Medhiama nigromagna 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: 178-180

publication ID 10.5281/zenodo.282239

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Medhiama nigromagna Zhou & Zhou

sp. n.

3. Medhiama nigromagna Zhou & Zhou  , sp. n.

( Fig. 5View FIGURE 5 A –H)

Type material. Holotype: male, CHINA: Sichuan: Batang co.: Cuola village, 3400 m, 06.VI. 2009, Zhou Yulingzi collected (IZ-CAS); Paratypes: same data as holotype, 2 females; Deda village, 1 female, 3512 m, 06.VI. 2009, Zhou Yulingzi collected (IZ-CAS).

Description.Measurement. BL= 8.05 mm, FL= 4.55 mm, HL= 1.45 mm, HW= 1.05 mm, PL= 1.50 mm, PW= 0.93 mm, EL= 1.45 mm, EW= 1.33 mm.

Body nearly cylindrical and relatively large sized. Entirely black, except last segment of both maxillary palpus and labial palpus, posterior 1 / 3 of both abdominal segment VII and VIII lighter in color.

Head. Subrectangular (HL to HW ratio 1.38), tempora (behind eyes) widened, posterior angles widely rounded. Dorsal integument entirely bearing mixed and distinct microsculpture composed of isodiametric microsculpture and transverse microstriae, and extensively distributed deep and medium punctures, puncture intervals less than puncture diameter. Median longitudinal region impunctate, width equals to 2–3 puncture diameters; frontal region wrinkled basally, bearing distinct microstriae, and 3 pairs of symmetrical tiny punctures. Each side of cranium with anterolateral puncture near antennal insertion, midlateral puncture relatively near dorsal margin of eye (3–4 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 medium sized and slightly protruding, diameter slightly longer than 1 / 4 of temporal length (eye: tempora = 0.25: 0.95 mm). Epistoma relatively wide, subrectangular and flat, with a pair of tiny punctures. Distance between antennal insertions 0.30 mm, longer than distance from antenna to eye (0.25 mm).

Antennae. Scape stout, thickened apically, much longer than three subsequent antennomeres combined, 0.63 mm; antennomere II elongate, 0.18 mm; III elongate, of same length as II; IV and V subequal in length, 0.13 mm; last antennomere of medium length, 0.25 mm, subequal to two preceding antennomeres combined.

Mouthparts. Labrum bilobed, 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 (0.43 mm), slightly longer than 1 / 3 of head width, with a transverse substraight ridge on anterior 1 / 3.

Pronotum. Subrectangular, rather elongate (PL to PW ratio 1.62), of same length as head, but narrower. Widest at anterior 1 / 4, narrowest at posterior 1 / 3. Anterior angles widely rounded, not protruding, lateral margins slightly sinuate from middle, posterior angles rounded. Integument bearing shallow microstriae, and a pair of admedian row of 13–16 smaller punctures. Areas outside admedian rows with additional, irregular, sparsely set punctures.

Mesoscutellum. Shiny, extensively bearing microstriae and with 5–6 irregular punctures.

Elytra. Subrectangular (EL to EW ratio 1.1), slightly shorter but distinctly wider than pronotum. Humeri well developed, lateral margins widened posteriorly, hind margin rounded. Integument 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 opaque, surface entirely covered with a distinct mixture of extensive microstriae and polygonal reticulum; punctures small, sparsely scattered, interspace between them 4–5 puncture diameters, but much denser on tergite VII. 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. 5View FIGURE 5 A –F). Abdominal segment VIII entirely covered with setiferous punctures, posterior margins of tergite VIII slightly emarginated; that of sternite VIII slightly protruding posteriorly ( Fig. 5View FIGURE 5 A, B). Tergite IX symmetrical, connected mediobasally. Sternite IX, with short linear-shaped base and unique apex ( Fig. 5View FIGURE 5 D). Tergite X symmetrical and oblong, broadest at anterior 1 / 3 ( Fig. 5View FIGURE 5 C). Aedeagus subrectangular and large ( Fig. 5View FIGURE 5 E, F), basal bulb 1.09 mm long. Parameres symmetrical and thicken, 0.37 mm and subequal to 1 / 3 of basal bulb length. Internal sac cylindrical and black, lateral margin substraight or slightly arcuate, and with dense cell-shaped structure medially ( Fig. 5View FIGURE 5 E).

Female ( Fig. 5View FIGURE 5 G, H). Sternite VIII oblong, and posterior margin quite protruding posteriorly ( Fig. 5View FIGURE 5 G). Genital segment with a pair of subtriangular supplementary sclerites, and a broad sternite with distinctly sinuate anterior margin ( Fig. 5View FIGURE 5 H).

Distribution. China (Sichuan).

Etymology. The specific epithet is derived from Latin adjectives “ niger ” (black) and “ magnus ” (large). It refers to the combined characters of the black body color and relatively large body size of the species.

Remarks. This new species can be easily distinguished from its congeners by the following character combinations: black body color, large body size, slightly backward protruding posterior margin of male sternite VIII, special form of sternite IX and tergite X, unique form of inner sac, female sternite VIII and female sternite with sinuate anterior margin.