Metrocoris stranguloides 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 : 112-116

Metrocoris stranguloides Chen & Nieser, 1993

( Figs. 3, 4 , 32 , 44–46 )

Metrocoris stranguloides Chen & Nieser, 1993: 16–18 , Figs, 29, 38, 44–45 (type locality: Hainan Island, China); Zettel & Chen, 1996: 152, 176 (faunistic notes).

Material examined. VIETNAM: Quang Binh Prov.: 1 female (apt) , 1 male (mpt), Phong Nha, upstream of Thac Xoi waterfall, coll. Tran A.D., 15 July 2004, DY0407 ( ZRC) . Da Nang Prov.: 6 males, 3 females (apt) , 1 male, 3 females (mpt), Ba Na - Nui Chua, Suoi Cat Lon , 700 m asl, coll. Tran A.D. & Tan H.H., 28 February 2005, THH05-19 ( ZRC) ; 1 male, 1 female (apt), Ba Na - Nui Chua , rocky cascade along road to summit, coll. Tran A.D. & Tan H.H., 28 February 2005, THH05-20 ( ZRC) ; 1 male, 1 female (mpt), Ba Na-Nui Chua, Suoi Nai - Thac Cau Vong , coll. Tran A.D. & Tan H.H., 01 March 2005, THH05-23 ( ZRC) ; 2 males, 1 female (apt), 3 males (mpt), Ba Na - Nui Chua foothills, Suoi Lanh , coll. Tran A.D. & Tan H.H., 01 March 2005, THH05-25 ( ZMHU) . Quang Ngai Prov.: 18 males, 27 females (apt) , 4 males, 1 female (mpt), rocky stream crossing road on E. side of Via Lac Pass, 109 km NE. of Kontum on Hwy. 24, 305 m asl, 14°46′27″N, 108°32′18″E, water temp. 26.5°C, 17 March 2001, CL 4297, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( USNM, BPBM) . Kon Tum Prov.: 2 males, 5 females (apt.), stream 77 km NE. of Kontum on Hwy. 24, 1195 m asl, 14°38′23″N, 108°23′38″E, water temp. 19°C, 6 March 2001, CL 4283, coll. J.T. Polhemus and P. Nguyen ( USNM) ; 3 males, 6 females (apt), 3 females (mpt), small stream 97 km NE. of Kontum on Hwy. 24, 1065 m asl, 14°42′28″N, 108°27′46″E, water temp. 21°C, 20 March 2001, CL 4303, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( USNM, BPBM) ; 4 males, 12 females (apt), 1 male, 2 females (mpt), stream 96 km NE. of Kontum on Hwy. 24, 1020 m asl, 14°41′58″N, 108°27′33″E, water temp. 22°C, 20 March 2001, CL 4304, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( USNM, BPBM) . Gia Lai Prov.: 12 males, 11 females (apt) , 2 males, 3 females (mpt), 40 km NW. An Khe, Buon Luoi , 14°10′N, 108°30′E, 620–750 m asl, coll. Pacholátko & Dembicky, 28 March–12 April 1995 ( NHMW, 5 males, 5 females in ZRC) ; 12 males, 16 females (apt), 1 female (mpt), Tral Stream, 60 km N. of An Khe , 700 m asl, 14°20′28″N, 108°34′49″E, water temp. 23.5°C, 22 March 2001, CL 4309, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( USNM, BPBM) ; 4 males, 7 females (apt), 1 male, 1 female (mpt), small hill stream in primary forest, 68 km N. of An Khe , 840 m asl, 14°20′52″N, 108°32′57″E, water temp. 21°C, 22 March 2001, CL 4311, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( USNM, BPBM) ; 1 female, 1 male (apt), Nuoc Stream, 47 km N. of An Khe , 580 m asl, 14°14′17″N, 108°36′17″E, water temp. 24°C, 23 March 2001, CL 4312, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( USNM, BPBM) . Binh Dinh Prov.: 9 males, 4 females (apt), stream in boulders on E. side of An Khe Pass, 16 km E. of An Khe on Hwy. 19, 365 m asl, 13°57′43″N, 108°45′48″E, water temp. 19.5°C, 21 March 2001, CL 4307, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( USNM, BPBM) . Phu Yen Prov.: 1 male, 5 females (apt), seeps and streamlets on S. side of Ca Pass, 33 km S. of Tuy Hoa on Hwy. 1, 105 m asl, 12°51′47″N, 109°23′53″E, water temp. 25°C, 25 March 2001, CL 4315, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( USNM, BPBM) . Lam Dong Prov.: 19 males, 10 females (apt), Suoi Vang, 18 km NW. of Da Lat, coll. Vásárhelyi, 17 October 1988, No. 308 ( MTMB, NHMW) ; 69 males, 115 females (apt), 7 males, 13 females (mpt), 12 km N Dalat-LangBian, coll. P. Pacholátko & L. Dembicky, 28–30 April 1994 ( NHMW, ZRC) ; 5 males, 3 females (apt), 2 females (mpt), 12 km N Dalat-Langbian , 12°03′N 108°27′E, 1680–1750 m asl, coll. Pacholátko & Dembicky, 17–21 April 1995 ( NHMW, 4 males, 4 females in ZRC) ; 1 male, 3 females (apt), 1 female (mpt), 16 km N Da Lat-Ankreot , 12°05′N, 108°24′E, 1400 m asl, coll. Pacholátko & Dembicky, 15 April 1995 ( NHMW) ; 5 females (apt), Duc Me, 15 km S. of Bao Loc , 700 m asl, coll. Vásárhelyi, 23 October 1988, No. 371 ( MTMB) ; 1 male, 1 female (apt), Suoi Baco, 12 km S. of Bao Loc , 800 m asl, coll. Vásárhelyi, 25 October 1988, No. 386 ( MTMB) ; 1 male, 1 female (apt), 1 male, 4 females (mpt), Da Lat, a stream running into Dankia lake , coll. Tran A.D., 21 May 2003, TAD0330 ( ZRC) ; 4 males, 3 females (apt), 1 female (mpt), Da Lat, Datanla waterfall, coll. Tran A.D., 22 May 2003, TAD0333a ( ZRC) ; 3 males, 3 females (apt), 1 female (mpt), Dambri Waterfall, N. of Bao Lac , 850 m asl, 11°38′14″N, 107°44′54″E, water temp. 24°C, 7 May 1998, CL 3075, coll. J.T. Polhemus & P. Nguyen ( USNM, BPBM) ; 7 males, 12 females (apt), small steeply dropping stream at Mother Mary Shrine, along Hwy. 20 on S. side of Bao Lac Pass , 18 km W. of Bao Lac , 800 m asl, 11°27′09″N, 107°43′21″E, water temp. 24.5°C, 7 May 1998, CL 3076, coll. J.T. Polhemus & P. Nguyen ( DAPC) ; 3 males, 3 females (apt), stream below Suoi Vàng hydro project (= Gold Stream), 16 km N. of Dalat , 1430 m asl, 11°59′26″N, 108°22′06″E, water temp. 24.5°C, 9 May 1998, CL 3078, coll. J.T. Polhemus & P. Nguyen ( DAPC) ; 10 males, 9 females (apt), 1 female (mpt), small tribs. to stream below Suoi Vàng hydro project (= Gold Stream), 16 km N. of Dalat , 1430 m asl, 11°59′26″N, 108°22′06″E, water temp. 19.5°C, 9 May 1998, CL 3079, coll. J.T. Polhemus & P. Nguyen ( DAPC) ; 1 male (apt), spring fed trib. to stream below Suoi Vàng hydro project (= Gold Stream), 16 km N. of Dalat , 1430 m asl, 11°59′26″N, 108°22′06″E, 9 May 1998, CL 3080, coll. J.T. Polhemus & P. Nguyen ( DAPC) ; 6 males, 8 females (apt), 2 males, 1 female (mpt), Prenn Falls, 13 km S. of Dalat on Hwy. 20, 1160 m asl, 11°52′43″N, 108°28′19″E, water temp. 25.5°C, 10 May 1998, CL 3083, coll. J.T. Polhemus & P. Nguyen ( DAPC) ; 3 males, 1 female (apt), 4 males, 5 females (mpt), small rocky stream at Lang Biang Mtn., 12 km N. of Dalat , 1465 m asl, 12°01′12″N, 108°25′27″E, water temp. 20°C, 11 May 1998, CL 3084, coll. J.T. Polhemus & P. Nguyen ( USNM, BPBM) ; 35 males, 27 females (apt), 3 males, 7 females (mpt), tributary stream to main river at Suoi Vang , 1430 m asl, 11°59′26″N, 108°22′06″E, water temp. 21°C, 11 and 18 May 1998, CL 3085, coll. J.T. Polhemus & P. Nguyen ( USNM, BPBM) ; 3 females (apt), 2 males (mpt), stream and cascade 6 km S. of Dalat on Hwy. 20, 1390 m asl, 11°54′10″N, 108°26′46″E, 20 May 1998, CL 3095, coll. J.T. Polhemus & P. Nguyen ( DAPC) ; 15 males, 24 females (apt), 4 males, 5 females (mpt), stream in pine forest 13 km N. of Dalat on Suoi Vang road, 1495 m asl, 11°59′26″N, 108°23′19″E, water temp. 21.5°C, 28 March 2001, CL 4317, D.A. Polhemus, J.T. Polhemus and P. Nguyen ( USNM, BPBM) . Ninh Thuan Prov.: 1 male (apt), Nui Chua N’Park , suoi Lo O, coll. Quang N.V., 26 June 2004, NC-03 ( ZRC) ; 19 males, 40 females (apt), 2 males (mpt), first small stream on E. side of Belleview Pass (Ngoan Muc Pass), 66 km NW. of Phan Rang , pools and cascades, 915 m asl, 11°50′25″N, 108°39′21″E, water temp. 24°C, 12 May 1998 and 26 March 2001, CL 3087, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( DAPC, USNM, BPBM) ; 3 males, 1 female (apt), 1 male (mpt), spring fed stream in granite at shrine on E. side of Belleview Pass (Ngoan Muc Pass), 58 km NW. of Phan Rang , 700 m asl, 11°50′41″N, 108°39′57″E, water temp. 724°C, 12 May 1998, CL 3089, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen ( DAPC) .

CHINA: Hainan Prov.: 1 female (apt), Hainan (193), 30 km E. Maoyang, 600 m asl, Wuzhi Shan Resort, coll. Jäch, 17–18 January 1996 ( NHMW) ; 1 female (mpt), Wuzhishan, hill stream near Fanxiang, before Shuiman , coll. I-S. Chen et al., 9 September 2005, THH05-67 ( ZRC) ; 13 males, 7 females (apt), 1 female (mpt), Qiongzhong, Baihua waterfall, near Qiongzhong town , coll. I-S. Chen et al., 11 September 2005, THH05-73 ( ZRC) ; 1 male (apt), Qiongzhong, Linmushan forest park, ca. 15 km into track from road, coll. I-S. Chen et al., 11 September 2005, THH05-77 ( ZRC) ; 1 male, 4 females (apt), 1 female (mpt), Baisha, river along road near Yuanmen, to Wuzhishan , coll. I-S. Chen et al., 12 September 2005, THH05-82 ( ZRC) .

LAOS: Luang Nam Tha Prov.: 3 males, 1 female (apt) , 2 females (mpt), 20 km SE. Muang Sing, 950 m asl, coll. Schillhammer (25), 12 June 1996 ( NHMW) .

Diagnosis. Male: fore femur strongly incrassate with two sub-apical teeth and a median tooth ( Figs. 44, 45 ). Male genitalia large: pygophore sub-ovate (ventral view), slightly raised posteriorly (lateral view); proctiger elongate; paramere long and slender, curved at distal part, but not twisted ( Fig. 32 ); endosoma as in Chen & Nieser (1993: Figs. 44, 45 ). Female: sternum 7 with broad median lobe, posterior margin of median lobe almost straight ( Fig. 46 ).

Size: apterous males: length 5.5–6.5, width 2.81–3.23, macropterous males: length 7.2–8.3, width 2.71–3.14; apterous females: length 4.8–5.4, width 2.57–3.05, macropterous females: length 6.2–7.4, width 2.67–3.20.

Remarks. Metrocoris stranguloides is the only species of the M. strangulator group known from Vietnam. As defined by Chen & Nieser (1993), the following are characteristics of this group: strongly incrassate fore femur (males), with two sub-apical teeth and a median tooth; large male genitalia with prominent paramere; sternum 7 of female with broad medial lobe. This group contains five species: M. stragulator Breddin (from Java and Sumatra), M. armatus Chen & Nieser (from Thailand), M. malayensis Chen & Nieser (from Thailand and Peninsular Malaysia), M. nieseri Chen & Zettel (from Thailand), and M. stranguloides Chen & Nieser (initially described from Hainan Island and S. Vietnam). Metrocoris stranguloides can be easily distinguished from the other four species in this group by having a long and slender paramere, simply curved on the distal part but not twisted ( Chen & Nieser, 1993). Females of this species are also rather different from those of the other four taxa in having a straight hind margin of the median lobe on sternum 7 (females of the other four species have a clearly notched posterior margin on sternum 7).

Distribution. Vietnam: Quang Binh (first record), Da Nang (first record), Ninh Thuan (first record), Gia Lai, Lam Dong, Kon Tum (first record), Quang Ngai (first record) ( Fig. 138 ). Extralimital records: Hainan Island ( China), Laos (first record).

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. 44–55. Morphological features of Metrocoris species. 44–46: M. stranguloides. 44, 45: right fore legs of male. 46: sternum 7 of female, ventral view. 47–51: M. bilobatoides. 47, 48: right fore leg of male, same scale. 49, 50: tergum 7 of female, dorsal view (49: specimen from Tam Dao; 50: specimen from Lao Cai). 51: sternum 7 of female, ventral view. 52–55: M. vietnamensis (52–55 reproduced and modified from Tran & Zettel, 2005). 52, 53: right fore legs of male. 54: left paramere. 55: sternum 7 of female, in situ (44, 45, 47, 48, 52, 53 same scale; 46, 49–51, 55 same scale).

Fig. 138. Distribution records in Vietnam of Metrocoris stranguloides, M. bilobatoides, M. johnpolhemi, new species, and M. vietnamensis.