Diochus japonicus Cameron , 1930

Zhou, Yu-Lingzi & Zhou, Hong-Zhang, 2016, Taxonomy of the genus Diochus Erichson, 1839 (Coleoptera: Staphylinidae, Staphylininae, Diochini) in China with descriptions of four new species, Zootaxa 4127 (1), pp. 1-30 : 25-26

7. Diochus japonicus Cameron, 1930

( Fig. 3 A)

Cameron, 1930: 206 (Type locality: Kobe); Scheerpeltz, 1933: 1324 (catalog); Nakane, 1963: 90 (habitus photograph; Japan); Herman, 2001: 2446 ( Diochus ; catalog); Smetana, 2004: 624 (Palaearctic catalog; Jilin, Liaoning; Japan, South Korea); Löbl & Löbl, 2015: 1007 (Palaearctic catalog; Jilin, Liaoning; Japan, South Korea).

Type material examined: female, with labels as follows: “Holo-, Typus ”/ “D., japonicus Came , TYPE ”/ “ HOLOTYPE, Diochus , japonicus , cameron, 1930, det. R.G. Booth 2013”/ “M. Cameron., Bequest., B.M.1955– 147.”/ “ JAPAN, Kobe, 27-11-30 ” ( BMNH).

Description. Measurement. BL= 5.95 mm, FL= 2.51 mm, HL= 0.67 mm, HW= 0.56 mm, PL= 0.94 mm, PW= 0.74 mm, EL= 0.82 mm, EW= 1.01 mm.

Body nearly fusiform shaped, large sized ( Fig. 3 A). Body brown, except abdominal intersegmental membrane yellowish brown. Legs yellow brown. Antennae brown, basal two antennomeres smoother and lighter than remaining antennomeres. Maxillary and labial palpi yellow brown.

Head. Oval in shape (HL to HW ratio 1.2), tempora (behind eyes) dilated and arcuate posteriad, widest at basal 1/3, posterior angles rounded. Dorsal integument shiny, extensively bearing micropunctures and microstriae, also with 5–7 large, scattered punctures around each eye, and numerous smaller punctures on deflexed portion of tempus and near the posterior margin. Each side of cranium with large characteristic punctures: one frontal puncture on frontal region, two anterolateral punctures near antennal insertion, three ocular punctures near dorsal margin of eye, temporal puncture at the basal 1/5, also with occipital puncture at the basal 1/4. Frontal furrows and anteocular furrows absent. Eye medium sized, slightly longer than half the length of tempora (eye: tempora = 0.20: 0.38 mm), distinctly protruding laterad. Epistoma not flattened, abruptly oblique, anterior margin emarginate medially. Distance between antennal insertions 0.16 mm being distinctly longer than distance from antenna to eye (0.11 mm).

Antennae. Total length 1.69 mm. Scape rod-shaped, slightly thickened apically, 0.26 mm, shorter than two subsequent antennomeres combined; antennomere II elongate, 0.15 mm; III 0.19 mm, distinctly longer than II; IV 0.11 mm, IV to X gradually shortened, IV slightly longer than X; XI 0.11 mm, slightly longer than X.

Neck. Surface shiny, only bearing shallow microsculpture, in trapezoidal shape, width of 0.21 mm, slightly wider than 1/3 width of head.

Pronotum. Elliptical (PL to PW ratio 1.3), distinctly longer than head. Anterior region near anterior angles deflexed and narrowed, lateral margins widened posteriad to basal 1/3 (with the widest at apical 1/3), then convergent backwards, anterior and posterior angles broadly rounded. Dorsal surface glossy extensively with micropunctures, but without any microsculpture. Each side of the midline with symmetrical five large lateral punctures, with additional 13–15 punctures near each margins (including anterior, lateral and posterior margins).

Mesoscutellum. Triangular and small. Surface shiny, bearing some light microstriae, but without any punctures.

Elytra. Transverse and short (EL to EW ratio 0.81), distinctly wider and shorter than pronotum. Humeri well developed, lateral margins divergent posteriorly, hind margin not rounded, but obliquely truncate. Dorsal integument shiny, flattened, without microsculpture; each elytron with a row of 5 punctures along suture, a row of 5 punctures in median, also with 4–5 rows of punctures on deflexed portion.

Legs. First four segments of protarsi stout, wider than those of meso- and metatarsi slender. Last segment of protarsi longer than II–IV together; that of mesotarsi slightly longer than II and III together; that of meta- longer than II and III together.

Abdomen. Broadest at segment V. Tergites III–VII covered with dense and obvious transverse microstriae; each tergite with dense yellow pubescence, also with a row of darker and coarser setae at posterior margin of III– VI. Tergites III–VII with a basal impression near anterior margin, respectively, each one only possessing one basal transverse carina; surface shiny, bearing polygonal reticulum, but without any punctures. The intersegmental membrane bearing transparent yellow fenestra. All abdominal sternites shiny, with microstriae and punctures as those on tergites.

Male. Unknown.

Distribution. China (Jilin, Liaoning, Taiwan); Japan; South Korea.

Remarks. This species possesses some similar characters to D. bicornutus sp. nov., like the shape of the antennomeres, pronotum shape and body color, but the body size is large (ca. 6.0 mm), and the head is shorter, length 1.2 times longer than width. However, up to now, only one female specimen has been found, this problem is thus left open for further study.

Figures

FIGURE 3. Habitus of seven species in dorsal view: A. Diochus japonicus Cameron, 1930; B. D. bicornutus sp. nov.; C. D. conicollis (Motschulsky, 1858); D. D. ampullaceus sp. nov.; E. D. bisegmentatus sp. nov.; F. D. membranaceus sp. nov.; G. D. pulchellus Cameron, 1918. Scale bars 0.50 mm.