Ranatra rafflesi, Tran & Polhemus, 2012

Tran, A. D. & Polhemus, Dan A., 2012, Notes On Southeast Asian Ranatra Heteroptera Nepidae, With Description Of A New Species From Singapore And Neighbouring Indonesian Islands, Raffles Bulletin of Zoology 60 (1), pp. 101-107 : 104-106

publication ID	https://doi.org/ 10.5281/zenodo.5347071
persistent identifier	https://treatment.plazi.org/id/91798795-F678-FF83-0EBA-FF2066334B46
treatment provided by	Tatiana
scientific name	Ranatra rafflesi
status	sp. nov.

Treatment

Ranatra rafflesi View in CoL , new species

( Figs. 7, 8 View Figs , 10 View Figs , 12–15 View Figs View Figs View Fig )

Type material examined. — Holotype, male, Upper Seletar Reservoir , coll. Tran A. D. & A. Lok, 27–28 May 2008, TAD0830 ( ZRC, dry mounted).

Paratypes (alcohol preserved unless otherwise stated): SINGAPORE: 1 male, 1 female, same data as holotype ( BPBM); 1 male, 1 female, Nee Soon, coll. K. L. Yeo, 19 Sep.1991, #Y771 ( ZRC); 1 female, Murai Reservoir, coll. Tran A. D., 20 May 2008, TAD0822 ( ZRC); 1 female, Murai Reservoir, coll. Tran A. D., 26 Aug.2008, TAD0855 ( ZRC); 2 females, Murai Reservoir, coll. Tran A. D., 15 Jul.2008, TAD0847 ( ZRC); 1 female, Murai Reservoir, 8 May 2007, coll. unknown ( ZRC); 1 female, Upper Seletar Reservoir, coll. Tran A. D. & A. Lok, 26 May 2008, TAD0828 ( ZRC); 1 female, Upper Seletar Reservoir, coll. Tran A. D. & A. Lok, 23 May 2008, TAD0827 ( ZRC); 1 male, Nature Reserve Survey, Seletar Reservoir, Mandai Rd., coll. H. K. Lua et al., 16 May 1994, NS134B ( ZRC, dry mounted); 1 male, Nature Reserve Survey, Seletar Reservoir, Mandai Rd., coll. H. K. Lua et al., 17 May 1994, NS136B ( ZRC, dry mounted); 1 male, Upper Peirce Reservoir, coll. Tran A. D., 18 Apr.2008, TAD0816 ( ZRC, dry mounted); 2 males, Nature Reserve In addition to specimens from Thailand, the majority of the material previously assigned to R. longipes that we have examined from Peninsular Malaysia, with the exception of certain samples from Johor, in fact represents R. thai . By contrast, R. longipes was described from Java, and we have also seen specimens of this species from Singapore, Sumatra, Borneo, and the southern extremity of the Peninsular Malaysia. It therefore appears that R. longipes is a predominantly insular species occurring on the Greater Sunda Islands and immediately adjacent smaller islands, whereas R. thai is confined to continental Southeast Asia.

Distribution. — Thailand, Vietnam, Peninsular Malaysia.

Survey, Lorong Banir, coll. T. B. Lim et al., 24 May 1994, NS141C (ZRC, dry mounted); 1 male, MacRitchie Catchment Reservoir , coll. K. L. Yeo et al., 21 Apr.1994, NS124A&B ( ZRC, dry mounted) ; 1 male, Pulau Tekong Reservoir , coll. C. M. Yang, 27 Nov.2001, YCM272 ( ZRC) ; 1 male, 1 female, Pulau Tekong Reservoir , coll. Tran A. D., 26 Sep.2007, TAD0709 ( ZRC) ; 1 female, Pulau Tekong Reservoir , coll. Tran A. D. & A. Lok, 30 Jul.2008, TAD0850 ( ZRC) . INDONESIA: Riau Islands Prov.: 5 males, Batam , coll. C. M. Yang et al., 29 Jan.1992 ( ZRC.6.15699–15703) ; 1 male, Pulau Batam , southeast, covered, coll. H. H. Tan, S. H. Tan & H. H. Ng, 5 Sep.1994 ( ZRC) : 1 male, 2 females, Riau, Pulau Bintan North , coll. H. K. Lua, 26 Jun.1995, LHK259 ( ZRC) ; 1 male, 1 female, Pulau Bintan , coll. H. H. Tan, 30 Jun.1995, THH9542 ( ZRC) .

Description. — General colouration: dark brown, legs paler, lacking distinct annulations but with faint yellowish patches on fore femora.

Measurements: Males: body length 21.5–24.0 (holotype: 24.0); length of siphon 19.0–22.5 (holotype: 22.5), width of head 2.49–2.70 (holotype: 2.70); width of eye 0.82–0.91 (holotype: 0.90); interocular width 0.82–0.91 (holotype 0.91); anterior width of pronotum 1.62; humeral width of pronotum 2.18; length of anterior lobe along median line 3.72; length of posterior lobe along median line 1.91; fore leg: length of coxa 6.50, of femur 10.10; middle leg: length of femur 14.50, of tibia 16.50; hind leg: length of femur 14.50, of tibia 17.0. Females: body length 25.0–29.0; length of siphon 20.0–24.0; width of head 3.10; width of eye 1.00; interocular width 1.05; anterior width of pronotum 1.96; humeral width of pronotum 2.49; length of anterior lobe along median line 4.60; length of posterior lobe along median line 2.25; fore leg: length of coxa 8.10, of femur 12.0; middle leg: length of femur 16.5, of tibia 19.0; hind leg: length of femur 16.5, of tibia 19.25.

Head: Brown, with vertex clearly raised above eyes into low, conical tumescence; eyes red, width subequal to width of vertex; frons triangular; tylus raised, longitudinally tumescent; lora swollen, raised above clypeus, bearing scattered long, slender, golden setae; clypeus lacking apical nodules, bearing short, stout, pale setae along longitudinal midline, similar setae also present apically on tylus; second segment of antennae with long, finger-like projection, slightly shorter in length than segment III.

Thorax: Dark brown; prothorax in lateral view subequal in length to fore coxa; anterior lobe slightly over twice as long as posterior lobe when measured along longitudinal midline; anterior margin very slightly raised when viewed laterally; ratio of humeral width/anterior width 1.35 (male), 1.27 (female); pronotal grooves weakly developed; anterior margin when viewed ventrally nearly straight, anteroventral angles not produced; posterior lobe with humeri slightly tuberculate. Scutellum 1.7× longer than wide, posterior section with a pair of roughly circular subapical depressions, one on each side of midline. Mesosternum broadly domed, anterior margin weakly bisinuate medially, not raised, narrow posterior projection between mid-coxae truncate and deeply grooved along midline; metasternum with strongly raised longitudinal carina on posterior half, posterior margin truncate ( Fig. 15 View Fig ); space between middle and hind coxae subequal to diameter of coxae.

Legs: Pale yellowish brown, without distinct annulations or mottling. Fore femur with a median tooth, width of femur across larger tooth about equal to or slightly larger than maximum width of femur in basal half ( Figs. 12–14 View Figs View Figs ), a second smaller tooth present immediately anterior to median tooth on inner face of femur; ratio of width of femur across larger tooth/width of femur at basal half: 1.04–1.21 (holotype 1.04); ratio of width of femur across larger tooth/width at base of larger tooth at proximal side: males 1.78–2.15 (holotype 1.78), females 2.10–2.47; ratio of femur across larger tooth/width at base of larger tooth at distal side: males 2.36–2.61 (holotype 2.40), females 2.52–3.00. Lengths of middle and hind femora subequal; hind femur clearly surpassing tip of operculum. Middle and hind tibiae each longer than respective femora; middle and hind femora both bearing fringe of long, slender, pale setae on posterior margins along their entire length. Hind femur when folded back along the body extending beyond tip of abdomen (excluding siphon) in males, reaching tip of abdomen in females.

Abdomen: Male operculum as long as connexivum. Female operculum reaching base of respiratory siphon.

Male genitalia: Paramere tapering along distal one third, with apical hook open and evenly curved, bearing a broadly triangular tooth along inner margin before hook, apex expanded ( Figs. 7, 8 View Figs ); phallotheca as in Fig. 10 View Figs .

Etymology. — The epithet “ rafflesi ” is dedicated to Sir Stamford Raffles, the founder of Singapore, and also a naturalist who contributed greatly to our knowledge of the biodiversity of Singapore and the surrounding region.

Distribution. — Known at present from Singapore and nearby Indonesian islands (Bintan and Batam).

Discussion. — In the key by Lansbury (1972), Ranatra rafflesi runs to the couplet 10, and from here can be ambigously keyed to either R. malayana or to couplet 11, because the width of the fore femur across the larger tooth is slightly larger than the widest part of the femur, whereas couplet 10 offers the choice of either “about the same as” (leading to couplet 11) or “clearly greater than” (leading to R. malayana ). If one follows couplet 11, this new species will eventually key to the R. longipes species and subspecies complex in the R. biroi species group. We would note that the key of Lansbury (1972) is at this point out of date because subsequent to his revision, nine additional species of Ranatra have been described from China and Southeast Asia (Nieser & Chen, 1991; Nieser, 1996, 1997; Zettel, 1999; Chen et al., 2004).

The male paramere structure of Ranatra rafflesi is very similar to that of R. malayana Lundblad, 1933 , particularly with regard to the flared apex of the distal hook, but this new species can be separated from the latter by both the length of the hind femur, and the width of fore femur across its larger tooth. According to the description by Lansbury (1972) the hind femur in both sexes of R. malayana extends beyond the posterior margin of the wing membrane but does not reach the tip of the operculum, while in R. rafflesi it reaches or exceeds the tip of the abdomen in both sexes.

Lansbury (1972) tentatively treated Ranatra malayana as a species group by itself. Nieser (1997) subsequently described Ranatra katsara , placed it into the R. malayana species group, and formally defined this species group. Based on the characters provided by Lansbury (1972) and Nieser (1997), the R. malayana species group differs from the R. biroi species group in the length of the respiratory siphon (which in the R. malayana group is equal to or longer than the length of the body, while in the R. biroi group its is shorter than the length of the body); the eye width (which in the R. malayana group is less than the interocular space, while in the R. biroi group it is equal to or greater than the interocular space); and by the size of larger tooth of fore femur (in the R. malayana group the width of the fore femur across the larger tooth is much greater than the widest part of the femur proximally, while in the R. biroi group the width of the fore femur across the larger tooth is about the same as widest part of the femur proximally). We would note that the phylogenetic validity of the Ranatra species groups proposed by Lansbury (1972) and Nieser (1997) has never been evaluated, and that Lansbury’s R. biroi species group in particular may prove to be polyphyletic.

Based on these definitions, Ranatra rafflesi clearly falls into the R. biroi group, and appears most closely related to R. natunaensis Lansbury, 1972 from Natuna Island (off the west coast of Borneo), which has a similar paramere structure. It can be separated from R. natunaensis by the longer hind femora, which exceed the tip of the abdomen (excluding the respiratory siphon) in males and reach its posterior apex in females, and by the wider space between the middle coxa. By contrast, in R. natunaensis the hind femur in both sexes reaches about one third of the way along the operculum, and middle coxae are closely appressed, with their inner margins nearly contiguous.

Ranatra rafflesi also may be separated from the superficially similar R. longipes longipes and R. thai by the more open curve in the process at the apex of the male paramere (compare Figs. 1–6 View Figs with 7, 8), the more acute dorsal margin of the sclerotized distal section of the male phallotheca when viewed laterally (compare Figs. 9, 10 View Figs ), the larger, more truncate tooth on the fore femur (compare Figs. 11, 12 View Figs ), and the longer hind femur (in R. longipes longipes the hind femur reaches slightly beyond tip of operculum). In addition, females of R. rafflesi can be separated from R. longipes longipes by the distinctly larger ratio of the width of the fore femur across its larger tooth to the width at the base of the larger tooth on the proximal side (in R. rafflesi 2.10–2.47, in R. longipes longipes 1.70–1.83) and to the width at the base of the larger tooth on the distal side (in R. rafflesi 2.52–3.00, in R. longipes longipes 2.05–2.40).