Dexia ventralis Aldrich, 1925

Zhang, Chun-Tian, Shima, Hiroshi & Chen, Xiao-Lin, 2010, A review of the genus Dexia Meigen in the Palearctic and Oriental Regions (Diptera: Tachinidae) 2705, Zootaxa 2705, pp. 1-81 : 72-75

Dexia ventralis Aldrich, 1925

Figs. 93−96

Dexia ventralis Aldrich, 1925: 33 . — Sabrosky & Arnaud 1965: 982 (catalog). — Kolomiets 1970: 61, 68 (key and redescription). — Mesnil 1980: 48. — Herting 1984: 144 (catalog). — Herting & Dely-Draskovits 1993: 366 (catalog). — Ziegler 1998: 164, 185 (larvae and puparia). — O’Hara & Wood 2004: 25 (catalog). — Richter 2004: 355 (key). — Zhang & Shima 2004: 55. — Zhang et al. 2004: 128. — Hao et al. 2008: 99. — O’Hara et al. 2009: 29 (catalog). — Chao et al. 2009: 577.

Dexia vacua of Chao, 1998: 2154, not Fallén, 1817, misidentification.

Diagnosis. Facial carina developed; thoracic dorsum with 4 longitudinal vittae; 3 presutural and 3 postsutural dorsocentral setae; 2 katepisternal setae; tegula reddish yellow to dark brown; lower calypter with long fringe; legs reddish yellow; and abdominal tergites with whitish pruinosity on anterior 1/3 to 2/3.

Description. Mesnil (1980) redescribed this species in detail. Here we give some additional measurements and some other characters.

Body length. 8.8−10.0 mm.

Male. Head. Frons 0.13−0.18 times as wide as head width; parafacial 2.5−3.0 times as wide as 1st flagellomere at middle height; gena 0.42−0.55 times as wide as eye height. 1st flagellomere 3−4 times as long as pedicel; prementum 2.5−3 times as long as wide. Thorax black in ground color, with yellowish or brownish pruinosity; with 4 longitudinal black vittae on dorsum, an inner vitta on presutural scutum about 1/5 as wide as pruinose portion between inner and outer vittae and 1/3 as wide as outer vitta; scutellum dark on basal half and reddish yellow on apical half, covered with grayish white pruinosity. Proepisternum bare; 2−3 postpronotal setae; 1−2 presutural and 1−3 postsutural acrostichal setae; 3 presutural and 3 postsutural dorsocentral setae; 2 postsutural intra-alar setae; 2−3 supra-alar setae; 2 katepisternal setae. Wing hyaline; tegula reddish yellow to dark brown; basicosta dark brown; costal spine about as long as r-m crossvein; relative lengths of 2nd, 3rd and 4th costal sectors approximately 2:5:3; vein M from dm-cu crossvein to its bend 2−3 times distance between the bend and wing margin; lower calypter with dense long fringe on outer margin. Legs reddish yellow; mid tibia with 2 fine posterodorsal setae; hind tibia with 2−3 anterodorsal, 2−3 posterodorsal and 2 ventral setae. Abdomen translucent yellowish on tergites 2 to 4 and reddish brown on tergite 5, brown to dark brown on mid dorsal longitudinal portion of tergites 2 to 4, narrow posterior margin of tergite 4 and sometimes posterior 1/2 of tergite 5; rather dense whitish pruinosity on anterior 1/3−1/4 of tergite 3, anterior 1/3−1/2 of tergite 4 and 1/2−3/4 of tergite 5, the pruinosity extending to posterior 1/2 on tergites 3 and 4 along mid dorsal longitudinal vitta. Syntergite 1+2 with several rather fine lateral discal and 1−2 lateral marginal setae, without median marginal setae; tergite 3 with 2 − 4 median discal, 0−1 lateral discal, 2 median marginal and 2 lateral marginal setae; tergite 4 with 1−2 pairs of median discal, 0−2 pairs of lateral discal setae and a row of marginal setae; tergite 5 with regular rows of discal and marginal setae. Male terminalia. V-shaped median cleft of sternite 5 about 2/3 length of the sternite, posterior lobe wide and blunt apically; cerci slender on apical half; surstylus narrowed and apex slightly pointed; postgonite shorter than basiphallus.

Female. Frons about 5/12 head width; fronto-orbital plate wider than frontal vitta; parafacial about 3 times as wide as 1st flagellomere; gena about 0.5 times as wide as eye height; 5 frontal setae; 2 proclinate orbital setae; 1 reclinate prevertical setae. Abdomen ovate; reddish yellow, dark brown on syntergite 1+2; posterior 3/4 of tergite 3, 3/5−1/2 of tergite 4 and 3/5−1/2 of tergite 5; grayish white pruinosity on anterior 1/ 4−1/3 of tergites 3 and 2/5−1/2 of tergites 4 and 5; tergites 3 and 4 each with a pair of discal setae. Other characters almost same as in male.

Type material examined. Holotype male of Dexia ventralis Aldrich, Suigen [= Suwon , SOUTH KOREA, 23.v.1922. Paratypes. SOUTH KOREA. 1 male, 1 female, Suigen, 23.v.1922, ex. Japanese beetle, Parasite Exp ( USNM).

Additional material examined. CHINA. Beijing: 1 female, Miyun, Shicheng , 3.viii.1982, F.-S. Li . 1 female, Beianhe , 3.ix.2003, Y.-P. Zhou . 5 males, 1 female, Changping, Heishanzhai , 5.ix.2006, S.-S. Zhang, P.-M. Dong, Q. Li . 1 male, ix.2005, Xiangshan, L.Q. Wu. 1 male, Science and Technology Park of CAU, R.- G. Li. 1 male, Mt. Baiwang , 24.viii.2005, X. Feng . 1 male, Fenghuangling , 17.viii.2007, M. Chen ( CAU) . 10 males, 8 females, Shangfangshan , 15.vii−2.viii.1980, E.-Y. Liang ( IZCAS) . Hebei: 1 male, 3 females, Xinglong, Mt. Wuling , 21−28.viii.1973, J.-K. Yang, H.-M. Chen ( CAU) . 2 females, Qinhuangdao, Yansai Lake , viii.1980 . 20 males, 23 females, Mts. Xiaowutai , 29.vi.2009, C. Fu and Y.-Y. Zhou ( SNU) . Heilongjiang: 1 male, Shangganling , 25.xii.1990 (artificial incubation) . Jilin: 2 males, 2 females, Changbai Shan , 3.viii.1981, X.-W. Liu ( SEMC) . Liaoning: 1 male, Sitaizi, Fengcheng , 29.vi.1962, Y.-S. Shi . 1 male, 1 female, Changan, Donggou, Dandong , 17.vi.1972 and 1.ix.1972, W.-Q. Xue . 1 male, Mt. Tiecha, 900 m, Benxi , 15.ix.2006, J.-Y. Liu . 1 female, Daiyoujiang, Huanren , 25.ix.1974, W.-Q. Xue . 1 female, Shenyang , vi.2000 ( SNU) . Inner Mongolia: 6 males, 2 females, Zhongqi, Xingan Prefecture , 22−31.vii.1983, G.-S. Mu . 1 male, Yongshou , 21.viii.1991, J.-L. Nian . 1 male, Guodong vil., Qianqi , 29.viii.1986, D. Guo ( IZCAS) . 1 female, Dongsheng , 14.viii.2006 . Ningxia: 2 males, 1 female, Lüyuan Forestry Center, 2100 m, Jingyuan , 30.vi.2008, J.-Y. Liu . 1 male, Tawan Villege, 1700−1800 m, 2.vii.2008, J.-Y. Liu. 1 male, 1 female, Longtan Forestry Center, 2100 m, 10.vii.2008, J.-Y. Liu. 1 male, 1 female, Xixia Forestry Center, 2000 m, 11.vii.2008, Z.-Y. Yao. 4 males, 2 females, Hongxia Forestry Center, 2100 m, Jingyuan , 14.vii.2008, J.-Y. Liu, Z.-Y. Yao ( SNU) . 1 male, Jingyuan, Liangdianxia , 2000 m, 17.vii.2007, Q.-B. Dong ( CAU) . Qinghai: 1 male, Guide, 2340−2640 m, 29.vi.1957, Y.-R. Zhang . 1 male, Cuogesongduo, 3750 m, Yushu , 4.vii.1964, S.-Y. Wang ( IZCAS) . 1 male, Yushu , 7.vii.1975, Q.-S. Fan, J.-S. He ( SEMC) . Shaanxi: 1 male, Taibai Shan , 12.vi.1989, M.-F. Wang ( SNU) . Shandong: 1 male, Yahou, Mt. Yashan , 18.vi.1964, S. Song ( IZCAS) . 1 male, Shidao , 11.ix.1962, G.-T. Jin ( SEMC) . Shanxi: 2 males, Shuangfeng, Mengshe , 16.vi.1999 . 1 female, S. Yulin, Suoxian , 20.ix.1979 . 1 male, Fanjiazhai, Youyu , 18.vi.1982 . 1 female, Shangbaiyang, Guangling , 9.viii.1985 . 1 female, Matian, Zhuoquan , 12.vi.1999 . 1 male, 4 females, Mt. Lishan, Hengqu , 30.v−1.vi.2000, All from Shanxi collected by M.-F. Wang ( SNU) . Yunnan: 1 female, Shangri-la, Geze , 3200 m, 18.viii.2010, C.-T. Zhang . 3 males, 7 females, Shigu Town, 1800 m, Lijiang , 20.viii.2010, Q. Wang ( SNU) .

Distribution. China (Beijing, Gansu, Hebei, Heilongjiang, Jilin, Liaoning, Inner Mongolia, Ningxia, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Xizang, Yunnan), Mongolia, Russia (Far East, E. Siberia), South Korea; North America (introduced into New Jersey).

Remarks. This species is similar to D. flavipes of Japan, but differs from it in having longer 1st flagellomere, black posterior margin on tergite 3, wider surstylus and shorter postgonite in male, and abdominal tergites with median discal setae in female. The apical half of cerci from Kolomiets (1970: 60) was wider than our cerci here. Chao et al. (1992: 806; 1998: 2154; 2009: 577) and Shi (2004: 90) misidentified this species as D. vacua (Fállen) .

Host. An unidentified species of Rutelinae ( Coleoptera : Scarabaeidae ) is recorded as a new host of D. ventralis collected in Shangganling, Yichun, Heilongjiang Province, China, and 1 male of D. ventralis was artificially incubated from the beetle in Shenyang on Oct. 25, 2009.