Metolinus emarginatus 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 : 57-59

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Metolinus emarginatus Zhou & Zhou

sp. n.

2. Metolinus emarginatus Zhou & Zhou   ZBK sp. n. Fig. 11 A–HFig. 11-1 A–E

Type material.

Holotype: CHINA:Sichuan: male, Baoxing co. (E 102.8146, N 30.3681), Pujigou, 2450 m, 11.VIII.2003, Wu Jie collected (IZ-CAS); Paratypes: CHINA:Sichuan: 2 males, 4 females, same data as holotype.


Measurement.BL=5.8 mm, FL=2.9 mm, HL =0.84 mm, HW=0.78 mm, PL= 1.00 mm, PW=0.69 mm, EL=1.00 mm, EW=1.00 mm.

Body medium sized and nearly compressed. Body entirely dark brown, except each apical 1/3 of abdominal segment lighter. Legs dark brown, tarsi lighter. Antennae, maxillary palpi and labial palpi light brown.

Head (Fig. 11-1A). Subquadrate (HL to HW ratio 1.1), tempora (behind eyes) widened posteriorly, posterior angles rounded. Dorsal integument shiny, extensively covered with distinct transverse microstriae, and with sparse, scattered setiferous punctures of medium size, distance between punctures ca. 3 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 parallel and of medium length, longer than 1/2 of eye length. Ocular furrows deep and long, over eye length. Eye medium sized, nearly 1/3 of temple length (eye: temple =0.18:0.53 mm), slightly protruding laterad. Epistoma not protruding, anterior margin subtruncated, dorsally flat and broad, over 1/2 of eye length. Distance between antennal insertions ca. 0.23 mm, subequal to that from antenna to eyes (ca. 0.26mm). Ventral integument shiny, with same microstriae and setiferous punctures as on dorsal integument. Mentum with three pairs of setae inserted at each anterior angle in addition to other irregularly scattered setae, submentum with four pairs of setae. Gular sutures fused at middle, but separated at base of occiput. Gular plate devoid of punctures, but with distinct transverse microstriae.

Antennae (Fig. 11-1B). Scape stout, thickened apically, longer than three subsequent antennomeres combined, ca. 0.45 mm; 2nd elongate, ca. 0.15 mm, distinctly longer than 3rd; 3rd globular, ca. 0.075 mm; 4th and 5th subequal, ca. 0.06 mm; last antennomere moderately long, ca. 0.15 mm, subequal to preceding 2 antennomeres combined.

Mouthparts. Labrum short and U-shaped bilobed, two subtruncated teeth on anterior margin. Mandibles falciform, left one with two teeth on medial edge. 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. 0.24 mm), slightly wider than 1/4 of head width.

Pronotum (Fig. 11-1A).Subrectangular, distinctly elongate (PL to PW ratio 1.4), obviously longer than head, but of same width. Widened anteriad, lateral margins concavely sinuate; anterior angles well defined, posterior angles broadly rounded. Integument shiny, extensively with oblique microstriae; with two rows of setiferous punctures on each side, admedian row consisting of 7-9 punctures, lateral row of 6-8 punctures obliquely arranged; hind angle puncture ca. 1-2 puncture diameters distant from lateral margin. Antesternal plate integrated and not shallowly concave; medial longitudinal suture missing, transverse suture at anterior 1/5 fine but visible. Prosternum with demarcated medial longitudinal carina on posterior 1/5 of basisternum, anteriorly fused with prosternal process (between anterior legs). Mesoventrite extensively covered with transverse microstriae, medial longitudinal carina demarcated, process of mesoventri te arcuately protruding backwards. Metaventrite rather long, medial longitudinal keel sharp and obvious, with a fine furrow on posterior 1/2 of keel top; process of metaventrite subtruncated.

Elytra (Fig. 11-1A). Subquadrate, distinctly elongate (EL to EW ratio 1.0), of same length as pronotum, but distinctly wider. Humeri well developed, lateral margins widened posteriorly, hind margin convex. Integument shiny and flattened, without microsculpture, with setiferous punctures arranged in several rows (more than 3) on each side; deflexed portion of each elytron with 3-5 rows of 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; 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 (Fig. 11A) and sternite VIII (Fig. 11B) broadly arcuately protruding backwards,. Tergite of genital segment (Fig. 11C) symmetrical and medium sized, widest at midlength, with sharp base and rounded apex, in situ broadly exposed between pleurites. Pleurites of genital segment symmetrical, connected mediobasally. Sternite (Fig. 11D) asymmetrical, with rounded base and subtruncated right side. Aedeagus (Fig. 11-1DFig. 11 E–G) pear-shaped and small sized, basal bulbus ca. 0.75 mm long; median lobe medium sized and sharply narrowed towards apex, ca. 1/3 of basal bulbus length. Parameres symmetrical and thin, ca. 1/3 of basal bulbus length. Internal sac (Fig. 11-1E; Fig. 11H) with brown and slightly sclerotized structure, composed of soft scales and 2-3 darker and transverse tubular-shaped structures medially.

Female. Posterior margin of tergite VIII and sternite VIII distinctly arcuate backwards. Genital segment (Fig. 11-1C)small, ca. 0.50 mm long. Sternite with subtruncated base. In addition, with some membranous structures attached to base of genital segment.


China (Sichuan).


The specific epithet is the Latin word emarginatus (emarginate) and refers to the shape of anterior margin of the epistoma.


Although the shape of the median lobe of the aedeagus seems similar to that of Metolinus yunnanus Bordoni, 2002 and Metolinus loebli Bordoni, 2002, the species may be distinguished by the longer parameres (Fig. 11E), different shape and composition of the internal sac (Fig. 11G), and by the tergite and sternite of the genital segment (Fig 11A, B).