Rhagovelia kalawai, Polhemus, 2024

Polhemus, Dan A., 2024, Thirty-four new species of Rhagovelia (Heteroptera: Veliidae) from the East Papua Composite Terrane, far eastern New Guinea, Zootaxa 5400 (1), pp. 1-214 : 63-67

Rhagovelia kalawai new species

( Figs. 22 , 28 , 99–105 , 132 )

Type material examined. Holotype, wingless male: PAPUA NEW GUINEA, Milne Bay Prov., Basilaki Is., Kalawai River and rocky trib., 5–145 m., 10°36'52"S, 151°01'07"E, water temp. 26.5 °C., pH 8.27, 17 January 2004, 09:00–14:00 hrs., along main channel, CL 7294a, D. A. & J. T. Polhemus ( BPBM) . Paratypes: PAPUA NEW GUINEA, Milne Bay Prov.: 22 wingless males, 18 wingless females, Basilaki Island , same data as holotype, D.A. & J. T. Polhemus ( USNM, BPBM) ; 2 winged males, 3 winged females, 3 wingless males, 5 wingless females, Basilaki Is., same data as preceding except on small rocky tributary, CL 7294b, D. A. & J. T. Polhemus ( USNM) ; 1 winged female, 14 wingless males, 24 wingless females, Basilaki Is., same data as preceding except on small tributary, CL 7294c, D. A. & J. T. Polhemus ( USNM, BPBM) ; 21 wingless males, 16 wingless females, Sideia Is., hill streamlet in south central interior, headwater trib. to Kwabunamoa River , 35– 40 m., 10°36'16.8"S, 150°50'55.6"E, water temp. 26.5 °C., 15 January 2004, 10:00–11:00 hrs., CL 7287, D. A. & J. T. Polhemus ( USNM) .

Description.

Wingless male: Size: Length = 3.50–3.75 mm (x = 3.61, n = 5); width = 1.20–1.30 mm (x = 1.27, n = 5). Wingless female, length = 3.50–3.70 mm (x = 3.64, n = 5); width = 1.30–1.45 mm, (x = 1.37, n = 5). Winged male, length = 3.95 mm (n = 1); width = 1.50 mm (n = 1). Winged female, length = 3.90 mm (n = 1); width = 1.45 mm (n = 1).

Color: Dorsal ground color dark grey, marked with pale orange on anterior pronotum and outer connexiva, yellow on basal antennae and legs ( Fig. 99 ). Head dark grey; rostrum pale yellowish-brown, fuscous medially, piceous distally; eyes dark red. Pronotum dark grey, with transverse yellowish-orange patch anteriorly behind head vertex, this pale anterior coloration not extending laterally onto propleurae. Mesonotum, metanotum and abdominal tergites dark grey, all tergites uniformly dull and lacking shining areas except for tergite VII slightly shining, connexiva dark grey on inner halves, pale orange on outer halves. Antennal segment I with basal one-third pale yellow, distal half plus all of segments II–IV black. Legs generally black, with coxae, trochanters, basal half of fore femur dorsally, basal one-fifth of hind femur dorsally, basal four-fifths of fore and hind femora ventrally, extreme base of middle femur ventrally pale yellow. Venter dark grey, with ventral sections of propelurae, prosternum, pro- and mesoacetabulae, abdominal ventrites VII–X dark orange.

Structural characters: Head moderately short, declivant anteriorly, with weakly impressed median line; length 0.40, width 0.85; length of eye along inner margin 0.40, anterior/posterior interocular space, 0.15/0.45. Pronotum short, width 1.05, length along midline 0.25, shorter than dorsal length of head, leaving mesonotum broadly exposed; mesonotum smooth, tumescent, lacking foveae, with a weakly impressed longitudinal midline, length at midline 0.70. Metanotum moderately exposed, roughly crescent-shaped, length at midline 0.10. Lengths of abdominal tergites I–VIII, respectively: 0.18: 0.25: 0.20: 0.20: 0.15: 0.20: 0.40: 0.35. Connexiva with margins of even width throughout, margins nearly straight and evenly convergent posteriorly, posterolateral angles not modified, separated by entire width of tergite VIII.

Entire dorsum and laterotergites covered with fine appressed golden pubescence, intermixed with scattered long, erect black setae; legs and antennae thickly clothed with short appressed gold setae, with scattered long, erect black setae on anterodorsal faces of antennal segments I and II, anterior margins of all femora; fore femur with posterior margin bearing a thick fringe of pale, semi-erect, moderately long setae plus a comb of 7–8 long, slender, erect, evenly spaced black setae; fore tibia with anterior margin bearing numerous erect, pale, moderately long setae intermixed with long, slender, erect black setae; middle femur bearing scattered long, slender, erect black setae along posterior margin; fore and middle trochanters lacking pegs or teeth; fore and middle femora and tibiae with margins straight, not flattened or otherwise modified; fore tibia slightly expanded and ventrally flattened on distal one-fourth; hind trochanter bearing 12 small black denticles ventrally; hind femur highly incrassate, with scattered very long, slender, pilose brown setae posterodorsally, posterior margin bearing two parallel rows of teeth, ventral row lying in area covered by infolded hind tibia and consisting of approximately 18 tiny black pegs on basal half, followed by about 12 small, subequal sized black teeth on distal half, dorsal row of teeth commencing near middle of femur with a large, acute orange-brown tooth with a black apex, followed by an open space lacking teeth, then by 3 large orange-brown teeth with black apices, then 3 smaller black teeth of progressively declining size toward femoral apex; hind tibia broadly and gently sinuate, inner surface bearing 2 parallel rows of 12–15 small black teeth on basal two-thirds, then a large, acute tooth, then 3 more moderate sized teeth of progressively declining size, these latter 4 teeth all orange-brown with black apices ( Figs. 101, 102 ).

Venter of head and thorax lacking black denticles; meso- and metasterna slightly depressed centrally, margins of this depression and adjacent lateral metasternum bearing long, fine gold setae arranged in a V-shaped pattern with apex directed anteriorly; abdominal venter set with short appressed gold setae; basal abdominal ventrites highly sculptured, ventrite I lying in vertical orientation, remaining ventrites horizontal and all in similar plane, ventrite II with an acute longitudinal carina of V-shaped cross section medially, ventrites III–VI unmodified, ventrite VII broadly and shallowly depressed centrally.

Male paramere shape elongate, with scattered short, stiff setae present centrally along ventral margin, distal portion expanded, apex upturned and bluntly rounded ( Fig. 103 ). Male proctiger with basolateral lobes prominent, angular; distolateral lobes not developed; apical cone tapering evenly to an angular apex ( Fig. 104 ).

Lengths of antennal segments I–IV: 0.90: 0.50: 0.60: 0.55.

Lengths of leg segments as follows: femur, tibia, tarsal 1, tarsal 2 of fore leg, 1.10: 1:15: 0.03: 0.02: 0.20; of middle leg, 1.75: 1.25: 0.05: 0.55: 0.80; of hind leg, 1.70: 1.80: 0.05: 0.10: 0.30.

Wingless female: Similar to wingless male in general structure and coloration, with following exceptions: connexival margins straight, unmodified, bearing short, stiff black setae, converging evenly to posterior apex of abdomen, separated by full width of abdominal tergite VII and just slightly covering anterolateral sections of tergite VIII ( Fig. 100 ), posterolateral angles of connexiva slightly acute, with a few short, posteriorly-directed black setae but lacking major setal tufts ( Fig. 22 ); abdominal tergites II–V with narrow patches of slightly raised, moderate length pale setae along longitudinal midlines, tergites VI–VIII with small, longtitudinally elongate, shining black patches centrally; abdominal tergite VIII lying in horizontal orientation, proctiger angled downward at 45° from horizontal; hind femur only weakly incrassate, bearing a single row of teeth below infolded tibia, beginning with a small, sharp black tooth near midpoint, followed by a long, slender, acuminate tooth with a black apex, then 5 more smaller teeth of progressively decreasing size to femoral apex; hind tibia straight, inner surface lacking teeth; ventral coloration predominantly dark grey, with ventral section of propleura, prosternum, proacetabula, abdominal ventrite VII and gonocoxae yellowish orange; ventrite VII angular posteromedially ( Fig. 28 ).

Winged male: Similar to wingless male in general structure and coloration, with following exceptions: pronotum greatly enlarged, width 1.50, length 1.40, completely covering meso- and metanotum; anterior lobe with transverse ovate orange-brown patch along anterior margin in area behind head vertex, this patch bounded laterally by silvery pruinose areas, separated by dark coloration behind eyes from paler coloration on propleurae; humeri enlarged, slightly protrusive laterally; posterior pronotal lobe dark blackish-brown, broadly domed, posterior half with small, obscure foveae, posterior margin broadly angular, bearing scattered long, gently curving, semi-erect black setae; forewings uniformly dark blackish-brown, extending past apex of abdomen when intact, bearing 4 closed cells consisting of two elongate cells in basal half of wing followed by 2 smaller cells of subequal size distally near center of wing. Hind femur less incrassate than in wingless male.

Winged female: Similar to winged male in general form and coloration, but slightly less robust, pronotum width 1.45, length 1.40.

Etymology. The name “kalawai ” is a noun in apposition and refers to the Kalawai River type locality on northern Basilaki Island.

Distribution. Endemic to Basilaki and Sideia islands, east of the China Strait ( Fig. 132 ). The species range as presently known falls within the Basilaki Island area of freshwater endemism (Area 36) as delineated by D. Polhemus & Allen (2007).

Discussion. This is a member of the R. dibuwa subgroup occurring on the islands immediately east of the China Strait, which represented a durable deep water barrier between these islands and far eastern New Guinea during the Pleistocene low sea level stands. It is similar in many respects to R. dibuwa , and the two might be considered subspecies, although they are clearly allopatric based on their current ranges on different island groups. Both species have a pair of raised, angular ridges at the base of the proctiger ( Fig. 5 ); similarly shaped male parameres ( Figs. 103 , 114 ); and the posteromedial margin of abdominal ventrite VII in females is produced and angular posteromedially. In R. kalwai the angular posterior margin of female abdominal ventrite VII is not as strongly produced as in R. dibuwa (compare Figs. 28, 29 ); the male proctiger has the distolateral lobes somewhat more strongly produced and angling outward from the base of the distal cone (compare Figs. 104 , 115 ); and shining patches are present on female abdominal tergites VI–VIII only.

The specimens of R. kalawai currently in hand from multiple localities at varying elevations on Basilaki and Sideia islands also exhibit a uniformly dark grey ground color, with no indication of intrasexual color polymorphism involving both dark grey and orange-brown morphs, as seen in R. dibuwa and R. torrenticola . Specimens from the interior hills of Sideia Island are also notably smaller than other populations in this assemblage, only attaining maximum body lengths of 3.5 mm.

On the upland streams of Basilaki and Sideia islands R. kalawai co-occurs with R. guiagoila , a member of the R. papuensis group. The two species are easily separated in mixed samples by the short pronotum in R. kalawai (versus a long pronotum in R. guiagoila ); the significantly denser setiferation on the dorsum and legs of R. kalawai ; and the unmodified female connexiva with uniformly setiferous margins that taper evenly to the posterior apex of the abdomen. In females of R. guiagoila , by contrast, the connexiva are strongly convergent adjacent to abdominal segments I–IV and then parallel thereafter, and the connexival margins adjacent to tergites III and IV are glabrous along their outer margins.

Ecological notes. The Kalawai River at the type-locality (CL 7294) was a clear, moderately fast stream flowing through a partially shaded bed of water-rounded boulders, rocks, cobbles, and coarse alluvium, with occasional exposures of metamorphic bedrock ( Fig. 105 ). The river was sampled from the head of the estuary upstream to the 15 m-high Tumalinaliboe Falls, and then above the falls to the point where a swift tributary entered by a cascade on the north bank. This tributary was followed upstream to where it headed in a set of small springs emerging over metamorphic bedrock exposures. Rhagovelia kalawai was common on the small pools along this tributary, and in lesser numbers in sheltered pockets along the margins of the main river channel.

This species was also collected on adjacent Sideia Island from the headwater reach of the Kwabunamoa River, in the island’s interior, which was reached by hiking in from the island's south coast over a set of low hills. At the point sampled the river headwaters consisted of a shallow trickle of water running over exposures of metamorphic bedrock into small, still pools. The specimens of R. kalawai , which were slightly smaller than those from neighboring Basilaki island, were taken at the upstream heads of these pools where the entering water formed small ripples on the surface, in habitats similar to those where it was found on the upper tributary to the Kalawai River described previously.

Figures

FIGS. 20–25. Species of the Rhagovelia dibuwa subgroup, female terminal abdomen, lateral view, showing structural variation on ventrites VII and VIII. 20. R. watuti n. sp., specimen from New Guinea, Cloudy Mtns., CL 7175; 21. R. peninsularis n. sp., specimen from New Guinea, Alotau, CL 7163; 22. R. kalawai n. sp., specimen from Sideia Is., Kwabunamoa River, CL 7287; 23. R. dibuwa n. sp., specimen from Normanby Is., Dibuwa River, CL 7230; 24. R. awaetowa n. sp., specimen from Fergusson Is., Awaetowa River, CL 7225; 25. R. torrenticola n. sp., specimen from Goodenough Is., Tuabeda River, CL 7184.

FIGS. 26–31. Species of the Rhagovelia dibuwa subgroup, female terminal abdomen, ventral view, showing structural variation on posterior margin of ventrite VII. 26. R. watuti n. sp., specimen from New Guinea, Cloudy Mtns., CL 7175; 27. R. peninsularis n. sp., specimen from New Guinea, Alotau, CL 7163; 28. R. kalawai n. sp., specimen from Sideia Is., Kwabunamoa River, CL 7287; 29. R. dibuwa n. sp., specimen from Normanby Is., Dibuwa River, CL 7230; 30. R. awaetowa n. sp., specimen from Fergusson Is., Awaetowa River, CL 7225; 31. R. torrenticola n. sp., specimen from Goodenough Is., Tuabeda River, CL 7184.

FIGS. 99–104. Rhagovelia kalawai n. sp., structural details; specimens from Sideia and Basilaki islands. 99. Wingless male, dorsal habitus, Basilaki Island, CL 7294. 100. Wingless female, dorsal habitus, Sideia Island, CL 7287. 101. Male right hind leg, posterior view. 102. Male right hind leg, dorsal view. 103. Male left paramere, outer lateral view. 104. Male proctiger, dorsal view; 101–104 all from Basilaki Island, CL 7294.

FIG. 105. Kalawai River, Basilaki Is., Milne Bay Province, Papua New Guinea, CL 7294, type-locality for R. kalawai n. sp.

FIG. 132. Distributions of species in the R. dibuwa subgroup in eastern New Guinea and adjacent islands.

FIGS. 4, 5. Rhagovelia dibuwa n. sp., male genitalic structures, with specific characters as discussed in text labelled. 4. Proctiger. 5. Intact male genitalic complex, right lateral view.

FIGS. 110–115. Rhagovelia dibuwa n. sp., structural details; specimens from Normanby Island. 110. Male right hind leg, weakly developed individual, posterior view. 111. Male right hind leg, weakly developed individual, dorsal view. 112. Male right hind leg, strongly developed individual, posterior view. 113. Male right hind leg, strongly developed individual, dorsal view; 110–113 from Dibuwa River, CL 7230. 114. Male left paramere, outer lateral view. 115 Male proctiger, dorsal view; 114 and 115 from Bunama, Apatabuia River, CL 7228.