Rhagovelia ivimkana, 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 : 157-160

Rhagovelia ivimkana new species

( Figs. 180 , 187 , 260‒265 , 266 )

Type material examined. Holotype, wingless male: PAPUA NEW GUINEA, Gulf Prov., New Guinea, Ivimka Creek along Kakoro Track , SE of Ivimka Research Station, 30 m., 07°44'20"S, 146°30'06"E, water temp. 25° C., 17 January 2001, 07:30–13:00 hrs., CL 7149, D. A. Polhemus ( USNM) . Paratypes: PAPUA NEW GUINEA, Gulf Prov., New Guinea: 1 winged male, 24 wingless males, 18 wingless females, CL 7149, D. A. Polhemus ( USNM, BPBM) ; 3 winged males, 31 wingless males, 15 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 rocky trib., CL 7148c, D. A. Polhemus ( USNM) ; 1 wingless female, same data as preceding but from very small rocky hill streamlet entering rocky tributary, CL 7148d, D. A. Polhemus ( USNM) ; 6 wingless males, 5 wingless females stream crossing old Bulldog Track , 1.6 km. SW of Ivimka Research Station, 30 m., 07°44'45"S, 146°29'24"E, water temp. 25° C., 18 January 2001, 08:30–09:30 hrs., CL 7152, D. A. Polhemus ( BPBM, USNM) ; 1 wingless male, 1 wingless female, small rocky tributary to Wampupayo River at old Bulldog Track , 1.75 km. NE of Ivimka Research Station, 70– 100 m., 07°43'06"S, 146°30'09"E, water temp. 24° C., 19 January 2001, 08:30–13:00 hrs., on secondary tributary with mossy rocks and cascades, CL 7153b, D. A. Polhemus ( USNM, BPBM) ; 40 wingless males, 28 wingless females sandy stream crossing Transect 1 trail, 1.25 km. SW of Ivimka Research Station, 30 m., 07°44'37"S, 146°29'36"E, water temp. 25° C., 20 January 2001, 09:00–11:30 hrs., CL 7154, D. A. Polhemus ( USNM, BPBM) . Central Prov.: 2 winged males, 13 wingless males, 12 wingless females, 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 ( USNM, BPBM) .

Description

Wingless male: Size: Length = 2.80–3.00 mm (x = 2.94, n = 5); width = 1.00– 1.10 mm (x = 1.05, n = 5). Wingless female, length = 3.10–3.40 mm (x = 3.24, n = 5); width = 1.20–1.30 mm, (x = 1.28, n = 5). Winged male, length = 3.20–3.30 mm (x = 3.25, n = 2); width = 1.30 mm (x = 1.30, n = 2).

Color: Dorsal ground color dark brown to black, marked with yellow or yellowish-orange on anterior pronotum, connexiva, basal antennae and legs ( Fig. 260 ). Head black; rostrum and gula dark whitish-yellow, rostrum piceous distally; eyes silver with red undertones. 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 black, tergites VII–IX dark brown, tergites I–VI uniformly dull and lacking glabrous areas, tergites VII and VIII broadly shining; connexiva black on inner halves, dark orange on outer halves, ventral faces also dark orange. Antennal segment I with basal one-third pale whitish-yellow, distal two-thirds plus all of segments II–IV dark brown. Legs generally black dorsally, dark brown ventrally, with coxae, fore and hind trochanters, basal half of fore femur dorsally and ventrally, and extreme base of hind femur ventrally dark yellow. Venter generally black, acetabula dark yellow, abdominal ventrite VII dark brown, abdominal ventrites VIII and IX orange-brown.

Structural characters: Head moderately short, declivant anteriorly, with weakly impressed median line; head length 0.30, width 0.70; length of eye along inner margin 0.30, anterior/posterior interocular space, 0.15/0.35. Pronotum long, length along midline greater than dorsal length of head, entirely covering mesonotum, length 0.60, greater than dorsal length of head, leaving mesonotum exposed only as a small crescent posterior to pronotum, lacking foveae, width 0.95. Mesonotum length at midline 0.10. Metanotum moderately exposed, length at midline 0.10. Lengths of abdominal tergites I–VIII, respectively: 0.15: 0.15: 0.15: 0.15: 0.15: 0.18: 0.35: 0.25. Connexiva of even width throughout, with margins nearly straight except very slightly bowed inward adjacent to abdominal tergites I–III, 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 on dorsal head, propleurae, connexiva and abdominal tergites I–VII with scattered longer, semi-erect, dark setae; legs and antennae thickly clothed with short appressed gold setae, with scattered long, erect, spine-like black setae on anterodorsal faces of antennal segments I and II, anterior margins of all femora, anterior margin of hind tibia; scattered long, straight, slender, evenly spaced brown setae present along posterior margins of all femora; anterior margin of fore tibia with slender erect black setae plus a fringe of shorter, semi-recumbent gold setae, posterior margin of fore femur with fringe of moderately long, semi-recumbent brown setae on anterior two thirds; fore and middle trochanters lacking pegs or teeth; fore and middle femora and middle tibia with margins straight, not flattened or otherwise modified; fore tibia very slightly expanded and ventrally flattened on distal one-fourth, slightly ventrally concave adjacent to grasping comb; hind trochanter bearing 5 small dark pegs ventrally; hind femur moderately incrassate, bearing teeth ventrally in area covered by infolded hind tibia, these teeth arranged in a single longitudinal row on basal half of femur, splitting into two parallel rows on distal half, the single basal row consisting of approximately 10 tiny black pegs of slightly increasing size progressing distally, the dorsal row distally consisting of a large, acuminate black spine followed by 7–8 smaller spines of progressively decreasing size; the ventral tooth row distally consisting of 6–8 small subequal black teeth; hind tibia straight, inner surface bearing an irregular longitudinal row of 14 small dark teeth plus a single larger black spur near apex ( Figs. 262, 263 ).

Venter of head and thorax bearing numerous small black denticles, these denticles extending upward along propleuron in narrow band immediately behind eye; mesosternum slightly depressed centrally, margins of this depression bearing long, fine gold setae; metasternum bearing a pair (1+1) of broad depressions to either side of slightly raised longitudinal midline, lateral margins and incipient midline carina bearing erect, pale setae; abdominal venter set with moderately long, recumbent, silvery setae intermixed along longitudinal midline with very fine, semi-erect pale 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 ventrites III–V, ventrite VI unmodified, ventrite VII bearing a pair (1+1) of broad, shallow depressions to either side of longitudinal midline, lateral margins of these depressions bordered with brushes of stiff, brown, posteriorly-directed setae, ventrite IX slightly constricted basally.

Male paramere moderately short, roughly crescent-shaped, distal section angled upward at ~45°, bearing stout setae, with dorsal margin straight, ventral margin broadly curved, apex angular ( Fig. 264 ). Male proctiger with basolateral lobes weakly developed, broadly truncate; distolateral lobes prominent, apices slightly hooked posteriorly; distal cone dome-shaped, apex blunt ( Fig. 265 ).

Lengths of antennal segments I–IV: 0.65: 0.35: 0.45: 0.45.

Lengths of leg segments as follows: femur, tibia, tarsal 1, tarsal 2, tarsal 3 of fore leg, 0.70: 0.75: 0.02: 0.02: 0.25; of middle leg, 1.35: 1.05: 0.05: 0.40: 0.60; of hind leg, 1.10: 1.10: 0.02: 0.05: 0.20.

Wingless female: Similar to wingless male in general structure and coloration, with following exceptions: anterior margin of pale band on anterior pronotum bearing small black denticles behind eyes and vertex; mesonotum black; abdominal tergites V–VIII brown and shining centrally; connexival margins strongly curving and inwardly convergent posteriorly adjacent to abdominal tergites I–IV, then parallel and appressed over tergites V–VII, inner faces of connexiva adjacent to abdominal tergites I–IV bearing numerous black denticles, connexival margins adjacent to abdominal tergites IV and V expanded, forming ovate glabrous pads, remaining connexival margins unmodified and of uniform narrow thickness; posterolateral connexival angles slightly rounded when viewed laterally, bearing small, angular tufts of posteriorly-directed stiff black setae; abdominal tergite VIII flat, lying in horizontal orientation with posterior half projecting beyond apices of appressed connexiva, lateral margins bearing a pair (1+1) of tufts of stiff black setae, these tufts arcuate in shape when viewed from above ( Fig. 261 ); proctiger deflected downward approximately 45° from vertical, lacking lateral setal tufts; middle tibia blade-like, strongly flattened ventrally; hind femur only weakly incrassate, ventral margin concave on basal one-third, posterior margin near midpoint bearing a moderately long, acute gold spine with a black apex, followed by 5 smaller black teeth of steadily declining size toward femoral apex; hind tibia straight, inner surface lacking teeth or pegs; ventral coloration predominantly dark brown, abdominal ventrites VI and VII medium brown, ventrites VIII and IX yellowish brown; jugum, prosternum and all acetabula bearing numerous tiny black denticles; abdominal ventrites I–V swollen, arcuate ( Fig. 210 ), ventrites VI–VII smaller in comparison, of notably lesser width and curvature; all abdominal ventrites lacking raised setae tufts along longitudinal midlines.

Winged male: Similar to wingless male in general structure and coloration, with following exceptions: pronotum greatly enlarged, width 1.30, length 1.20, completely covering meso- and metanotum, anterior lobe orange-brown, lacking dark stripe along longitudinal midline, lateral sections faintly frosted with silvery pruinosity; 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 brown setae; forewings with basal cells whitish tan interiorly, veins dark, distal portion of wing including distal cells fumate 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 distally near center of wing, with outer distal cell slightly smaller than inner.

Winged female: Unknown.

Etymology. The name “ivimkana ” is based on a noun in apposition, and refers to the Ivimka Creek type-locality.

Distribution. Southeastern New Guinea; currently known only from the Lakekamu River basin ( Fig. 266 ). The species range as presently known occupies the Papuan Gulf Foreland area of freshwater endemism (Area 25) as delineated by D. Polhemus & Allen (2007).

Discussion. Females of R. ivimkana are easily distinguished by the form of the female abdominal connexiva, which are bowed outward on their anterior halves, but converge rapidly to meet over abdominal tergite V and are then closely appressed for the remainder of their lengths, completely covering abdominal tergites VI and VII, and the anterior half of tergite VIII ( Fig. 261 ). The protruding posterior half of tergite VIII bears long, sickle-shaped tufts of dark setae at its posterolateral angles ( Fig. 261 ). In addition, the connexival margins on the third and fourth segments, lying adjacent to abdominal tergites III–V, are flattened and glabrous. The female abdominal ventrites lack setal patches or depressions.

The male proctiger is also diagnostic, bearing posteriorly-hooked distolateral lobes ( Fig. 265 ) that are unique within currently described members of the R. papuensis group from New Guinea. Male abdominal ventrite VII has a pair (1+1) of shallow, longitudinally ovate depressions separated by a low, rounded carina along the longitudinal abdominal midline. Both sexes bear numerous black denticles on the prosternum and adjacent proacetabula, extending upward across the entire propleural region, as well as on the middle acetabula.

Specimens from lower elevations (30–150 m) have a dark blackish ground color ( Figs. 260, 261 ), in comparison to to specimens taken at higher elevations (300 m and above), which are noticeably more orange-brown in coloration.

Ecological notes. At the Ivimka Creek type-locality (CL 7149), lying at 30 m elevation ( Fig. 180 ), this species occurred in company with R. aviavi . By contrast, at Tekadu (CL 7157), lying at 300 m ( Fig 187 ), the species was taken syntopically with R. tekadu . At this latter locality many small, clear, spring-fed streamlets ran off a hillside into a garden area on the valley floor. Rhagovelia ivimkana was present here on small, flowing pools, but not in partricularly high abundance, and appeared to be near the upper elevational limit of its distribution.

Rhagovelia ivimkana may also occur along larger rivers, having been taken along the margins of the Sapoi River upstream of the Lakekamu research station. The river channel was braided in this reach, with samples being taken along the easternmost channel, where it entered a long, wide, and fairly shallow pool against the base of the valley wall. Individuals of R. ivimkana were taken from small eddies along the river margin in flowing sections.

Figures

FIG. 180. Ivimka Creek in the Lakekamu River basin of Gulf Province, southern Papua New Guinea, CL 7149, habitat for R. aviavi n. sp. and R. ivimkana n. sp.

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.

FIGS. 260–265. Rhagovelia ivimkana n. sp., structural details; specimens from New Guinea, Lakekamu River basin. 260. Wingless male, dorsal habitus; specimen from Sapoi River tributary, CL 7148. 261. Wingless female, dorsal habitus; specimen from Tekadu, CL 7157. 262. Male right hind leg, posterior view. 263. Male right hind leg, dorsal view; 262 and 263 from Sapoi River tributary, CL 7148. 264. Male left paramere, outer lateral view. 265. Male proctiger, dorsal view; 264 and 265 from Tekadu, CL 7157a.

FIG. 266. Distributions of species in the R. priori and R. transbintuni subgroups on eastern New Guinea and adjacent islands.

FIGS. 209–211. Rhagovelia papuensis group, female ventral abdomen showing locations of depressions and patterns of setiferation. 209. Rhagovelia suloga n. sp.; specimen from Woodlark Is., Suloga Peninsula, CL 7217. 210. Rhagovelia ivimkana n. sp.; specimen from New Guinea, Tekadu, CL 7157. 211. Rhagovelia dinga n. sp.; specimen from New Guinea, Kamiali, CL 7243.