Enithares stylata Lansbury, 1968

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

Enithares stylata Lansbury

( Figs. 28–30 , 37 )

Material examined. PAPUA NEW GUINEA, Eastern Highlands Prov.: 2 males, 3 females, Kassam , 1350 m, 48 km E of Kainantu, 28-X-1959, T. C. Maa (holotype and paratypes, BPBM, USNM ex. JTPC) ; 1 male, 1 female, Tapo [= Tapu], 1650 m, 3 km W of Kainantu, 22-X-1959, T. C. Maa (paratypes, BPBM) . Western Highlands Prov.: 1 male, 5 females, stream 17 km. N. of Mt. Hagen on Baiyer River Road , 1930 m., [5°43′46′′S, 144°12′10′′E], 6 September 1983, CL 1780, D. A. Polhemus & J. T. Polhemus ( USNM ex. JTPC, BPBM) . Morobe Prov.: 1 male, 1 female, stream 1.5 km. N. of Mumeng, 800 m ., [vic. 6°57′38′′S, 146°37′03′′E], 19 September 1983, CL 1832, D. A. Polhemus and J. T. Polhemus ( USNM ex. JTPC) ; 5 males, 21 females, Bamboo Creek, near Wau , 16 September 1983, 945 m ., [vic. 7°18′10′′S, 146°44′05′′E], CL 1817, D. A. Polhmemus and J. T. Polhemus ( USNM ex. JTPC) ; 1 female, Kauli Creek, near Wau , 16 September 1983, CL 1826, D. A. Polhemus and J. T. Polhemus ( USNM ex. JTPC) ; 3 males, stream 17.8 km. N. of Mumeng, 200 m . , [vic. 6°47′41′′S, 146°38′23′′E], 19 September 1983, CL 1835, D. A. Polhemus and J. T. Polhemus ( USNM ex. JTPC); 1 male, 3 females, Clearwater Creek , 3 km. S. of Mumeng, 710 m ., [6°58′12′′S, 146°37′49′′E], CL 1831, 19 September 1983, D. A. Polhemus and J. T. Polhemus ( USNM ex. JTPC) ; 1 male, 3 females, Wampit River , 10.7 km. N. of Mumeng, 660 m ., [6°51′45′′S, 146°36′36′′E], 19 September 1983, CL 1833, D. A. Polhemus and J. T. Polhemus ( USNM ex. JTPC). Central Prov .: 1 male, Eio Creek , nr. Baruanumu, E. of Port Moresby, ~ 500 m ., [vic. 9°24′54′′S, 147°32′25′′E], 22 September 1983, CL 1840, D. A. Polhemus and J. T. Polhemus ( USNM ex. JTPC) ;

Discussion. I have examined the holotype of this species, a male from Kasam, in the central highlands of Papua New Guinea. The holotype has not been dissected, but a male paratype from the same locality in the Bishop Museum line collection has the genital capsule and some leg segments stored dry in a vial beneath it, in Lansbury’s typical curation style, and is clearly the specimen illustrated in his 1968 monograph. The male genitalia with a notched PL, and curving, acuminate LABP are diagnostic ( Fig. 37 ), and match the character states in the other specimens listed above. For comparisons to E. peninsularis and E. ziwa , which have certain genitalic similarities, see the discussions under those respective species.

Ecological notes. At the locality 17 km north of Mt. Hagen (CL 1780), this species was taken from a rushing mountain stream with cold water, flowing in a rocky bed. Collections were made upstream of the road crossing, where the stream flowed through a series of waterfalls 3–6 m high, connected by long, deep pools, with E. stylata found in the latter habitat. The Bamboo Creek locality, near Wau (CL 1817), was a small, shallow stream with a gravel bed, flowing in a deep, narrow gorge with smooth bedrock walls. The stream profile consisted of a series of deep, still pools in which E. stylata occurred, connected by shallow riffles; the walls of the gorge were wet and mossy with forest above, keeping the water in deep shade. Shade is not essential to this species, however, since at other localities in the New Guinea highlands it was taken in rocky streams with unshaded beds traversing open anthropogenic grasslands.

Based on current records, E. stylata is distributed in the central mountain ranges of Papua New Guinea from the Western Highlands Province around Mt. Hagen eastward through the Goroka area to Morobe Province in the vicinity of Wau ( Fig. 30 ). This is an upland, cold water species, with all records coming from above 500 m. elevation, and many from much higher. Further east from Wau, in the Owen Stanley Range of the Papuan Peninsula, E. stylata is replaced by E. peninsularis at similar elevations. The western limit of distribution for E. stylata is not known, due to an absence of collections from the central mountains of Indonesian New Guinea in the area bordering the Papua New Guinea frontier. Much further west, in the Wapoga River basin, one finds E. ziwa at similar elevations, and this latter species also shares certain genitalic similarities to E. stylata (see discussion below), indicating a sequential west-to-east replacement of related species in the central mountains. Based on the above distribution, E. stylata occupies the East Papuan Central Highlands and Morobe Highlands areas of freshwater endemism (Areas 21 and 22) as defined by D. Polhemus & Allen (2007).

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.