Guide To The Aquatic Heteroptera Of Singapore And Peninsular Malaysia. Xi. Infraorder Nepomorpha- Families Naucoridae And Aphelocheiridae Author Polhemus, Dan A. Author Polhemus, John T. text Raffles Bulletin of Zoology 2013 2013-08-30 61 2 665 686 journal article 10.5281/zenodo.5352700 2345-7600 5352700 Naucoris sigaloeis La Rivers, 1974 ( Figs. 1–4 , 13 ) Naucoris sigaloeis La Rivers, 1974: 4 Extralimital material examined . — THAILAND , Nakhon Sawan Prov. : 2 males , 1 female , Bung Borapet , Sep.1971 , coll. J. K ( paratypes , JTPC ) . Nakhon Ratchasima Prov. : 5 male , 5 females , Sakaerat Exp. Station , 60 km S. of Nakhon Ratchasima , 300–600 m , 14°30'N , 101°55'E , 2–4 Mar.1971 , coll. P. & P. Spangler ( USNM ) . Khon Kaen Prov. : 1 female , Ubolratana Dam , 20 km W. of Mae Nam Pong , 16°46'30"N , 102°36'30"E , 10 Mar.1971 , coll. P. & P. Spangler ( USNM ) . Prov. uncertain : 1 male , NE Thailand , 10 Jan.1953 , FN 537, coll. M. E. Griffith ( JTPC ) . VIETNAM , Dông Nai Prov. : 4 males , 3 females , Nam Cát Tiên National Park , Crocodile Lake , ~ 100 m , 11°27'25"N , 107°20'58"E , 5 May 1998 , CL 3071, coll. J. T . Polhemus ( JTPC ) . Diagnosis . — Length 7.0– 8.2 mm , maximum width (across abdomen) 4.2–4.5 mm ( Fig. 1 ). Head and pronotum shiny, yellowish brown with numerous scattered, small, medium brown spots, these spots aggregated in posteriomedial section of pronotum to form larger medium brown maculations to either side of longitudinal midline, anterior pronotal margin with a small brown spots medially, lateral margins of pronotum not explanate, lacking darker markings; scutellum and hemelytra yellowish brown, heavily flecked with medium brown with basal half of embolium broadly dark yellow, wing membrane attenuated, dark brown; abdominal laterotergites dark yellow on anterior two-thirds, dark brown on posterior one-third, creating a striped appearance. Male genitalia with left paramere stout, apex blunt ( Fig. 2 ), right paramere slender, twisted, apex rounded, phallotheca as in Fig. 4 ; female subgenital plate elongate, roughly trapezoidal, apex truncate ( Fig. 13 ). Distribution . — Originally described from Bung Borapet, Thailand , and newly recorded from Vietnam herein. Discussion . — This species may recognised by its relatively large size for the genus, shiny head and pronotum, absence of explanate lateral margins on the pronotum ( Fig. 1 ), the reduced wing membrane of the hemelytra, the shape of the female subgenital plate ( Fig. 13 ), and the distinctive male genitalic structures ( Figs. 2–4 ). This shiny, chestnut brown species is known from Thailand and Vietnam , and may also possibly occur in the extreme northern portion of Peninsular Malaysia . It has been collected from both lotic and lentic habitats, including slow stream pools and shallow, standing waters along the margins of lakes, including the Crocodile Lake in southern Vietnam and Bung Borapet in Thailand .