On Chinese species of Dianous group I (Coleoptera, Staphylinidae, Steninae)

Abstract Chinese species of Dianous group I are studied and three new species are described: Dianous fengtingae sp. n. from Hainan Province, Dianous zhujianqingi sp. n. from Jiangxi and Guizhou Province, and Dianous huanghaoi sp. n. from Yunnan Province. Dianous shan Rougemont and Dianous viridicupreus Rougemont are discovered from China for the first time. Their diagnostic characters are illustrated and a key to Chinese species of Dianous group I is provided.


Introduction
The members of Dianous group I have large eyes and simple tarsi, and therefore were regarded as Stenus by earlier entomologists. In 1981 Puthz made a systematic comparison between these two genera and revealed that this group without protrudable labium surely belonged to Dianous. To distinguished it from other members of Dianous, the following characters can be used: eyes large, usually without temples; tarsi simple, without tarsal shoes; frons with median portion not elevated.
Up to the present, 59 species of Dianous group I have been described, which account for nearly 30 percent of the genus. All of the species are distributed in the Oriental region and seem to be rare. In Chinese fauna, only four species were previously reported by Puthz (2000): D. yao Rougemont, 1981 from Guizhou and D. tonkinensis (Puthz), 1968 from Yunnan, Puthz (2001): D. limitaneus Puthz, 2001 from Yunnan, Shi and Zhou (2010): D. viriditinctus (Champion), 1920 from Xizang. In this paper, we complement the list with several new records and new species based on material from South China.

Material and methods
Specimens examined in this paper were all collected near streams through forests and killed with ethyl acetate. For examination of male genitalia, the last three abdominal segments were detached from the body after softening in hot water. The aedeagus together with other dissected pieces were mounted in Euparal (Chroma Geselschaft Schmidt, Koengen, Germany) on plastic slides. Photos of sexual characters were taken with Cannon G7 attached to Olympus SZX 16 stereoscope; habitus photos were taken with a Cannon macro photo lens MP-E 65mm attached to Cannon EOS40D camera.
The type specimens treated in this study are deposited in the following public and private collections: Head 1.04 times as wide as elytra; interocular area gently inclined inward forming a shallow and broad concavity; punctures round, distinctly delimited, slightly larger on median area than near dorsal margins of eyes, diameter of large punctures about as wide as widest cross section of 2nd antennal segment, interstices smooth, mostly smaller than half diameter of punctures. Antennae when reflexed exceeding posterior margin of pronotum; length of segments from base to apex: 10.0: 7.0: 17.5: 11.0: 9.0: 8.0: 8.0: 7.0: 7.0: 8.0: 10.0.
Pronotum 1.28 times as long as wide, widest slightly before middle and constricted at base; punctures round, partially slightly confluent, distinctly larger than those on frons, interstices smooth, mostly smaller than half diameter of punctures.
Elytra nearly rectangular; punctation on average slightly coarser than that of pronotum, punctures on humeral area mostly distinctly delimited, and those on inner 2/3 portion of elytra (especially those on posterior half ) obliquely confluent, interstices similar to those on pronotum.
Male. Seventh sternite (Fig. 29) with a distinct posteriomedian emargination, 8th sternite ( Fig. 30) with a broad triangular emargination posteromedially; 9th sternite ( Fig. 31) with the apicolateral portion serrate, posterior margin slightly emarginate; 10th tergite ( Fig. 32) with the posterior margin broadly rounded. Median lobe of aedeagus ( Fig. 18) with an acutely pointed and setose apex (Fig. 19), parameres extending far beyond the apex of median lobe. Distribution. China (Hainan). Diagnosis. The new species is similar to D. tonkinensis (Puthz, 1968) from South Asia and D. lividus (L. Benick, 1929) from Philippines and Indonesia. It may be distinguished from both by the coarser and less confluent punctation on pronotum and especially on elytra. Rougemont, 1981 Head about as wide as elytra; lateral portions of front slightly rising, medial portion concave; punctures round, distinctly delimited, slightly larger on median area than near dorsal margins of eyes, diameter of large punctures about as wide as apical cross section of 3rd antennal segment, interstices smooth, smaller than or as broad as half diameter of punctures. Antennae when reflexed extending to the posterior margin of pronotum; Length of segments from base to apex: 9.0: 6.5: 9.0: 8.0: 8.0: 5.5: 8.0: 6.0: 7.0: 6.5: 9.0. Pronotum 1.10 times as long as wide, widest slightly before middle and constricted at base; punctures partially confluent, diameter of large punctures about as wide as apical cross section of 2nd antennal segment, interstices smooth, mostly smaller than or about as broad as half diameter of punctures. Elytra nearly rectangular; punctation similar to that of the pronotum, punctures on humeral area mostly distinctly delimited, those on medial two thirds obliquely confluent, interstices similar to those on pronotum.
Diagnosis. The new species slightly resembles D. cyaneovirens (Cameron, 1930) from India, Nepal, Bhutan and D. bracteatus (Champion, 1920) from India, and Nepal. From both it may be easily distinguished by the faint metallic coloration (D. cyaneovirens and D. bracteatus: strongly metallic green), and from D. bracteatus also by darker legs. Description. Body entirely black with a faint plumbeous lustre. Antennae blackish brown, antennal club slightly lighter than preceding segments. Maxillary palpi brownish. Legs black with a brownish tint, tibiae and tarsi slightly lighter.
Pronotum 1.15 times as long as wide, widest slightly before middle and constricted at base; punctures partially confluent, similar in size to those on head, interstices similar to those on frons.
Elytra nearly rectangular; punctation similar to that of the pronotum, punctures on humeral area mostly distinctly delimited, those on posterior half of elytra strongly confluent, forming a narrowly vorticose sculpture.
Relative length of segments of hind legs from base to apex as 15.0: 8.5: 5.5: 3.5: 14.5. Abdomen subcylindrical; 3rd to 6th segments with broad and densely punctate paratergites, paratergites on 4th segment as broad as largest width of hind tibia; 7th tergite with an apical membranous fringe; punctures on 3rd tergite distinctly smaller than eye facet, interstices smooth.

Dianous yao
Diagnosis. No Chinese material was examined by us; a photograph of a paratype (cPut) from Myanmar is provided here. Distribution. China (Yunnan). Diagnosis. This species was only known from the female holotype, which is actually deposited in "the collection of the Laboratory of Entomology, Tokyo University of Agriculture", not in "Shanghai Institute of Entomology, Academia Sinica" (Present name: Shanghai Entomology Museum, the Chinese Academy of Science) as original published paper described.
Diagnoses. No Chinese material was examined by us, and a photograph of specimen (cPut) from Nepal is provided here.