Erymus gilvus Zhou & Zhou

Zhou, Yu-Lingzi & Zhou, Hong-Zhang, 2014, Taxonomy of the genus Erymus Bordoni (Coleoptera: Staphylinidae, Staphylininae, Xantholinini) in China with descriptions of two new species, Zootaxa 3814 (4), pp. 521-536 : 523-527

1. Erymus gilvus Zhou & Zhou , sp. n.

( Fig. 1 A; 3A–F)

Type material. Holotype: male, CHINA: Hainan: Ledong co.: Jianfeng Ling (E 108.8792, N 18.7211), 808 m, 27.III.2008, Li Liang collector ( IZ-CAS) ; paratypes: CHINA: Hainan: Ledong co.: Jianfeng Ling, one male, 800 m, 16.VII.2004, Wu Jie & Chen Yongjie collectors ; one female, same data as above, except 24.VII.2004 ; Guangxi: Xingan co.: Miaoer Shan (E 110.4943, N 25.8810), one male, one female, 06.VII.1985, Cui Yunqi collector ; one female, same data as above, except 30.VI.1985 ; one female, same data as above, except 11.VII.1985 ; Guangdong: Zhaoqing city: Dihu Shan (E 112.5533, N 23.1714), one male, 150 m, 21.VIII.2004, Wu Jie & Chen Yongjie collectors (IZ-CAS).

Description. Measurements. BL= 3.72 mm, FL= 1.98 mm, HL= 0.57 mm, HW= 0.48 mm, PL= 0. 65 mm, PW= 0.41 mm, EL= 0.67 mm, EW= 0.58 mm.

Body nearly cylindrical, small-sized. Body light brown, except head dark brown; antennae, legs and last abdominal segment yellowish.

Head ( Fig. 1 A). Subrectangular (HL to HW ratio 1.2), tempora slightly arcuate, occasionally dilated posteriorly, posterior angles rounded. Dorsal integument extensively bearing micropunctures, without any microsculpture; median longitudinal region (of the width ≈ 0.15 mm) smooth, without punctures, other surface (posterior half of head and temporal region) with deep, sparsely-scattered, medium sized punctures, distance between punctures about the diameter of 5–6 punctures; each deflexed portion of tempora with two rows of larger and deeper punctures. Each side of cranium with anterolateral puncture near antennal insertion, midlateral puncture adjacent to dorsal margin of eye. Frontal furrows deep and long, fused with two paired tiny punctures, reaching line connecting mid-length of each eye. Anteocular furrows indistinct. Eyes large, distinctly longer than half length of tempora (eye: tempora = 0.19: 0.28 mm), distinctly protruding laterad. Epistoma relatively broad, not narrowed forwards. Distance between antennal insertions 0.13 mm, longer than distance from antenna to eye (0.08 mm).

Antennae. Scape stout, thickened apically, subequal to length of three subsequent antennomeres combined, 0.20 mm; antennomere II dilated subapically, 0.10 mm; III spherical and small, much shorter than II, 0.04 mm; IV and V obviously wider than III, subequal in length of 0.05 mm; last antennomere medium in length, 0.13 mm, subequal to length of two preceding antennomeres combined.

Neck. Medium width (0.17 mm), slightly wider than 1/3 of head width.

Pronotum ( Fig. 1 A). Subrectangular, distinctly elongate (PL to PW ratio 1.6), longer but narrower than head. Widened anteriad, lateral margins sinuate, anterior angles rounded, posterior angles broadly rounded, with widest at anterior 1/3 and narrowest at posterior 1/3. Dorsal surface extensively bearing micropunctures, without any microsculpture. Each side bearing a pair of admedian row of 5 larger punctures, a pair of lateral row of 4 punctures, and also with few irregular punctures distributing near anterior margin.

Mesoscutellum. Glossy, without any microsculpture, and with a pair of small punctures at apical 1/3.

Elytra ( Fig. 1 A). Subrectangular, elongate (EL to EW ratio 1.2), the same length of pronotum, but distinctly wider. Humeri well-developed, lateral margins distinctly dilated outwards, hind margin distinctly rounded. Integument glossy, flattened, without microsculpture, each side with 2–3 rows of small punctures along median suture, a row along midwidth, and also with 1–2 rows of tiny punctures on deflexed portion.

Abdomen. Cylindrical, broadest at segment VI. Tergites III–VII glossy, each segment covered with shallow transverse microstriae, also with small scattered punctures, interspaces between punctures near 2–3 punctures’ diameter, and punctures denser on tergites VI and VII. Each tergite with a shallow basal impression near anterior margin; surface between two basal transverse carinae glossy, covered with polygonal reticulum, and without punctures. All abdominal sternites glossy, with microstriae and punctures as those on tergites.

Male ( Fig. 3 A–F). Abdominal segment VIII entirely covered with setiferous punctures, posterior margin of both tergite and sternite subtruncated ( Fig. 3 A, B). Tergite IX symmetrical, connected mediobasally. Sternite IX asymmetrical, lateral margins arcuate, with linear-shaped base and rounded apex ( Fig. 3 C). Tergite X symmetrical, subrhomboidal, with elongate base and rounded apex ( Fig. 3 D). Aedeagus elliptical, anterior portion missing, apical margin slightly emarginated ( Fig. 3 E–F), bulbus very small, 0.22 mm long. Parameres symmetrical and quite elongate, 0.27 mm, with paired inner process at basal 1/3. Internal sac entirely membranous and variably shaped, without any visible sclerotized structures.

Distribution. China (Guangxi, Guangdong, Hainan).

Etymology. The specific epithet is derived from the Latin words “ gilv ” (light yellow), and refers to the body coloration.

Remarks. Based on the long parameres, the new species is similar to E. gracilis ( Fauvel, 1895) . But it can be distinguished from the latter by paler body color, more sparsely-scattered punctures on head, a process on each paramere, and by the distinctly narrower tergite X.

Figures

FIGURE 1. Forebody: A. Erymus gilvus sp. n.; B. E. wufengensis sp. n.; C. E. dalianus Bordoni. Scale bars 0.30 mm.

FIGURE 3. Erymus gilvus sp. n.: A. male tergite VIII; B. male sternite VIII; C. male sternite IX; D. male tergite X; E. aedeagus, dorsal view; F. aedeagus, ventral view. Scale bars 0.15 mm.