Medhiama xiaolongmenensis Zhou & Zhou

Zhou, Yu-Lingzi & Zhou, Hong-Zhang, 2012, Taxonomy of the genus Medhiama Bordoni, 2002 (Coleoptera: Staphylinidae, Staphylininae, Xantholinini) with descriptions of three new species, Zootaxa 3478, pp. 169-191 : 173-175

1. Medhiama xiaolongmenensis Zhou & Zhou , sp. n.

( Fig. 3 A–H)

Type material. Holotype: male, CHINA: Beijing: Mentougou District: Xiaolongmen, 1600 m, 03.VII.1998, Zhou Haisheng collected (IZ-CAS); Paratypes: 2 males, 11 females, same data as holotype; Sichuan: Baoxing co.: Longdong town, Ganyang Gou, 1 male, 5 females, 1796 m, 12.VIII.2003, Wu Jie collected; same locality, 1 female, 1795 m, 12.VIII.2003, Yu Xiongdong collected; Puji Gou, 1 female, 2180 m, 14.VIII.2003, Yu Xiaodong & Peng Xuewei collected (IZ-CAS).

Description. Measurement. BL= 6.75 mm, FL= 3.52 mm, HL= 1.16 mm, HW= 0.86 mm, PL= 1.20 mm, PW= 0.74 mm, EL= 1.05 mm, EW= 1.05 mm.

Body nearly cylindrical and medium sized. Entirely dark brown. Legs brown. Antennae dark brown, apical half of last antennomere lighter in color. Maxillary and labial palpi dark brown.

Head. Oblong (HL to HW ratio 1.36), tempora widened posteriorly, posterior angles widely rounded. Dorsal integument entirely bearing microsculpture composed of distinct polygonal reticulum, and extensively distributed deep and medium sized punctures, puncture intervals rather narrow, about 1/2 puncture diameter. Median longitudinal region impunctate, width equals to 2–3 puncture diameters; frontal region with distinct transverse microstriae, and 3 pairs of tiny punctures. Each side of cranium without anterolateral puncture, but with midlateral puncture far from dorsal margin of eye (5–6 puncture diameters to eye), temporal puncture rather near lateral margin (at lateral 1/6) and occipital puncture rather near posterior margin (at posterior 1/6). Frontal furrows deep and long, convergent backwards; anteocular furrows indistinct, scarcely observable. Eye of small size and flat, diameter nearly 1/4 of temporal length (eye: tempora = 0.19: 0.76 mm). Epistoma relatively wide, subrectangular and flat, with a pair of tiny punctures. Distance between antennal insertions 0.23 mm, subequal to distance from antenna to eye (0.21 mm).

Antennae. Scape stout, thickened apically, much longer than three subsequent antennomeres combined, 0.44 mm; antennomere II slightly elongate or subglobular, 0.10 mm; III elongate, slightly longer than II, 0.11 mm; IV and V subequal in length, 0.09 mm; last antennomere of medium length, 0.19 mm, subequal to two preceding antennomeres combined.

Mouthparts. Labrum bilobed and relatively long, with a median longitudinal groove. Maxillary palpus elongate, segment III longest, last segment slender and obconical and shorter than the penultimate. Labial palpus distinctly slender, last segment longest.

Neck. Medium width (0.30 mm), nearly 1/3 of head width, with a transverse substraight ridge on anterior 1/3.

Pronotum. Distinctly elongate (PL to PW ratio 1.62), of same length as head, but narrower. Widest at anterior 1/3, narrowest at posterior 1/3. Anterior angles widely rounded, not protruding, lateral margins sinuate from middle, posterior angles rounded. Integument bearing distinct transverse microstriae, and a pair of admedian row of 12–14 punctures, smaller than those on head. Areas outside admedian rows with additional, irregular, sparsely set punctures.

Mesoscutellum. Shiny, extensively bearing polygonal reticulum and with a pair of small punctures on apical 1/4.

Elytra. Subquadrate (EL to EW ratio 1.0), shorter but distinctly wider than pronotum. Humeri well developed, lateral margins widened posteriorly, hind margin rounded. Integument slightly wrinkled, without microsculpture; each side symmetrically with regular rows of punctures, interspaces between rows 1–2 puncture diameters; deflexed portion of each elytron with 3–4 rows of punctures.

Legs. First four segments stout but not dilated in protarsi and metatarsi, whereas relatively slender in mesotarsi; each last segment as long as the II–IV combined. Protibia with apical ctenidium and subapical ctenidia, meso- and metatibia only with apical ctenidium.

Abdomen. Cylindrical, broadest at segment VII. Tergites III–VII shiny, surface entirely covered with observable transverse microstriae, also with denser polygonal reticulum near anterior margin; punctures small, sparsely scattered, interspace between them approximately 3–4 puncture diameters, but much denser on tergites VII and VIII. Each tergite without distinct basal impression near anterior margin. Surface between two basal transverse carinae of tergites III–VII bearing distinct polygonal reticulum. All abdominal sternites shiny, with microstriae and setiferous punctures as those on tergites.

Male ( Fig. 3 A–F). Abdominal segment VIII entirely covered with setiferous punctures, posterior margin of tergite VIII subtruncated, that of sternite VIII sharply protruding posteriorly ( Fig. 3 A, B). Tergite IX symmetrical, connected mediobasally. Sternite IX, with long linear-shaped base and sharp apex ( Fig. 3 D). Tergite X symmetrical, broadest at anterior 1/3, lateral margins quite expanded outwards ( Fig. 3 C). Aedeagus of irregular shape and small in size ( Fig. 3 E, F), basal bulb 0.48 mm long. Parameres asymmetrical and foot-shaped, right one obviously larger than left one in dorsal view ( Fig. 3 F), base distinctly darker; large sized, 0.40 mm long and subequal to 4/5 of basal bulb length. Internal sac located outside basal bulb, brown and soft, without distinct spines ( Fig. 3 E).

Female ( Fig. 3 G, H). Sternite VIII not distinctly oblong, and posterior margin protruding medially ( Fig. 3 G). Genital segment with pair of subtriangular supplementary sclerites and broad sternite with distinctly protruding anterior margin ( Fig. 3 H).

Distribution. China (Beijing, Sichuan).

Etymology. The specific epithet is derived from the Chinese name (Pin-yin) of the type locality, Xiaolongmen.

Remarks. This new species could be distinguished from its congeners by the following character combination: in male by widened anterior angles of pronotum, protruding posterior margin of male sternite VIII, distinctive shape of sternite IX, tergite X, asymmetrical parameres, unique form of inner sac, and in female by broad sternite of genital segment with a distinctly protruding anterior margin. This is the second species of the genus with asymmetrical parameres (the other being M. puetzi Bordoni, 2003 ), and the two could be distinguished from each other by different shapes of sternite IX, tergite X and aedeagi. The new species also shared similar foot-shaped parameres with M. schawalleri Bordoni , but the pronotum widened distinctly near anterior angles, punctures on abdomen more densely distributed, and tergite X more outwardly expanded.

Figures

FIGURE 3. Medhiama xiaolongmenensis sp. n.: A. male tergite VIII; B. male sternite VIII; C. male tergite X; D. male sternite IX; E. aedeagus, ventral view; F. aedeagus, dorsal view; G. female sternite VIII; H. female genital segment. Scale bars 0.15 mm.