Diochus bicornutus, 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 : 6-10

1. Diochus bicornutus sp. nov.

( Fig. 3 B; Fig. 4 A–P; Fig. 4-1 A–O)

Type material. Holotype: male, CHINA: Fujian: Shanghang co.: Meihua Shan: Shuangche (E 116.8568°, N 25.3411°), 475 m, 06.XI.2008, Wang Fengyan collected (IZ-CAS). Paratypes: Hainan: Ledong co.: Jianfeng Ling (E 108.8792°, N 18.7211°): Tianchi, one male, one female, 1000 m, 13.XI.2008, Zhao Zongyi collected (IZ-CAS); Yulingu, one male, 900 m, 23.XI.2008, Zhao Zongyi collected (IZ-CAS); Qiongzhong co.: Limu Shan (E 109.8016°, N 19.2349°), Sanquling, one male, 630 m, 04.XII.2007, Yang Zhuo collected; Lingshui Lizu autonomous co., Diaoluoshan (E 109.9160°, N 18.6598°), one male, 930 m, 30.VII.2004, Wu Jie & Chen Yongjie (IZ-CAS); Zhejiang: Lanao co.: Fengyang Shan (E 119.1989°, N 27.9381°), Fengyangjian, one male, 1400 m, 01.VIII.2008, Xu Jinhua collected (IZ-CAS); Guangxi: Fangchenggang City: Fulong co. (E 107.9518°, N 21.8146°), four males, one female, 660 m, 21.IV.1998, Zhou Haisheng collected (IZ-CAS); Yunnan: Mengla co.: Menglun (E 101.2490°, N 21.9375°), one female, 550 m, 08.II.2004, Wu Jie & Bai Daiyuan collected (IZ-CAS); Longmen village, Xiaoniupeng (E 101.3252°, N 21.3095°), one female, 1010 m, 06.X.2010, Zhou Yu-Lingzi collected (IZ-CAS); Jinghong City: Jinghong Nature Reserve (E 100.82263°, N 20.0665°), one female, 800 m, 26.II.2004, Wu Jie collected (IZ-CAS).

Description. Measurement (n=10). BL= (5.1–5.2) mm, FL= (2.8–2.9) mm, HL= (0.6–0.7) mm, HW= (0.5– 0.6) mm, PL= (0.9–1.0) mm, PW= (0.8–0.9) mm, EL= (0.9–1.0) mm, EW= (1.1–1.2) mm.

Body nearly fusiform shaped, large sized ( Fig. 3 B). Body dark brown, except elytra darker and abdominal intersegmental membrane yellowish brown ( Fig. 4 O). Legs brown, tarsi distinctly lighter. Antennae brown, apex of each antennomere lighter. Maxillary and labial palpi brown.

Head ( Fig. 4 A, D). Oblong in shape (HL to HW ratio 1.41), tempora (behind eyes) straight and paralleled, posterior angles rounded. Dorsal integument shiny, extensively bearing micropunctures and microstriae, also with 5–7 irregular, scattered punctures around each eye, and numerous smaller punctures on deflexed portion of tempus and near the posterior margin. Each side of cranium with 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 1/6, also with occipital puncture at the basal 1/5; in addition, disc surface bearing two additional paired punctures ( Fig. 1). Frontal furrows and anteocular furrows absent, a longitudinal linear elevation present between eyes ( Fig. 1). Eye medium sized, distinctly protruding laterad, longitudinal diameter slightly shorter than half the length of tempora (eye: tempora = 0.22: 0.45 mm). Epistoma not flattened, abruptly oblique, anterior margin slightly emarginate medially. Distance between antennal insertions 0.17 mm being distinctly longer than distance from antenna to eye (0.09 mm). Ventral surface ( Fig. 4 D) with scattered punctures, interspaces between them ca. 4 punctures’ diameter. Gular sutures deep, confluent at basal 1/4, then extended to base.

Antennae ( Fig. 4 G). Total length 1.6 mm. Scape rod-shaped, slightly thickened apically, 0.29 mm, shorter than two subsequent antennomeres combined; antennomere II elongate, 0.16 mm; III 0.19 mm, distinctly longer than II; IV 0.13 mm, IV to X gradually shortened, IV observably longer than X; XI 0.16 mm, distinctly longer than X.

Mouthparts ( Fig. 4 H–J, P). Labrum subrectangular ( Fig. 4 H), lateral margin slightly wave-shaped, anterior margin sinuous. Mandibles falciform, left one with three small teeth on inner edge, right one with a small tooth ( Fig. 4 I–J).

Neck ( Fig. 4 K–L). Surface shiny and nearly trapezoidal shaped, only bearing shallow microsculpture, with a bisinuate basal furrow near posterior margin ( Fig. 4 K), width of 0.22 mm, wider than 1/3 width of head. Ventral surface with deep gular sutures to form obvious triangular region, which missing transverse median furrow ( Fig. 4 L).

Prothorax ( Fig. 4 B, E). Pronotum elliptical (PL to PW ratio 1.19), markedly wider than head, also distinctly longer. 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 margin (including anterior, lateral and posterior margins). Prosternum bearing a distinct transverse ridge between basisternum and furcasternum, which angularly backwards ( Fig. 4 E).

Pterothorax ( Fig. 4 F, N). Mesoscutellum triangular and small ( Fig. 4 N), surface shiny, bearing obvious microstriae, but without any punctures. The transverse ridge on mesoventrites substraight ( Fig. 4 F); the longitudinal ridge distinct; the paired oblique furrows short but deep; the carina (limiting mesocoxal cavity) slightly arcuate. The discrimen region on metaventrite normally elevated.

Elytra ( Fig. 4 C). Transverse and short (EL to EW ratio 0.84), distinctly wider than pronotum, and shorter. Humeri well developed, lateral margins divergent posteriorly, posterior 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. 4 M). First four segments of protarsi stout, wider than those of meso- and metatarsi. Last segment of protarsi longer than II–IV together; that of meso- slightly longer than II and III together; that of meta- longer than II and III together.

Abdomen ( Fig. 4 O) 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. Tergite VII possessing a transparent palisade fringe on posterior margin. All abdominal sternites shiny, with microstriae and punctures as those on tergites.

Male ( Fig. 4-1 A–G, K–M). Posterior margin of tergite VIII sinuate ( Fig. 4-1 A), that of sternite VIII slightly triangularly incised ( Fig. 4-1 B), sometimes more distinctly ( Fig. 4-1 K), also bearing coarser setae. Tergite IX symmetrical, connected mediobasally ( Fig. 4-1 C), sharpened apically. Sternite IX symmetrical, widest near the middle, with paired longitudinal furrow near each lateral margin, and basal margin wide and subtruncate ( Fig. 4- 1 D); sometimes basal 1/2 distinctly wider ( Fig. 4-1 M). Tergite X symmetrical, triangular, with curved basal margin ( Fig. 4-1 C). Aedeagus normally sclerotized, elongate, large in size ( Fig. 4 E, F), ca. 0.6 mm long, ventral surface with scattered dots. Parameres symmetrical and slightly curved, thin and slightly shorter than 1/3 times the length of basal bulb; paired sclerites attached to base of parameres in ventral surface. Internal sac possessing inner sclerites composed of three parts: two paired sclerites at top (one soft and light color; the other horn-like shaped and black color), paired C-shaped sclerites in centre, and also rectangular sclerite in centre ( Fig. 4-1 E, L). Sperm pump spirally coiled, thinned toward apex ( Fig. 4-1 G).

Female ( Fig. 4-1 H–J, N–O). Tergite IX bearing numerous setae, elongate and sharply pointed apically ( Fig. 4- 1 O). Sternite IX symmetrical, each integrated, and with an observable concaved margin on apical 1/3 ( Fig. 4-1 H). Tergite X nearly triangular, basal margin curved ( Fig. 4- 1 I). Sternite X slender and rhomboidal ( Fig. 4-1 N). Outer capsule of spermatheca with parallel sides and sharp apical margin, and tube with two apical dilated lobes ( Fig. 4- 1 J).

Distribution. Fujian, Hainan, Zhejiang, Guangxi, Yunnan.

Etymology. The specific epithet is derived from the combination of Latin adverb “ bis ” (twice) and the adjective “ cornutus ” (having horns), which refer to the paired horn-like sclerites of internal sac.

Remarks. The short, paired parameres and paired sclerites present on the apex of aedeagus are the similar to those of D. conicollis (Motschulsky) , but the shape of the aedeagus is elongate, and the apical sclerites are hornlike. The body size is bigger, with a longer head; the outer capsule of the female spermatheca possesses parallel sides and a sharp apex. The shape of the spermatheca in D. punctipennis (Motschulsky) (Female, 1 syntype examined, MMZ) is similar to this species, but the ratio of spermatheca length/width in D. bicornutus is smaller and the outer capsule is parallel-sided.

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 4. Diochus bicornutus 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 four segments of abdomen, dorsal view; P. labial & maxillary palpi, ventral view. Scale bars 0.30 mm.