Rhagovelia elongata, 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 : 175-179

Rhagovelia elongata new species

( Figs. 206 , 215 , 219 , 290–295 )

Type material examined. Holotype, wingless male: PAPUA NEW GUINEA, Milne Bay Prov., D’Entrecasteaux Islands, Goodenough Is., Matalamoia River, 3.4 km. NW of Bolubolu on road to Vivigani , 75 m., 9°21'54"S, 150°20'03"E, water temp. 24.5° C., 26 August 2002, 15:00–15:30 hrs., CL 7187, D. A. & J. T. Polhemus ( BPBM) . Paratypes: PAPUA NEW GUINEA, Milne Bay Prov., D'Entrecasteaux Islands, Goodenough Island : 5 winged males, 57 wingless males, 68 wingless females, same data as holotype, CL 7187, D. A. & J. T. Polhemus ( USNM) ; 36 wingless males, 37 wingless females, Kuliana Creek at Ewaoiana, near Kalauna village , 290 m., 9°22'54"S, 150°19'30"E, water temp. 24.5° C., 26 August 2002, 10:00–12:00 hrs., CL 7185, D. A. & J. T. Polhemus ( USNM, BPBM) ; 47 wingless males, 36 wingless females, 3 immatures, Waidala Creek, 3 km. W. of Bolubolu on road to Vivigani , 15 m., 9°22'05"S, 150°21'14"E, water temp. 25° C., 27 August 2002, 08:30–10:00 hrs., CL 7188, D. A. & J. T. Polhemus ( USNM, BPBM) ; 1 wingless male, Goodenough Island, Tuabeda River at Kalauna village , 335 m., 9°23'01"S, 150°19'32"E, water temp. 22.5° C., 26 August 2002, 10:00–12:00 hrs., CL 7184, D. A. & J. T. Polhemus ( BPBM) .

Description

Wingless male: Size: Length = 3.70–4.00 (x = 3.84, n = 5); width = 1.10–1.30 mm (x = 1.20, n = 5). Wingless female, length = 3.80–4.00 mm (x = 3.90, n = 5); width = 1.30–1.40 mm, (x = 1.37, n = 3). Winged male, length = 3.80–4.00 mm (x = 3.92, n = 4); width = 1.35–1.40 mm (x = 1.39, n = 4).

Color: Dorsal ground colour black, marked with pale orange on anterior pronotum and connexiva, pale yellow to orange on basal antennae and legs ( Fig. 290 ). Head black; tylus pale brown; jugae dark yellow; rostrum pale brown, piceous distally; eyes dark red. Pronotum yellowish-orange on anterior one-third, black on posterior two-thirds, the pale anterior coloration extending laterally and ventrally to become confluent with burnt orange area on propleurae. Mesonotum, metanotum and abdominal tergites I–VI, VIII and IX black, tergite VII dark orange-brown anteromedially, all tergites except tergite VII uniformly dull and lacking shining areas, tergite VII broadly shining centrally; connexiva black on inner halves, pale brown on outer halves. Antennal segment I with basal half dull pale yellow, distal half plus all of segments II–IV black. Legs generally black, with coxae, trochanters, basal half of fore femur, basal quarter of hind femur dorsally, majority of ventral fore and hind femur dull pale yellow. Venter mostly dark blackish-grey, except acetabula dull pale yellow, ventrites VIII and IX brown.

Structural characters: Head moderately short, declivant anteriorly, with weakly impressed median line; length 0.30, width 0.65; length of eye along inner margin 0.35, anterior/posterior interocular space, 0.20/0.40. Pronotum long, width 1.15, length along midline 0.85, much greater than dorsal length of head, leaving mesonotum barely exposed, posterior lobe lacking evident foveae; mesonotum exposed only as a small crescent posterior to pronotum, lacking foveae, length at midline 0.02; metanotum moderately exposed, length at midline 0.15. Lengths of abdominal tergites I–VIII, respectively: 0.20: 0.25: 0.25: 0.25: 0.25: 0.30: 0.45: 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 pale pubescence, intermixed with scattered longer, semi-recumbent setae, a few stout black setae present anterolaterally on pronotum; 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, posterior margins of fore and middle femora; fore tibia with a brush of semi-erect brown setae along posterior margin; hind femur with a few long, pilose, brown setae along posterior margin; fore and middle trochanters lacking pegs or teeth; fore and middle femora straight, with ventral faces slightly flattened; fore tibia slightly expanded, ventrally flattened and concave on distal one-fourth; middle tibia straight, cylindrical, not modified; hind trochanter bearing 6 small dark pegs ventrally; hind femur highly incrassate for most of its length but markedly constricted just before distal apex ( Fig. 292 ), bearing two parallel rows of teeth, dorsal row lying in area covered by infolded hind tibia and consisting of approximately 12 tiny black pegs basally, followed by 3 small teeth of steadily increasing size then a much larger tooth, then three much smaller teeth of subequal size, the another large tooth, then two more smaller teeth of progressively decreasing size toward apex, all these teeth orange-brown with black apices; ventral row of teeth commencing near middle of femur with two small teeth preceding a much larger, acute orange-brown tooth with a black apex, followed by 4 smaller black teeth of subequal size; hind tibia broadly and gently sinuate, inner surface bearing single row of teeth consisting of 10 small, dark, peg-like teeth on basal two-thirds, the 4 larger black teeth of gradually increasing size, followed by 5 teeth of steadily decreasing size approaching tibial apex ( Fig. 292 ).

Venter of head and thorax with jugum, adjacent inner propleural area bordering eye, lateral portions of meso- and metasterna, pro- and metacetabula bearing small black denticles, such denticles occasionally present in small numbers on mesoacetabulum, but absent on metapleura ( Fig. 215 ); mesosternum slightly depressed centrally, margins of this depression and central metasternum bearing long, fine, erect gold setae; abdominal venter set with short appressed gold setae, patches of longer, fine, erect gold setae present along longitudinal midline of abdominal ventrites II–V; 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–VI, ventrite VII with broad, shallow, roughly circular depressed area centrally, ventrite VIII longitudinally carinate medially, with a pair (1+1) of shallow, concave depressions to either side of this raised midline.

Male paramere small, bean-shaped, distal section upturned, bearing stout setae, apex rounded ( Fig. 293 ). Male proctiger with central section raised, basolateral lobes well developed, angular; distolateral lobes large, broadly rounded; distal cone broadly rounded, apex blunt ( Fig. 294 ).

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, 1.10: 1:25: 0.03: 0.02: 0.25; of middle leg, 1.90: 1.50: 0.08: 0.50: 0.75; of hind leg, 1.80: 1.45: 0.05: 0.10: 0.35.

Wingless female: Similar to wingless male in general structure and coloration, with following exceptions: abdominal tergites I–IV reddish brown centrally, tergites V–VIII orange-brown and shining; tergites III and VI slightly domed and tumescent centrally; connexival margins vertical, strongly convergent posteriorly adjacent to abdominal tergites I and II, then bowed strongly inward, thinned and glabrous adjacent to tergites III and IV ( Fig. 219 ), then bowed slightly outward and weakly convergent posteriorly adjacent to tergites V–VII, then nearly parallel with only slight posterior convergence adjacent to tergites VIII–IX; posterolateral connexival angles forming right angles, bearing dense tufts of moderately long black setae, these tufts posteriorly angular in lateral view; abdominal tergite VIII and proctiger deflected downward 45° from vertical, bearing small tufts of golden-brown setae laterally; hind femur only weakly incrassate, posterior margin bearing a single row of teeth on distal third, consisting of a large, slender, sharp tooth with a black apex, followed by 5 smaller black teeth of progressively decreasing size to tibial apex; hind tibia straight, inner surface lacking teeth or pegs; ventral coloration predominantly orange-brown, with meso- and metasternum plus abdominal ventrites I and II darker reddish brown; all abdominal ventrites lying in similar horizontal plane; metasternum and abdominal ventrites I–III medially tumescent, with patches of short, dense gold setae centrally ( Fig. 206 ), ventrites IV and V depressed basomedially; presence of black denticles as in male.

Winged male: Similar to wingless male in general structure and coloration, with following exceptions: pronotum greatly enlarged, width 1.40, length 1.45, completely covering meso- and metanotum, anterior lobe orange-brown, faintly divided by narrow reddish-brown stripe along longitudinal midline; humeri enlarged, slightly protrusive laterally; posterior pronotal lobe dark brown, broadly domed, posterior half with obscure dark fovae, posterior margin broadly angular, bearing scattered long, gently curving, semi-erect black setae; forewings uniformly dark blackish-brown, slightly paler basally, veins darker, wing apicies 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: Unknown.

Etymology. The name “elongata ” is derived from the Latin elongatus, meaning “prolonged,” and refers to the more elongate body shape of this species in comparison to others in the R. loriae subgroup.

Distribution. D’Entrecasteaux Islands; endemic to Goodenough Island ( Fig. 295 ). The species range as presently known falls within the D’Entrecasteaux Islands area of freshwater endemism (Area 35) as delineated by D. Polhemus & Allen (2007).

Discussion. Rhagovelia elongata is the member of the R. loriae subgroup endemic to Goodenough Island in the D’Entrecasteaux group. The characters separating it from other members of this subgroup are provided in the key, and detailed in the discussion under R. loriae .

This is the largest of the insular species in this subgroup, with a body length exceeding 3.8 mm in both males and females. Females are similar to those of R. basima from adjacent Fergusson and Normanby islands in having patches of posteriorly-directed golden setae posteromedially on abdominal ventrites II–IV, rather than on only ventrites II and III as in R. loriae and R. guiagoila (compare Fig. 206 to Figs. 203–205 ). However, the central depressions on ventrites IV and V are rather shallow and rounded, rather than deep and transverse as in R. basima (compare Figs. 205, 206 ). The female connexival margins adjacent to abdominal tergites III and IV are also thinner and more shining in R. elongata as compared to other members of the R. loriae subgroup (compare Fig. 219 to Figs. 216–218 ).

Males of R. elongata have the apex of the paramere blunt and rounded ( Fig. 293 ), and the proctiger shape is shorter and stouter than that seen in R. basima , with the basolateral lobes angular and of greater width than the distolateral lobes, and the length of the distal cone distinctly less than that of the distolateral lobes (compare Figs. 287 , 294 ).

Ecological notes. Rhagovelia elongata is common on Goodenough Island at elevations below 300 m, but is scarce on the swifter, colder streams above this elevation, where R. torrenticola predominates instead. The Matalamoia River at the type-locality (CL 7187) was a clear, shallow stream in an open, rocky bed, slightly impounded upstream of the Bolubolu to Vivigani road crossing. Rhagovelia elongata was present in very high densities here along the margins of this pooled section, sheltering from the midday sun beneath overhanging grasses, but rare elsewhere along the stream reach sampled.

The species was also abundant at Waidala Creek (CL 7188), a clear stream of moderate depth formed from the confluence of several intertwined creeks issuing from numerous spring outflows at the base of a set of low hills. The water depth here was 15–60 cm, flowing over a substrate of firm, dark sand with an overlying layer of small dark gravel. This was one of only three drainages with permanent water crossing the road between Bolubolu and Vivigani, and had by far the largest and most steady base flow; it was also the only one of these watercourses lined with a gallery forest. Brass (1956) refers to this as the Wufa Branch of Waidala Creek, and it was used as a water source by the Fourth Archbold Expedition for their Bolubolu camp in 1953. Most of the other clear, cold streams that drain from the high mountains of Goodenough Island vanish into alluvial beds upon reaching the savannahs of the lowlands, leaving only dry, flood-scoured channels. Continuous connection with the perennially flowing upland reaches is apparently established only during spates, which further serves to separate the lowland populations of R. elongata from the upland populations of R. torrenticola .

Figures

FIGS. 203–208. Rhagovelia papuensis group, female ventral abdomen showing locations of depressions and patterns of setiferation. 203. Rhagovelia loriae n. sp.; specimen from New Guinea, Dorobisoro, CL 7260. 204. Rhagovelia guiagoila n. sp.; specimen from Basilaki Is., Kalawai River, CL 7294. 205. Rhagovelia basima n. sp.; specimen from Fergusson Is., Yaya River, CL 7178. 206. Rhagovelia elongata n. sp.; specimen from Goodenough Is., Matalamoia River, CL 7187. 207. Rhagovelia bwagabwaga n. sp.; specimen from Misima Is., Keyana Creek, CL 7206. 208. Rhagovelia priori n. sp.; specimen from New Guinea, Kofure River, CL 7304.

FIGS. 212–215. Rhagovelia loriae subgroup, ventral thorax showing distribution and density of black denticles on the fore and middle acetabula. 212. Rhagovelia loriae n. sp.; specimen from New Guinea, Dorobisoro, CL 7260. 213. Rhagovelia guiagoila n. sp.; specimen from Basilaki Is., Kalawai River, CL 7294. 214. Rhagovelia basima n. sp.; specimen from Fergusson Is., Yaya River, CL 7178. 215. Rhagovelia elongata n. sp.; specimen from Goodenough Is., Kuliana Creek, CL 7185.

FIGS. 216–219. Rhagovelia loriae subgroup, female dorsal abdomen showing central portion of the connexival margin, with varying degrees of flexure and thinning. 216. Rhagovelia loriae n. sp.; specimen from New Guinea, Watuti River, CL 7175. 217. Rhagovelia guiagoila n. sp.; specimen from Sideia Is., Kwabunamoa River, CL 7287. 218. Rhagovelia basima n. sp.; specimen from Fergusson Is., Yaya River, CL 7178. 219. Rhagovelia elongata n. sp.; specimen from Goodenough Is., Matalamoia River, CL 7187.

FIGS. 290–294. Rhagovelia elongata n. sp., structural details; specimens from Goodenough Island. 290. Wingless male, dorsal habitus; specimen from Kuliana Creek, CL 7185. 291. Wingless female, dorsal habitus; specimen from Matalamoia River, CL 7187. 292. Male left hind leg, dorsal view; specimen from Kuliana Creek, CL 7185. 293. Male left paramere, outer lateral view. 294. Male proctiger, dorsal view; 293 and 294 from Matalamoia River, CL 7187.

FIG. 295. Distributions of species in the R. loriae subgroup on eastern New Guinea and adjacent islands.

FIGS. 285–288. Rhagovelia basima n. sp., structural details; specimens from the D’Entrecasteaux Islands. 285. Male right hind leg, posterior view. 286. Male right hind leg, dorsal view; 285 and 286 from Normanby Is., Dibuwa River tributary, CL 7230. 287. Male left paramere, outer lateral view. 288. Male proctiger, dorsal view; 287 and 288 from Fergusson Is., Yaya River, CL 7178.