Metrocoris sichuanensis Chen & Nieser 1993
Creators: name: Chen, Zhen Ye Ping-Ping
name: Bu, Wen-Jun
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Gerridae
Metrocoris
Metrocoris sichuanensis

description: Metrocoris sichuanensis Chen & Nieser, 1993
(Figs. 1–16, 21–24, 29, 34, 39, 44, 49, 54, 59, 60, 61, 62, 67, 84)
Metrocoris sichuanensis Chen & Nieser, 1993: 52; Chen, 1994: 126. Metrocoris bui Chen & Zettel, 1999: 25. New synonym.
Material examined. CHINA, Sichuan Prov., 1 apterous male, Qingcheng mountain, stream near the entrance, 22 July 1989, leg. Ping-ping Chen (Holotype, NKUM); 1 apterous male, Mt. Emei, Wannian Temple, stream, 2 VIII 1989, leg. Wen-jun Bu (Holotype of M. bui, NCTN); 3 apterous males, 4 apterous females, Dujiangyan city, Qingcheng mountain (30°55'N, 103°29'E), 14 July 2015, 815 m, leg. Zhen Ye (NKUM); 2 apterous males and 2 apterous females (NCTN), 5 apterous males and 6 apterous females (NKUM), Jiangyou city, Laojun mountain (32°01'N, 104°56'E), 19 July 2015, 850 m, leg. Zhen Ye; 4 apterous males, 7 apterous females, Guangyuan city, Wangcang county, Qilixia Nature Reserve (32°37'N, 106°31'E), 22 July 2015, 1235 m, leg. Zhen Ye (NKUM); 5 apterous males, 3 apterous females, Yaan city, Zhougong mountain (29°57'N, 103°01'E), 9 May 2015, 800 m, leg. Zhuo Chen. CHINA, Hubei Prov., 1 apterous males and 3 apterous females (NCTN), 9 apterous males and 8 apterous females (NKUM), Shiyan city, Zhuxi county, Chengguan town, Xinmin village (32°18'N, 109°42'E), 11 August 2015, 600 m, leg. Zhen Ye; 8 apterous males, 10 apterous females, Shiyan city, Yunxi county, Yangwei town, Hubaoxia Forest Park (32°51'N, 110°14'E), 13 August 2015, 500 m, leg. Zhen Ye (NKUM).
Diagnosis. The moderately incrassate male fore femora (Figs. 3, 9, 39); fore femora with only with a subapical indentation and a small single apical tooth (Figs. 3, 9, 39); the unmodified inner surface of the fore tibiae (Figs. 3, 9, 39); male segment VIII more or less rectangular (Fig. 44); the relatively small segment VIII and pygophore (Figs. 44, 49); the elongate male proctiger with a pair of blackish dots laterally (Fig. 54); the diagnostic shape of the male paramere (Figs. 5, 10, 59–62); female abdominal sternum VII laterally moderately constricted, with the apical half forming a very broadly half round lobe, and the caudal margin with a shallow median notch (Fig. 34), are the diagnostic features of M. sichuanensis.
Redescription. Apterous male (Figs. 1, 6, 7, 13–16, 21–24). Body length 6.54–7.10, body width (across acetabula) 3.15–3.52. Colour: dorsum yellow with prominent black stripes; interocular dark mark usually arrowhead shaped, bifid posteriorly, along inner margin of eyes with narrow indistinctly dark line; first antennal segment yellowish brown, remaining segments usually blackish; rostrum yellowish with black apex; pronotum with T-shaped black stripe, lateral pronotal stripe very broad; mesonotum with median slender longitudinally stripe, sublateral stripes broader than lateral stripes, nearly equal in width to transverse bands; longitudinal dark stripe of mesopleuron slender, running at least 1/2 of its length, close to anterior margin but far from short acetabular mark; anterior transverse stripe of metanotum laterally confluent with posterior stripe of metanotum; fore femora with apical dark ring and four longitudinal marks, ventral mark connected with ring, remaining marks not confluent, inner mark pale and bright, external mark broad and blackish brown; middle and hind femora yellowish, tibiae and tarsi black; abdomen mainly blackish dorsally, abdominal tergites II–III blackish, abdominal tergites IV–VII blackish anteriorly and yellowish posteriorly; abdominal segment VIII with a large rectangular blackish mark in dorsal view, posteriorly with slightly bifid-shaped. Genital segments yellowish. Structural characters: head length 0.80–0.84, head width 1.79–1.83, minimum interocular width 0.65–0.68; antenna about 0.86 times as long as body, lengths of antennal segments I–IV: 2.41, 1.38, 1.22, 0.81; pronotum slightly narrower than head, pronotum length 0.71–0.73, pronotum width 1.90–1.93; fore femora moderately incrassate (Figs. 3, 9, 39), ratio length/width 4.4, inner side not modified, with a subapical indentation, and a small single apical tooth (Figs. 3, 9, 39); inner surface of fore tibiae not modified (Figs. 3, 9, 39); lengths of leg segments (femur, tibia and tarsus): fore leg: 3.28, 2.85 and 1.09 (0.08+1.01), middle leg: 8.23, 6.12 and 2.99 (2.49+0.50), hind leg: 7.82, 5.24 and 0.89 (0.47+0.42); dorsum of abdomen clothed with short shiny golden hair, venter of abdomen densely clothed with pale yellow hairs. Male terminalia: abdominal segment VIII more or less rectangular, length 1.22, width 0.73, about 1.67 times as long as wide, posterior margin with dense brown erect hairs (Fig. 44); pygophore relatively small and subovate (Fig. 49), proctiger laterally with a pair of blackish dots (Fig. 54); paramere relatively slender, curved upwards, extending beyond genital segments, apex truncate and blunt (Figs. 5, 10, 59–62). Endosoma (Figs. 4, 11, 12, 67): dorsal sclerite long and recurved proximally, apical accessory sclerites small, accessory lateral sclerites straight, ventral sclerites present and long.
Apterous female (Fig. 29). Body length 6.18–6.23, body width (across acetabula) 3.32–3.36. Colour similar to apterous male. Structural characters: head length 0.73–0.76, head width 1.65–1.67, minimum interocular width 0.66–0.68; antenna about 0.74 times as long as body, lengths of antennal segments I–IV: 1.89, 0.92, 1.01, 0.75; pronotum slightly narrower than head, pronotum length 0.49–0.51, pronotum width 1.58–1.61; fore femora slender without teeth, ratio length/width 7.1, inner surface of fore tibiae not modified; lengths of leg segments (femur, tibia and tarsus): fore leg: 2.51, 2.19 and 0.91 (0.07+0.84), middle leg: 6.45, 4.92 and 2.49 (2.11+0.38), hind leg: 6.18, 4.34 and 0.84 (0.45+0.39). Female terminalia: abdominal sternum VII large, about as long as length of preceding abdominal sterna together, laterally constricted, apical half forming a broad lobe, caudal margin with a shallow median notch, not completely covering apex of abdomen in ventral view (Fig. 34).
Distribution. China (Sichuan, Hubei). M. sichuanensis currently widely distributed around the northern and western regions of Sichuan Basin extending to southeast areas of Qinling mountains in China (Fig. 84).
Discussion. Chen & Zettel (1999) described M. bui which was collected from Mountain Emei, Sichuan, China. It was mentioned in their comparative notes that this species was very similar to M. sichuanensis, but mainly differentiated from the shape of paramere: the blade apex being more or less blunt and truncate in M. bui but tapering in M. sichuanensis (Chen & Zettel, 1999). However, after checking the parameres of the two holotypes, we have been convinced that M. bui is the objective synonym of M. sichuanensis. Our opinion is based on the evidence of their general morphology, especially on the shape of paramere, which in general are the most reliable characteristics of specific identification within the genus. The paramere of M. sichuanensis (Fig. 142 in Chen & Nieser, 1993) was illustrated in fact in dorso-external view, which led to a view of “sharp apex”. However, from the external view, the apex of paramere is blunt and more or less truncate. The all given paramere illustrations (Figs. 5, 10, 59–62; see also the Figs. 21 & 22 in Chen & Zettel, 1999) to M. sichuanensis and M. bui are identical to each other. Taking also the other morphological similarities into account, we therefore synonymize M. bui Chen & Zettel 1999 with M. sichuanensis Chen & Nieser, 1993.
Chen & Nieser (1993) proposed that M. sichuanensis might be a species in the M. stali group, and their opinion was mainly based on the general structure of the male fore leg. After examining the type series and the recent samples from the Sichuan Basin, we conclude that M. sichuanensis is more adequate to be assigned to the M. lituratus group, because they seem more agreeable to each other morphologically by the following set of characters: male fore femora moderately incrassate (Figs. 3, 39–43); subapical indentation of male fore femora only with a single tooth (Figs. 3, 39–43); the inner surface of fore tibiae unmodified (Figs. 3, 39–43); male abdominal segment VIII more or less rectangular (Figs. 44–48); and female abdominal sternum VII laterally moderately constricted, with the posterior half forming a broad lobe (Figs. 34–38). The morphological differences between the M. stali group and the M. lituratus group are indicated in the Table 1 (modified from Chen & Nieser, 1993).
description: Published as part of Chen, Zhen Ye Ping-Ping & Bu, Wen-Jun, 2016, Notes on the Metrocoris lituratus group (Heteroptera: Gerridae: Metrocoris) with descriptions of four new species in Sichuan Basin from China, pp. 359-374 in Zootaxa 4117 (3) on pages 360-364, DOI: 10.11646/zootaxa.4117.3.4, http://zenodo.org/record/269712