Enithares stridulata Brooks, 1948

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 : 176

Enithares stridulata Brooks

Enithares stridulata Brooks 1948:37

Material examined. VIETNAM, Vinh Phuc Prov.: 1 male, 1 female, Tam Dao Nat. Park, headwater streamlet on Bamboo Forest Trail, 880 m ., 21°28′20′′N, 105°38′18′′E, water temp. 19° C., 28 November 2014, CL 6014, D. A . Polhemus ( BPBM) . Lào Cai Prov.: 3 males, 7 females, 1 immature, rocky river and tributary 7 km. NE of Sa Pa on Lào Cai road, 1220 m., 22°22′19′′N, 103°52′16′′E, water temp. 17° C., 7 April 2000, 08:30–10:00 hrs., CL 4395, D. A . Polhemus, J. T. Polhemus and P. Nguyen ( USNM) ; 1 female, small rocky stream 19 km. NE of Sa Pa on Lào Cai road, 595 m ., 22°25′39′′N, 103°55′00′′E, water temp. 20° C., 7 April 2000, 15:15–16:00 hrs., CL 4399, D. A . Polhemus, J. T. Polhemus and P. Nguyen ( USNM). Hà Tây Prov .: 1 female, Ba Vi Nat. Park , nr. Són Tây, W. of Hànôi, third small stream on lower road, 625 m . 21°03′32′′N, 105°21′16′′E, water temp. 18.5° C., 4 April 2000, CL 4393, J. T. Polhemus and P. Nguyen ( USNM) . Lam Dong Prov.: 1 female, 1 immature, small rocky stream at Lang Biang Mtn., 12 km. N. of Dalat , 1465 m., 12°01′12′′N, 108°25′27′′E, water temp. 20° C., 11 May 1998, CL 3084, J. T. Polhemus ( USNM)

Ecological notes. Enithares stridulata is a large-sized species that is apparently restricted to upland habitats in Indochina with cool water temperature regimes ( Nieser et al. 2008). Although these authors listed the species as occurring only in northern Vietnam, the record provided here from the Dalat Plateau demonstrates that it is found at suitable elevations in southern Vietnam as well.

The Tam Dao series noted above was taken from small, shallow pools in a headwater streamlet with an alluvial bed, the largest pools being 1–2 m across and having a maximum depth of 0.5 m. The water was very clear, and flowing gently, with the reach above being dry with only hyporheic flow, thus the pools represented the uppermost limit of permanent water in this system. Most of these small pools contained 1–3 individuals of E. stridulata , with both adults and immatures present. Other aquatic Heteroptera occurring here included Amemboa vasarhelyii (Zettel) , Perrittopus asiaticus Zettel, a few Metrocoris bilobatoides Chen & Nieser on the largest pools just above the cascade, and a fairly large but undetermined Microvelia species taken along the edges of larger rocks on the pool margins. The channel was 50–70 percent shaded by mixed upland bamboo and moderate stature evergreen broadleaf forest.