Rhagovelia mbo, 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 : 103-107

Rhagovelia mbo new species

( Figs. 15 , 161–168 , 226 )

Type material examined. Holotype, wingless male: PAPUA NEW GUINEA, Milne Bay Prov., Louisiade Archipelago, Rossel [Yela] Island, small cascading tributary to Woa River , approx. 4 km. upstream from estuary, 30–60 m., 11°20'54"S, 154°07'55"E, 1 September 2002, CL 7196c, D. A. Polhemus ( BPBM) . Paratypes: PAPUA NEW GUINEA, Milne Bay Prov.: Louisiade Archipelago, Rossel [Yela] Island: 93 wingless males, 73 wingless females, same data as holotype, CL 7196c, D. A. & J. T. Polhemus ( USNM, BPBM) ; 8 winged males, 16 wingless males, 54 wingless females, 17 immatures, Woa River , approx. 4 km. upstream from estuary, 0–150 m., 11°20'37"S, 154°07'06"E, water temp. 23 °C., 31 August–1 September 2002, along margins of main river channel, CL 7196a, D. A. & J. T. Polhemus ( USNM) ; 2 winged males, 1 winged female, 38 wingless males, 27 wingless females, 13 immatures, rocky tributary to Woa River , approx. 4 km. upstream from estuary, 15–30 m., 11°20'45"S, 154°07'30"E, 31 August 2002, CL 7196b, D. A. & J. T. Polhemus ( USNM) .

Description.

Wingless male: Size: Length = 3.15–3.25 mm (x = 3.21, n = 5); width = 1.15–1.20 mm (x = 1.18, n = 5). Wingless female, length = 3.50–3.90 mm (x = 3.69, n = 5); width = 1.25–1.50 mm, (x = 1.36, n = 5). Winged male, length = 3.60 mm (n = 1); width = 1.30 mm (n = 1). Winged female, length = 3.80–3.90 mm (x = 3.85, n = 2); width = 1.50 (x = 1.50, n = 2).

Color: Dorsal ground color dark brown, marked with dark yellow to yellowish brown on basal antennae, anterior pronotum, connexiva and legs ( Fig. 161 ). Head dark brown; tylus, genae and rostrum dark yellow, rostrum fuscous ventromedially, piceous distally; eyes dark reddish black. Pronotum dark yellow on anterior two-thirds, this yellowish coloration continuing laterally as a continuous band onto the propleurae, posterior one-third dark brown to black. Mesonotum broadly dark brown to blackish laterally, reddish brown centrally. Metanotum and abdominal tergites I–VI dark blackish-brown, uniformly dull and lacking shining areas, tergite VII dark brown laterally, longitudinally orange-brown along medial section, abdominal tergites VIII and IX (proctiger) medium brown, connexiva dark brown on inner one-third, dark yellow on outer two-thirds, ventral faces also dark yellow. Antennal segment I with basal one-third dark yellow, distal two-thirds plus all of segments II–IV dark brown. Legs generally medium brown, with coxae, trochanters, basal half of fore femur, basal one-fourth of hind femur dark yellow. Venter medium brown, with pro- and metasterna, entire abdominal ventrite VII, genital segments, and patches on ventrolateral abdomen adjacent to spiracles dark yellow to yellowish brown.

Structural characters: Head moderately short, declivant anteriorly, with weakly impressed median line; length 0.38, width 0.76; length of eye along inner margin 0.35, anterior/posterior interocular space, 0.22/0.45. Pronotum short, length along midline 0.23, less than dorsal length of head, leaving mesonotum broadly exposed, width 0.95; mesonotum smooth, lacking deep foveae, humeri depressed, length 0.55. Metanotum barely exposed, length 0.10. Lengths of abdominal tergites I–VIII, respectively: 0.20: 0.20: 0.17: 0.15: 0.20: 0.20: 0.35: 0.25. Connexiva with margins of even width throughout, weakly outwardly convex, convergent posteriorly, posterolateral angles not modified, separated by entire width of tergite VIII.

Entire dorsum and laterotergites covered with fine appressed golden pubescence, intermixed with scattered long, erect black 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, and anterior margins of all femora, plus long pilose brown setae along posterior margins of all femora; 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 slightly expanded and ventrally flattened on distal one-fourth, hind trochanter bearing 10–12 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, closely appressed black pegs basally, followed by a large orange-brown tooth with a black apex, then by 8 smaller and subequal sized orange-brown teeth with black apices, dorsal row of teeth commencing near middle of femur with a large, acute, orange-brown tooth with a black apex, followed by 4–5 teeth of progressively declining size, all these teeth orange-brown basally with black apices, ventral surface of femur below ventral spine row with an additional 4–5 scattered small, dark teeth or pegs; hind tibia broadly and gently sinuate, inner surface bearing 2 parallel rows of 18–20 small dark teeth, plus one large, acute, orange-brown tooth with a dark apex approximately two-thirds distance from base ( Figs. 163, 164 ).

Venter of head and thorax lacking small black denticles; meso- and metasterna slightly depressed centrally, margins of this depression bearing long, fine gold setae; abdominal venter set with short appressed gold setae intermixed with scattered long, fine, erect dark brown setae centrally; 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 and V unmodified, ventrites VI and VII broadly and shallowly depressed centrally, ventrite VIII weakly depressed laterally to either side of midline.

Male paramere slender, elongate, ventral margin broadly curving with a few short setae centrally, apex slightly curved upward, acute ( Fig. 165 ). Male proctiger short and broad basally, basolateral lobes represented by small, angular processes; distolateral lobes not prominent; distal cone roughly triangular, tapering evenly to blunt apex forming an approximate 90° angle ( Fig. 166 )

Lengths of antennal segments I–IV: 0.95: 0.50: 0.67: 0.55.

Lengths of leg segments as follows: femur, tibia, tarsal 1, tarsal 2 of fore leg, 1.00: 1:07: 0.05: 0.02: 0.20; of middle leg, 1.62: 1.35: 0.10: 0.47: 0.70; of hind leg, 1.50: 1.65: 0.05: 0.10: 0.35.

Wingless female: Similar to wingless male in general structure and coloration, with following exceptions: mesonotum uniformly dark reddish brown, broadly domed; frosty grey pruinosity present narrowly along posterior margin of mesonotum, broadly across posterior margin of metanotum and lateral sections of abdominal tergite I, and more or less completely covering abdominal tergites II–VI; connexival margins straight, converging evenly to posterior apex of abdomen, meeting over abdominal tergite VIII and covering lateral portions of tergite VII and all of tergite VIII ( Figs. 15 , 162 ), posterolateral connexival margins forming right angles, bearing bushy tufts of long, stiff black setae; abdominal tergite VIII and proctiger lying in nearly vertical orientation, hind femora only weakly incrassate, bearing only 3 very small dark spinules on posterior face near apex; hind tibiae straight, inner surface lacking teeth; ventral coloration predominantly orange-brown, with metasternum and V-shaped area on central mesosternum dark brown; all abdominal ventrites lying in similar horizontal plane, sternite II with weak longitudinal medial carina basally, central sections of abdominal sternites III–VI flattened centrally.

Winged male: Similar to wingless male in general structure and coloration, with following exceptions: pronotum greatly enlarged, width 1.40, length 1.35, completely covering meso- and metanotum, general color dark blackish-brown, anterior lobe dark yellow, posterior lobe broadly margined with pale brown posteriorly; humeri enlarged, slightly protrusive laterally; posterior pronotal lobe broadly domed, lacking obvious foveae, posterior margin broadly angular, bearing scattered long, gently curving, semi-erect black setae; forewings uniformly dark blackish-brown with veins darker brown, extending past apex of abdomen when intact, bearing 3 closed cells, consisting of two elongate cells in basal half of wing followed by a single much smaller distal cell near the middle of the wing, set laterally behind the outer basal cell; hind femur less incrassate than in wingless male.

Winged female: Similar to winged male in general body form and coloration, pronotum width 1.50, length 1.40.

Etymology. The name “mbo ” is a noun in apposition and refers to Mt. Mbo on Rossel Island, the source area for the Woa River along which the type series was taken.

Distribution. Louisiade Archipelago; endemic to Rossel Island ( Fig. 168 ). The species range as presently known occupies the Rossel Island area of freshwater endemism (Area 39) as delineated by D. Polhemus & Allen (2007).

Discussion. Rhagovelia mbo is an attractive orange and brown species occurring on the hill streams of Rossel Island. It is similar in many respects to R. kolukolu from adjacent Tagula Island, but may be separated by its smaller size (mean body length of males is 3.21 mm in R. mbo , versus 3.85 mm in R. kolukolu ); the more closely appressed female connexiva which converge posteriorly to cover most of abdominal tergite VII and all of tergite VIII (compare Figs. 155 , 162 ); the presence of thick tufts of black setae at the posterolateral angles of the female connexiva; the presence of broad and shallow central depressions on both male abdominal ventrites VI and VII, rather than only on ventrite VII as in R. kolukolu ; and the shape of the male paramere (compare Figs. 158 , 165 ). For additional discussion of characters separating these species see the discussion under R. kolukolu .

Ecological notes. The Woa River at the type-locality was a broad, clear stream in a cobble bed, draining the east slopes of Mt. Mbo and flowing north and east to a terminus at Wulanga Bay. In its middle course the river approaches closely to the head of Yonga Bay, which extends deeply into the west side of Rossel Island, but is separated from this embayment by a narrow ridge of metamorphic Calvados Schist, which in some places is only 30 m high; this formation underlies the entire Woa River catchment (see geologic map in Webb et al. 2014). It was possible to take a trail from a landing beach at the head of Yonga Bay, over this narrow ridge, and into the midreach of the river, lying at about 15 m above sea level. Collections were then made upstream from this point for approximately 2 km, to where the stream became confined between walls of Calvados Schist bedrock, with alternating small rapids and deep pools ( Fig. 226 ). Collections were also made up several steeply dropping tributary streamlets, to elevations of about 150 m. The type series of R. mbo was taken in large part from these small, clear, first order tributaries that cascaded from the slopes of Mt. Mbo to join the main river ( Fig. 167 ). Rhagovelia mbo was syntopic here with R. woa , but was largely confined to very shallow, flowing pools, rather than the deeper pools favored by R. woa .

Species not assigned to subgroups (Incertae Sedis)

The following species have combinations of character states that do not allow them to fit well into the subgroups proposed above within the R. novacaledonica group. As such, they are treated as incertae sedis pending a comprehensive phylogenetic analysis of the Rhagovelia biota occurring across the New Guinea region.

Figures

FIG. 15. Rhagovelia mbo, wingless female, dorsal habitus. Specimen from Rossel Island, Woa River, CL 7196. Young Sohn illustration.

FIGS. 161–166. Rhagovelia mbo n. sp., structural details; specimens from Rossel Is., Woa River, CL 7196. 161. Wingless male, dorsal habitus. 162. Wingless female, dorsal habitus. 163. Male right hind leg, posterior view. 164. Male right hind leg, dorsal view. 165. Male left paramere, outer lateral view. 166. Male proctiger, dorsal view.

FIG. 167. Woa River tributary, Rossel Is., Milne Bay Province, Papua New Guinea, CL 7196, habitat for R. mbo n. sp.

FIG. 168. Distributions of species in the R. kolukolu subgroup in the Louisiade Islands.

FIG. 226. Woa River, Rossel Is., Milne Bay Province, Papua New Guinea, CL 7196, type-locality for R. yela n. sp., and habitat for R. woa n. sp. and R. mbo n. sp.

FIGS. 154–159. Rhagovelia kolukolu n. sp., structural details; specimens from Tagula Is., Kolukolu Creek, CL 7194. 154. Wingless male, dorsal habitus. 155. Wingless female, dorsal habitus. 156. Male right hind leg, posterior view. 157. Male right hind leg, dorsal view. 158. Male left paramere, outer lateral view. 159. Male proctiger, dorsal view.