Rhagovelia gapudi, Zettel & Laciny & Freitag, 2020

Zettel, Herbert, Laciny, Alice & Freitag, Hendrik, 2020, Review of the genus Rhagovelia Mayr, 1865 (Insecta: Heteroptera: Veliidae) in the Palawan biogeographic region, the Philippines, Raffles Bulletin of Zoology 68, pp. 810-837 : 825-834

Rhagovelia gapudi , new species

( Figs. 6A–C , 7H , 8E , 9F–H , 10G–I , 11F , 12B )

Etymology. This species in named in honour of the late Victor P. Gapud, the pioneer of water bug research in the Philippines.

Type material. Holotype (apterous males; NMNH) labelled “ PHILIPPINEN: Palawan / W Sabang, 0 - 30 m / 29.3.1994 / leg. H. Zettel (52e)” . Paratypes (in NHMW, UPLB, ZCVA): 11 apterous males, 1 macropterous male, 5 apterous females, 1 macropterous female from the same locality (# 52e); 1 apterous male, 2 apterous females from Busuanga, 13 road-km WNW Coron, Balulu Falls ; 6 macropterous males, 2 macropterous females from same locality; 1 apterous male, 4 macropterous males, 2 macropterous females from Busuanga , Coron , Tagumpay , Balingasan , Panpang River , 12°00′32″N, 120°14′10″E, ca. 40 m a.s.l. ; 2 macropterous males, 1 apterous female from northern Palawan, El Nido, Sibaltan, lowland creek, 11°15′43″N, 119°32′18″E, ca. 30 m a.s.l. ; 2 apterous males, 1 apterous female, 1 macropterous female from northern Palawan, SW Roxas, Poblacion, stream below Umalat Falls; 1 apterous male, 1 macropterous male, 2 macropterous females from central Palawan, Puerto Princesa, Cabayugan, Nagdayan Creek at Manturon Bridge , 10°10′N, 118°53′E, 30 m a.s.l. ; 3 apterous males, 1 apterous female from central Palawan, Puerto Princesa, Santa Cruz, km 29 on Northern Highway, streamlet and puddles near Calatoboc Bridge , 9°56′46″N, 118°44′38″E, 25 m a.s.l. ; 2 apterous females from central Palawan, Puerto Princesa, Santa Cruz, km 29 on Northern Highway, stream at Calatoboc Bridge , 9°56′41″N, 118°44′55″E, 5–10 m a.s.l. ; 12 apterous males, 2 macropterous males, 11 apterous females, 1 macropterous female from central Palawan, 20 km WSW Puerto Princesa, Montible River; 3 apterous males, 2 apterous females from central Palawan, 20 km W Puerto Princesa, Tacduan Area, Tacduan River .

Type locality. Northern Palawan, Puerto Princesa City, barangay Cabayugan, sitio Sabang, 10°11′N, 118°54′E, 10–30 m a.s.l.

Diagnosis. Gracile species; body length 2.78–3.69 mm. Colour black; anterior part of head typically pale orange to brown, very rarely dark, almost black; all margins of pronotum yellow; coxae, trochanters, base and underside of metafemur yellow. Juga without, proepisterna with small black spinulae. Male: Metatrochanter with short teeth, one tooth usually larger than the others. Metafemur very strongly enlarged (less so in winged specimens), with dense row of short spinules at base and two rows of teeth in distal two thirds. Metatibia almost evenly curved, often with a few longer teeth at apical third. Genitalia of moderate size. Paramere ( Fig. 7H ) small, with narrow, almost straight distal part bearing a small, ventrally directed apical lobe. Proctiger ( Fig. 8E ) slender, with hardly protruded lateral wings. Female: Basal half of metafemur without or with one minute tooth. Ventral outline of gonocoxa slightly concave. Proctiger directed posteroventrally. Apterous female: Abdomen ( Fig. 10G, H ) almost evenly narrowed, with connexival corners close to each other posteriorly. Laterotergites 5–7 with long posteromedially directed pilosity. Tergite 7 bare and with shiny area in middle.

Description of apterous male. Measurements of holotype: Body length 2.78; maximum body width (at metapleura) 1.00. Head length 0.38, width 0.66; minimum eye distance 0.15. Pronotum length 0.66, width 0.88. Lengths of antennomeres: I 0.60, II 0.37, III 0.49, IV 0.45. Lengths of leg segments: profemur 0.72, protibia 0.78, protarsus 0.03 + 0.03 + 0.19, mesofemur 1.25, mesotibia 1.03, mesotarsus 0.07 + 0.31 + 0.59, metafemur 1.19, metatibia 1.09, metatarsus 0.05 + 0.07 + 0.27.

Measurements of paratypes (n = 10): Body length 2.88–3.25; maximum body width (at metapleura) 1.00–1.13. Head width 0.67–0.72. Pronotum length 0.64–0.80, width 0.91–1.00.

Colour: Black with numerous, variably extended orangeyellow parts. Anterior part of head between eyes and antennal fossae usually yellowish to brown, only rarely more strongly infuscated. Juga, labrum, and base of rostrum yellow. Prothorax yellow, except disc of pronotal lobe blackish brown, only its hind margin with usually narrow orange margin. Ventral parts of mesopleuron and all acetabula yellow. Connexival margins orange-yellow; medial parts of sternite 7 and ventral part of segment 8 brown. All coxae and trochanters yellow; profemur yellow, with black posterior stripe; protibia anteriorly often more or less yellowish; metafemur yellow, with posterior face largely black except basal fourth or third.

Pilosity: Propleuron and mesopleuron with a few moderately long setae. Connexival margins at segments 5–7 with few decumbent setae. Dorsal surface of thoracic nota and abdominal tergites with appressed greyish pilosity; metanotum and tergites 1–3 with few, rather short decumbent setae.

Structures: Head broader than anterior margin of pronotum. Juga flat, strongly inclined, moderately broad, without spinulae. Pronotum long, along midline about 1.7 times as long as head. Mesonotum not visible, or as a very narrow stripe. Proepisterna bearing small black spinulae anteromesally. Propleuron with row of black pits near hind margin; mesopleuron with similar scattered pits, metapleuron in some specimens with few pits.

Profemur on extensor side lacking distinct concavity. Coxae and trochanters lacking black spinulae. Metatrochanter with one small subapical tooth and a very few minute spinulae. Hind femur strongly or very strongly enlarged, dentition on flexor side rich: basal row consisting of numerous minute, very densely set spinules, the most distal one slightly larger and a bit distant; other dentition quite variable, depending on femur size, but the two rows rather regular and parallel; posterodistal row, almost in continuation of basal row, consisting of about 7–10 teeth, starting in basal half, usually two longer teeth each followed by several shorter teeth, but in some specimens the longer teeth indistinct; anterodistal row consisting of ca. 6–10 very short, distantly set teeth, either parallel with posterodistal row, or reaching more basally, almost to base of femur. Specimens with strong hindlegs possessing strongly, almost evenly curved metatibiae, with rich dentition on flexor side including a tooth approximately at distal fourth; such with smaller hindlegs almost straight metatibiae with less developed dentition; apex always with two spines.

Laterotergites moderately inclined. Tergites slightly convex, tergite 7 about 1.5 times as long as tergite 6, and 0.8 times as long as broad. Abdominal venter simple, without modifications. Proctiger ( Fig. 8E ) slender, with hardly protruded lateral wings ( Fig. 8E ). Paramere small, elongated, with almost straight distal part bearing a small, ventrallydirected apical lobe ( Fig. 7H ).

Description of apterous female. Measurements (n = 10): Body length 2.81–3.50; maximum body width (at metapleura) 0.95–1.20. Head width 0.64–0.73. Pronotum length 0.67–0.81, width 0.88–1.05.

Colour: Similar to apterous male, except yellowish brown colour of medial parts of abdominal sternites much more extended anteriorly.

Pilosity: Pilosity of thorax similar to that in males. Only tergites 1–2 (3) with rows of subdecumbent setae; tergite 7 bare; tergite 8 posteriorly with brush of long black, posteriorly directed setae. Laterotergites 5–7 with long, posteromedially directed setae (not very dense); connexival corner with dense tuft of black setae. Gonocoxa with some long setae dorsally. Structures: Head and thorax similar to those in apterous male. Fore and middle leg (including mesofemur) unmodified. Metatrochanter with one small spine only. Metafemur slenderer than in male; basal row of spinules lacking, a single small spine present in some specimens might correspond with the last enlarged spinule of males; dentition of posterodistal pronotum) 1.19–1.34. Head width 0.69–0.73. Pronotum length 1.09–1.25.

Colour: Similar to apterous female. Forewing blackish, with pale ivory to yellowish streak at base.

Pilosity: Setae on forewing veins as in macropterous male. Setae on abdomen compared to apterous female strongly reduced, except for long setae on tergite 8 and on connexival corners, which, however, do not form a dense tuft.

Structures: Pronotum and forewings as in macropterous male. Hindleg structures as in apterous female. Abdomen broad; connexival margins subparallel; sternite 7 not visible in dorsal view. Tergite 8, gonocoxa, and proctiger as in apterous female.

row consisting of 6–8 teeth, two longer teeth each followed by several shorter teeth; anterodistal row lacking. Metatibia straight to weakly curved, dentition on flexor side weaker than in male.

Abdomen ( Fig. 10G, H ) elongated. Connexival margins almost straight, steadily converging posteriorly, apices only with short distance. Laterotergites anteriorly steep, 3–7 almost vertical. Sternite 7 narrowly visible in dorsal view. Tergites 1–2 convex, 3–8 flat; tergite 7 about 1.2 times as long as tergite 6 and about 1.3 times as long as anteriorly wide, with shiny area at middle. Tergite 8 with indistinct shiny area (due to pilosity), directed posteriorly. Connexival corner in lateral view acute, but not elongated. Gonocoxa small, ventral margin weakly concave. Proctiger small, narrow, knob-like.

Description of macropterous male. Measurements (n = 5): Body length 3.06–3.56; maximum body width (at pronotum) 1.25–1.31. Head width 0.67–0.73. Pronotum length 1.09–1.27.

Colour: Similar to apterous male. Forewing blackish, with pale ivory to yellowish streak at base.

Pilosity: Basal and lateral (anterior) veins of forewing with rows of rather short setae.

Structures: Pronotum large, with protruding humeri. Forewing with 4 closed cells reaching distal fourth; dealate specimens unknown. Metafemur on average slenderer when compared to apterous male, dentition similar. Metatibia never strongly curved, with moderate dentition at flexor side, without subapical tooth.

Description of macropterous female. Measurements (n = 6): Body length 3.06–3.69; maximum body width (at

Comparative notes. Rhagovelia gapudi , new species, belongs to the R. cotabatoensis subgroup (sensu Zettel, 1996), which has never been revised in detail. Within this subgroup, it is the only species inhabiting the Palawan Region. The new species can be distinguished from R. cotabatoensis Hungerford & Matsuda, 1961 , a widespread species in other parts of the Philippines, by the absence of black spinulae on the juga, the shape of the paramere (distally slenderer, smaller apical lobe), and in the apterous female by less convergent connexival margins (more or less touching each other in R. cotabatoensis ) and the presence of shiny areas on tergites 7 and 8. In the Palawan Region, R. gapudi , new species, can only be mistaken for R. kawakamii hoberlandti , but the light anterior of the head distinguishes all morphs of Rhagovelia gapudi , new species, from that species (except freshly moulted imagines of R. kawakamii ). Moreover, R. kawakamii also possesses some spinulae on the caudal areas of the juga. Males of the two species can be immediately identified by the shape of the parameres (comp. Fig. 7G, H ), apterous females by the shape of the abdomen (comp. Figs. 5B , 6B ). In both female morphs of R. gapudi , new species, the ventral outline of gonocoxa 1 is slightly concave ( Fig. 10H, I : arrows), but straight in R. kawakamii .

Habitats. Rhagovelia gapudi , new species, inhabits a large variety of running waters in the lowlands, including very small streamlets ( Fig. 12B ). Observations suggest a preference for running sections, especially if compared to R. kawakamii , which prefers quiet water. This more or less corresponds to unpublished habitat notes on R. cotabatoensis and other related species ( R. cotabatoensis subgroup). Rhagovelia gapudi , new species, can be found in rather disturbed habitats in open land as well. Within the Cabayugan River System, it was found only in Nagdayan Creek, a moderately disturbed, shallow lowland tributary with low stream bed heterogeneity (predominantly continuous, slow run), in contrast to R. matillanoi , which occupies the upper tributaries in the undisturbed uplands.

Distribution. Busuanga Island, Palawan Island (North and Central) ( Fig. 11F ).

Figures

Fig. 6. Habitus of Rhagovelia gapudi, new species. A, apterous male; B, apterous female; C, macropterous male.

Fig. 7. Left parameres of Rhagovelia species, lateral view. A, R. minutissima; B, R. palawanensis; C, R. matillanoi, new species; D, R. estrella; E, R. abbreviata, new species; F, R. lansburyi; G, R. kawakamii hoberlandti; H, R. gapudi, new species.

Fig. 8. Proctiger of Rhagovelia species, dorsal view pilosity omitted. A, R. matillanoi, new species; B, R. abbreviata, new species; C, R. lansburyi; D, R. kawakamii hoberlandti; E, R. gapudi, new species.

Fig. 9. Hindlegs of Rhagovelia species, showing characteristic armatures pilosity omitted. A, R. matillanoi, new species, apterous male; B, R. matillanoi, new species, apterous female; C, R. abbreviata, new species, apterous male; D, R. abbreviata, new species, macropterous male; E, R. abbreviata, new species, apterous female; F, G, R. gapudi, new species, apterous males, two morphs; H, R. gapudi, new species, apterous female.

Fig. 10. Abdominal terminalia of females of Rhagovelia species, pilosity partly omitted. A–C, R. matillanoi, new species, arrow in A pointing to characteristic setae; D–F, R. abbreviata, new species; G–I, R. gapudi, new species, arrows in H, I pointing to concave ventral outline of gonocoxa. A, D, G, apterous specimen, dorsal aspect; B, E, H, apterous specimen, lateral aspect; C, F, I, macropterous specimen in 48 dealate, lateral aspect.

Fig. 11. Area and distribution maps of Rhagovelia species. A, overview of the Palawan Region with major islands and towns, insert showing the location of the area within the Philippines as well as the northern part of Borneo belonging to Malaysia; B, allopatric distribution of the species of the R. sarawakensis group related with R. minutissima; C, allopatric distribution of the species of the R. sarawakensis group related with R. estrella; D, distribution of R. lansburyi; E, distribution of R. kawakamii hoberlandti; F, distribution of R. gapudi, new species.

Fig. 12. Habitats. A, a larger river at Napsan Road, kilometre 29, with high water level after heavy rain; R. palawanensis and R. estrella were recorded in quieter rock pools and between flooded vegetation. B, a small streamlet at Calatoboc Bridge over Northern National Highway was inhabited by R. kawakamii hoberlandti and R. gapudi, new species. Whereas the first species is euryoecious, R. gapudi, new species, prefers such small running waters.

Fig. 5. Habitus of Rhagovelia kawakamii hoberlandti. A, apterous male; B, apterous female; C, macropterous male; D, macropterous female.