Two new species of Oxycera (Diptera, Stratiomyidae) from Ningxia, China

Abstract Two new speices, Oxycera rozkosnyi sp. n. and Oxycera ningxiaensis sp. n., are described from Liupanshan Nature Reserve, Ningxia Hui Autonomous Region, Northwest China. All essential diagnostic characters are figured and possible relationships of both taxa are briefly discussed, and a new key to species of Oxycera from China. The type specimens are deposited in the Institute of Entomology, Guizhou University, Guiyang (GUGC).


Introduction
The genus Oxycera Meigen was erected by Meigen (1803) on the basis of the type species Musca hypoleon Linnaeus [= O. trilineata (L).]. At present 94 species are described worldwide (Woodley 2001;Hasbenli 2004, 2007;Yang et al. 2008Yang et al. , 2009Li et al. 2009;Zhang et al. 2009Zhang et al. , 2010; Wang et al. 2010). The highest number of species is known from the Palaearctic Region (61 spp.), followed by the Oriental Region (16 spp.), 11 spp. were found in the Afrotropical Region and 8 spp. in the Nearctic. As for research on the genus Oxycera in China, Kertész (1914) first described three new species from Taiwan, following which Pleske (1925), Séguy (1934), and Lindner (1940) described four species. Yang and Nagatomi (1993) recorded 13 spp. (not including O. meigenii) from China and recently 8 new species and a new country record have been published for China Wang et al. 2010;Yang et al. 2008Yang et al. , 2009Zhang et al. , 2010. In the present paper, two new Chinese species are described.

Material and methods
External morphology was studied under a stereoscopic microscope, and measurements were made with an ocular micrometer. The genital segments of the examined specimens were macerated in 10% KOH and were preserved in glycerin for examination. All photographs were taken through a Canon 450D Camera, and were edited by Helicon Focus and Photoshop CS softwares. Illustrations of the specimens were made with a Nikon SMZ800 stereomicroscope and scanned with Canon CanoScan 5600F + , and then imported into Adobe Photoshop CS for labeling and plate composition.
Specimens examined in this study were collected in Ningxia Hui Autonomous Region, and are deposited in the Institute of Entomology, Guizhou University, Guiyang, Guizhou Province, P. R. China (GUGC). Morphological terminology follows Merz and Haenni (2000).  (Yang et al. 2009: Fig. 5), male head almost completely covered with dense hairs, thorax and lateral margin of abdomen with long and erect hairs : Fig. 1  Female scutum with 4 small and inconspicuous median yellow spots (Yang and Nagatomi 1993: Fig. 31); abdominal dorsum with two pairs of lateral yellow spots, a median yellow spot on tergite 2, and an apical yellow spot on tergite 5 (Yang and Nagatomi 1993: Fig. 32); male abdominal tergite 2 and anterior part of tergite 3 with a large transverse yellow band (Yang et al. 2008: Fig. 5)  Body larger (about 6.0 mm); male tergite 3 with a pair of lateral yellow spots : Fig. 18), female tergite 3 with four yellow spots in a transverse row : Fig. 19); male aedeagal complex bipartite : Fig. 26)  Body smaller (about 4.5 mm); abdomen with transverse yellow band on tergite 3 in both sexes (rarely divided into 3 spots in some females); male aedeagal complex tripartite (Yang and Nagatomi 1993: Fig. 58) ......O. tangi Lindner, 1940 24 Antenna yellowish brown; median process of male genital capsule with two rounded lobes (Rozkošný 1983: Pl. 46, Fig. 7 Paratypes. 3♂♂, the same locality labels as the holotype, all in GUGC. Diagnosis. Dark species with brownish yellow postpronotal callus, scutellar spines, postalar callus and narrow upper margin of anepisternum. Body hairs black, R 4 present, legs mostly dark to black but bases and tips of coxae, femora and tibiae yellow, tarsi black but 1-2 basal tarsomeres on mid and hind tarsus yellow.

Key to species of Oxycera Meigen from China
Description. Male (Figs 1-6). Length: body 4.8-5.2 mm, wing 4.3-5.0 mm. Head elliptical in frontal view, shining black, with black hairs; slightly broader than thorax, 1.4 times as long as high in profile and 0.8 times as high as broad. Vertex and ocellar tubercle black, both with black hairs. Ocelli and contiguous eyes brown, nearly bare, slightly darker in lower part, upper facets distinctly larger than lower. Frons shiny black; face black with some punctures and pale hairs, and a white lateral pollinose stripe on each side along eyes. Antenna dark brown to black, relative length of antennal scape, pedicel and flagellum (without arista) 3:5:10, relative width 7:9:10; arista about equal to length of rest of antenna. Occiput shiny black with some black hairs. Proboscis pale and palpus dark brown, both with some pale hairs.
Thorax (Figs 1, 2) mostly shining black, densely punctate and black haired; postpronotal callus, scutellar spines, postalar callus and narrow upper margin of anepisternum yellowish brown; length of scutellar spines only 1/4 as long as scutellum length. Wing black, stigma and veins darker than the mambrane, vein R 4 present. Legs mostly dark brown to black, but each femur and tibia with yellow base and apex, mid and hind tarsi 1 yellow; legs wholly with short pale hairs. Halter yellow with yellowish brown base.
Remarks. This new species is very similar to O. qiana Yang et al. 2009. Both are black but the new species is slender, with the scape and pedicel black, the male eyes are only sparsely haired or bare, and the male terminalia are species-specific (Figs 3-6). O. qiana is stouter, with a somewhat paler scape and pedicel and densely haired eyes. The male terminalia are of quite different shape (cf. Figs 7-11 in Yang et al. 2009), i.e. the genital capsule is narrowed distally and without a medial process, and the aedeagal complex is trilobate.
Etymology. The species is named after the type locality Ningxia in the Hui Autonomous Region.
Distribution. China (Ningxia). Diagnosis. Dark species without yellow stripes or spots on scutum (except postalar calli), eyes sparsely brown haired, legs mainly yellowish although femora mostly black. Abdomen with round yellow lateral markings on tergites 3 and 4 and a large central spot on tergite 1, and the posterior portion of tergite 5 yellow.
Description. Male unknown. Female (Figs 7-10). Length: body 6.3mm, wing 5.6 mm. Head (Figs 7-8, 10) shining black with yellow pattern, 1.5 times as high as long in profile and 0.7-0.8 as high as broad in dorsal view. Frons with 3 pairs of medial pruinose yellow spots above antennae and a subtriangular yellow spot at eye margin on each side. Eyes sparsely short brown haired. Postocular rim with a oblong yellow spot on upper part and a pale subtriangular spot above postgena. Antenna (Fig. 9) yellowish brown, but scape and basal part of pedicel dark brown; relative lengths of antennal scape, pedicel and flagellum (without arista) 1:1.5:4, relative widths 5:7:9; arista about 0.9 times as long as rest of antenna. Face with white pollinose stripes along eye margin at each side. Hairs on head pale. Proboscis (Fig. 8)  episternum with a narrow yellow stripe at upper margin from postalar callus to wing base; entire pleura with pale hairs. Legs: coxae and basal 4/5 of femora black, 3 rd to 5 th tarsomeres dark brown to black, rest of legs yellow to yellowish brown though tibiae slightly darkened at middle. Wing hyaline, veins pale yellow to brownish yellow, vein R 4 present. Halter yellow with dark brown base.
Abdomen  shining black with following yellow pattern (Fig.7): tergite 1 with a large central spot, tergites 3 and 4 each with a pair of yellow lateral spots, tergite 5 with yellow posterior margin. Dorsum densely punctate and sparsely haired; venter entirely black, entire abdomen pale haired.
Remarks. This new species is similar to O. dives Loew, 1845 and O. locuples Loew, 1857 known from Europe, but it may be separated from both by the missing dorsolateral stripes on the scutum and the large central spot on tergite 1. Lateral markings on tergite 2 are absent in the new species (and usually also in O. dives) but distinct in O. locuples. Using the most recent key to species of Oxycera from China (Zhang et al. 2010) the new species runs to couplet 9 (R 4 present) but spines on the scutellum are not almost vertical.
Etymology. The species is named in honor of Prof. Rudolf Rozkošný, a prominent Czech dipterist who contributed significantly to the knowledge of Palaearctic and Oriental Stratiomyidae.