Rhagovelia caesius Lansbury, 1993

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 : 193-195

Rhagovelia caesius Lansbury

( Figs.152 , 316–320 , 330 )

Rhagovelia caesius, Lansbury, 1993: 50 . Type-locality: Popondetta, Sambogo River, Northern Prov., Papua New Guinea.

Material examined. PAPUA NEW GUINEA, Morobe Prov., New Guinea: 1 winged female, 52 wingless males, 37 wingless females, tributary to lower Aleater [=Alewiri] River, W. of Sachsen Bay , 5 m., 7°19'14.7"S, 147°07'34.9"E, water temp. 27 °C., 3 May 2003, 13:00–15:00 hrs., CL 7241, D. A. Polhemus ( USNM, BPBM). Northern (Oro) Prov.: 1 winged male, 1 winged female, 17 immatures, Boikiki , 26 July 1985, J. Ismay ( BPBM) .

Redescription

Wingless male: Size— Length = 2.20–2.45 mm (x = 2.37, n = 5); width = 1.05–1.10 mm (x = 1.09, n = 5). Wingless female, length = 3.20–3.40 mm (x = 3.30, n = 5); width = 1.50–1.70 mm, (x = 1.60, n = 5). Winged male, length = 3.40 mm (n = 1); width = 1.60 mm (n = 1). Winged female, length = 4.20 mm (n = 1); width = 1.90 mm (n = 1).

Color: Dorsal ground colour dark pruinose grey, marked with dull yellow on basal antennae, pronotum slightly paler grey with dark orange patch anteromedially ( Fig. 316 ); legs predominantly shining black, with basal segments dark brown. Head dark pruinose grey; tylus, juga, rostrum and antennal sockets dark brown; eyes dark red; frons and vertex set with scattered long erect black setae. Pronotum pruinose grey, with small, transversely ovate, dark orange spot anteromedially behind head vertex, this orange coloration not extending onto the propleura; surface bearing scattered long, erect black setae. Mesonotum, metanotum, and all abdominal tergites and connexiva dark pruinose grey, surfaces bearing scattered long, erect black setae, lacking shining, glabrous areas.Antennal segment I with basal one-third dark yellow, distal third plus all of segments II–IV black. Legs predominantly black, except all trochanters and coxae dark brown. Venter pruinose grey, middle and hind acetabula shining dark brown on ventral margins, abdominal ventrites VII–IX shining black.

Structural characters: Head moderately short, declivant anteriorly, with weakly impressed median line; head length 0.30, width 0.75; length of eye along inner margin 0.25, anterior/posterior interocular space, 0.25/0.40. Pronotum length along midline less than dorsal length of head, leaving mesonotum broadly exposed, length 0.20, width 0.90; mesonotum lacking foveae, length along midline 0.70; metanotum length along midline 0.05. Lengths of abdominal tergites I–VIII, respectively: 0.10: 0.10: 0.10: 0.10: 0.10: 0.15: 0.25: 0.15. Connexiva with margins of even width throughout, margins bowed outward, posterolateral angles not modified, separated by entire width of tergite VIII, posterolateral angles lacking setal tufts.

Entire dorsum and laterotergites covered with very short, fine, appressed pale pubescence, interspersed with numerous longer, 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; fore trochanter with a dense tuft of short black setae ventrally at apex; middle and hind trochanters lacking setal tufts, pegs or teeth; fore femur with ventral surface slightly flattened, bearing a single very long, slender black seta basally, and thick fringe of short, erect, pale setae along entire length; fore tibia bowed, dorsal face bearing long, erect, dark setae, lengths of these setae exceeding thickness of tibia, ventral face bearing very short erect pale setae, grasping comb short, length 1/7 that of entire femur; middle femur slender and unmodified, with posterior margin bearing 8–10 erect, bristly black setae; middle tibia straight, cylindrical; hind femur very weakly incrassate, lacking spines; hind tibia straight, unmodified, bearing scattered long, bristly black setae, these setae becoming more numerous and closely spaced on distal section of anterior margin ( Fig. 318 ).

Venter lacking minute black denticles on ventral head or thorax; mesosternum weakly depressed centrally, bearing V-shaped line of erect gold setae with apex directed anterad; metasternum not tumescent; abdominal ventrites I–VII horizontal, not carinate or otherwise sculptured; ventrites VIII–X strongly narrowed.

Paramere small, stout, weakly crescent-shaped, posteroventral margin bearing a few short setae, apex truncate ( Fig. 319 ). Proctiger small, compact, lacking development of basolateral or distolateral lobes; distal cone broadly rounded ( Fig. 320 ).

Lengths of antennal segments I–IV: 0.75: 0.40: 0.35: 0.40.

Lengths of leg segments as follows: femur, tibia, tarsal 1, tarsal 2, tarsal 3 of fore leg, 0.90: 0.90: 0.01: 0.02: 0.15; of middle leg, 1.35: 1.10: 0.07: 0.60: 0.65; of hind leg, 1.00: 1.35: 0.05: 0.05: 0.25.

Wingless female: Similar to wingless male in general structure and coloration, with following exceptions: overall body size much larger; dorsum lacking long, erect, black setae except at lateral margins of pronotum; mesonotum broadly tumescent and domed, posteriorly bilobate, posterior margin truncate, slightly anteriorly concave centrally; metanotum and abdominal tergite I with a pair (1+1) of weakly developed depressions to either side of slightly tumescent longitudinal midline ( Fig. 317 ); abdominal tergites very broad in relation to lengths; proctiger shining black dorsally; connexiva broadly bowed outward ( Fig. 317 ); all trochanters lacking setal tufts or spines; abdominal ventrite VII with a broad glabrous dark brown patch centrally; gonocoxae vertical, commissure not carinate; proctiger angled downward at 45° when viewed laterally.

Legs longer than in male, proportions as follows: femur, tibia, tarsal 1, tarsal 2, tarsal 3 of fore leg, 1.15: 1.20: 0.01: 0.02: 0.30; of middle leg, 1.75: 1.30: 0.10: 0.70: 0.95; of hind leg, 1.25: 1.75: 0.05: 0.20: 0.35.

Winged male: Similar to wingless male in general structure and coloration, with following exceptions: pronotum greatly enlarged, width 1.60, length 1.50, completely covering meso- and metanotum, humeri enlarged, anterior lobe dark gray faintly overlain with silvery pruinosity; posterior pronotal lobe broadly domed, lacking obvious foveae, posterior margin broadly angular, bearing scattered long, semi-erect black setae; forewings including veins uniformly dark brown, extending far past apex of abdomen when intact, bearing 4 closed cells, consisting of two elongate cells in basal half of the wing followed by two much smaller distal cells of roughly equal size, all in basal half of wing.

Winged female: Similar to winged male in general structure and coloration, with following exceptions: overall size larger, pronotum width 1.90, length 1.70.

Distribution. This species was previously recorded from Popondetta, Kokoda, Buso, and the Lae-Bulolo road ( Lansbury 1993), although it is possible that the latter series may represent a different species. The new records from the foothills of the Bowutu Mountains at Kamiali are not far from Buso ( Fig. 330 ), and the specimens from there match Lansbury’s figures well. The species range as presently known occupies the Morobe Highands area of freshwater endemism (Area 22) as delineated by D. Polhemus & Allen (2007).

Discussion. Rhagovelia caesius is superficially similar to R. grisea , which occurs further east near the tip of the Papuan Peninsula, but can be distinguished from that species by posteriorly bilobate female mesothorax with an anteriorly concave posterior margin ( Fig. 317 ); the uniformly dark male coxae and trochanters, in contrast to the yellowish-brown fore and hind coxae and trochanters in R. grisea ; the male hind tibia with a group of closely spaced bristly black setae on distal section of the anterior margin ( Fig. 318 ); and the longer female hind tibia, with the hind femur/tibia ratio being 1.00/ 1.35 in R. caesius , versus 1.00/ 1.09 in R. grisea . In the few winged females at hand both the inner and outer distal cells of the forewing are developed, though quite small, whereas in the one winged male only the outer cell is present.

Ecological notes. Rhagovelia caesius was common along the terminal reach of the Aleater River near Kamiali village ( Fig. 152 ), where it co-occurred with R. hirsuta . For a description of this locality see the notes under the latter species.

Figures

FIG. 152. Lower Aleater River, near Kamiali, Morobe Province, Papua New Guinea, CL 7241, habitat for R. caesius Lansbury and R. hirsuta Lansbury.

FIGS. 316–320. Rhagovelia caesius Lansbury, structural details; specimens from New Guinea, Aleater River, CL 7241. 316. Wingless male, dorsal habitus. 317. Wingless female, dorsal habitus. 318. Male right hind leg, dorsal view. 319. Male left paramere, outer lateral view. 320. Male proctiger, dorsal view.

FIG. 330. Distributions of species in the R. grisea subgroup on eastern New Guinea and adjacent islands.