Enithares insularis, Polhemus, 2020

Polhemus, Dan A., 2020, Nine new species of Enithares (Heteroptera: Notonectidae) from New Guinea, with distributional notes on other species and an updated world checklist, Zootaxa 4772 (1), pp. 132-182 : 149-150

Enithares insularis new species

( Figs. 4 , 13, 14 , 18 , 55 )

Type material examined. Holotype, male (dissected): PAPUA NEW GUINEA, Milne Bay Prov., D’Entrecasteaux Islands, Fergusson Island, east coast, cascading tributary to Mebulibuli Creek , 0.9 km. upstream of mouth, S. of Basima , 15 m., 9°30′42′′S, 150°52′06′′E, water temp. 24.5° C., 24 August 2002, 13:30–14:30 hrs., CL 7181, D. A. and J. T. Polhemus ( USNM) . Paratypes: 3 males, 7 females, 1 immature, same data as holotype, CL 7181, D. A . and J. T. Polhemus ( USNM, BPBM) ; 2 males, 3 females, 1 immature, D’Entrecasteaux Islands , Goodenough Island, Yalaauau River, NW of Kalauna village, 320 m . 9°22′51′′S, 150°19′22′′E, water temp. 22.5° C., 26 August 2002, 12:30–13:15 hrs., CL 7186, D. A . and J. T. Polhemus ( USNM, BPBM) ; 6 males, 3 females, D’Entrecasteaux Islands , Normanby Island , east end, upper Dibuwa River and rocky tribs., W. of Yeluyelua, 245 m ., 10°02′46.2′′S, 151°14′53.0′′E, water temp. 24° C., 30 January 2003, 09:30–12:30 hrs, CL 7231, D A . Polhemus ( USNM, BPBM) . Additional specimens examined (not paratypes): 2 females, D’Entrecasteaux Islands , Fergusson Island , east coast, upper Awaetowa River and rocky tribs., W. of Basima, 575–650 m., 9°30′34′′S, 150°48′17′′E, water temp. 22° C., 27 January 2003, 10:00–14:00 hrs., CL 7225, D. A . Polhemus ( USNM, BPBM) .

Description. Male: Length 9.20 mm, width across pronotum 3.65 mm.

Coloration: Ground color dark brown to black, with scattered paler markings on pronotum and hemelytra ( Fig. 13 ). Vertex and frons yellowish-brown, with an irregular dark brown patch at apex of head flanked by reddish; irregular dark brown transverse fascia present on lower frons, isolating a roughly triangular dark yellow patch above base of labrum. Pronotum yellowish-brown on anterior two-thirds between and surrounding pronotal fovea, dark brown on posterior third. Scutellum dark brown to black. Hemelytra greyish-brown, with inner margins of clavus, outer base of clavus, basal two-thirds of embolium yellowish-brown; wing membrane dark fumate brown. Legs with coxae, trochanters and femora brown, tibiae and tarsi yellowish brown, anterior faces of femora broadly suffused with black; ventral surfaces of fore trochanters, middle and hind trochanters and femora marked with dark reddish brown. Venter brown.

Structural characters: Head broadly rounded anteriorly when viewed dorsally. Head length 1.00; greatest width 2.80, equal to 0.77 pronotal width; anterior width of vertex 0.90, equal to 0.90 head length. Synthlipsis 0.50, about 0.55 anterior width of vertex and clearly shorter than pronotum. Pronotal length along midline 1.10, humeral width 3.65, lateral margins convex, posterior margin weakly sinuate. Dorsal margin of pronotal fovea directed caudad behind eyes ( Fig. 13 ). Nodal furrow nearly straight, removed by 1.6× its length from membranal suture, length 0.50, distance to membranal suture 0.80.

Fore tibia with extremely thick, dense pad of short black setae along anteroventral margin, covering anterior half of ventral face of tibia. Middle trochanter rounded. Middle femur with single moderately large, elongate, sharp subapical tooth, bordered basally by about 20 small black pegs, distally by about 3 similar pegs. Hind legs typical for genus, lacking unusual modifications. Lengths of leg segments as follows: fore femur–tibia–tarsal 1–tarsal 2 = 1.30/1.80/0.60/0.30; middle femur–tibia–tarsal 1–tarsal 2 = 2.30/2.10/0.60/0.40; hind femur–tibia–tarsal 1–tarsal 2 = 3.70/3.00/1.40/0.80.

Ventral abdomen with metaxyphus triangular, slightly concave, tip acuminate ( Fig. 4 ).

Male genitalia when viewed laterally ( Fig. 18 ) with ventral margin of proctiger broadly rounded, apex blunt; posterior lobe of pygophore with posteroventral angle broadly obtuse, bearing a prominent tapering setal tuft, posterior lobe of pygophore erect, apex broad and blunt, posteriorly setiferous, slightly notched anteriorly on dorsal margin; paramere elongate, slightly tapering and curved anteriorly, posterior margin straight, apex rounded, reaching slightly above dorsal margin of posterior lobe; lateral arm of basal plate gently curving, stout basally, more slender distally, apex slightly expanded and bulb-like; aedeagus semicircular, with numerous transverse folds.

Female: Length 9.20, width across pronotum 3.70 mm. Similar to male in general structure and coloration, but with pad of black setae along anteroventral margin of fore femur not as thick or extensive.

Etymology. The name “insularis” refers to the geographic range of this species, which is endemic to the D’Entrecasteaux Islands lying to the northeast of the Papuan Peninsula of eastern New Guinea.

Discussion. Enithares insularis is similar in general size and coloration to E. atra , but differs in aspects of its male genitalia. Although the shape of the paramere and PL are similar in both species, the male proctiger in E. atra has a pronounced angle on the ventral margin, whereas in E. insularis the ventral margin is gently curving (compare Figs. 17, 18 ). The structure of the LABP is notably different between the two species, with the distal portion slender with a slightly upturned apex in E. atra , versus slightly thicker and expanded into a rounded, bulb-like apex in E. insularis (compare Figs. 17, 18 ). In addition to these genitalic differences, the male fore femur of E. insularis has a very thick and extensive pad of short, dense black setae which runs the length of the anteroventral margin; this setal pad is only weakly developed in E. atra , and is composed of paler golden setae.

Ecological notes. Enithares insularis is apparently endemic to the D’Entrecasteaux Islands, lying to the northeast of the Papuan Peninsula ( Fig. 55 ). The species has been taken from rocky upland streams on Goodenough, Fergusson and Normanby islands. Based on current records, E. insularis appears to be confined to the D’Entrecasteaux Islands area of freshwater endemism (Area 35) as defined by D. Polhemus & Allen (2007). At the Dibuwa River on Normanby Island (CL 7231) this species was taken in a ponded area along a tributary to the main river.

Figures

FIGURE 55. Distribution of species in the E. atra group on New Guinea. Square = E. digitata Lansbury; circles = E. elongata Lansbury; triangles = E. insularis n. sp.; pentagon = E. tagula n. sp.

FIGURES 2–7. Enithares species, metaxiphus. 2. E. arfak n. sp.; specimen from Indonesia, West Papua Prov., Mupi River, CL 2646. 3. E. bosavi n. sp.; holotype specimen from Papua New Guinea, Southern Highlands Prov., Mt. Bosavi, CL 7206. 4. E. insularis n. sp.; specimen from Papua New Guinea, Milne Bay Prov., Fergusson Island, CL 7181. 5. E. kasim n. sp.; specimen from Indonesia, West Papua Prov., Kasim, CL 2630. 6. E. orsaki n. sp.; specimen from Papua New Guinea, Madang Prov., Reinduk, CL 7036. 7. E. papua n. sp.; specimen from Papua New Guinea, Central Prov., Tekadu, CL 7157.

FIGURES 9–15. Enithares species in the E. atra group, dorsal habitus photographs. 9–10. Enithares orsaki n. sp., male and female; specimens from Papua New Guinea, Madang Prov., Reinduk, CL 7036. 11–12. Enithares atra Brooks, male and female; specimens from Papua New Guinea, Central Prov., Dorobisoro, CL 7260. 13–14. Enithares insularis n. sp., male and female; specimens from Papua New Guinea, Milne Bay Prov., Fergusson Island, CL 7181. 15. Enithares bosavi n. sp., holotype male; specimen from Papua New Guinea, Southern Highlands Prov., Mt. Bosavi, CL 7206.

FIGURES 16–21. Enithares species in the E. atra group, male genitalic complex, left lateral view. 16. Enithares orsaki n. sp.; specimen from Papua New Guinea, Madang Prov., Baitabag, CL 7034. 17. Enithares atra Brooks; specimen from Papua New Guinea, Central Prov., Dorobisoro, CL 7264. 18. Enithares insularis n. sp.; specimen from Papua New Guinea, Milne Bay Prov., Fergusson Island, CL 7181. 19. Enithares bosavi n. sp., holotype; specimen from Papua New Guinea, Southern Highlands Prov., Mt. Bosavi, CL 7206. 20. Enithares papua n. sp.; specimen from Papua New Guinea, Central Prov., Tekadu, CL 7157. 21. Enithares peninsularis n. sp.; specimen from Papua New Guinea, Central Prov., Woitape, CL 7248.