Rhagovelia tekadu, 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 : 113-116

Rhagovelia tekadu new species

( Figs. 181–187 , 201 )

Type material examined. Holotype, wingless male: PAPUA NEW GUINEA, Central Prov. , New Guinea, small tributary streamlets to Yaniwe River at Tekadu, 300 m., 07°40'36"S, 146°33'05"E, water temp. 24° C., 21 January 2001, 12:00–16:30 hrs, CL 7157a, D. A. Polhemus ( BPBM) . Paratypes: PAPUA NEW GUINEA, Central Prov., New Guinea: 4 wingless males, 15 wingless females, same data as holotype, CL 7157a, D. A. Polhemus ( USNM, BPBM) ; 1 wingless female, Yaniwe River at Tekadu, 300 m., water temp. 24° C., 21 January 2001, 12:00–16:30 hrs., 07°40'36"S, 146°33'05"E, 7157b, D. A. Polhemus ( BPBM) . Gulf Prov., New Guinea: 5 wingless males, 8 wingless females, Sapoi River and rocky tributary upstream of Ivimka Research Station, 120– 150 m., 7°43'36"S, 146°29'59"E, water temp. 27° C. (river), 24.5° C. (rocky trib.), 16 January 2001, 07:00–13:00 hrs., from margins of pools on main river channel, next to logs and vertical banks, CL 7148b, D. A. Polhemus ( BPBM) ; 3 wingless males, 2 wingless females, New Guinea, same data as preceding except from rocky trib., CL 7148c, D. A. Polhemus ( USNM, BPBM) ; 14 wingless males, 14 wingless females, New Guinea, same data as preceding except from very small rocky hill streamlet entering rocky tributary to Sapoi River, CL 7148d, D. A. Polhemus ( USNM, BPBM) .

Description

Wingless male: Size: Length = 3.20–3.50 mm (x = 3.38, n = 5); width = 1.00–1.20 (x = 1.10, n = 5). Wingless female, length = 3.90–4.00 mm (x = 3.96, n = 5); width = 1.10–1.30 mm, (x = 1.19, n = 5).

Color: Dorsal ground color dark brown, marked with dark yellow to orange-brown on basal antennae, anterior pronotum, connexiva and legs ( Fig. 181 ). Head black; lower frons orange-brown, juga and rostrum dark yellow, rostrum fuscous ventromedially, piceous distally; eyes dark reddish black. Pronotum dark yellow on anterior half, this yellowish coloration continuing laterally as a continuous band onto the propleurae, posterior half black, narrowly margined with dark yellow posteriorly. Mesonotum broadly medium brown centrally, lateral sections dark brown. Metanotum and abdominal tergites uniformly dark brown, thinly overlain with weak pruinosity; all abdominal tergites uniformly dull and lacking shining, glabrous areas; connexiva dark brown on inner halves, dark yellow on outer halves, ventral faces also dark yellow. Antennal segment I with basal one-third dark yellow, distal two-thirds plus all of segments II–IV black. Legs generally black dorsally, dark brown ventrally, with coxae, trochanters, basal half of fore femur, ventral face of hind femur pale yellow. Venter dark brown, with all acetabula pale yellow; lateral portions of abdominal ventrites VII and VIII orange-brown, flanking dark brown central patch along midline.

Structural characters: Head moderately short, declivant anteriorly, with weakly impressed median line; length 0.32, width 0.75; length of eye along inner margin 0.30, anterior/posterior interocular space, 0.20/0.40. Pronotum short, length along midline 0.47, less than dorsal length of head, leaving mesonotum broadly exposed, width 0.85; mesonotum smooth, lacking deep foveae, humeri depressed, length along midline 0.40. Metanotum barely exposed, length along midline 0.12. Lengths of abdominal tergites I–VIII, respectively: 0.15: 0.25: 0.20: 0.20: 0.20: 0.20: 0.40: 0.30. Connexiva with margins of even width throughout, very weakly bowed outward, convergent posteriorly, posterolateral angles not modified, separated by entire width of tergite VIII, lacking prominent setal tufts.

Entire dorsum and laterotergites bearing numerous long, erect black setae; legs and antennae thickly clothed with short appressed pale setae, with scattered long, erect, bristly black setae on anterodorsal faces of antennal segments I and II, and anterior margins of all femora, plus long pilose brown setae along posterior margins of all femora, these setae particularly long and thick on posterior margin of hind femur, with lengths equal to the width of the incrassate femur; all trochanters lacking pegs or teeth; fore and middle femora and middle tibia with margins straight, not flattened or otherwise modified; fore tibia slightly flattened ventrally on distal one-fourth, with small concavity adjacent to grasping comb; hind femur highly incrassate, a single row of teeth, ventral row lying in area covered by infolded hind tibia and consisting of a moderate sized, dark tipped spine basally followed by approximately 12 small black pegs running from base of femur to apex, dorsal row commencing near middle of femur and consisting of 8 small black pegs; hind tibia broadly and gently sinuate, inner surface bearing a row of about 17 small dark teeth, plus one large, acute, black spine approximately two-thirds two-thirds distance from base ( Figs. 183, 184 ).

Venter of head and thorax lacking small black denticles; mesosternum slightly depressed centrally, margins of this depression bearing long, fine gold setae; metasternum slightly tumid; abdominal venter set with short appressed gold setae intermixed with scattered long, fine, erect pale setae laterally; 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, this carina continuing in less pronounced form onto ventrites III and IV; ventrites V and VI unmodified, ventrite VII slightly flattened centrally, ventrite VIII unmodified.

Male paramere bilobate, slightly constricted centrally, basal section with ventral margin rounded, bearing numerous stout setae, distal section angled upward at ~45°, dorsal margin straight, ventral margin forming nearly a right angle, posterior margin broadly curving, apex blunt ( Fig. 185 ). Male proctiger with basolateral lobes moderately developed, rounded; distolateral lobes small, sharply angular; distal cone dome-like, apex coming to small angle ( Fig. 186 ).

Lengths of antennal segments I–IV: 0.80: 0.40: 0.55: 0.55.

Lengths of leg segments as follows: femur, tibia, tarsal 1, tarsal 2, tarsal 3 of fore leg, 1.00: 1.00: 0.02: 0.02: 0.22; of middle leg, 1.60: 1.15: 0.05: 0.45: 0.70; of hind leg, 1.40: 1.55: 0.05: 0.10: 0.35.

Wingless female: Similar to wingless male in general structure and coloration, with following exceptions: mesonotum bright orange-brown; metanotum and abdominal tergites I–V dark brown, thinly overlain with silvery pruinosity, bearing long, erect, dark setae on lateral portions of metanotum and posterior margin of abdominal tergite II; connexival margins strongly convergent posteriorly, margins meeting over posterior section of abdominal tergite V and completely covering abdominal tergite VI and all but narrow posterior medial portion of abdominal tergite VII, posterolateral angles slightly divergent when viewed from above, apices rounded when viewed laterally and bearing very small tufts of short black setae, connexival margins of even thickness throughout, lacking thickened or glabrous areas; posterolateral margins of abdominal segment VII bearing tufts of stiff, black, posteriorly-directed setae ( Fig. 182 ); abdominal tergite VIII and proctiger angled downward at 45° angle; hind femora only weakly incrassate, bearing a single row of teeth consisting of a small basal peg, then a large sharp spine near midpoint, followed by 7 smaller teeth of progressively decreasing size distally; hind tibiae straight, inner surface with about 16 small black pegs; ventral coloration predominantly orange-brown, with mesosternum, metasternum and abdominal ventrite I dark brown; all abdominal ventrites lying in similar horizontal plane.

Winged male: Unknown.

Winged female: Unknown.

Etymology. The name “tekadu ” is a noun in apposition, and refers to the type-locality near the village of Tekadu, in Papua New Guinea.

Distribution. Southeastern New Guinea; currently known only from the Lakekamu River basin ( Fig. 201 ). The species range as presently understood occupies the Papuan Gulf Foreland area of freshwater endemism (Area 25) as delineated by D. Polhemus & Allen (2007).

Discussion. Rhagovelia tekadu is a somewhat aberrant member of the R. novacaledonica group, with a relatively narrow pronotum, and numerous long, erect setae on the dorsum, lateral abdomen, and posterior margin of the highly incrassate male hind femur. It is similar in many respects to R. udabe and R. goilala , species which occur at higher elevations in the Owen Stanley Range, but is smaller in overall form, with body lengths ranging from 3.2–4.0 mm, versus 4.1–4.8 mm in the other two species; has the female abdominal connexiva folded inward over abdominal tergites V–VIII ( Fig. 182 ), versus widely separated in the other two species ( Figs. 71 , 78 ); and the anterior lobe of the pronotum slightly constricted in both sexes, and nearly parallel-sided in wingless females ( Figs. 181, 182 ), rather than broadly expanded and with anteriorly convergent margins. The coloration is also distinctive in the field, with the bright yellowish-brown markings on the anterior pronotum, basal legs, and connexiva strongly contrasting with the overall reddish-brown to blackish ground color.

Ecological notes. This species prefers shaded, first-order headwater streamlets, and is found almost exclusively in such habitats. The type locality was a small, swift, rocky tributary to the Sapoi (Aviavi) River, flowing through a bed of rocks and cobbles in a catchment shaded by primary premontane rain forest. The insects were found near the stream margins, next to vertical banks or fallen logs. Another series was taken from a small headwater streamlet at Tekadu, 150 m. higher in elevation within the same Sapoi River catchment ( Fig. 187 ). At the latter locality, the insects skated on pools along a small, shaded channel draining hill slopes covered with lightly disturbed premontane rain forest. The specimens from lower elevation along the Sapoi River (CL 7148) have a darker, blackish ground color compared to the specimens taken higher up at Tekadu (CL 7157), which are more orange-brown.

Figures

FIGS. 181–186. Rhagovelia tekadu n. sp., structural details; specimens from New Guinea, Lakekamu River basin, Papua New Guinea. 181. Wingless male, dorsal habitus; specimen from Sapoi River tributary, CL 7148. 182. Wingless female, dorsal habitus. 183. Male right hind leg, posterior view. 184. Male right hind leg, dorsal view. 185. Male left paramere, outer lateral view. 186. Male proctiger, dorsal view; 182–186 from streamlets at Tekadu, CL 7157a.

FIG. 187. A small headwater tributary to the Yaniwe River near Tekadu, Morobe Prov., southern Papua New Guinea, CL 7157a, type-locality for R. tekadu n. sp. and habitat for R. ivimkana n. sp.

FIG. 201. Distributions in eastern New Guinea of species held as Incertae Sedis within the R. novacaledonica group in regard to subgroup assignments.

FIGS. 70–75. Rhagovelia udabe n. sp., structural details; specimens from New Guinea, Woitape, CL 7252. 70. Wingless male, dorsal habitus. 71. Wingless female, dorsal habitus. 72. Male right hind leg, posterior view. 73. Male right hind leg, dorsal view. 74. Male left paramere, outer lateral view. 75. Male proctiger, dorsal view.

FIGS. 77–82. Rhagovelia goilala n. sp., structural details; specimens from New Guinea, Fane, CL 7256. 77. Wingless male, dorsal habitus. 78. Wingless female, dorsal habitus. 79. Male right hind leg, posterior view. 80. Male right hind leg, dorsal view. 81. Male left paramere, outer lateral view. 82. Male proctiger, dorsal view.