Metolinus binarius Zhou & Zhou

Zhou, Yu-Lingzi & Zhou, Hong-Zhang, 2011, Taxonomy of the genus Metolinus Cameron (Coleoptera, Staphylinidae, Staphylininae, Xantholinini) from China with description of three new species, ZooKeys 112, pp. 53-87 : 59-61

3. Metolinus binarius Zhou & Zhou sp. n. Fig. 12 A–HFig. 12-1 A–E

Type material.

Holotype: CHINA: Yunnan: male, Xishuangbanna Dai Autonomous Prefecture, Menglun town (E 100.9876, N 22.1711), 860 m, 11.II.2004, Wu Jie collected (IZ-CAS); Paratypes: CHINA: Yunnan: Xishuangbanna Dai Autonomous, 5 males, 1 female, same data as holotype (IZ-CAS); 1ex., same data as holotype, except Wu Jie & Bai Dayuan collected (IZ-CAS); 2 males, 1 female, same locality as holotype, 560 m, 09.II.2004, Wu Jie collected (IZ-CAS); 1 male, 4 females, same locality as holotype, 550 m, 08.II.2004, Wu Jie & Bai Dayuan collected (IZ-CAS); 1ex., same locality as holotype, 730 m, 13.II.2004, Wu Jie collected (IZ-CAS); 1 female, same locality as holotype, 760 m, 10.II.2004, Wu Jie collected (IZ-CAS); Mengyang town: 1 female, Kungenaban 2nd village, 910 m, 08.X.2010, Zhou Yulingzi collected; 1 female, Mengla co., Nanman river, 857 m, 07.X.2010, Zhou Yulingzi collected (IZ-CAS).

Description.

Measurement. BL=5.0 mm, FL=2.3 mm, HL=0.62 mm, HW=0.53 mm, PL=0.75 mm, PW=0.51 mm, EL=0.83 mm, EW=0.72 mm.

Body medium sized and nearly compressed. Body entirely dark brown. Legs dark brown, tarsi lighter. Antennae, maxillary palpi and labial palpi light brown.

Head (Fig. 12-1A). Subrectangular (HL to HW ratio 1.2), tempora (behind eyes) obviously widened posteriorly, posterior angles rounded. Dorsal integument shiny, extensively covered with distinct transverse microstriae, and sparse, scattered setiferous punctures of medium size, distance between punctures ca. 5-6 puncture diameters. With pair of frontal puncture on epistoma, 2 antennal punctures near antennal insertion, ocular puncture near medial margin of eye (ca. 3-4 puncture diameters from eye), temporal puncture at posterior 1/5 and occipital puncture at lateral 1/3; deflexed portion of tempora with same setiferous punctures and microstriae as on dorsal integument. Frontal furrows superficial and short, slightly shorter than 1/2 of eye length. Ocular furrows of medium length, subequal to 1/2 of eye length. Eye of relatively large size, longer than 1/2 temporal length (eye: temple =0.18:0.29 mm), distinctly protruding laterad. Epistoma protruding forwards, anterior margin subtruncated, dorsally flat and broad, as wide as 1/2 of eye length. Distance between antennal insertions ca. 0.20 mm, obviously wider than distance from antenna to eyes (ca. 0.09 mm). Ventral integument shiny, with same microstriae and setiferous punctures as on dorsal integument. Mentum with a pair of setae inserted at each anterior angle in addition to other irregularly scattered setae, submentum with 2 pairs of setae. Gular sutures fused at middle, and not separated at base of occiput. Gular plate devoid of punctures, but with distinct transverse microstriae.

Antennae(Fig. 12-1B). Scape stout, thickened apically, longer than three subsequent antennomeres combined, ca. 0.23 mm; 2nd elongate, ca. 0.075 mm, distinctly longer than 3rd; 3rd globular, ca. 0.045 mm; 4th and 5th subequal, ca. 0.045 mm; last antennomere relatively long, ca. 0.11 mm, subequal to preceding 3 antennomeres combined.

Mouthparts. Labrum transverse and U-shaped bilobed, two lateral teeth subtruncated on anterior margin. Mandibles falciform, left medial edge bearing two teeth. Maxillary palpus elongate, with 3rd segment longest, last slender and aciculate. Labial palpus distinctly slender, with 2nd longest, last slender and aciculate.

Neck. Rather narrow (ca. 0.12 mm), approximately of 1/4 of head width.

Pronotum (Fig. 12-1A).Subrectangular, distinctly elongate (PL to PW ratio 1.5), obviously longer than head, but of same width. Slightly dilated anteriad, sides slightly concavely sinuate; anterior angles well defined, posterior angles broadly rounded. Integument shiny, extensively covered with oblique microstriae; with two rows of setiferous punctures on each side, admedian row consisting of 4-5 punctures, lateral row with 3-4 punctures obliquely arranged; hind angle puncture ca. 1-2 puncture diameters distant from lateral margin. Antesternal plate integrated, not concave; medial longitudinal and anterior transverse sutures both missing. Prosternum with demarcated medial longitudinal carina on furcasternum, prosternal process (between anterior legs) triangularly projecting upwards. Mesoventrite extensively covered with transverse microstriae, medial longitudinal carina missing, process of mesoventrite triangularly protruding backwards. Metaventrite rather long, medial longitudinal keel sharp and obvious, a fine furrow on posterior 1/3 of keel top; process of metaventrite subtruncated.

Elytra(Fig. 12-1A).Subrectangular, distinctly elongate (EL to EW ratio 1.2), obviously longer and wider than pronotum. Humeri well developed, lateral margins widened posteriorly, hind margin curved backwards. Integument shiny and flattened, without microsculpture. Each elytron with three rows of setiferous punctures, along suture, in middle and near lateral margin, with additional punctures irregularly scattered between them; deflexed portion of each elytron with 2-3 rows of sparse setiferous punctures.

Legs.First four segments of protarsi obviously dilated, heart shaped, bearing extremely dense clothing of white fine hairs ventrally, last tarsomere as long as III–IV combined. Last segment of both meso- and metatarsi longer than that of protarsi and about equal to length of II–IV combined. Tibiae with apical ctenidium, only protibia with 2-3 rows of subapical ctenidia.

Abdomen.Cylindrical, broadest at segment VI. Terga III–VII shiny, entire surface covered with distinct transverse microstriae, with sparse, scattered, tiny setiferous punctures, but denser laterobasally; each tergite with impunctate basal impression bearing more obvious transverse microstriae. All abdominal sterna shiny, with microstriae and setiferous punctures as those on terga.

Male. Tergite VIII entirely covered with setiferous punctures, except a narrow medial longitudinal impunctate band; posterior margin of tergite VIII and sternite VIII both broadly arcuate backwards (Fig. 12A, B). Tergite of genital segment (Fig. 12C) symmetrical and small, with sharp base and rounded apex, in situ broadly exposed between pleurites. Pleurites of genital segment symmetrical, connected mediobasally. Sternite (Fig. 12D) asymmetrical, with subtruncated base and more angular left side. Aedeagus (Fig. 12-1D; Fig. 12 E–G) elliptical and small sized, basal bulbus ca. 0.80 mm long; median lobe distinctly shorter than 1/3 of basal bulbus length. Parameres symmetrical and thin, distinctly shorter than 1/3 of basal bulbus length. Internal sac (Fig. 12-1E; Fig. 12H) with well sclerotized structure, spines composed of larger tubular-shaped spines and dark brown complex spines, apical portion with a pair of spines and a lighter spine.

Female. Posterior margin of tergite VIII subtruncated, but sternite VIII broadly arcuate. Genital segment (Fig. 12-1C) small, ca. 0.45 mm long. Sternite with subtruncated base. Additional brown and transverse sclerite attached at base of genital segment.

Distribution.

China (Yunnan).

Etymology.

The specific epithet is derived from the Latin word binarius and refers to the pair of spines on the apical portion of the internal sac.

Remarks.

Although the large eyes and the number of punctures on the pronotum are similar to Metolinus schulzvocki Bordoni, 2003 and Metolinus heuresilogus Bordoni, 2002, it may be distinguished by the combined characters of the male genital segment (Fig. 12C, D) and the aedeagus (Fig. 12-1D; Fig. 12 E–G).