Metrocoris nigriventris A.D. & Polhemus 2017, new species
Creators: name: A. D., Tran
name: Polhemus, D. A.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Gerridae
Metrocoris
Metrocoris nigriventris

description: Metrocoris nigriventris, new species
(Figs. 24, 25, 42, 100–107)
Material examined. Holotype (apterous male) and allotype (apterous female): VIETNAM, Lao Cai Prov., Sa Pa, Thanh Phu, near junction of Nam Cang and Muong Hoa streams, coll. Dinh N.H. et al., 23 October 2012, DNH12.06 (ZMHU).
Paratypes: VIETNAM: Lao Cai Prov.: 1 male, 3 females (apt), same locality data as holotype (ZMHU); 1 male (apt), Sa Pa, Ban Ho, Nam Pu stream 2, coll. Dinh N.H. et al., 22 October 2012, DNH12.02 (ZRC); 1 female (apt), Sa Pa, Seo Trung Ho stream, coll. Dinh N.H. et al., 22 October 2012, DNH12.05 (ZRC); 1 male (apt), Sa Pa, Nam Cang, Nam Cang stream, coll. Dinh N.H. et al., 23 October 2012, DNH12.08 (ZMHU); 1 female (apt), Sa Pa, Nam Sai, Seo Nam Sai stream 1, coll. Dinh N.H. et al., 24 October 2012, DNH12.09 (ZMHU); 3 males, 2 females (apt), rocky river and tributary 7 km NE. of Sa Pa on Lao Cai road, 1220 m asl, 22°22′19″N, 103°52′16″E, water temp. 17°C, 7 April 2000, 0830–1000 hrs., CL 4395, coll. D.A. Polhemus, J.T. Polhemus & P. Nguyen (USNM, BPBM); 5 males, 1 females (apt), 1 male (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); 4 males, 2 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); 5 males, 3 females (apt), cascading stream 20 km NE. of Sa Pa on Lao Cai road, 565 m asl, 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). Lai Chau Prov.: 2 males, 3 females (apt), 3 males (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). Phu Tho Prov.: 1 male (apt), Xuan Son N’Park, Lap stream, site 1, at Ngoc waterfall, coll. Nguyen T.S. et al., 27 August 2014, TS1409 (ZMHU); 1 male (mpt), Xuan Son N’Park, Lap stream, site 1, at Ngoc waterfall, coll. Nguyen T.S. et al., 23 May 2015, TS1511 (ZMHU).
Diagnosis. Both sexes: body sub-ovate, ventral surface with distinct dark marks; fore femur relatively short, about subequal to length of mesosternum) slender (ratio length/ width: males, 5.12–6.40; females, 6.34–6.98); in males, proximal half of fore femur about as wide as distal half, ventral surface slightly notched near the middle (Fig. 100), pilosity denser and longer at proximal half (in females, fore femur simple). Male: genitalia of medium size, abdominal segment 8 longer than wide and clearly longer than sternum 7; pygophore simple, on ventral view apex of pygophore straight, postero-lateral surface covered with long yellowish hairs; proctiger simple, lateral margins almost parallel, with long hairs on lateral margins; paramere not extending beyond genital segment, hook-shaped, curved dorsad at distal one-third, with apex projected outwards and anteriorly (Figs. 101–103); endosoma (Figs. 104, 105): dorsal sclerite long and recurved proximally, apical accessory sclerite large but weakly sclerotised, lateral sclerite broad and short, thin accessory lateral sclerite present. Female: hind trochanter produced posteriorly, forming a small process with some long hairs (Fig. 106); abdomen shortened, tip of abdomen barely surpassing apex of hind coxa; sternum 7 large, clearly longer than previous sterna together, constricted laterally, posterior part producing a median lobe with rounded apical margin, directed dorsad, and completely enclosing genitalia on ventral view (Fig. 107).
Description. Size: apterous males: length 4.75–5.31 (holotype 5.13), width 2.25–2.63 (holotype 2.41), macropterous males: length 6.00–6.45, width 2.22–2.45; apterous females: length 4.34–5.19 (allotype 4.70), width 2.36–2.66 (allotype 2.45), macropterous females: length 6.80, width 2.50.
Colour (Figs. 24, 25): Apterous morph: Interocular area with dark brown mark medially. Antenna: segment 1 yellowish at proximal half and brown at distal half; segments 2–4 brown. Dorsum of thorax yellowish with black markings. Pronotum with median black T-shaped mark at anterior margin and confluent with two lateral black marks which run to propleura. Mesonotum: black mark on anterior margin slender and connected with lateral stripes and median longitudinal stripe; lateral stripes slender, reaching posterior margin of mesonotum; sublateral marks slender anteriorly and broadened posteriorly, confluent with black mark on anterior margin (sublateral marks sometimes variable, indistinct); mesopleura with a longitudinal brown stripe. Metanotum with broad black mark running along anterior and lateral margins, confluent with medial longitudinal mark and metacetabular stripes, bordering yellowish background; metacetabular stripes black, slender and short, about half of metacetabular length; yellow areas on meso- and metacetabula covered with silvery pubescence. Fore femur with apical dark ring and a distinct longitudinal mark on external side usually connected with ring, inner and ventral side chiefly brown; fore tibia and tarsus dark brown. Middle and hind legs: coxae and trochanters chiefly yellowish; middle femur mostly yellow, dorsal and ventral surface each with a longitudinal slender brown mark; hind femur only yellowish proximally; tibiae and tarsi dark brown. Abdomen mostly black dorsally. Venter of body with distinct dark marks: pro-, meso-, and metasternum with broad longitudinal black mark medially; mesosternum with additional broad black or dark brown marks on antero-lateral and postero-lateral areas; abdominal sterna chiefly brown, genital segment usually yellowish. Macropterous morph: Pronotum with dark mark on anterior margin, confluent with the median longitudinal stripe, and connected with dark mark on lateral area between anterior corner and humeri; two brown sublateral marks running toward apex of protonal lobe usually confluent with the median stripe posteriorly; posterior margin between humeri and apex light yellowish. Fore wings chiefly dark brown, posterior part of wings light brown.
Apterous male (holotype): Head width 1.32, interocular width 0.67, eye size 0.56. Lengths of antennal segments 1–4: 2.06: 0.90: 0.85: 0.70. Pronotum length 0.55, mesonotum length 1.32. Lengths of leg segments (femur: tibia: tarsus 1: tarsus 2): fore leg: 2.05: 1.80: 0.09: 0.67; middle leg: 5.19: 3.50: 1.90: 0.34; hind leg: 5.00: 2.78: 0.30: 0.38. Fore femur: width 0.32, other characteristics as in Diagnosis above. Abdomen length on ventral view: 1.71, pregenital length 0.68; sternum 7 about as long as sterna 3–6 combined, length 0.28. Genital segments medium size: segment 8 broadened posteriorly, length 0.49, width 0.61; characteristics of pygophore, proctiger, paramere, and endosoma as in Diagnosis above.
Apterous female (allotype): Head width 1.33; interocular width 0.59; eye size 0.58. Lengths of antennal segments 1–4: 1.90: 0.81: 0.86: 0.71. Pronotum length 0.45, mesonotum length 1.57. Lengths of leg segments: fore leg: 2.03: 1.75: 0.11: 0.67; middle leg: 5.06: 3.43: 2.00: 0.34; hind leg: 4.90: 2.66: 0.29: 0.40. Fore femur slender, width 0.32. Hind coxae simple, without apical projection, hind trochanter produced posteriorly, forming a small process with some long hairs, length of hind trochanter 0.70. Abdominal venter length 1.32, length of tergum 7: 0.20, length of sternum 7 (caudal view): 0.72. Shape of sternum 7: see Diagnosis above. Connexival margin with scattered long hairs.
Macropterous male: Head width 1.35, interocular width 0.63, eye size 0.60. Lengths of antennal segments 1–4: 2.05: 0.92: 0.87: 0.72. Pronotum: apex of pronotal lobe rounded, median length 3.03, humeral width 2.25. Fore wing length 4.9. Lengths of leg segments: fore leg: 2.18: 1.75: 0.11: 0.72; middle leg: 5.19: 3.75: 2.13: 0.38; hind leg: 5.19: 2.97: 0.30: 0.42. Fore femur: width 0.38. Abdomen length on ventral view: 1.95, pregenital length 0.72; sternum 7 about as long as sterna 3–6 combined, length 0.27. Abdominal segment 8: length 0.63, width 0.65. Other characteristics as in apterous males.
Macropterous female: Head width 1.35, interocular width 0.63, eye size 0.58. Lengths of antennal segments 1–4: 1.83: 0.83: 0.90: 0.72. Pronotum: apex of pronotal lobe rounded, median length 3.20, humeral width 2.35. Fore wing length 5.25. Lengths of leg segments: fore leg: 2.15: 1.95: 0.11: 0.72; middle leg: 5.38: 3.60: 2.18: 0.37; hind leg: 5.25: 2.78: 0.32: 0.42. Fore femur as slender as in apterous female, width: 0.32. Abdominal venter length 1.08, length of sternum 7: 0.76. Other characteristics as in apterous females.
Remarks. See Remarks under Metrocoris monticola, new species.
Etymology. This species epithet refers to the extensive black marks on ventral surface of the body, a character state usually present in members of the M. compar species group.
Distribution. Vietnam: Lao Cai, Lai Chau, Phu Tho (Fig. 141).
Habitats. Metrocoris nigriventris, new species has been collected from montane streams, at elevations ranging from 290 to 1220 m.
description: Published as part of A. D., Tran & Polhemus, D. A., 2017, The genus Metrocoris Mayr, 1865 (Gerromorpha: Gerridae) in Vietnam, with descriptions of five new species, pp. 109-149 in Raffles Bulletin of Zoology 65 on pages 133-135, DOI: 10.5281/zenodo.4502634