Enithares ziwa, 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 : 146-149

Enithares ziwa new species

( Figs. 27 , 30 , 36 )

Type material examined. Holotype, male: INDONESIA, Irian Jaya Prov. [Papua Prov.], New Guinea, pools on rainforest floor near PTFI Wapoga Alpha drilling camp, upper Ziwa River valley, 1050 m., 3°08′41′′S, 136°34′25′′E,

water temp. 20° C., 18 April 1998, 10:00–17:00 hrs., 19 April 1998, 14:00–18:00 hrs., CL 7100, D. A . Polhemus ( USNM). Paratypes : INDONESIA, Irian Jaya Prov.: 4 females, same data as holotype, CL 7100, D. A . Polhemus ( USNM, BPBM) ;

Description. Male: Length 10.90 mm, width across pronotum 4.20 mm.

Coloration: Ground color black, with frons and vertex pale, limited pale markings on pronotum and hemelytra ( Fig. 27 ). Vertex and frons dark yellow, with a pair (1+1) of irregular dark brown patches on frons at apex of head; 3 irregular dark brown patches present on lower frons, running transversely above base of labrum. Pronotum black, with incipient pale creamy white fascia across transverse midline. Scutellum uniformly shining black. Hemelytra black, with limited creamy white markings along embolar suture; wing membrane dark fumate brown. Legs yellowish-brown dorsally, medium brown ventrally, with anterior faces of fore and middle femora weakly suffused with reddish brown; posterior femur narrowly margined with black along anterior face; ventral surfaces of all trochanters and femora sparingly marked with darker brown. Venter brown.

Structural characters: Head broadly rounded anteriorly when viewed dorsally. Head length 1.10; greatest width 3.40, equal to 0.81 pronotal width; anterior width of vertex 1.30, equal to 1.18 head length. Synthlipsis 0.75, about 0.58 anterior width of vertex and clearly shorter than pronotum. Pronotal length along midline 1.30, humeral width 4.20, lateral margins convex, posterior margin weakly sinuate. Dorsal margin of pronotal fovea directed caudad behind eyes ( Fig. 27 ). Nodal furrow nearly straight, removed by 2.3× its length from membranal suture, length 0.60, distance to membranal suture 1.40.

Fore and hind legs typical for genus, lacking unusual modifications. Middle trochanter rounded. Middle femur with single moderately large, elongate, sharp subapical tooth, bordered basally by about 16 small black pegs, distally by about 3 similar pegs. Lengths of leg segments as follows: fore femur–tibia–tarsal 1–tarsal 2 = 1.70/1.70/0.70/0.45; middle femur–tibia–tarsal 1–tarsal 2 = 2.50/2.20/0.90/0.50; hind femur–tibia–tarsal 1–tarsal 2 = 4.30/3.60/1.80/0.90.

Ventral abdomen with metaxyphus triangular, slightly concave, tip acuminate.

Male genitalia when viewed laterally ( Fig. 36 ) with posterior lobe of pygophore with posteroventral angle sharp, bearing a prominent tapering setal tuft, posterior margin strongly bowed posteriorly and bearing long setae, apex truncate, slightly notched anteriorly on dorsal margin; paramere elongate, slightly tapering, apex rounded, exceeding dorsal margin of posterior lobe; lateral arm of basal plate sinuate, basal half stout, distal half strongly tapering, apex acuminate; aedeagus semicircular, with numerous transverse folds.

Female: Length 10.50, width across pronotum 4.10 mm. Similar to male in general structure and coloration, but with coloration paler, ground color medium brown, scutellum entirely creamy yellowish-white.

Etymology. The name “ziwa” is a noun in apposition and refers to the Ziwa River type locality.

Discussion. In regard to its male genital structures, Enithares ziwa is similar to E. stylata from the central mountains of Papua New Guinea, and the paramere shapes are similar in the two species. However, the posterior lobe of the pygophore in E. ziwa has the posteroventral angle far more sharp and pronounced, and the posterior margin of the PL more prominently bowed (compare Figs. 36, 37 ). The LABP in both species is strongly tapering on the distal half, but in E. stylata it comes to a slightly hooked apex, whereas in E. ziwa the apex is sharp and acuminate (compare Figs. 36, 37 ). The two species may also be segregated on the basis of size, with E. stylata having body lengths ranging from 11.75–13.00 mm, whereas all examples of E. ziwa so far known have body lengths of 10.90 mm or less.

Enithares ziwa is currently known from a single series taken in the upper Wapoga River basin, draining the north slopes of the central mountains in western New Guinea ( Fig. 30 ). It will likely prove to be more broadly distributed when further collections are obtained from the remote regions lying between the Papua New Guinea border and the Paniai Lakes. Based on apparent homologies in the male gentalic characters, E. ziwa , E. stylata and E. peninsularis appear to be related, large-sized species occurring at elevations above 1000 m in the central mountains of New Guinea, which sequentially replace each other as one moves west-to-east along the uplift. Within this assemblage, E. ziwa occupies the West Papuan Central Highlands area of freshwater endemism (Area 20) as defined by D. Polhemus & Allen (2007).

This is the species treated in part under the concept of “ Enithares sp. undet #2” by D. Polhemus (2000) from sampling station 56 in the Conservation International rapid assessment report covering surveys in the Wapoga River Basin of north Indonesian New Guinea. The collections from this site were initially thought to contain only a single Enithares species, but upon closer examination proved to be a mixed series containing both E. elongata Lansbury and E. ziwa n. sp.

Ecological notes. The type series of E. ziwa was taken from a pooled area along the margin of the Ziwa River, a swift mountain torrent draining from the northern slope of the New Guinea central ranges. The pool was adjacent to a set of cobble riffles, which graded into swift rapids in the main channel. The habitat preference of this species is similar to that of E. stylata , which also occurs in slower areas along the margins of swift rivers in the highlands of Papua New Guinea.

Figures

FIGURE 30. Distribution of species in the E. atra group on New Guinea. Square = E. ziwa n. sp.; triangles = E. stylata Lansbury; pentagon = E. peninsularis n. sp.

FIGURES 23–29. Enithares species in the E. atra group, dorsal habitus photographs. 23–24. Enithares elongata Lansbury, male and female; specimens from Indonesia, Papua Province, Cyclops Mountains, CL 7145. 25–26. Enithares papua n. sp., male and female; specimens from Papua New Guinea, Southern Highlands Prov., male specimen from Swinging Bridge, CL 7020, female specimen from Tubage, CL 7022. 27. Enithares ziwa n. sp., male holotype, specimen from Indonesia, Papua Province, upper Ziwa River, CL 7100. 28–29. Enithares stylata Lansbury, male and female; specimens from Papua New Guinea, Western Highlands Prov., near Mt. Hagen, CL 1780.

FIGURES 35–40. Enithares species in the E. atra and E. bakeri groups, male genitalic complex, left lateral view. 35. Enithares elongata Lansbury; specimen from Papua New Guinea, Morobe Prov., Wareo. 36. Enithares ziwa n. sp.; specimen from Indonesia, Papua Prov., Ziwa River, CL 7100. 37. Enithares stylata Lansbury; specimen from Papua New Guinea, Morobe Prov., Wau, CL 1817. 38. Enithares tagula n. sp.; specimen from Papua New Guinea, Milne Bay Prov. Tagula Is., CL 7190. 39. Enithares bakeri Brooks, specimen from Indonesia, West Papua Prov., Aimasi River, CL 2651. 40. Enithares loria Brooks; specimen from Indonesia, Papua Prov., Siewa, CL 7085.