A new species of the genus Cenocorixa (Hemiptera, Heteroptera, Corixidae) from China

Abstract A new species of the genus Cenocorixa Hungerford (Hemiptera, Heteroptera, Corixidae) is described from China. Cenocorixayuanjiangensissp. nov. is reported from Yunnan Province. An updated key to the Chinese species of Cenocorixa is presented.


Introduction
The genus Cenocorixa was erected by Hungerford in 1948 and currently contains 11 species. Usinger (1956) provided a key to the Californian (USA) species based on male characters. Jansson (1972) revised the genus, provided a revised key to males, and suggested that stridulation is important for the reproductive isolation of species. Stonedahl and Lattin (1986) reported six species of this genus from Oregon and Washington states (USA). The genus Cenocorixa was widely distributed in the western United States and Canada Brooks and Kelton 1967;Jansson 1972). Ren and Zhu (2010) subsequently reported three species of this genus from Yunnan Province, China.
In the present paper, we add one new species, Cenocorixa yuanjiangensis sp. nov. With the addition of this new species, the genus Cenocorixa now contains four species in China and eight species in the United States and Canada (GBIF 2021).

Materials and methods
The specimens were obtained from the Institute of Entomology, Nankai University (NKU), Tianjin, China. All specimens were cleaned in an ultrasound cleaner. The antennae were dissected, dried in ethanol, mounted, and sputtered with gold or chromium. The whole specimens and prepared antennae were observed with the use of a Hitachi S-3400N scanning electron microscope in the microscopy laboratory of the large scale instrument and equipment sharing service platform of Northeast Agricultural University, Harbin. Photographs were taken with a camera mounted on a Zeiss Discovery V20 microscope. All specimens studied are deposited in the Institute of Entomology, Nankai University (NKU), Tianjin, China.

Taxonomy
Key to the species of Cenocorixa from China Strigil with 4 or 5 combs, basal 2 combs with less than 5 teeth, apical combs with more than 25 teeth (Fig. 3B, E) (Figs 2A, 3B), the distinct pronotal carina on anterior part of pronotum, the feature of strigil (Figs 2F, 3E), and the right paramere (Fig. 2E, G). The Cenocorixa of China are somewhat smaller than species from the Nearctic, varying from 5.10 to 5.80 mm in length. The Nearctic Cenocorixa are distinguished by the presence of the abdominal strigil and by the narrower, more reticulate dark bands of the hemelytra, which tend to form longitudinal stripes (Lauck 1979).    Moderately large and hairy, varying from 5.10 to 5.37 mm in length. Pattern on hemelytra consisting of numerous small, irregular, broken and anastomosing figures. Postocular space narrow; face depressed in male (Fig. 1A, B); median pronotal carina evident only on anterior third (Fig. 2C). Male pala broad, with longitudinal ridge on outside, at least basally; abdominal asymmetry dextral; strigil moderately large (Fig. 2F).
Color. Body brown, with yellowish patterns (Fig. 1); transverse bands on pronotum yellow; corium and membrane separated by a pale line; Basal 3 segments brown except lateral and posterior margin in male whereas abdomen ventral yellowish in female.
Vertex of head rounded and broad in both sexes; 7-9 bands on pronotum, sometimes discontinuous, equal or slightly wider than dark interspaces; lateral angle of pronotum blunt; lateral lobes of prothorax narrow, sides almost parallel, apex rounded; pala of male broad, with inconspicuous ridge across face, bearing a curving peg row consisting of 28-29 pegs, distal 5-7 pegs longer and spiculate ( Fig. 2A); upper palmar bristles separated into two parts, 5 anterior and 26 posterior ( Fig. 2A); metaxyphus tri- angular, base narrower than long; hemelytron with vermiculate patterns but irregular at apex of clavus (Fig. 2B); antennae with four segments, segment I-II thick and short, segment III thick and longest, segment IV slender and half the length of segment III (Fig. 2D); strigil quadrate consisting of 5 combs (Fig. 2F); median setiferous lobe of 7 th abdominal tergite narrow and curved, apex blunt (Fig. 2F); right paramere strongly curved at apical 1/3, with a small pointed lobe at tip (Fig. 2G); left paramere of male as shown in Figure 2E.
Etymology. Referring to Yuanjiang County in which the type locality situated.