Rhagovelia dibuwa, 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 : 68-74

Rhagovelia dibuwa new species

( Figs. 4, 5 , 23 , 29 , 106–117 , 132 )

Type material examined. Holotype, wingless male: PAPUA NEW GUINEA, Milne Bay Prov., D’Entrecasteaux Islands, Normanby Is., upper Apatabuia River and rocky tribs., above Bunama , 60–90 m., 10°07'04"S, 151°09'07"E, water temp. 23.5° C. (main river), 29 January 2003, 09:00–01:00 hrs., margins of main river channel, CL 7228a, D. A. & J. T. Polhemus ( BPBM) . Paratypes: PAPUA NEW GUINEA, Milne Bay Prov., D'Entrecasteaux Islands, Normanby Island : 1 winged male, 2 winged females, 50 wingless males, 29 wingless females, same data as holotype, CL 7228a, D. A. & J. T. Polhemus ( USNM, BPBM) ; 1 winged female, 27 wingless males, 18 wingless females, south coast, rocky trib. to upper Apatabuia River with pools amid boulders, above Bunama , 90 m., 10°07'12"S, 151°09'07"E, water temp. 25° C. (pools), 29 January 2003, 09:00–01:00 hrs., CL 7228b, D. A. & J. T. Polhemus ( USNM) ; 11 wingless males, 14 wingless females, tributary streamlet to upper Dibuwa River, W. of Yeluyelua , 320 m., 10°02'40"S, 151°15'05"E, water temp. 23° C., 30 January 2003, 08:45–09:00 hrs. and 12:45–13:00 hrs., CL 7230, D. A. Polhemus ( USNM) ; 2 wingless males, 1 wingless female, upper Dibuwa River and rocky tribs., W. of Yeluyelua , 245 m., 10°02'46"S, 151°14'53"E, water temp. 24° C., 30 January 2003, 09:30–12:30 hrs, ponded area along tributary, CL 7231b, D. A. Polhemus ( USNM, BPBM) ; 2 winged females, 25 wingless males, 25 wingless females, east coast, Golupona Stream above Yeluyelua , 90 m., 10°02'53"S, 151°15'35"E, water temp. 23° C., 30 January 2003, 08:00–13:00 hrs, CL 7232, J. T. Polhemus ( USNM, BPBM) .

Description.

Wingless male: Size: Length = 3.40–3.70 mm (x = 3.53, n = 6); width = 1.30–1.40 mm (x = 1.32, n = 6). Wingless female, length = 3.50–3.70 mm (x = 3.61, n = 6); width = 1.30–1.45, mm, (x = 1.39, n = 6). Winged male, length = 4.00 mm (n = 1); width = 1.60 mm (n = 1). Winged female, length = 3.95 mm (n = 1); width = 1.60 mm (n = 1).

Color: Dorsal ground color dark brown, marked with pale yellow on anterior thorax, outer connexiva, basal sections of antennae and legs, and central portion of venter ( Fig. 106 ). Head dark brown, juga and antennal tubercles pale yellow; rostrum pale yellowish-brown, fuscous medially, piceous distally; eyes dark red. Pronotum dark brown, with broad, transverse pale yellow patch anteriorly behind head vertex, this pale anterior coloration slightly interruped laterally with pale brown, then extending laterally onto propleurae. Mesonotum dark brown, with central portion paler chestnut brown. Metanotum, abdominal tergites I–VI, and inner sections of abdominal connexiva dark brown, tergites I–VI slightly paler reddish brown centrally, this coloration more broadly expanded on tergites I, V, and VI, these same tergites uniformly dull and lacking shining areas; abdominal tergite VII broadly orange-yellow and shining centrally, dark brown at corners; abdominal tergite VIII orange-yellow on basal third, remainder dark blackish-brown; outer sections of connexiva pale yellow. Antennal segment I pale yellow, extreme apex dark brown, antennal segment II pale yellow on basal third, grading to dark brown on distal portion, antennal segments III and IV dark brown to black. Legs with coxae, trochanters, femora, basal half of fore tibia pale yellow; apices of femora, distal half of fore tibia, entirety of middle and hind tibiae and tarsi dark brown. Venter pale yellow, triangular central section of mesosternum, lateral sections of abdominal sternites, and apex of abdominal ventrite VIII dark brown.

Structural characters: Head moderately short, declivant anteriorly, with weakly impressed median line; length 0.45, width 0.85; length of eye along inner margin 0.35, anterior/posterior interocular space, 0.20/0.45. Pronotum short, width 1.05, length along midline 0.30, shorter than dorsal length of head, leaving mesonotum broadly exposed; mesonotum slightly tumescent, set with numerous very small foveae, longitudinal midline not raised, length at midline 0.75; metanotum moderately exposed, roughly crescent-shaped, length at midline 0.10. Lengths of abdominal tergites I–VIII, respectively: 0.20: 0.30: 0.22: 0.20: 0.20: 0.22: 0.40: 0.35. Connexiva with margins of even width throughout, margins broadly sinuate in middle section, then convergent posteriorly, posterolateral angles not modified, separated by entire width of tergite VIII.

Entire dorsum and laterotergites covered with fine, appressed pale pubescence, intermixed with scattered long, erect black setae; legs and antennae thickly clothed with short appressed gold setae, with scattered long, erect, bristly black setae on anterodorsal faces of antennal segments I and II, anterior margins of all femora; fore and middle trochanters lacking pegs or teeth, hind trochanter bearing 13–14 small black pegs ventrally; fore femur with ventral margin bearing a thick fringe of moderately long, semi-erect, pale brown setae plus a comb of 8–9 long, slender, erect, evenly spaced black setae; fore tibia with anterior margin bearing numerous semi-erect, moderately long, pale brown setae intermixed with 8–10 long, slender, erect black setae, tibia dorsoventrally flattened and slightly widened on distal half, ventral surface bearing a small concavity adjacent and parallel to grasping comb at apex; middle femur simple, slightly tapering distally, bearing scattered long, slender, erect black setae along posterior margin; 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 18 tiny black asperities basally, followed by a small yellowish spine with a dark tip, then a large yellowish spine with a dark tip, separated by wide gap from another similar spine, separated by another wide gap from another similar spine, separated by another wide gap from 5 small but similarly colored teeth of steadily decreasing size to femoral apex, dorsal row of teeth commencing on distal half of femur and consisting of 8 very small yellowish teeth with black apices; hind tibia broadly and gently sinuate, inner surface bearing a single row of 12 small black teeth on basal two thirds, then 2 large, acute black teeth, then 4 teeth of progressively decreasing size to apex ( Fig. 110, 111 ).

Venter of head and thorax lacking black denticles; mesosternum with a roughly triangular depression centrally, raised margins of this depression bearing long, fine gold setae arranged in a V-shaped pattern with apex directed anteriorly; metasternum slightly tumid, bearing long, erect gold setae; abdominal venter set with short appressed gold setae, intermixed with long, fine gold setae on abdominal ventrites I and II; 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 with a shallow semicircular depression posteromedially, posterior margin broadly and shallowly concave, ventrite VIII excavate basally.

Male paramere shape elongate, with scattered short, stiff setae present centrally along ventral margin, distal portion expanded, apex angled upward, broadly rounded ( Fig. 114 ). Male proctiger with basolateral lobes prominent, angular; distolateral lobes not developed; apical cone tapering evenly to an angular apex ( Fig. 115 ).

Lengths of antennal segments I–IV: 1.00: 0.60: 0.75: 0.60.

Lengths of leg segments as follows: femur, tibia, tarsal 1, tarsal 2 of fore leg, 1.25: 1:25: 0.05: 0.02: 0.30; of middle leg, 2.00: 1.40: 0.10: 0.60: 0.75; of hind leg, 1.90: 2.00: 0.05: 0.15: 0.30.

Wingless female: Similar to wingless male in general structure and coloration, with following exceptions: connexival margins straight, unmodified, converging evenly to posterior apex of abdomen, apices separated by full width of abdominal tergite VII ( Figs. 107, 109 ), posterolateral angles slightly rounded, bearing small, posteriorly-directed, angular tufts of gold setae; abdominal tergites I and II dark brown laterally, reddish brown centrally, slightly tumid, tergites III and IV uniformly dark brown with narrow patches of slightly raised, moderate length pale setae along longitudinal midlines, tergites V and VI mostly dark brown with small shining orange patches centrally, tergites VII and VIII entirely shining orange; abdominal tergite VIII lying in horizontal orientation, proctiger angled downward at 45° from horizontal ( Fig. 23 ); hind femur only weakly incrassate, bearing a single row of teeth below infolded tibia, beginning with a moderate sized, sharply pointed, yellowish spine with a black tip near midpoint, followed by 3–4 more very small black teeth distally; hind tibia straight, inner surface lacking teeth; ventral coloration predominantly orange-brown, with ventral section of propleura and all acetabula pale yellowish, triangular central section of mesosternum dark brown.

Winged male: Similar to wingless male in general structure and coloration, with following exceptions: pronotum greatly enlarged, width 1.60, length 1.60, completely covering meso- and metanotum; anterior lobe with transverse ovate pale yellowish 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 transversely 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, wing apices extending past apex of abdomen when intact, bearing 4 closed cells consisting of two elongate cells in basal half of wing followed by two smaller cells of subequal size distally near center of wing.

Winged female: Similar to winged male in general body form and coloration, with following exceptions: body form slightly less robust, pronotum width 1.60, length 1.45.

Etymology. The name “dibuwa ” is a noun in apposition, and refers to the Dibuwa River on Normanby Island, from which part of the type series was taken.

Distribution. D’Entrecasteaux Islands; endemic to Normanby Island ( Fig. 132 ). The species range as presently known occupies the Cloudy Mountains area of freshwater endemism (Area 34) as delineated by D. Polhemus & Allen (2007).

Discussion. This is a moderate-sized, robust species from Normanby Island, which exhibits a notable degree of intraspecific color polymorphism. In darker individuals the head, mesonotum, metanotum, abdominal tergites, inner halves of the connexiva, and dorsal surfaces of the legs except for the basal sections of the fore and hind femora are predominantly dark brown. By contrast, paler individuals have the central sections of the mesonotum, metanotum and all abdominal tergites plus the entirety of all femora dorsally orange-brown. Some specimens thus appear predominantly black and others predominantly dark orange, although the key morphological characters are similar for all. The series from CL 7230, a tributary streamlet to the Dibuwa River, has both dark and orange forms intermixed, thus illustrating the entire polychromatic range of color variation at a single site.

Compared to other species in the R. dibuwa subgroup occurring in the D’Entrecasteaux Islands, R. dibuwa is somewhat smaller in size, with body lengths across both sexes ranging from 3.4–3.7 mm, versus 4.3–4.5 mm for R. awaetowa on Fergusson Island, or 4.0– 4.2 mm for R. torrenticola on Goodenough Island. In regard to the male genitalia, the paramere shape is similar to that seen R. awaetowa and R. torrenticola (compare Fig. 115 to Figs. 122 , 129 ), but the proctiger shape differs from both these species, being most similar to R. kalawai from Basilaki and Sideia island, but shorter and more compact (compare Fig. 115 to Figs. 123 , 130 ).

Females of R. dibuwa have the posterior margin of abdominal ventrite VII produced into a broadly triangular medial process at the base of the gonocoxal commissure. This process is far less produced in R. awaetowa , while in R. torrenticola there is a small, glabrous concavity at the base of the gonocoxal commissure (compare Fig. 29 to Figs. 30, 31 ). The angular setal tufts at the posterolateral angles of the connexixa are not as thick and dense in R. dibuwa when viewed laterally as they are in R. awaetowa or R. torrenticola , being instead more similar to the state seen in R. kalawai from the islands bordering the China Strait (compare Fig. 23 to Figs. 22, 24, 25 ). For comparisons to this latter species see the discussion under R. kalawai .

Ecological notes. The type series of R. dibuwa was taken from Apatabuia River (CL 7228) above the village of Bunama, on the east coast of Normanby Island. This locality was reached by following a steep trail up the valley through garden clearings, until the river was reached at 60 m elevation, and then followed upstream to the 100 m level. This was a clear, swiftly-flowing stream in a bed of very large metamorphic boulders ( Fig.116 ), partially shaded by relatively intact rain forest, with several clear, rocky tributaries also entering along the reach sampled. Rhagovelia bunama was common here on flowing pools amid the boulders, and on tributary pools.

Another series was taken on a small, shaded tributary to the Dibuwa River (CL 7230), in the interior of eastern Normanby Island. This locality was reached by walking on a rough trail from the island’s east coast, over an intervening 400 m ridge, and then down into the interior valley of the Dibuwa. The tributary was reached prior to arriving at the main river, and flowed in a heavily shaded bed of boulders and large rocks, with occasional bedrock exposures forming alternating cascades, riffles and pools ( Fig.117 ). Rhagovelia dibuwa was common here, while by contrast only a few specimens were encountered along the margin of the main Dibuwa River channel. Most of the specimens at this locality exhibited a distinctly more orange-brown coloration in comparison to those taken at the Apatabuia River, which were largely blackish.

Figures

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. 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. 106–109. Rhagovelia dibuwa n. sp., dorsal habitus photos, specimens from Normanby Island. 106. Wingless male, dark form, dorsal habitus. 107. Wingless female, dark form, dorsal habitus; 108. Winged male, dark form, dorsal habitus; 106–108 all from Bunama, Apatabuia River, CL 7228. 109. Wingless female, orange-brown form, dorsal habitus, specimen from Dibuwa River, CL 7230.

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.

FIG. 116. Apatabuia River above Bunama, Normanby Is., Milne Bay Province, Papua New Guinea, CL 7228, type-locality for R. dibuwa n. sp.

FIG. 117. Tributary to the upper Dibuwa River, Normanby Is., Milne Bay Province, Papua New Guinea, CL 7230, habitat for the orange-brown form of R. dibuwa n. sp.

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

FIGS. 118–123. Rhagovelia awaetowa n. sp., structural details; specimens from Fergusson Island. 118. Wingless male, dorsal habitus. 119. Wingless female, dorsal habitus. 120. Male right hind leg, posterior view. 121. Male right hind leg, dorsal view; 118–121 from upper Awaetowa River, CL 7225. 122. Male left paramere, outer lateral view. 123. Male proctiger, dorsal view; 122 and 123 from lower Awaetowa River, CL 7183.

FIGS. 125–130. Rhagovelia torrenticola n. sp., structural details; specimens from Goodenough Island. 125. Wingless male, dorsal habitus, specimen from Yalaauau, CL 7186. 126. Wingless female, dorsal habitus, specimen from Tuabeda River at Kalauna, CL 7184. 127. Male right hind leg, posterior view. 128. Male right hind leg, dorsal view; 127 and 128 from Yalaauau, CL 7186. 129. Male left paramere, outer lateral view. 130. Male proctiger, dorsal view; 129 and 130 from Tuabeda River at Kalauna, CL 7184.