Rhagovelia timikana, Polhemus, 2024

Polhemus, Dan A., 2024, Two anomalous new species of Rhagovelia (Heteroptera: Veliidae) from southern New Guinea, Zootaxa 5474 (5), pp. 489-502 : 495-501

Rhagovelia timikana n. sp.

( Figs. 8 , 10, 12–21 )

Type material examined. Holotype, wingless male: INDONESIA, Papua Prov., New Guinea, tributary to Iweka River, approx. 3 km. W. of Kuala Kencana, N. of Timika , 90 m., 4°24'05"S, 136°50'06"E, water temp. 25° C., water pH 6.95, 17 January 1997, 09:30–12:00 hrs., Timika survey station 2, CL 7042, D. A. Polhemus ( LIPI) . Paratypes: 2 wingless males, 11 wingless females, same data as holotype, CL 7042, D. A. Polhemus ( USNM ex JTPC, BPBM, LIPI). 3 wingless males, 8 wingless females, tributary to Iweka River , approx. 3 km. W. of Kuala Kencana, N. of Timika, side springs in forest, 90 m., 4°24'05"S, 136°50'06"E, water temp. 25° C., 26 March 1997, 09:30–12:00 hrs., Timika survey station 2, CL 7042c, D. A. Polhemus ( USNM, BPBM, LIPI) ; 3 wingless males, 2 wingless females, same locality and date as preceding except amber water tributary, CL 7042b, D. A. Polhemus ( USNM, BPBM) .

Description.

Wingless male:

Size: Length = 2.55–2.80 mm (x = 2.65, n = 5); width = 1.00– 1.10 mm (x = 1.05, n = 5).

Color: Wingless male: Dorsal ground black, with limited yellowish-orange markings on thorax and abdominal tergites ( Fig. 13 ); extreme antennal bases white; bases of legs pale brown. Head uniformly black dorsally; jugae and rostrum medium brown except rostrum fuscous ventromedially, piceous distally; eyes silvery-red. Pronotum black except for large, transversely rectangular yellowish-orange patch behind head vertex, this yellowish-orange coloration not extending onto the propleura, posterior pronotal margin black. Mesonotum black, with prominent yellowish-orange patch centrally, extending along longitudinal midline but not reaching posterior margin, this patch elongate triangular in shape, gradually tapering posteriorly. Metanotum and abdominal tergites I–VI black; tergites II–VII bearing broad, transverse shining patches when viewed in oblique light; tergite VII black, shining, with prominent, roughly circular yellowish-orange patch centrally; abdominal tergites VIII and IX (= proctiger) black; connexiva black on inner half, outer margins broadly shining when viewed in oblique light. Antennal segment I with basal one-third white, distal two-thirds plus all of segments II–IV dark brown. Legs generally dark brown to black, with fore coxae, hind coxae and trochanters, and basal third of fore femur dorsally pale whitish-brown. Venter predominantly matte black; proacetabula rusty orange-brown; mesosternum and adjacent mesopleural area pale yellow; abdominal ventrites VII and VIII orange-brown.

Structural characters: Wingless male: head moderately short, strongly declivant anteriorly when viewed laterally, with weakly impressed median line; length 0.30, width 0.70; length of eye along inner margin 0.35, eyes strongly convergent anteriorly ( Fig. 10 ), anterior/posterior interocular space, 0.10/0.35. Antennae with lengths of segments I: II: III: IV; 0.60: 0.30: 0.45: 0.45. Pronotum short, length along midline 0.15, less than dorsal length of head, leaving mesonotum broadly exposed, width 0.80; mesonotum smooth, lacking deep foveae, humeri depressed, length 0.50. Metanotum barely exposed, length 0.10. Lengths of abdominal tergites I–VIII, respectively: 0.15: 0.20: 0.15: 0.10: 0.15: 0.17: 0.25: 0.25. Connexiva with margins of even width throughout, bowed slightly outward, then gradually convergent posteriorly, posterolateral angles not modified, separated by entire width of tergite VIII, lacking setal tufts.

Entire dorsum and laterotergites thickly covered with fine, short, appressed pale pubescence, intermixed with scattered long, stiff, semi-erect black setae on lateral portions of metanotum; 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, long dark setae present on anterior margin of fore femur and posterior margins of fore and middle femora; a few long pilose pale setae present along posterior margin of hind 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, slightly channeled longitudinally adjacent to grasping comb ( Fig. 16 ); hind femur moderately incrassate, bearing two closely appressed parallel rows of teeth, ventral row lying in area covered by infolded hind tibia and consisting of approximately 10 small black teeth of relatively equal size originating near center of femur and running to distal apex, dorsal row commencing at about one-quarter distance from base of femur, with a small, slender sharp black spine, following by a very long slender, sharp black spine, then 9 progressively smaller black spines and teeth of similar shape running to femoral apex ( Fig. 19 ); hind tibia straight, inner surface bearing a row of about 16 small, dark, peg-like teeth running for entire length along longitudinal midline. Lengths of leg segments as follows: femur, tibia, tarsomere 1, tarsomere 2, tarsomere 3 of fore leg, 0.70: 0.80: 0.02: 0.02: 0.20; of middle leg, 1.25: 0.85: 0.02: 0.30: 0.60; of hind leg, 1.20: 1.00: 0.02: 0.02: 0.30.

Venter of head and thorax lacking small black denticles; mesosternum with a shallow, triangular depression centrally, margins of this depression bearing long, fine gold setae; metasternum not modified; abdominal ventrites lacking obvious setae centrally, lateral portions of segments VII–IX with numerous moderately long gold setae; abdominal ventrite very short, I lying in vertical orientation, ventrites II and III slightly tumid centrally, remaining ventrites lacking carinae or depressions, ventrite VIII not constricted basally.

Male paramere shape tapering distally, basal section stout, lacking a dorsal shoulder, distal arm concave ventrally, gently curved dorsally, apex rounded ( Figs. 8 , 15, 16 ); male proctiger with basolateral lobes weakly developed, rounded, distolateral lobes also small, rounded ( Fig. 18 ).

Wingless female:

Size: Length = 2.80–3.10 mm (x = 2.92, n = 5); width = 1.10–1.20 mm, (x = 1.16, n = 5).

Similar to apterous male ( Fig. 14 ), with following exceptions: yellowish-orange markings more extensive with patches on pronotum and mesonotum similar to male, plus large yellowish-orange patches centrally on abdominal tergites VI–VIII, and outer halves of all connexival segments; basal sections of abdominal tergites II–VIII and outer halves of all connexival segments bearing shining patches visible in oblique light; connexival margins straight and of even width throughout, nearly parallel adjacent to tergites I–IV, then converging evenly to posterior apex of abdomen adjacent to tergites V–VII, all segments angling outward and not infolded, leaving all abdominal tergites visible in dorsal view, posterolateral angles not produced, lacking setal tufts; proctiger lying in horizontal orientation, gonocoxae nearly vertical; hind femur with shape and armature similar to that of wingless male, hind tibia unarmed; ventral coloration similar to that of wingless male except abdominal ventrite VII broadly yellowish-orange with broad diffuse reddish-brown stripe down longitudinal midline; all abdominal ventrites lying in similar horizontal plane; gonocoxal commissure not carinate.

Winged male: Unknown.

Winged female: Unknown.

Etymology. The name “timikana ” refers to the town of Timika, Indonesia, which lies not far to the east of the type-locality.

Distribution. Southeastern New Guinea, Iweka River basin ( Fig. 21 ). The species range as presently known occupies the Arafura Coastal Lowland area of freshwater endemism (Area 26) as delineated by D. Polhemus & Allen (2007).

Discussion. Although similar to R. kiunga in general appearance, R. timikana may be separated from that species on the basis of multiple character states (in addition to those previously discussed under R. kiunga ):

1) The anterior to posterior interocular space ratio is slightly greater in R. timikana , being 0.10/0.35, versus 0.05/ 0.40 in R. kiunga where the head approaches a holoptic state (compare Figs. 9, 10 ).

2) In comparison to R. kiunga , the male paramere is more elongate, has a more truncate apex, and lacks a dorsal shoulder basally, which is present and prominent in R. kiunga (compare Figs. 5 , 7 to Figs. 8 , 16 ).

3) The females of R. timikana have prominent yellowish-orange patches on abdominal tergites V–VII, whereas such patches are well developed only on tergite VII in R. kiunga , and incipient on tergite VI. The basal connexival segment in R. kiunga also lacks the prominent yellowish-orange patch as seen in R. timikana , being instead narrowly margined with reddish-brown (compare Figs. 2 , 14 ).

Ecological notes. The type locality for R. timikana was an east bank tributary to the Iweka River, a narrow catchment with a north-south alignment lying east of Timika, in the premontane foreland outwash plains of southern New Guinea. The stream during the sampling periods in January and March was up to 1 m deep (although clearly deeper during the rainy season), flowing gently in a bed of fine sediment, sand, and water-rounded cobbles, the latter forming alternating bars on either side of the channel along the inner margins of bends. The center of the channel received direct sunlight, while the margins were heavily shaded by intact, tall-stature lowland rain forest. The stream was sampled in an upstream direction for approximately half a kilometer, starting from a crossing on a secondary road that led to a ford on main Iweka River. At the upper end of this reach the stream split into two forks, with the left fork having tannin-stained, tea-colored waters, and the right fork having clear, slightly bluish waters. About halfway between the road crossing and the confluence a small, shaded forest spring entered from the east bank, feeding into a slow bayou ( Fig. 20 ), and it was in this spring outflow that the majority of the Rhagovelia timikana specimens were collected, sheltering under the cover of low-hanging vegetation. The species co-occurred here with another currently undescribed species of Rhagovelia in the R. transbintuni subgroup of the R. papuensis group (for explanation of groupings see D. Polhemus, 2024), and with a gerrid species in the genus Tenagogonus .

A few additional specimens of R. timikana were also taken further upstream on the amber water tributary in areas of slow flow, again in company with the R. transbintuni subgroup species. By contrast, neither of these taxa were collected along the margins of the main channel below the confluence, or upstream along the clear water fork, where a currently undescribed species in the R. caesius group occurred instead, skating on open waters in company with the large gerrid Ptilomera timika and gyrinid beetles in the genus Macrogyrus . This indicates that the local occurrence of R. timikana may be influenced by water chemistry, stream flow rate, and degree of shading.

Figures

FIGURE 20. Tributary to the Iweka River, east of Timika, Indonesia, CL 7042, habitat for R. timikana n. sp.

FIGURE 21. Distributions of species in the R. kiunga group in southern New Guinea.

FIGURES 7, 8. Rhagovelia species in the R. kiunga group, male right parameres, outer lateral views. 7. Rhagovelia kiunga n. sp. 8. Rhagovelia timikana n. sp.

FIGURES 9–12. Rhagovelia species in the R. kiunga group, structural details. Head in anterior view: 9. Rhagovelia kiunga n. sp. 10. Rhagovelia timikana n. sp. Male terminal abdomen, ventral view: 11. Rhagovelia kiunga n. sp. 12. Rhagovelia timikana n. sp.

FIGURES 13, 14. Rhagovelia timikana n. sp., dorsal habitus; specimens from tributary to Iweka River, east of Timika, Indonesia, CL 7402. 13. Wingless male. 14. Wingless female.

FIGURES 15–19. Rhagovelia timikana n. sp., structural details; specimens from tributary to Iweka River, east of Timika, Indonesia, CL 7402. 15. Male left fore leg, ventral view. 16. Male left paramere, outer lateral view. 17. Male endosomal sclerites, left lateral view. 18. Male proctiger, dorsal view. 19. Male left hind leg, dorsal view.

FIGURES 3–6. Rhagovelia kiunga n. sp., structural details; specimens from stream near Kiunga, Papua New Guinea, CL 1775. 3. Male left hind leg, dorsal view. 4. Male left middle leg, dorsal view; 5. Male left paramere, outer lateral view. 6. Male proctiger, dorsal view.

FIGURES 1, 2. Rhagovelia kiunga n. sp. dorsal habitus; specimens from stream near Kiunga, Papua New Guinea, CL 1775. 1. Wingless male. 2. Wingless female.