Rhagovelia guiagoila, 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 : 167-170

Rhagovelia guiagoila new species

( Figs. 204 , 213 , 217 , 274–280 , 295 )

Type material examined. Holotype, wingless male: PAPUA NEW GUINEA, Milne Bay Prov., Basilaki Island, Guiagoila River and trib. with waterfall, 0–15 m., 10°36'08"S, 150°59'39"E, water temp. 26.5° C., 18 January 2004, 09:00–13:30 hrs., CL 7296, D. A. & J. T. Polhemus ( BPBM) . Paratypes: PAPUA NEW GUINEA, Milne Bay Prov.: 1 winged female, 29 wingless males, 25 wingless females, Basilaki Island , same data as holotype, CL 7296, D. A. & J. T. Polhemus ( USNM) ; 9 wingless males, 7 wingless females Basilaki Island, 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 ( USNM) ; 1 winged female, 39 wingless males, 41 wingless females, Basilaki Island , same data as preceding except on small rocky tributary, CL 7294b, D. A. & J. T. Polhemus ( USNM) ; 1 winged female, 21 wingless males, 3 wingless females, Basilaki Island , same data as preceding except on small tributary, CL 7294c, D. A. & J. T. Polhemus ( USNM) ; 1 winged female, 35 wingless males, 26 wingless females, Sideia Is., hill streamlet in south central interior, headwater trib. to Kwabunamoa River , on pools, 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) ; 2 winged females, 37 wingless males, 32 wingless females, Sideia Is., Kwabunamoa River , terminal reach, sea level, 10°35'04"S, 150°50'51"E, water temp. 27° C., 16 January 2004, 11:00–13:00 hrs., CL 7292, D. A. & J. T. Polhemus ( USNM) ; 49 wingless males, 39 wingless females, Sariba Is., Padi Stream , below falls, 0– 105 m., 10°35'37"S, 150°42'02"E, water temp. 26.5–28.5° C., pH 7.7–8.0, 14 January 2004, 09:45–14:00 hrs., CL 7285, D. A. Polhemus ( USNM, BPBM) .

Description

Wingless male: Size: Length = 3.20–3.50 mm (x = 3.30, n = 5); width = 1.00– 1.10 mm (x = 1.03, n = 5). Wingless female, length = 3.20–3.50 mm (x = 3.38, n = 5); width = 1.10–1.20 mm, (x = 1.16, n = 5). Winged female, length = 3.60 mm (n = 1); width = 1.35 mm (n = 1).

Color: Dorsal ground color black, marked with pale orange on anterior pronotum and connexiva, pale yellow on basal antennae and legs ( Fig. 274 ). Head black; rostrum pale yellowish-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 onto propleurae. Mesonotum, metanotum and abdominal tergites I–VI, VIII and IX black, tergite VII brown, all tergites uniformly dull and lacking shining areas, connexiva black on inner halves, dark orange on outer halves. Antennal segment I with basal one-third pale yellow, distal two-thirds plus all of segments II–IV black. Legs generally black, with coxae, trochanters, basal half of fore femur, basal third of hind femur ventrally pale yellow. Venter black, with abdominal ventrites VII–X dark orange.

Structural characters: Head moderately short, declivant anteriorly, with weakly impressed median line; length 0.30, width 0.80; length of eye along inner margin 0.35, anterior/posterior interocular space, 0.15/0.40. Pronotum long, width 1.10, length along midline 0.80, greater than dorsal length of head, leaving mesonotum barely exposed; mesonotum exposed only as a small crescent posterior to pronotum, lacking foveae; metanotum moderately exposed, length at midline 0.15. Lengths of abdominal tergites I–VIII, respectively: 0.20: 0.20: 0.20: 0.20: 0.25: 0.25: 0.40: 0.30. 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 long, erect brown 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, posterior margins of fore and middle femora; scattered long pilose brown setae present along posterior margin of hind femur; 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 3–4 small dark pegs ventrally; hind femur highly incrassate, bearing two parallel rows of teeth, ventral row lying in area covered by infolded hind tibia and consisting of approximately 15 tiny black pegs basally, followed by 6 subequal sized black teeth; dorsal row of teeth commencing near middle of femur with a large, acute orange-brown tooth with a black apex, followed by two smaller black teeth of subequal size, then another large orange tooth with a black apex, then 4–5 small black teeth of progressively decreasing size; hind tibia broadly and gently sinuate, inner surface bearing 2 parallel rows of 10–12 small dark teeth plus 3–4 larger black teeth near tip ( Figs. 276, 277 ).

Venter of head and thorax with jugum, adjacent inner propleural area bordering eye, lateral portions of meso- and metasterna, pro- and metacetabula, abdominal ventrites II and III bearing small black denticles, such denticles occasionally present in small numbers on mesoacetabulum, but absent on metapleura ( Fig. 213 ); meso- and metasterna slightly depressed centrally, margins of this depression and adjacent lateral metasternum bearing long, fine gold setae; abdominal venter set with short appressed gold setae intermixed laterally with long, fine, erect dark brown 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, this carina continuing in less pronounced form onto ventrite III, ventrites IV–VI unmodified, ventrite VII broadly and shallowly depressed laterally to either side of weakly carinate midline.

Male paramere small, bean-shaped, distal section upturned, with ventral margin bearing stout setae, dorsal apex with a small indentation ( Fig. 278 ). Male proctiger with basolateral lobes well developed, angular; distolateral lobes large, broadly rounded; distal cone blunt, with apex forming obtuse angle ( Fig. 278 ).

Lengths of antennal segments I–IV: 075: 0.45: 0.55: 0.50.

Lengths of leg segments as follows: femur, tibia, tarsal 1, tarsal 2 of fore leg, 0.90: 1:00: 0.03: 0.02: 0.20; of middle leg, 1.55: 1.10: 0.07: 0.35: 0.70; of hind leg, 1.50: 1.30: 0.05: 0.10: 0.25.

Wingless female: Similar to wingless male in general structure and coloration, with following exceptions: abdominal tergites V–VII brown and shining centrally; connexival margins strongly convergent posteriorly adjacent to abdominal tergites I–IV, then nearly parallel with only slight posterior convergence adjacent to tergites V–IX, margins slightly infolded so as to cover extreme lateral sections of tergites V–IX ( Fig. 275 ), connexival margins adjacent to tergites III and IV narrowed and glabrous, shining gold in colour ( Fig. 217 ); posterolateral connexival angles forming right angles, bearing dense, acuminate tufts of moderately long black setae; abdominal tergite VIII and proctiger deflected downward 45° from vertical, bearing dense, bushy tufts of black setae laterally; hind femur only weakly incrassate, posterior margin bearing a large brown tooth with a black tip at about two-thirds distance from the base, followed by 5 smaller black teeth, the large basal tooth in this series sometimes preceded by a small black tooth immediately basal to it near middle of posterior margin; hind tibia straight, inner surface lacking teeth or pegs; ventral coloration predominantly yellowish brown, with meso- and metasternum plus abdominal ventrites I–III dark brown to varying degrees; all abdominal ventrites lying in similar horizontal plane, ventrites I–III with patches of short, dense gold setae in a narrow band along longitudinal midline, ventrites IV and V depressed basomedially ( Fig. 204 ).

Winged female: Similar to wingless female in general structure and coloration, with following exceptions: pronotum greatly enlarged, width 1.35, length 1.25, completely covering meso- and metanotum, anterior lobe orange-brown, divided by narrow dark brown stripe along longitudinal midline; humeri enlarged, slightly protrusive laterally; posterior pronotal lobe dark brown, broadly domed, posterior half with obscure dark 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 two smaller cells of subequal size distally near center of wing.

Winged male: Unknown.

Etymology. The name “guiagoila ” is a noun in apposition and refers to the name of the river at the type locality. In the local language of Basilaki Island, this name means “the river that flows from the forest that it is forbidden to enter.”

Distribution. This species occurs on Sariba, Sideia, and Basilaki islands, lying east of China Strait ( Fig. 295 ). The species range as presently known includes the Basilaki Island area of freshwater endemism (Area 36) as delineated by D. Polhemus & Allen (2007), who noted that adjacent Sideia Island might also prove to be part of this area of endemism, a hypothesis supported by the distribution of R. guiagoila .

Discussion. The characters separating this species from others in the R. loriae subgroup are provided in the key, and further discussed under R. loriae . The female connexiva in R. guiagoila are parallel and of even width throughout, without prominent concavities centrally ( Fig. 275 ), although the outer faces of the connexival segments adjacent to abdominal tergitres III and IV are smooth and glabrous, in the area where the hind femur folds in and touches the abdomen when held vertically at rest ( Fig. 217 ). The posterolateral angles of the female connexiva also lack long setal tufts when viewed laterally. The female ventral abdomen possesses posteromedial golden setal patches on abdominal ventrites II and III and incipiently on ventrite IV; has abdominal ventrite IV with a shallow, glabrous transverse sulcus anteromedially; and ventrite V flattened centrally but not depressed or sulcate ( Fig. 204 ).

The measurements in the description are taken from specimens collected at the Guiagoila River type-locality on Basilaki Island, which are similar in size to those from neighboring Sideia Island. By contrast, specimens from Sariba Island are slightly smaller in size.

Ecological notes. The Guiagoila River at the type-locality (CL 7296) was a moderately swift stream draining from the hills of Basilaki Island through a heavily shaded bed of water-rounded rocks and gravels, with alternating riffle and pool habitat. Samples were made from the head of the estuary upstream to the confluence with a south bank tributary, and then further upstream along this tributary to a waterfall and plunge pool. Rhagovelia guiagoila was common throughout this stream reach, skating on gently flowing pools.

At the Kalawai River, also on Basilaki, R. guiagoila was again taken along a rocky stream with alternating riffle and pool habitat, partially shaded by relatively intact upland rain forest ( Fig. 280 ).

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. 274–279. Rhagovelia guiagoila n. sp., structural details; specimens from the China Strait islands. 274. Wingless male, dorsal habitus. 275. Wingless female, dorsal habitus; 274 and 275 from Sideia Is., Kwabunamoa River, CL 7287. 276. Male right hind leg, posterior view. 277. Male right hind leg, dorsal view; 278. Male left paramere, outer lateral view. 279. Male proctiger, dorsal view; 276–279 from Basilaki Is., Kalawai River, CL 7294.

FIG. 280. Kalawai River, Basilaki Is., Milne Bay Prov., Papua New Guinea, CL 7294, habitat for R. guiagoila n. sp.

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