Nepidae) from Burma. Linz. Biol. Beitr. 31 (1), 427-430.

Edited by

• Associate Editor:
  Jader Oliveira

Publication Dates

• Publication in this collection
  12 Dec 2025
• Date of issue
  2025

History

• Received
  17 Mar 2025
• Accepted
  01 Oct 2025