Metrocoris vietnamensis Tran & Zettel, 2005

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 : 119

Metrocoris vietnamensis Tran & Zettel, 2005

( Figs. 9 , 52–55 )

Metrocoris vietnamensis Tran & Zettel, 2005: 42–45 , Figs. 1–9 , 24, 26, 27 (type locality: Ba Na - Nui Chua , Da Nang, Vietnam).

Material examined. Holotype and paratypes: see Tran & Zettel (2005).

Others: VIETNAM: Da Nang Prov.: 1 male, 1 female (apt), Ba Na - Nui Chua, Suoi Nai - Thac Cau Vong , coll. Tran A.D. & Tan H.H., 01 March 2005, THH05-23 ( ZRC); 3 males, 5 females (apt), Ba Na - Nui Chua, Suoi Vong Nguyet, coll. Tran A.D. & Tan H.H., 01 March 2005, THH05-24 ( ZRC) .

Diagnosis. Male: fore femur variably incrassate (ratio length/width: 3.03–4.36), ventral surface of fore femur in distal one-fourth with black indentation which proximally marked by distinct tooth, and with single stout sub-apical tooth; inner surface of fore tibia subbasally with tooth-like elevation (indistinct in males with small fore leg) ( Figs. 52, 53 ). Male genitalia: pygophore not raised posteriorly, caudal margin broadly rounded, caudal face with paired, shallow impressions, dorso-lateral process curved and apically blunt (see Tran & Zettel, 2005: Figs. 4, 5 ); proctiger elongate (see Tran & Zettel, 2005: Fig. 5 ); paramere prominent, falciform, strongly curved and apically strongly narrowed ( Fig. 54 ); endosoma: dorsal sclerite long and recurved proximally, apical accessory sclerite distinct, lateral sclerite very large, slightly curved, ventral sclerite short, thin accessory lateral sclerite present (see Tran & Zettel, 2005: Figs. 7, 8 ). Sternum 7 of female ( Fig. 55 ): large, slightly longer than preceding abdominal sterna together, posterior one-third constricted, bifid forming two widely separated lobes, slightly slanting but not curved dorsad; notch between lobes as wide as each lobe; apices of lobes pointed, reaching apex of abdomen in ventral view.

Size: apterous males: length 6.0–6.8 (holotype 6.7), width 2.67–3.06 (holotype 2.96), macropterous males: length 6.2, width 2.73; apterous females: length 5.1–5.5 (allotype 5.4), width 2.81–3.10 (allotype 3.01).

Remarks. Metrocoris vietnamensis belongs to the Metrocoris bilobatus species group (sensu Chen & Nieser, 1993), and is the second species of this group found in Vietnam, the first being M. bilobatoides (see Chen & Nieser, 1993). A detailed comparison of Metrocoris vietnamensis with its congeners in the M. bilobatus group has already been provided by Tran & Zettel (2005: 44–45). For further comparisons with other members of M. bilobatus group which occur in Vietnam, see subsequent Remarks under M. johnpolhemi , new species.

Distribution. Vietnam: Da Nang ( Fig. 138 ).

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. 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).

Figs. 1, 2. In situ photographs of Metrocoris bilotatoides, from Vietnam, Vinh Phuc Prov., Tam Dao (photographed by TAD).

Figs. 18–31. Dorsal colour patterns of Metrocoris species. 18, 19: M. inthanon, specimens from Vietnam, Nghe An Prov., Pu Mat Nature Reserve (CL 4385). 20, 21: M. sicilis, new species, paratypes, from Vietnam, Hanoi, Ba Vi N’Park (CL 4393). 22, 23: M. triangulatus, specimens from Vietnam, Kontum Prov., 60 km NW. of Kontum (CL 4280). 24, 25: M. nigriventris, new species, paratypes, from Vietnam, Lai Chau Prov., 12 km N. of Lai Chau (CL 4410). 26, 27: M. monticola, new species, paratypes, from Vietnam, Lao Cai Prov., Sa Pa, Sin Chai (TAD1363). 28, 29: M. sapa, new species, paratypes, from Vietnam, Lao Cai Prov., Sa Pa, Nui Xe (TAD0416). 30, 31: M. tenuicornis, specimens from Vietnam, Gia Lai Prov., 60 km N. of An Khe (CL 4309).

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