Naucoris scutellaris Stål, 1860

Polhemus, Dan A. & Polhemus, John T., 2013, Guide To The Aquatic Heteroptera Of Singapore And Peninsular Malaysia. Xi. Infraorder Nepomorpha- Families Naucoridae And Aphelocheiridae, Raffles Bulletin of Zoology 61 (2), pp. 665-686 : 669-670

Naucoris scutellaris Stål, 1860

( Figs. 5, 6 , 12 )

Naucoris scutellaris Stål, 1860: 266

Thurselinus greeni Distant, 1904: 33 ; syn. by Lundblad, 1933: 65 Naucoris rhizomatus J. Polhemus, 1984: 157 . New synonymy.

Material examined. — SINGAPORE: 1 male, 1 female, Lower Fort Peirce Forest , standing pool in stream, 13 Jul.1990 ( ZRC) ; 2 females, Bukit Batok Nature Reserve Park, 7 Nov.1990, coll. K. L. Yeo, YKL0704 ( ZRC) ; 1 female, Chestnut Drive, Selatar Reservoir, “F” Stream , 16 May 1994, coll. T. B. Lim et al., NS133B ( ZRC) . MALAYSIA, Perlis: 1 female, Sintok–Padang, Senai Road , 13 Feb.1997, coll. H. K. Lua, LHK0330 ( ZRC) . Pahang: 2 females, Lake Chini , on shore near chalet, 14 Apr.1997, coll. K. L. Yeo, YKL901P ( ZRC) ; 1 female, 71 km to Kuantan , 15 May 1995, coll. B. Tan and G. Sumita, TG01 ( ZRC) . Johor: 1 female, Sungai Selangi , 28 Apr.1943, coll. C. M. Yang et al., Y827 ( ZRC) ; 1 male, swamp forest stream 15 km W. of Sedili Besar, 20 m . , 16 Oct.1986, CL 2218, coll. D. A. & J. T. Polhemus ( JTPC); 2 males, swamp forest stream 12 km N. of Labis, nr. Ayer Panas , 22 Aug.1985, CL 2087, coll. J. T. & D. A. Polhemus ( JTPC) . Malacca: 1 male, south of Malacca, polluted ditch, 29 Oct.1963 ( ZRC) ; 1 female, Jasin–Kesang Tua road, Station 1, 5 Nov.1966 ( ZRC) . Trengganu : 1 male, Kuala Arang , 16 May 1995, coll. B. Tan & G. Sumita, TG05 ( ZRC) . Perak: 1 male, 4 females, stream 58 km S. of Grik , 19 Aug.1985, CL 2077, coll. J. T. & D. A. Polhemus ( JTPC) ; 2 males, 2 females, Kerunai River, 9 km N. of Grik , 19 Aug.1985, CL 2078, coll. J. T. & D. A. Polhemus ( JTPC) .

Extralimital material examined. — INDONESIA, Bengkulu Prov.: 3 males, 3 females, 1 immature, Sumatra, Hutabarna River and trib. at Tabarenah, 7 km W. of Curup , 600 m, 7 Sep.1991, CL 2582, coll. D. A. & J. T . Polhemus ( JTPC) . THAILAND, Chiang Mai Prov.: 1 male, 1 immature, stream 10 km NW of Mae Rim , 19 Nov.1985, CL 2204, coll. D. A. & J. T . Polhemus ( JTPC) ; 2 males, 2 females, Fang Dist., ponds at Fang Horticultural Station , 500 m, 15 Nov.1985, CL 2201, coll. J. T . & D. A. Polhemus ( JTPC) . Nakhon Ratchasima Prov.: 8 males, 10 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) ; 3 females, 1 km. S. of Phi Mai , 15°14'N, 102°31'E, 10 Mar.1971, coll. P. & P. Spangler ( USNM) . VIETNAM, Nghe An Prov.: 1 male, Pu Mat Nature Reserve, Bac Stream , 2 Apr.2000, CL 4388, coll. P. Nguyen & J. T . Polhemus ( JTPC) ; 1 male, Pu Mat Nature Reserve, Kem Waterfall , 400 m, 1 Apr.2000, CL 4385, coll. P. Nguyen & J. T . Polhemus ( JTPC) . Kontum Prov.: 15 males, 15 females, Ialing Rapids, 64 km SW of Kontum, 4 km W. of Ialy , 500 m, 14°12'02"N, 107°48'42"E, water temp. 24°C, 8 Mar.2001, CL 4285, coll. J. T . Polhemus & P. Nguyen ( JTPC) . Gia Lai Prov.: 2 females, Voi River, 2.5 km N. of An Khe on Kanat road, 430 m, 13°59'15"N, 108°40'54"E, water temp. 24°C, 14 Mar.2001, CL 4295, coll. J. T . Polhemus and P. Nguyen ( JTPC) . LAOS, Khamouane Prov .: 1 male, Phon Tiou , 11 Jun.1965, coll. N. Wilson ( BPBM) . BURMA, Sagaing Division : 1 female, Kanbalu Township, Chatthin Wildlife Sanctuary, pools along Chaung Mito stream at Line Three Camp , 165 m, 23°32.446'N, 95°36.794'E, water temp. 28°C, 9 Oct.1998, CL 4007, coll. D. A. & J. T . Polhemus ( JTPC) ; 1 male, Kanbalu Township, Chatthin Wildlife Sanctuary, forest pond 1.5 km W. of San Myaung Camp , 230 m, water temp. 28°C, 9 Oct.1998, CL 4008, coll. D. A. & J. T . Polhemus ( JTPC) . Mandalay Division : 1 male, Maymyo Township, Gelaung River at Pwe Kauk Falls , 8 km E. of Maymyo , 1005 m, 22°03.523'N, 96°31.956'E, water temp. 24.5° C, 19 Oct.1998, CL 4008, coll. D. A. & J. T . Polhemus ( JTPC) .

Diagnosis. — Length 6.5–7.2 mm, maximum width (across abdomen) 4.1–4.5 mm. Head and pronotum dull yellowishbrown variably maculated with scattered darker brown markings, anterior pronotal margin with two small dark spots medially, lateral pronotal margins explanate, each with a pair (1+1) of widely separated, small dark patches; hemelytra brown, with basal half of embolium broadly dark yellow, wing membrane black; abdominal laterotergites dark yellow on anterior halves, dark brown on posterior halves, creating a striped appearance. This species may recognised by its moderate size, dull head and pronotum, explanate lateral pronotal margins, the fully developed wing membrane of the hemelytra, the shape of the female subgenital plate ( Fig. 12 ), and the distinctive male parameres ( Figs. 5, 6 ).

Distribution. — Originally described from Java, with subsequent records from Ceylon, India, Thailand, Peninsular Malaysia (Johor), Java, Sulawesi, the Philippines (Fernando & Cheng, 1974; Zettel et al., 1999) and Australia (J. Polhemus, 1984, as N. rhizomatus ). The records below are the first published for Singapore and the Peninsular Malaysian states of Perlis, Perak, Pahang, and Malacca.

Discussion. — Naucoris scutellaris is a widespread species in both lotic and lentic habitats throughout the lowlands of Southeast Asia, where it can be found along the margins of ponds and slow moving stream pools; for further discussion see Zettel et al. (1999). Within a given series from a single locality there can often be significant inter- and intrasexual variations in body size and wing development, but the distinctively broad body shape of this species, which is widest across the base of the abdomen and then tapers to an angular point at the posterior terminus of the abdomen, allows quick recognition of this taxon in the field.

The distinctive structures of the male genitalia were figured by Lundblad (1933, Figs. 19F–H ), and again by Zettel et al. (1999, Figs. 22–24 ), and a dorsal habitus figure was provided by Chen et al. (2005, Fig. 119). We have dissected paratypes of N. rhizomatus J. Polhemus , and determined that the male parameres are identical to those of N. scutellaris ; we therefore place the former species in synonymy.

Figures

Figs. 2–10. Naucoris species, structural details of male genitalia. 2–4. N. sigaloeis La Rivers, specimen from NE Thailand. 2. Left paramere. 3. Right paramere. 4. Phallotheca. 5, 6. N. scutellaris Stål, specimen from Singapore, Lower Fort Peirce Forest. 5. Left paramere. 6. Right paramere. 7–10. N. minutus, new species, specimen from Singapore, Chestnut Drive. 7. Left paramere. 8. Right paramere. 9. Phallotheca. 10. Proctiger.

Figs. 11–14. Naucoris species, female terminal abdomens showing shapes of subgenital plates. 11. N. minutus, new species, specimen from Singapore, Chestnut Drive. 12. N. scutellaris Stål, specimen from Malaysia, Perak, S. of Grik, CL 2077. 13. N. sigaloeis La Rivers, specimen from Vietnam, Dông Nai Prov., Nam Cát Tiên National Park. 14. N. sumatranus Fieber, holotype from Sumatra (after Zettel, 2011).

Figs. 17–20. Ctenipocoris asiaticus Montandon, structural details, specimen from Vietnam, Lam Dong Prov., nr. Lan Hanh, CL 3094. 17. Head, ventral view. 18. Male phallotheca. 19. Medial process of male phallotheca. 20. Male left paramere.

Fig. 22. Namtokocoris kem Sites & Vitheepradit, male, dorsal habitus, specimen from Vietnam, Quang Ngai Prov., Via Lac Pass (Young Sohn illustration).