Metrocoris acutus Chen & Nieser, 1993

A. D., Tran & Polhemus, D. A., 2017, The genus Metrocoris Mayr, 1865 (Gerromorpha: Gerridae) in Vietnam, with descriptions of five new species, Raffles Bulletin of Zoology 65, pp. 109-149 : 123-127

Metrocoris acutus Chen & Nieser, 1993

( Figs. 14, 15 , 37 , 74–76 )

Metrocoris acutus Chen & Nieser, 1993: 32–33 , Figs, 88, 95–96, 101–102 (type locality: Konthanthan, Chiang Mai, Thailand); Zettel & Chen, 1996: 152, 176–177 (records from Vietnam).

Material examined. VIETNAM: Dien Bien Prov.: 1 female (apt) , 3 males (mpt), Na Tau, Nam Rom river , coll. Tran A.D., 25 July 2004, DY0412 ( ZRC) ; 2 males, 4 females (apt), 1 male, 2 females (mpt), Muong Phang, Muong Phang stream, coll. Tran A.D., 26 July 2004, DY0415 ( ZRC) ; 5 males, 5 females (apt), 1 male, 2 females (mpt), Dien Bien Dong, Keo Lom, Huoi stream, coll. Tran A.D., 27 July 2004, DY0417 ( ZRC). Lai Chau Prov .: 2 males (mpt), Tam Duong , Ho Thau , stream at Su Thang brigde, km 9 Nat. Road #4D, coll. Tran A.D. et al., 31 May 2013, TAD1324 ( ZMHU) ; 1 female (apt), Muong Te , Nam Khao , Nam Puc , stream by the road from Muong Te town to Pac Ma, ca. 17 km from Muong Te town, coll. Tran A.D. et al., 2 June 2013, TAD1325 ( ZMHU) ; 1 male, 1 female (mpt), Muong Te , Nam Khao , Huoi Dang stream, by the road from Muong Te town to Pac Ma, ca. 21 km from Muong Te town, coll. Tran A.D. et al., 2 June 2013, TAD1326 ( ZMHU) ; 1 male, 5 females (apt), 1 male, 1 female (mpt), Muong Te , Bum Nua , Huoi Hon stream, by the road from Muong Te town to Pa Tan, ca. 10 km from Muong Te town, coll. Tran A.D. et al., 2 June 2013, TAD1327 ( ZMHU) ; 1 male (apt), 2 males, 1 female (mpt), Muong Te , Bum Nua , a stream by the road from Muong Te town to Pa Tan, ca. 13 km from Muong Te town, coll. Tran A.D. et al., 2 June 2013, TAD1328 ( ZMHU) ; 2 males, 3 females (apt), 3 males (mpt), Muong Te , Muong Mo stream, by the road from Muong Te town to Lai Ha, ca. 33 km from Muong Te town, coll. Tran A.D. et al., 3 June 2013, TAD1329 ( ZMHU) ; 2 males (mpt), Muong Te , Muong Mo , Ban 41 stream, by the road from Muong Te town to Lai Ha, ca. 45 km from Muong Te town, coll. Tran A.D. et al., 3 June 2013, TAD1330 ( ZMHU) ; 3 males, 3 females (apt), Nam Na River and Nam Ceung stream trib., 15.5 km N. of Lai Chau, 200 m asl, 22°08′52″N, 103°11′33″E, water temp. 21.5°C (trib.), 11 April 2000, 1000–1300 hrs., CL 4409, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( USNM, BPBM) ; 5 females (apt), 1 male, 1 female (mpt), cascading stream 12 km N. of Lai Chau , 290 m asl, 22°07′19″N, 103°11′30″E, water temp. 22°C, 11 April 2000, 1345–1600 hrs., CL 4410, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( USNM, BPBM) . Lao Cai Prov .: 2 males, 5 females (apt), 1 female (mpt), Sa Pa , Trung Chai , km 119 Nat. Road #4D, Mong Sen stream, coll. Dinh N.H. et al., 25 April 2011, DNH11.15 ( ZMHU) ; 2 males, 6 females (mpt), Sa Pa , Nam Cang, Nam Cang stream, coll. Dinh N.H. et al., 23 October 2012, DNH12.08 ( ZMHU) ; 1 male, 1 female (apt), Sa Pa , Nam Sai, Seo Nam Sai stream 1, coll. Dinh N.H. et al., 24 October 2012, DNH12.09 ( ZMHU) ; 1 male, 1 female (mpt), Sa Pa , Nam Sai, Seo Nam Sai stream 2, coll. Dinh N.H. et al., 24 October 2012, DNH12.10 ( ZMHU) ; 2 males (apt), 1 female (mpt), Sa Pa , Thanh Phu, Nam Cang stream, coll. Tran A.D. et al., 26 October 2013, TAD1359 ( ZMHU) ; 2 males (apt), Sa Pa , Thanh Phu , near junction of Nam Cang and Muong Hoa streams, coll. Ngo Q.H., 26 October 2013, TAD1360 ( ZMHU) ; 1 male (apt), 1 female (mpt), Sa Pa , Ban Ho , Nam Pu stream (feeder stream of Muong Hoa stream), site 1, at lower section, coll. Tran A.D. et al., 26 October 2013, TAD1361 ( ZMHU) ; 3 males, 4 females (apt), 1 female (mpt), Sa Pa , Trung Chai, km 119 Nat. Road #4D, coll. Ngo Q.H. et al., 28 October 2013, TAD1370 ( ZMHU) ; 7 males, 7 females (apt), 4 females (mpt), rocky river and small trib., 16 km NE. of Sa Pa on Lao Cai road, 850 m asl, 22°24′52″N, 103°53′51″E, water temp. 19°C (main river), 7 April 2000, 1115–1400 hrs.; 9 April 2000, 1500–1600 hrs., CL 4397, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( USNM, BPBM) ; 12 males, 12 females (apt), 1 female (mpt), small rocky stream 19 km NE. of Sa Pa on Lao Cai road, 595 m asl, 22°25′39″N, 103°55′00″E, water temp. 20°C, 7 April 2000, 1515–1600 hrs., CL 4399, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( USNM, BPBM) ; 4 males, 6 females (apt), 1 male (mpt), cascading stream 20 km NE. of Sa Pa on Lao Cai road, 565 m asl [1850 ft], 22°26′20″N, 103°55′36″E, water temp. 19°C, 9 April 2000, 1215–1430 hrs., CL 4406, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( USNM, BPBM) . Ha Giang Prov .: 1 female (apt), Bac Me , Minh Ngoc commune, small stream by Nat’ road 34 ca. 20 km to Bac Me town, coll. Tran A.D. et al., 07 May 2014, TAD1401 ( ZMHU) ; 3 males, 5 females (apt), 1 male, 2 females (mpt), Bac Me , road 176, Minh Son commune, stream at Ban Van bridge, coll. Tran A.D. et al., 07 May 2014, TAD1403 ( ZMHU) ; 1 female (apt), 2 males, 2 females (mpt), Vi Xuyen , Nat’ road 4C, Minh Tan commune, Nam Dieng stream, near bridge, ca. 17.5 km to Ha Giang city, coll. Tran A.D. et al., 09 May 2014, TAD1408 ( ZMHU) ; 2 males, 5 females (apt), 2 males, 3 females (mpt), Bac Quang , km 13 road 177, Tan Lap commune, waterfall & stream, ca. 86 km to Coc Pai town, coll. Tran A.D. et al., 10 May 2014, TAD1410 ( ZMHU) ; 1 female (apt), Hoang Su Phi , Nam Ty commune, bridge at km 34 road 177, waterfall & stream, ca. 65 km to Coc Pai, coll. Tran A.D. et al., 10 May 2014, TAD1411 ( ZMHU) ; 1 female (apt), 3 females (mpt), Xin Man , road 178, feeder stream of Nam Yen river, near bridge ca. 2 km from Coc Pai town, coll. Tran A.D. et al., 11 May 2014, TAD1412 ( ZMHU) . Cao Bang Prov .: 3 males, 6 females (apt), Le Nin stream at Pac Bo cave , 370 m asl, 22°58′36″N, 106°03′02″E, water temp. 18°C, 22 March 2000, CL 4371, coll. J.T. Polhemus & P. Nguyen ( USNM, BPBM) ; 2 females (apt), Bao Lac , Dinh Phung commune, near Tung Muu, stream by the Nat’ road 34, coll. Tran A.D. et al., 20 December 2013, TAD1378 ( ZMHU) ; 3 males, 3 females (apt), Bao Lac , Bao Toan commune, Na Roa village , Khuoi Rong stream, feeder of Gam river, coll. Tran A.D. et al., 20 December 2013, TAD1381 ( ZMHU) ; 1 male, 10 females (apt), 1 male (mpt), Bao Lac , near Bao Lam district town, Ban Chim steram, feeder of Gam river, coll. Tran A.D. et al., 20 December 2013, TAD1382 ( ZMHU) . Bac Kan Prov .: 1 female (apt), Ba Be , Hoang Tri commune, Hoang Tri waterfall, coll. Tran, A.D. et al., 22 August 2012, TAD1218 ( ZMHU) ; 6 males, 6 females (apt), Ba Be N’Park , streams and pools in lower Ba Be Falls area, 140 m asl, 22°27′00″N, 105°33′48″E, water temp. 20.5°C, 20 March 2000, CL 4363, coll. J.T. Polhemus & P. Nguyen ( USNM, BPBM) ; 2 males, 5 females (apt), Ba Be Nat. Park , spring fed stream nr. Ba Be Falls, 180 m asl, 22°27′07″N, 105°34′28″E, water temp. 19°C, 20 March 2000, CL 4365, coll. J.T. Polhemus & P. Nguyen ( USNM, BPBM) ; 3 males, 7 females (apt), 1 female (mpt), Ba Be Nat. Park , Na Phon river emerging from Pac Ngoi cave on W. side of Ba Be Lake, 175 m asl, 22°25′08″N, 105°46′06″E, water temp. 20.5°C, 21 March 2000, CL 4369, coll. J.T. Polhemus & P. Nguyen ( USNM, BPBM) . Vinh Phuc Prov .: 8 males, 8 females (apt), small stream nr. entrance to Tam Dao N’Park, NW. of Hanoi , 225 m asl, 21°25′53″N, 105°36′55″E, water temp. 19°C, 19 March 2000,CL 4361, coll. J.T. Polhemus & P. Nguyen ( USNM, BPBM) . Quang Ninh Prov.: 4 males, 2 females (apt), 1 male (mpt), Van Don, Cai Bau island , Van Yen, Cau Cao stream, coll. Tran A.D., 14 June 2003, TAD0349 ( ZRC) ; 5 females (apt), Dong Trieu Range , tributary stream nr. Yen Tú pagoda, 165 m asl, 21°07′44″N, 106°43′39″E, water temp. 17°C, 26 March 2000, CL 4378, coll. J.T. Polhemus & P. Nguyen ( USNM, BPBM) . Son La Prov .: 1 female (mpt), Moc Chau , 800 m asl, coll. Vásárhelyi, 25–27 May 1986, No. 96 ( NHMW) ; 1 male (apt), Moc Chau , 850 m asl, coll. Vásárhelyi, 26 October 1986, No. 112 ( NHMW) . Phu Tho Prov .: 3 males, 5 females (apt), 2 females (mpt), Xuan Son N’Park , Lap stream, site 1, at Ngoc waterfall, coll. Tran A.D. et al., 5 June 2013, TAD1331 ( ZMHU) ; 2 males, 1 female (apt), 1 female (mpt), Xuan Son N’Park , Lap stream, site 2, first concrete bridge from Ngoc waterfall, coll. Tran A.D. et al., 5 June 2013, TAD1332 ( ZMHU) ; 1 male, 2 females (apt), 1 female (mpt), Xuan Son N’Park , Lap stream, site 3, second concrete bridge from Ngoc waterfall, coll. Tran A.D. et al., 5 June 2013, TAD1333 ( ZMHU) ; 2 females (apt), Xuan Son N’Park , Kim Thuong , Tan Ong stream, site 1, at Chin Tang waterfall, coll. Tran A.D. et al., 6 June 2013, TAD1334 ( ZMHU) ; 1 male, 2 females (apt), Xuan Son N’Park , Kim Thuong, Tan Ong stream, site 2, ca. 2 km from Chin Tang waterfall, coll. Tran A.D. et al., 6 June 2013, TAD1335 ( ZMHU) ; 1 male (apt), Xuan Son N’Park , Kim Thuong , Tan Ong stream, site 3, ca. 4 km from Chin Tang waterfall, coll. Tran A.D. et al., 6 June 2013, TAD1336 ( ZMHU) ; 1 male, 1 female (mpt), Xuan Son N’Park , Ban Coi, Coi stream, site 1, water from underground, coll. Tran A.D. et al., 7 June 2013, TAD1337 ( ZMHU) ; 1 male, 5 females (apt), 1 male, 1 female (mpt), Xuan Son N’Park , Kim Thuong, Tan Ong stream, site 2, ca. 2 km from Chin Tang waterfall, coll. Tran A.D. et al., 28 August 2013, TAD1341 ( ZMHU) ; 1 male, 1 female (apt), Xuan Son N’Park , Kim Thuong, Tan Ong stream, site 3, ca. 4 km from Chin Tang waterfall, coll. Tran A.D. et al., 28 August 2013, TAD1342 ( ZMHU) ; 5 males, 7 females (apt), Xuan Son N’Park , Dong Son, Than stream, site 1, coll. Tran A.D. et al., 29 August 2013, TAD1346 ( ZMHU) ; 1 female (apt), Xuan Son N’Park , Dong Son, Than stream, site 2, coll. Tran A.D. et al., 29 August 2013, TAD1347 ( ZMHU) ; 1 male, 3 females (apt), Xuan Son N’Park , Lap stream, site 1, at Ngoc waterfall, coll. Tran A.D. et al., 30 August 2013, TAD1352 ( ZMHU) ; 1 male, 1 female (apt), Xuan Son N’Park , Lap stream, site 2, first concrete bridge from Ngoc waterfall, coll. Tran A.D. et al., 30 August 2013, TAD1353 ( ZMHU) ; 2 males (apt), Xuan Son N’Park , Lap stream, site 3, second concrete bridge from Ngoc waterfall, coll. Tran A.D. et al., 30 August 2013, TAD1354 ( ZMHU) . Hanoi : 3 females (apt), 2 males (mpt), Ba Vi N’Park , Khanh Thuong, Bang stream, 83 m asl, coll. Ngo Q.H. et al., 17 December 2011, TAD1122 ( ZMHU) ; 5 males, 10 females (apt), 2 females (mpt), Khanh Thuong , Mit stream, forest area, 80 m asl, coll. Ngo Q.H. et al., 17 December 2011, TAD1124 ( ZMHU) ; 3 males, 5 females (apt), 5 females (mpt), Minh Quang , stream near by Tan Vien Pagoda, 340 m asl, coll. Ngo Q.H. et al., 17 December 2011, TAD1125 ( ZMHU) ; 2 males (apt), Minh Quang , Cái stream, 65 m asl, coll. Ngo Q.H. et al., 17 December 2011, TAD1126 ( ZMHU) ; 8 males, 11 females (apt), Ba Vi N’Park , Khoang Xanh, Tien stream, 95 m asl, coll. Ngo Q.H. et al., 17 December 2011, TAD1127 ( ZMHU) ; 4 males, 2 females (apt), 3 males, 4 females (mpt), Khanh Thuong , Bang stream, 83 m asl, coll. Ngo Q.H. & Tran A.D., 26 April 2012, TAD1201 ( ZMHU) ; 5 males, 6 females (apt), Khanh Thuong , Mit stream, forest area, 80 m asl, coll. Ngo Q.H. & Tran A.D., 26 April 2012, TAD1203 ( ZMHU) ; 5 males, 10 females (apt), 1 female (mpt), Minh Quang, stream near by Tan Vien Pagoda, 340 m asl, coll. Ngo Q.H. & Tran A.D., 26 April 2012, TAD1206 ( ZMHU) ; 1 male, 1 female (mpt), Minh Quang , Cái stream, 65 m asl, coll. Ngo Q.H. & Tran A.D., 26 April 2012, TAD1207 ( ZMHU) ; 7 males, 1 female (apt), 3 males, 5 females (mpt), Khoang Xanh , Tien stream, 95 m asl, coll. Ngo Q.H. & Tran A.D., 27 April 2012, TAD1208 ( ZMHU) ; 2 males (mpt), Ba Vi N’Park , stream near Coste 400, ca. 550 m asl, coll. Ngo Q.H. & Tran A.D., 27 April 2012, TAD1210 ( ZMHU) . Hai Duong Prov .: 8 males, 27 females (apt), Khe La stream, 22 km N. of Chi Linh, 160 m asl, vic. 21°13′32″N, 105°35′09″E, water temp. 18°C, 25 March 2000, CL 4375, coll. J.T. Polhemus & P. Nguyen ( USNM, BPBM) . Hoa Binh Prov .: 1 female (apt), Hoa Binh , 100 m, coll. Vásárhelyi, 21 October 1986, No. 88 ( NHMW) . Ninh Binh Prov .: 2 males, 1 female (apt), 1 male, 1 female (mpt), Cuc Phuong , 400 m asl, coll. Vásárhelyi, 17 October 1986, No. 68 ( NHMW) . Thanh Hoa Prov .: 10 males, 17 females (apt), 1 female (mpt), Ben En N’Park , Nhu Xuan , Tan Binh , Xuan Ly ranger station, Khe Lo 4 stream, coll. Pham T.D., 26 February 2013, BE1301 ( ZMHU) ; 2 males, 9 females (apt), Ben En N’Park , Nhu Xuan, Tan Binh, stream 300 m behind Xuan Ly ranger station, coll. Pham T.D., 26 February 2013, BE1302 ( ZMHU) ; 2 males, 3 females (apt), Ben En N’Park , Nhu Xuan , Son Binh, Khe Cay Khe stream, site 1, coll. Pham T.D., 01 March 2013, BE1304 ( ZMHU) ; 1 male, 4 females (apt), Ben En N’Park , Nhu Xuan , Son Binh, Khe Cay Khe stream, site 2, 300 m down-stream from site 1, coll. Pham T.D., 01 March 2013, BE1305 ( ZMHU) ; 11 males, 14 females (apt), 1 female (mpt), Ben En N’Park , Nhu Xuan , Son Binh, Khe Trai Cao stream, coll. Pham T.D., 04 March 2013, BE1308 ( ZMHU) ; 1 male (apt), Pu Hu Nature Reserve , Quan Hoa , Hien Chung , Ban Pheo, Pheo stream, coll. Pham T.D., March 2013, PH 1302 ( ZMHU) ; 1 female (apt), Pu Hu Nature Reserve , Quan Hoa , Hien Chung , Ban Pheo, Ham stream, coll. Pham T.D., 09 April 2013, PH 1303 ( ZMHU) ; 4 females (apt), 1 female (mpt), Pu Luong Nature Reserve , Ba Thuoc , Co Lung , Ban Khuyn, Khuyn stream, coll. Pham T.D., 18 March 2013, PL1303 ( ZMHU) . Nghe An Prov .: 2 males (apt), Pu Mat Nature Reserve, SW.of Con Cuong , Kem waterfall, 400 m asl, vic. 18°58′13″N, 104°48′03″E, water temp. 22°C, 1 April 2000, CL 4385, coll. J.T. Polhemus & P. Nguyen ( USNM, BPBM) ; 6 males, 12 females (apt), 1 male, 2 females (mpt), Bac stream, nr. Pu Mat Nature Reserve, 200 m asl, 18°59′18″N, 104°50′33″E, water temp. 24°C, 2 April 2000, CL 4388, coll. J.T. Polhemus & P. Nguyen ( USNM, BPBM) ; 1 female (mpt), Pu Mat N’Park , Khe Kem waterfall & stream, site #1, coll. Ngo Q.H., 20 December 2012, NQH1203 ( ZMHU) ; 2 males, 3 females (apt), Pu Mat N’Park , Khe Kem stream, site #2, ca. 300 m downstream from waterfall, coll. Ngo Q.H., 20 December 2012, NQH1204 ( ZMHU) ; 6 males, 7 females (apt), Con Cuong , near Tung Huong, Khe Num stream, coll. Ngo Q.H., 21 December 2012, NQH1211 ( ZMHU) ; 1 male, 3 females (apt), 1 male (mpt), Ky Son , Ta Ca, feeder stream of Loi stream, coll. Tran A.D. & Nguyen V.H., 16 April 2013, TAD1302 ( ZMHU) ; 1 female (apt), Ky Son , Muong Xen , Ta Ca, Hoi Giang stream, coll. Tran A.D., 16 April 2013, TAD1303 ( ZMHU) ; 2 males, 2 females (apt), 2 males (mpt), Pu Mat N’Park , Kem stream, site 2, ca. 500 m from waterfall, coll. Tran A.D. et al., 18 April 2013, TAD1311 ( ZMHU) ; 4 females (mpt), Pu Mat N’Park , Kem stream, site 3, near visitors’ shelter, coll. Tran A.D. et al., 18 April 2013, TAD1312 ( ZMHU) . Ha Tinh Prov .: 7 males, 13 females (apt), 1 female (mpt), Vu Quang N’Park, Khe Lim waterfall, coll. Tran A.D., 24 April 2003, TAD0304 ( ZRC) ; 5 males, 17 females (apt), 2 females (mpt), Vu Quang N’Park, a small branch of Khe Lim, coll. Tran A.D., 24 April 2003, TAD0305 ( ZRC) ; 1 female (mpt), Vu Quang N’Park, small waterpools near Khe Lim, coll. Tran A.D., 24 April 2003, TAD0306 ( ZRC) ; 6 males, 18 females (apt), 2 males, 4 females (mpt), Vu Quang N’Park , Song Con, old Sao La station, coll. Tran A.D., 25 April 2003, TAD0307a ( ZRC) ; 3 males, 3 females (apt), Vu Quang N’Park , Song Con, old Sao La station, coll. Tran A.D., 25 April 2003, TAD0307b ( ZRC) .

CHINA: Yunnan Prov.: 1 male (apt), Gejiu Pref., 10 km N Gejiu, ca. 1300 m asl, coll. Schönmann & Wang, 22 November 1999, CWBS 398 ( NHMW) .

THAILAND: Mae Hong Son Prov.: 1 male (apt), NW. Thailand, waterfall near Mae Sariang, coll. C.M. Yang & T.B. Lim, 11 September 1998, YCM219 ( ZRC) ; 3 females (apt), NW. Thailand, New waterfall, stream, fast flowing with boulder, coll. C.M. Yang & T.B. Lim, 7 September 1998, YCM203A ( ZRC) ; 1 male, 1 female (apt), Pha Bong, 12 km S. Mae Hong Son, coll. H. Zettel (13a), 12 November 1995 ( NHMW) . Chiang Mai Prov.: 1 male, 1 female (apt), W. Mae Rim, Mae Sa N’Park, Mae Sa Falls , coll. H. Zettel (2), 30–31 October 1995 ( NHMW) . Phetchabun Prov.: 1 male, 1 female (apt), 36 km SE. Sila, N Ban Nam Nao, Ban Pala Yai, coll. H. Zettel (27), 25 November 1995 ( NHMW) .

Diagnosis. Male: fore femur incrassate (ratio length/width variable, in apterous males about 2.70–4.02), with a bifid subapical tooth; fore tibia without indentation on inner surface ( Figs. 74, 75 ). Male genitalia moderate in size: pygophore sub-ovate; proctiger elongate; paramere slender, falciform with pointed apex ( Fig. 37 ); endosoma as in Chen & Nieser (1993: Figs. 101, 102 ). Female: sternum 7 large, constricted laterally, medially produced tongue-like lobe (with diagonal lateral margins) on posterior margin, sometimes directed dorsad, completely enclosing the genitalia ( Fig. 76 ).

Size: body length about twice as width: apterous males: length 4.60–6.30, width 2.28–3.14, macropterous males: length 6.40–8.20, width 2.34–2.97; apterous females, length 4.40–5.80, width 2.41–3.14, macropterous males: length 6.20–6.90, width 2.52–2.67.

Remarks. Metrocoris acutus belongs to the M. nigrofasciatus species group, as defined by Chen & Nieser (1993), on the basis of the following character states: male fore femur incrassate, ventral surface of apical part indented with a single or bifid sub-apical tooth; paramere slender and curved; female sternum 7 large, with median lobe produced. Two species belonging to the M. nigrofasciatus group are found in Vietnam, M. acutus and M. nigrofascioides . Males of these two species can be separated from each other by the structures of the fore leg, parameres and endosoma. By contrast, the females of the two species are very similar to each other, especially in regard to colour pattern. However, they can be separated by size (the females of M. acutus are slightly larger), shape of the median lobe of sternum 7 (tongue-like in M. acutus , sub-rectangular in M. nigrofascioides ), and pubescence on the inner surface of the hind trochanter (more distinct and longer in M. nigrofascioides ).

Distribution. Vietnam: Dien Bien, Son La, Quang Ninh, Hoa Binh, Ninh Binh, Ha Tinh, Cao Bang (first record), Hai Duong (first record), Thanh Hoa (first record), Nghe An (first record), Lao Cai, Lai Chau, Bac Kan, Vinh Phuc ( Fig. 139 ). Extralimital records: China (Yunnan), Laos (Luang Prabang), Thailand (northern).

Figures

Figs. 3–17. Dorsal colour patterns of Metrocoris species, all apterous morph. 3, 4: M. stranguloides, specimens from Vietnam, Gia Lai Prov., 60 km N. of An Khe (CL 4309). 5, 6: M. bilobatoides, specimens from Vietnam, Lao Cai Prov., 12 km NW. of Sa Pa (CL 4404). 7, 8: M. johnpolhemi, new species, specimens from Vietnam, Lai Chau Prov.; male from 12 km N. of Lai Chau (CL 4410), female from Nam Ceung stream (CL 4409). 9: M. vietnamensis, paratype, from Vietnam, Da Nang Prov., Ba Na - Nui Chua (TAD0334) (9 reproduced and modified from Tran & Zettel, 2005). 10, 11: M. quynhi, specimens from Vietnam, Lao Cai Prov., 18 km NW. of Sa Pa (CL 4400). 12, 13: M. obscurus, specimens from Vietnam, Lao Cai Prov., 4 km NE. of Sa Pa (CL 4407). 14, 15: M. acutus, specimens from Vietnam, Hai Hung Prov., 22 km N. of Chi Linh (CL 4375). 16, 17: M. nigrofascioides, specimens from Vietnam, Binh Dinh Prov., An Khe Pass (CL 4291).

Figs. 32–43. Parameres of Metrocoris species. 32: M. stranguloides, specimen from Vietnam, Gia Lai Prov., 60 km N. of An Khe (CL 4309). 33: M. bilobatoides, specimen from Vietnam, Lao Cai Prov., 12 km NW. of Sa Pa (CL 4404). 34: M. johnpolhemi, new species, specimen from Vietnam, Lai Chau Prov., Nam Ceung stream (CL 4409). 35: M. quynhi, specimen from Vietnam, Lao Cai Prov., 18 km NW. of Sa Pa (CL 4400). 36: M. obscurus, specimen from Vietnam, Lao Cai Prov., 4 km NE. of Sa Pa (CL 4407). 37: M. acutus, specimen from Vietnam, Hai Hung Prov., 22 km N. of Chi Linh (CL 4375). 38: M. nigrofascioides, specimen from Vietnam, Binh Dinh Prov., An Khe Pass (CL 4291). 39: M. sicilis, new species, specimen from Vietnam, Hanoi, Ba Vi N’Park (CL 4393). 40: M. triangulatus, specimen from Vietnam, Gia Lai Prov., N. of Tram Lap (ROM-961066). 41: M. ciliatus, paratype, from Vietnam, Lai Chau Prov., Muong Te (TAD1329). 42: M. nigriventris, new species, paratype, from Vietnam, Lao Cai Prov., 20 km NE. of Sa Pa (CL 4406). 43: M. monticola, new species, paratype, from Vietnam, Lao Cai Prov., Sa Pa, Sin Chai (TAD1363).

Figs. 74–79. Morphological features of Metrocoris species. 74–76: M. acutus. 74, 75: right fore legs of male, same scale. 76: sternum 7 of female, ventral view. 77–79: M. nigrofascioides. 77: right fore leg of male. 78: hind trochanter of female. 79: sternum 7 of female, ventral view (74, 75, 77 same scale; 76, 78, 79 same scale).

Figs. 100–107. Morphological features of Metrocoris nigriventris, new species. 100: right fore leg of male. 101–103: left paramere, three different views. 104, 105: endosomal sclerites, lateral and dorsal views. 106: hind coxa and trochanter of female. 107: sternum 7 of female, ventral view (101–105 same scale; 106, 107 same scale).

Fig. 139. Distribution records in Vietnam of Metrocoris obscurus, M. quynhi, M. acutus, and M. nigrofascioides.