Loxocera (Loxocera) maculithorax, Zhou & Yang, 2023

Zhou, Jiale & Yang, Ding, 2023, A review of the subgenus Loxocera Meigen, 1803 (Diptera, Brachycera, Psilidae) in China, ZooKeys 1186, pp. 71-96 : 71

Loxocera (Loxocera) maculithorax sp. nov.

Figs 18-19 , 20-22 , 23-26

Type materials.

Holotype (♂): China, Shaanxi, Baoji, Longxian, Guanshan Grassland, 2034 m, 2020.viii.13, leg. Bing Zhang (CAU). Paratypes: same collection data as for holotype (1♂1♀, CAU).

Diagnosis.

Generally dark brown; face brown; antennal scape and pedicel subequal in length; apex of antennal first flagellomere produced beyond base of arista; arista laterally compressed and very high, arising at apex of antennal first flagellomere and 2.1 times as long as the latter; mesonotum blackish, with irregular, brownish margin; wing with broad, transverse, dark band at level of posterior crossvein; hypandrial lobe large, short, covered with long setae; pregonite stout, lobate, apically blunt, with some rounded processes; phallus tongue-like, relatively short, with rounded posterior margin.

Description.

Male and female. Body length 8.8-10.5 mm, wing length 6.2-7.0 mm, length of antenna 1.9-2.3 mm. Generally dark brown, moderately shining (Figs 18 , 19 ). Frontal vitta black, with anterior and median parts dark yellow (Fig. 20 ); face brown; parafacial, gena, postgena, proboscis, and palpus pale brown (Fig. 21 ). Postpronotum brown. Mesonotum largely blackish brown, with irregular, dark brown margin as shown in Fig. 22 . Wing slightly infumated, with broad, transverse, dark band at level of posterior crossvein, band more or less interrupted along center of cells r2+3, r4+5 and dm; wing veins yellowish brown to brown. Halter white with base slightly darkened. Legs dark brown to blackish brown; trochanters, apex of femora, fore and mid tibiae, and tarsomere 1 yellowish brown; hind tibia in male dark brown except base and apex slightly paler (Fig. 18 ), in female yellowish brown, with wide, median, dark brown ring (Fig. 19 ). Abdomen reddish brown (♀, Fig. 19 ) to dark reddish brown (♂, Fig. 18 ); syntergite 1+2, tergite 6 and posterior portion of tergite 5 in male, and tergite 7 and posterior margin of tergite 6 in female blackish brown. Bristles on head and thorax black.

Head (Figs 20 , 21 ) transverse oblong in dorsal view, largely glabrous; length along midline 0.7 times as long as width across eyes, width across eyes 2 times as broad as interocular space. Frons slightly protruding beyond level of anterior eye margin; frontal vitta with shallow depression at middle; frontal orbit with some short, scattered hairs. Ocellar triangle broad, smooth, with silvery tomentose stripes along lateral margins. Face strongly slanting, with moderately elevated median carina. Parafacial narrow, with a tomentose golden patch between anterior eye margin and lunule. Gena swollen; postgena covered with silvery tomentum. Occiput with a large silvery tomentose patch at middle above foramen. Head chaetotaxy: 1 ocellar seta, 1 postvertical seta, 1 inner vertical seta, 1 outer vertical seta. Antenna (Fig. 21 ) long and thick, with short, dense setulae; scape nearly as long as pedicel, gradually widened towards apex; first flagellomere about 2 times as long as pedicel, apex strongly curving ventrally, produced beyond base of arista; arista laterally compressed and very high, arising at apex of first flagellomere, 2.1 times as long as first flagellomere, divided into small aristomere 1 and large aristomeres 2+3. Palpus elongate oval, with short, dense setulae and long, scattered setae.

Thorax (Figs 18 , 19 , 22 ) robust, with short, dense, whitish-yellow setulae, except anepisternum (anterior half), anepimeron, katatergite, meron, scutellum, and mediotergite (middle portion) glabrous; anatergite with fine tomentum. Scutum 1.4 times as long as wide. Scutellum (Fig. 22 ) subtriangular, slightly swollen, and wider than long. Thoracic chaetotaxy: 1 dorsocentral seta, 1 notopleural seta, 2 posterior supra-alar setae, 1 apical scutellar seta. Wing with last sector of M1 strongly curved; apex of M4 nearly reaching wing margin. Legs with dense, whitish-yellow setulae, except ventral surface of fore and mid femora largely glabrous; femora subfusiform, slightly compressed laterally; tibiae gradually widened towards apex, fore and mid tibiae straight, hind tibia finely curved.

Abdomen elongate, with short, dense, whitish-yellow setae; syntergite 1+2 with several long hair-like setae laterally.

Male genitalia: Sternite 8 (Figs 23 , 24 ) broad, with long, dense setae, dorsally with a wide, blunt protrusion at middle. Cerci (Figs 23 , 24 ) relatively broad, elongate, with short, dense setae. Hypandrium (Fig. 26 ) well developed; hypandrial arms fused posterodorsally, posteriorly produced into large, short, convex lobes covered with long setae (Figs 23-26 ). Hypandrial bridge present and robust. Pregonite (Figs 23-25 ) stout, lobate, apically blunt, with some rounded processes. Phallus (Figs 23-25 ) tongue-like, relatively short, with rounded posterior margin. Phallotrema (Fig. 25 ) large, flanked by some peculiar, tiny processes. Ejaculatory apodeme (Fig. 24 ) small, hook-like, strongly curved.

Female terminalia: Segment 7 laterally compressed; sternite 7 keeled along midline. Segment 8 coriaceous and longitudinally striate, posterodorsal margin shallowly emarginate, posterolateral margin forming acute angular protrusion, posteroventral margin with deep linear incision. Tergite 10 relatively short and narrow, with scattered tiny setulae. Cerci relatively broad, separate from tergite 10, with rows of long setulae on posterior margin.

Etymology.

The specific epithet is derived from Latin macula (meaning spotted) and Greek thorax (meaning thorax), referring to the mesonotum of the new species, which is blackish with an irregular brownish margin.

Distribution.

China - Shaanxi: Baoji (Fig. 37 ).

Comparative notes.

This new species is similar to L. (L.) fujiana , but it can be readily separated from the latter by the different coloration of head, mesonotum, hind tibia, and abdomen, the apically curved and produced first flagellomere, and the shortened scutum. It also resembles L. (L.) chikuni sp. nov., and their differences are discussed above [see under L. (L.) chikuni sp. nov.]. The Japanese species L. (L.) monstrata Iwasa, 1992 shares a similar antennal morphology with the new species, but its arista is less than 2 times as long as the first flagellomere, and it has different coloration on thorax, legs and abdomen.

Figures

Figure 37. Known distribution of species of the subgenus Loxocera Loxocera in China.

Figures 18, 19. Loxocera (Loxocera) maculithorax sp. nov., habitus, lateral 18 male, holotype 19 female, paratype. Scale bar: 3 mm.

Figures 20 - 22. Loxocera (Loxocera) maculithorax sp. nov., holotype, male 20 head, dorsal 21 same, lateral 22 thorax, dorsal. Scale bar: 1 mm.

Figures 23 - 26. Loxocera (Loxocera) maculithorax sp. nov., male genitalia 23 sternite 8 to genitalia, caudal 24 same, lateral 25 pregonite and phallus, ventral 26 hypandrium and associated structures, ventral. Abbreviations: ce = cercus, ea = ejaculatory apodeme, ep = epandrium, ha = hypandrial arm, hb = hypandrial bridge, hl = hypandrial lobe, pg = pregonite, s 8 = sternite 8, ph = phallus, pt = phallotrema. Scale bars: 0.25 mm (23, 24, 26); 0.1 mm (25).