Diochus membranaceus, Zhou, Yu-Lingzi & Zhou, Hong-Zhang, 2016

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 : 17-20

4. Diochus membranaceus sp. nov.

( Fig. 3 F; Fig. 7 A–O; Fig. 7-1 A–F)

Type material. Holotype: male, CHINA: Fujian: Jiangle co., Longxishan, Yujiaping (E 117.2980°, N 26.4911°), 21.VI.1991, Wang Huifu collected (IZ-CAS). Paratype: Fujian: Jiangle co., Longxishan, Yujiaping (E 117.2980°, N 26.4911°), one male, 21.VI.1991, Wang Huifu collected (IZ-CAS).

Description. Measurement. BL= (3.4–3.5) mm, FL= (1.6–3.5) mm, HL= (0.4–0.5) mm, HW= (0.4–0.5) mm, PL= (0.5–0.6) mm, PW= (0.4–0.5) mm, EL= (0.5–0.6) mm, EW= (0.5–0.6) mm.

Body nearly fusiform shaped, small sized ( Fig. 3 F). Body entirely brown, except antennae, legs, maxillary and labial palpi light brown.

Head ( Fig. 7 A, D). Nearly triangular (HL to HW ratio 0.96), tempora (behind eyes) extraordinarily widened backwards, posterior angles rounded. Dorsal integument shiny, extensively bearing microsculpture mixed by polygonal reticulum (mainly on frontal region) and microstriae, without punctures around each eye, but bearing scattered smaller punctures on deflexed portion of tempus and larger punctures near the posterior margin. Each side of cranium with characteristic punctures: one frontal puncture on frontal region, two anterolateral punctures near antennal insertion, three lateral punctures near dorsal margin of eye, but occipital puncture and temporal puncture unidentified; besides, disc surface bearing two additional paired punctures. Frontal furrows and anteocular furrows absent, without elevation between eyes. Eye small, smaller than 1/3 length of temple (eye: tempora = 0.08: 0.29 mm), flat, not protruding laterad. Epistoma broadly emarginate. Distance between antennal insertions 0.15 mm being distinctly longer than distance from antenna to eye (0.07 mm). Ventral side shiny and smooth, each side with two large-sized punctures along lateral margin, 3–4 small punctures near base. Gular plate distinctly broad, gular sutures widely separated ( Fig. 7 D).

Antennae ( Fig. 7 G). Total length 1.0 mm. Scape rod-shaped, slightly thickened apically, 0.19 mm, longer than two subsequent antennomeres combined; antennomere II elongate, subequal length to III, 0.08 mm; IV and V rectangular, subequal in length (0.07 mm); VI to X square in shape, slightly shorter than length of V; XI 0.10 mm, distinctly longer than X.

Mouthparts ( Fig. 7 H–J). Labrum not transverse, but nearly pentagon ( Fig. 7 H). Mandibles falciform and slender; left one with two sharp teeth on inner edge, right one also bearing two closer teeth ( Fig. 7 I–J).

Neck ( Fig. 7 K–L). Cylindrical, width of 0.14 mm, narrower than 1/3 width of head; shiny, only bearing observable microsculpture, with a bisinuate basal furrow near posterior margin ( Fig.7 K). Ventral surface missing triangular region, with observable transverse median furrow ( Fig. 7 L).

Prothorax ( Fig. 7 H–J). Pronotum quite elongate (PL to PW ratio 1.25), distinctly longer than head, but of same width. Anterior region near anterior angles not very deflexed, lateral margins slightly divergent backwards, with widest at basal 1/3, 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). Prosternum bearing observable transverse ridge between basisternum and furcasternum, slightly arcuate backwards ( Fig. 7 E).

Pterothorax ( Fig. 7 F, N). Mesoscutellum slightly sharp triangular and small ( Fig. 7 N), surface shiny, bearing some light microstriae, but without any punctures. The transverse ridge on mesoventrites in wave shape ( Fig. 7 F); the longitudinal ridge not distinct; the paired oblique furrows short but deep; the carina limiting mesocoxal cavity curved, not wave-shaped. The discrimen region on metaventrite normally elevated.

Elytra ( Fig. 7 C). Transverse and short (EL to EW ratio 0.86), shorter and wider 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 ( Fig. 7 M). First four segments of protarsi heart-shaped, dilated, and those of meso- and metatarsi slender. Last segment of protarsi equal to length of II–IV, that of meso-, meta- equal to length of each II–III.

Abdomen ( Fig. 7 O). Broadest at segment V. Tergites III–VII covered with dense and obvious transverse microstriae; each tergite with dense and brown pubescence, posterior margin of III–VI with coarser brown setae. Tergites III–VII with a basal impression near anterior margin, respectively, each one only possessing one basal transverse carina; surface shiny, without any punctures or microsculpture. Tergite VII possessing a transparent palisade fringe on posterior margin. All abdominal sternites shiny, with microstriae and punctures as those on tergites.

Male ( Fig. 7-1 A–F). Posterior margin of tergite VIII slightly arcuate backwards ( Fig. 7-1 A), that of sternite VIII broadly emarginate ( Fig. 7-1 B). Tergite IX symmetrical, connected mediobasally, sharpened apically. Sternite IX symmetrical, widest at basal 1/3, basal margin emarginate, a small tooth at each hind angle ( Fig. 7-1 D). Tergite X in reuleaux triangular shape ( Fig. 7-1 C). Aedeagus small sized ( Fig. 7 E, F), 0.35 mm long, dorsal and ventral surface mostly membranous. Parameres symmetrical, small and horizontal ( Fig. 7-1 E). Internal sac with asymmetrical and sclerotized structures ( Fig. 7-1 E). Sperm pump relatively long, folded basally, and coiled apically ( Fig. 7-1 F).

Female. Unknown.

Etymology. The specific epithet is derived from the Latin adjective word “ membranaceus ” (of membrane) and refers to the membranous aedeagus.

Distribution. Fujian.

Remarks. Although this new species is similar in head shape and coloration to the Indian species D. ochraceus Cameron (Female, 1 syntype examined, BMNH), it can easily be distinguished by the following combination of characters: 1) distinctly dilated tempora; 2) lack of elevation on head; 3) smaller eyes; 4) widely separated gular sutures; 5) elongate mandibles; 6) fully membranous aedeagus.

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.

FIGURE 7. Diochus membranaceus sp. nov.: A. head, dorsal view; B. pronotum, dorsal view; C. elytra, dorsal view; D. head, ventral view; E. pronotum, ventral view; F. elytra, ventral view; G. antennae; H. labrum; I. left mandible; J. right mandible; K. neck, dorsal view; L. neck & cervical sclerites, ventral view; M. proleg; N. mesoscutellum; O. basal visiable three segments of abdomen, dorsal view. Scale bars 0.10 mm.