Three New and Two New Record Species of the Genus Dichaetomyia Malloch (Diptera: Muscidae) from China ^†

Abstract

The genus Dichaetomyia Malloch, 1921 of Muscidae from China is recorded, and an updated identification key to Chinese species based on males is provided. Three new species, namely Dichaetomyia villscutellata sp. n., Dichaetomyia bimaculata sp. n., and Dichaetomyia maculiventra sp. n., are described, along with two new country records, Dichaetomyia varicauda Emden, 1965, and Dichaetomyia latistriata Malloch, 1924. Photographs of the habitus and male genitalia, as well as illustrations of the male genitalia of the new species and new records, are provided.

1. Introduction

The genus Dichaetomyia was established by Malloch (1921), with Dichaetomyia polita Malloch, 1921, designated as the type species [1]. Subsequent taxonomic revisions have led to the transfer of numerous species from other genera into Dichaetomyia Malloch, 1921. Regional catalogs by Pont recorded the genus’ diversity in the Oriental (87 species) [2,3], Ethiopian (33 species) [4], and Australian (74 species) Regions [2,3,4]. Shinonaga and Kano recorded six species from the Palaearctic Region [5]. Recent contributions to the Oriental Region fauna include works by Shinonaga and Singh [6], Shinonaga and Thinh [7], Shinonaga [8,9,10], and Pont and Evenhuis [11]. Zielke’s comprehensive studies on Madagascar’s fauna, including revisions and redescriptions of existing species, have greatly enhanced the genus’ taxonomy [12,13,14,15,16,17,18]. Currently, 366 species of Dichaetomyia are recognized globally [19].

In the Ethiopian Region, the genus is divided into two subgenera: Dichaetomyia s.str. and Panaga Curran, with most species endemic to Madagascar. A total of 70 species of the region have been described, with 38 species classified under the subgenus Dichaetomyia and 32 under Panaga [12,13,18,20]. These two subgenera can be distinguished by the presence of setulae or stiff hairs on the greater ampulla (infra-alar bulla) in Panaga, whereas these structures are absent in Dichaetomyia. The metallic green, blue, or violet species of the subgenus Dichaetomyia were primarily described by Zielke under the genus Annaria Zielke, 1972, which was based solely on their metallic coloration [21,22,23]. Pont later synonymized Annaria with Dichaetomyia [4]. Notably, except for the 70 species in the Ethiopian Region, no other species in this genus have been placed in the subgenus.

Research on Chinese Dichaetomyia commenced relatively recently. Fan [24] recorded 16 species, and Xue and Zhao [25] identified 24 species of this genus. Subsequent contributions include descriptions of two new species by Feng et al. [26,27] and five new species by Xue and Liu [28]. To date, a total of 34 species are known in China, with 3 species distributed in the Palearctic Region and 31 species in the Oriental Region [29,30,31,32].

This genus is diagnosed by the following characteristics: the lower margin of the posterior spiracle has at least a row of setae; the prosternum has setae on the sides; the anepimeron is setulose; the radial node and ventral face of the basal R₄₊₅ have setula; vein M₁ is only slightly curved forwards before the apex; the lower calypter lacks a lobe (Phaonia type); the anterior part of the metepisternum has short hairs; and the anatergite has short hairs or is bare [1,24,25].

Adults are most frequently collected through two primary methods: direct collection from leaves or sweep-netting of vegetation. They have been trapped in multiple trap types, such as carrion-baited blowfly traps, Malaise traps, and light traps. Some species exhibit anthropophilic tendencies, with collection records from human feces and indoor environments. Adults may pose limited hygienic significance due to their potential role as mechanical vectors for pathogens associated with fecal matter and decomposing organic substrates. The larvae are typically saprophagous, often found in decaying organic matter [33].

This study describes three new species and report two new records of the genus from China. An updated identification key to all known Chinese species in the genus and additional distribution information are provided.

2. Materials and Methods

All materials were collected between 2013 and 2023 using sweep netting and Malaise traps, comprising over a thousand specimens. These specimens are deposited in the Insect Collection of Henan University of Science and Technology, Luoyang, China (HAUST). The data collection for this study was conducted between September 2022 and February 2025. This study focused on 38 specimens selected based on morphological characteristics, with particular attention to terminalia.

External morphological characters were examined using a Zeiss Stemi 305 stereomicroscope. Habitus photographs were captured with a Canon EOS 5DsR camera (Tokyo, Japan) fitted with a Laowa FF 100mm F2.8 CA-Dreamer Macro 2× lens (Hefei, China), and photographs stacks were processed using Helicon Focus 7 software. Male genitalia were photographed with the same camera system coupled to a Mitutoyo M Plan Apo 10× objective (Tokyo, Japan) and illustrated using SAI Ver.2 software. All photographs were edited in Adobe Photoshop CC 2017.

For genitalic preparations, the abdominal apex was softened in warm lactic acid for 5 min, rinsed in distilled water, and examined in glycerin. Cleared genitalia were preserved in glycerin within microvials pinned below specimens. For alcohol-preserved specimens, genitalia were stored in separate alcohol-filled tubes within the same vial as the specimen.

The morphological nomenclature follows that of Cumming and Wood [34]. Body length was measured in millimeters (mm) from the anterior margin of the head without the antenna to the apex of the abdomen. The following abbreviations are used in the text: ad—anterodorsal seta; av—anteroventral seta; d—dorsal seta; dc—dorsocentral seta; fr—frontal seta; h—humeral seta; ial—intra-alar seta; M₁—branch of vein M; R₄₊₅—branches of 4th and 5th ridial vein; m-m, medial crossvein; npl—notopleural seta; kepst—katepisternal seta; orb—orbital seta; p—posterior seta; pal—postalar seta; pd—posterodorsal seta; ph—posthumeral seta; pv—posteroventral seta; r-m—radial-medial crossvein; sa—supra-alar seta; Sc—subcostal.

3. Results

3.1. Taxonomy

Treatment of Species

• Dichaetomyia villscutellata sp. n.

(Figure 1a–e and Figure 2a–f)

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Type locality. China (Guangdong).

Type series. Holotype male (HAUST); CHINA: Gongdong Province, Guangzhou City, Haizhu National Wetland Park, 23°3′16.83″ N, 113°21′21.93″ E, 11. VIII-11. IX. 2021, 4m, MT-6. Paratype, one male (HAUST), same data as holotype.

Other specimens studied. One male and one female (HAUST), Gongdong Province, Guangzhou City, Haizhu National Wetland Park, 23°4′32.36″ N, 113°18′23.76″ E, 17. XI-17. XII. 2021, 7m, MT–1. One female (HAUST), Gongdong Province, Guangzhou City, Haizhu National Wetland Park, 23°4′12.16″ N, 113°19′41.94″ E, 11. VIII-11. Ⅸ. 2021, 8m, MT–7. One female (HAUST), Gongdong Province, Guangzhou City, Haizhu National Wetland Park, 23°9′48.15″ N, 113°18′23.62″ E, 27. V-11. Ⅵ. 2021, 8m, MT–3.

Diagnosis. Eyes are bare; antennae are yellow, palpi are dark brown; thorax has a black ground color; the scutellum is entirely yellow; the sides and lower margins feature small setulae; the ventral surface is bare; the postalar wall features a distinct group of long, black hairs; dc 2+4; all posterior dc are strong; the lower margin of the posterior spiracle features two rows of setulae; the subalar area near the posterior spiracle has small but distinct hairs; the ventral surface of the radial node and R4+5 have hairs; the legs are entirely yellow except for brownish tarsi; the fore femur is without av; the hind tibia is without pd, but with one ad and one av; the abdomen are entirely yellow and heart-shaped.

Description. Male. Body length: 7.8 mm; wing length: 7.5 mm. Head: Figure 1d, slightly flattened; eyes are bare; upper frontal facets are slightly enlarged; frons are slightly wider than the width of the anterior ocellus; fronto-orbital plural is touching in the upper half, frontal vitta is black with silvery pruinosity; fr 5; three of the upper pairs are shortened and situated on the lower half of the frons, without an orb; the parafacial is narrow, about half the width of postpedicel; the antennae are yellow, and the postpedicel is mostly brownish-yellow and 4 times as long as it is wide; the arista is plumose, and the longest arista hair is about 3 times the width of the antenna; the vibrissal angle is situated behind the frontal angle in profile; the occiput hairs are black, the palpi are dark brown, with the labella approximately equal in length to the palpi; the proboscis is short, about half the length of the palpi. Thorax: Figure 1a,c, ground color is black, sides of the thorax are yellow; scutum is silvery pruinosity, slightly shiny, with two black vitta that are dense and connect before the scutoscutellar suture and extend to the suture; the scutellum is entirely yellow; the sides and lower margins feature small setae; the ventral surface is bare; h 2; ac 0+1; dc 2+4, all developed; ial 0+2; sa 3; pal 2; npl 2; kepst 1+2; basisternum of prosternum, notopleuron, and anepimeron have hairs; the postalar wall features distinct hairs; there is no anterior parasquamal tuft; katepimeron bare; the posterior spiracles are yellowish-white, with two rows of setae in the lower margin; the meron with small but distinct hairs below the spiracle. Wings: Figure 1e, pale yellow; the basicosta and tegula are yellow; the Sc is bow-shaped; the ventral surface of the radial node and R₄₊₅ have hairs; the M₁ is slightly curved upward at the apex; 2/3 of the m-m is curved; the lower calypter is tongue-shaped; the halter is brownish-yellow. Legs: Figure 1c, yellow except the tarsi are brownish; the fore femur does not feature an av at the apex; the fore tibia does not feature a median p; the mid femur has rows of pv on the basal half and three subapical ps; the mid tibia has two pds; the hind femur features complete rows of ad; the apex has a row of av, with rows of pd on the basal half; the hind tibia does not have a pd, but features one av and two ads. Abdomen: Figure 1b, yellow, heart-shaped, without pruinosity; the postmarginal and lateral setae on tergites 4 and 5 are distinct, and sternite 1 features hairs. Terminalia: Figure 2a–f, ground yellow. The cerci are short, and the tip is blunt and rounded; the terminal margin is flat; the medial process is slightly protruding and inwardly concave in the posterior view; the cerci are broad and short in the lateral view, with medial process being distinct; the surstylus are broad and short, rectangular in lateral view, and slightly concave medially.

Female. The frons’ width is about 1/3 the width of the head; the postpedicel is brownish; the other characteristics are the same as the male.

Comparative notes. This species is similar to D. luteiventris (Rondani, 1873) in general body coloration and the presence of lateral scutellar setae [35]. It can be distinguished by the following characteristics: in D. villscutellata sp. n., dc 2+4, the scutellum is yellow; the legs are entirely yellow except for the brown tarsi; the apical part of the medial process on cercus is not prominently protruding. By contrast, in D. luteiventris, dc 2+3, the scutellum and legs are more intensely pigmented; and a prominently protruding apical part of the medial process on the cercus is present.

Etymology. The species was named after the scutellum with small setae in the sides and lower margins. Chinese name of the species: “毛盾重毫蝇”, derived from the morphological characteristics reflected in its scientific name.

Distribution. China (Guangdong).

• Dichaetomyia bimaculata sp. n.

(Figure 3a–e and Figure 4a–f)

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Type locality. China (Hunan).

Type series. Holotype male (HAUST); CHINA: Hunan Province, Chenzhou City, Mangshan National Forest Park, 21. VI. 2020. Paratype, one male (HAUST), same data as holotype.

Diagnosis. Eyes are bare; the postpedicel is yellow at the base, mostly dark brown; the palpi are yellow and brown at the base; the thorax has a black ground color; the scutellum is yellowish, the central area is dark brown, and the sides and ventral surface of the scutellum are bare; the lower margin of the posterior spiracle has two rows of setulae; the legs are yellow, with the tarsi being brownish; the fore femur does not have a row of avs at the apex, and the hind tibia has two avs and one ad; the abdomen with the syntergite 1 and 2 are yellowish-transparent and slightly darker at the apical margin; tergite 3 is yellow except for a slightly darker apical margin bearing a median longitudinal stripe; tergites 4 is all black, and tergite 5 has a pair of small yellow spots on the lower margin.

Description. Male. Body length 7.3 mm; wing length 7.2 mm. Head: Figure 3d, slightly flattened; the eyes are bare; the frons width is less than or equal to the width of the anterior ocellus; the fronto-orbital plural is touching in the upper half; the interfrontal area is black with a silvery pruinosity; fr 6 is situated on the lower half of the frons, with one small orb; the parafacial is narrow, about 1/3 the width of postpedicel; the pedicel is yellow, and the postpedicel I syellow at the base, mostly dark brown, and 4 times as long as it is wide; the arista is plumose, and the longest arista hairs are about 3 times the width of the antenna; the vibrissal angle is situated behind the frontal angle in the profile view; the occiput hairs are black; the palpi are yellow and brown at the base; the labella are relatively short, about 2/3 the length of the palpi; the proboscis is short, about half the length of the palpi. Thorax: Figure 3a,c, ground color black, and the margins of the thorax are yellow; the scutum features a pale pruinosity and four black, dense vitta; the dorsal view of scutellum is mostly dark brown, except for the yellow margins; the sides and ventral surface of the scutellum are bare; an anterior parasquamal tuft is present; the proepisternum is yellow, concave, and hairy; h 2; ac 0+1; dc 2+3; ial 0+2; pal 2; npl 2; kepst 1+2; the basisternum of prosternum, anepimeron, and notopleuron have hairs; the postalar wall and meron are bare; the posterior spiracles are yellowish-white, with two rows of setae in the lower margin.

Wings: Figure 3e, pale yellow; the basicosta and tegula are yellow; the Sc is bow-shaped; the ventral surface of the radial node and R₄₊₅ feature 3–4 hairs; the end of the M₁ is straight; the m–m is slightly S-shaped; the lower calypter is tongue shaped, light brown, and with a brownish margin; the halter is brownish-yellow. Legs: Figure 3e, yellow except the tarsi are brownish; the fore femur is without rows of av at the apex, with five pvs on basal half and complete rows of pds; the fore tibia is without a median p; the mid femur features three pvs at the apex; the mid tibia features two pds; the hind femur features complete rows of ads, with four avs on the basal half; the hind tibia is without pds but with two avs and one ad. Abdomen: Figure 3b, elongate-oval, with a sparse pruinosity and slightly shiny; syntergite 1 and 2 are yellowish-transparent and slightly darker at the apical margin; tergite 3 is yellow except for a slightly darker apical margin, bearing a median longitudinal vittae; tergites 4 is black; tergite 5 has a pair of small yellow spots on the lower margin; all tergites feature strong marginal and lateral setae. Terminalia: Figure 4a–f, the cerci taper gently, with the margin arched in the posterior view; both the medial and lateral process are present, with the medial process fused in the posterior view; the cerci are flattened; the medial process is distinct in the lateral view; the surstylus is narrow in the lateral view.

Female. Unknown.

Comparative notes. This species is similar to D. biangulata Xue, 1998, in terms of abdominal coloration and the presence of a distinctive color patch on tergite 5. It can be distinguished by the following points: in D. bimaculata sp. n., the postpedicel is mostly dark brown with yellow at the base; the legs are yellow except for the brownish tarsi; the occiput hairs are black; the fore femur is without rows of avs at the apex; the hind tibia is without pds. By contrast, the D. biangulata antennae are yellow; the occiput hairs are yellow; the legs are dark brown except for the tibiae which are yellow; the fore femur features rows of avs at the apex; the hind tibia has one small pd [25].

Etymology. This species is named based on the tergite 5 with a pair of small yellow spots on the lower margin. Chinese name of the species: “双斑重毫蝇”, derived from the morphological characteristics reflected in its scientific name.

Distribution. China (Hunan).

• Dichaetomyia maculiventra sp. n.

(Figure 5a–e and Figure 6a–f)

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Type locality. China (Fujian).

Type series. Holotype male (HAUST); CHINA: Fujian Province, Wuyishan City, Tongmu County, Tianchan Mountain Spring Water Factory, 27°42′3″ N, 117°45′2″ E, 23.VII.2022, leg. Wenqiang Cao. Paratypes, three males (HAUST), same data as holotype.

Diagnosis. Compound eyes are bare and slightly ciliated; the antennae are yellowish-brown; the maxillary palps are dark brown, with yellow tips; the thorax is mostly black, with yellow areas on the postpronotum, supra-alar bristles, and post-alar bristles; the scutellum is brown and bare on the sides, with lower margins and a ventral surface with 3–4 small setae on the horizontal margin; the post-scutellum is slightly pubescent; a row of setae are featured on the lower margin of the posterior spiracle; the radial node and R₄₊₅ are bare on the ventral side; the M₁ vein is almost straight at the end; the femora is yellow, and the tibiae are brown, while the tarsi are black; the fore femur is without avs; the hind tibia features two avs, one ad, and one pd; the abdomen are entirely yellow, oval-shaped, and slightly dusted, with long triangular median stripes on tergites 3, 4, and 5 and semicircular spots on the lateral margins of tergites 3 and 4.

Description. Male. Body length: 6.5 mm; wing length: 6.8 mm. Head: Figure 5d, slightly flattened; the eyes are bare, slightly ciliated, and with the upper frontal facets slightly enlarged; the frons width is less than or equal to the width of the anterior ocellus, with the fronto-orbital plural touching in the upper half; the frontal vitta is black, linear, and with a silvery dusting; fr 3 is situated on the lower half of the frons, with one small arb; the parafacial is narrow, about 1/4 the width of the postpedicel; the antennae are yellowish-brown, with their length 5 times their width; the arista is plumose, with the longest arista hairs being about three times the width of the antenna; the vibrissal angle is approximately at the same level as the frontal angle in the profile view; the occiput hairs are black; the palpi are dark brown, with yellow tips; the labella is relatively short, about half the length of the palpi; the proboscis length is equal to the palpi. Thorax: Figure 5a,c, entirely black, except for the postpronotum and the sides of the thorax which are yellow; the scutum is densely covered with a silvery pruinosity, with the vitta being indistinct; the scutellum is brown, with the lateral and ventral face bare; the postalar wall features a few hairs; h 2; ph 2; ac 0+1; dc 2+3; ial 0+2; pal 2; npl 2; kepst 1+2; the basisternum of prosternum, notopleuron, and anepimeron feature hairs; the anterior parasquamal tuft is absent; the katepimeron and meron are bare; the posterior spiracles are yellow, with a row of setae on the lower margin. Wings: Figure 5e, pale yellow; the basicosta and tegula are black; the Sc is bow-shaped; the radial vein base has hairs; the radial node and R₄₊₅ are bare on the ventral side; the M₁ and m-m are straight; the lower calypter is tongue-shaped and light brown with the margin brown; the halter is yellowish-brown. Legs: Figure 5c; the femora are yellow, the tibiae are brown, and the tarsi are black; the fore femur is without avs but features complete rows of ads, pds, and pvs; the fore tibia is without a median p; the mid femur has two proximal ps; the mid tibia has two pds; the hind femur features rows of avs and pvs on the distal half, with complete rows of ads; the hind tibia has two avs, one ad, and one pd. Abdomen: Figure 5b, yellow, oval-shaped, and slightly dusted; tergites 3, 4, and 5 feature long triangular median vittae; tergites 3 and 4 have semicircular spots on the lateral margins; tergite 4 has posterior marginal setae that are interrupted in the middle; tergite 5 features posterior marginal and lateral setae distinctly. Terminalia: Figure 6a–f, the distal half of the cerci taper gently; the posterior view of the medial process is separated; the cerci reveals a terminal margin that is concave in the lateral view; the surstylus is distally bulbous in the lateral view, with tip rounded and slightly upturned.

Female. Unknown.

Remark. This species can be easily distinguished from others by the following characteristics: the abdomen is entirely yellow; tergites 3, 4, and 5 possess long median vittae; tergites 3 and 4 have semicircular spots on the lateral margins, while tergite 5 is without spots.

Etymology. This species is named based on the abdomen with semicircular spots on the lateral margins of tergites 3 and 4. Chinese name of the species: “斑腹重毫蝇”, derived from the morphological characteristics reflected in its scientific name.

Distribution. China (Fujian).

• Dichaetomyia varicauda Emden, 1965

(Figure 7a–e and Figure 8a–f)

Dichaetomyia varicauda Emden, 1965. Fauna of India and the Adjacent Countries. Diptera 7, Muscidae I: 400. Type locality: Burma: Kambaiti; India: Siruvani-Muthikolam [29].

Material studied. CHINA: one male (HAUST), Chongqing, Jiangjin, Taihe, Heishen Temple, 836 m, 28°48′9.21″ N, 106°15′46.04″ E, 30.VII.2022, leg. Xulong Chen. Four males and two females (HAUST), Chongqing, Jiangjin, Dayuandong, Liubudeng, 728 m, 28°52′54.45″ N, 106°15′14.53″ E, 23. VII. 2022, leg. Xulong Chen; four males and four females (HAUST), Chongqing, Jiangjin, Zhuyang Town, Yunwuping, Dashibao, 542 m, 29°9′6.99″ N, 105°57′34.51″ E, 23. VII. 2022, leg. Xulong Chen. One female (HAUST), Chongqing, Jiangjin, Dayuandong, Confucius Temple Management Station, 709 m, 28°53′9.68″ N, 106°15′24.28″ E, 13. VIII. 2022, leg. Xulong Chen. One female (HAUST), Fujian Province, Wuyishan National Park, Huanggangshan Daoban, 1803 m, 27°50′17.29″ N, 117°45′28.28″ E, 27. VIII. 2023, leg. Wenliang Li. One male (HAUST), Guangdong Province, Shaoguan, Nanling National Forest Nature Reserve, 1247 m, 23°3′16.83″ N, 113°21′21.93″ E, 17. XI-17. XII. 2021, MT-6. Two males (HAUST), Guangdong Province, Shaoguan city, Nanling National Forest Nature Reserve, 834 m, 24°54′45.81″ N, 113°2′33.64″ E, 28. IX. 2022-7. Ⅰ. 2023, MT-15. Two males and one female (HAUST), Yunnan Province, Gongshan city, Dulongjiang, 1542m, 1. VII. 2013, leg. Weiwei Zhang.

Diagnosis. Figure 7a–e, antennae are yellowish-brown; the palps are entirely fuscous; dc 2+3, with three strong posterior dc; the scutellum are yellow, with the ventral surface and lower lateral margins bare; the M₁ is distinctly curved upward; the femora and coxae are entirely pale yellowish-brown; the hind tibiae feature one median ad, one weak pd, and two avs; the abdomen are pale yellowish-brown; tergites 3, 4, and 5 each bear a black median longitudinal vittae and lateral spots, and the spots potentially merge with the vittae [29].

Comments. This species was assigned the Chinese name “异尾重毫蝇”, derived from the morphological characteristics reflected in its scientific name [29].

Distribution. Burma (Kambaiti); India (Siruvani-Muthikolam); China (Chongqing, Fujian, Guangdong, Yunnan).

• Dichaetomyia latistriata Malloch, 1924

(Figure 9a–e and Figure 10a–f)

Dichaetomyia latistriata Malloch, 1924. Ann. Mag. n. H., (9) XV, p. 136, ♂. Type-locality: Malaya: Kuala Tahan, Pahang [1].

Dichaetomyia latistriata Malloch, 1924. Fauna of India and the Adjacent Countries. Diptera 7, Muscidae I: 419. Type-locality: Malaya: Kuala Tahan, Pahang; Borneo: Sandakan [29].

Material studied. CHINA: Three males (HAUST), Hunan Province, Chenzhou City, Mangshan National Forest Park, 21. Ⅵ. 2020.

Diagnosis. Figure 9a–e, pale yellowish-brown; the antennae are yellow-orange; the maxillary palps are yellow; the scutellum is brown with yellow margins; anterior spiracle tufts are present; a katepisternum with pale hairs is featured above the coxae and below the spiracle; the R₄₊₅ vein is posteriorly curved and slightly wavy; the M₁ vein is distinctly upturned at the apex; syntergite 1 and 2 are yellow; tergites 3 and 4 feature a median longitudinal stripe, and tergite 4 is posteriorly dark brown, merging with the median stripe; tergite 5 is dark brown and posteriorly orange-yellow; the hind tibia is slightly brownish; the tarsi are black; the fore femur has a row of short, robust, comb-like avs; the hind tibia has 1 small pd, 1 ad, and 2–3 avs [1,29].

Comments. Following its redescription by Emden (1965), this species was assigned the Chinese name “宽条重毫蝇”, derived from the morphological characteristics reflected in its scientific name [29].

Distribution. Malaya (Kuala Tahan, Pahang); Borneo (Sandakan); China (Hunan).

3.2. Key to the Species

• Key to Chinese species of genus Dichaetomyia Malloch, 1921 (males)

The key is modified from Xue and Liu [28] and Xue and Zhao [25], with some important diagnostic characters being re-selected and modified [24,26,27,28,29,31].

1. Post-dc 4 ......................................................................................................................................2

- Post-dc 3 ........................................................................................................................................6

2. Margin of lower lateral scutellum with flat hairs or ventral surface of scutellum with hairs..................................................................................................................................................3

- Margin of lower lateral scutellum without flat hairs; ventral surface of scutellum bare...................................................................................................................................................5

3. Abdomen entirely yellow; antennae brownish-yellow and palpi dark brown..................

........................................................................................................................D. villscutellata sp. n.

- Abdomen base black...................................................................................................................4

4. Lower stpl markedly closer to posterior than to anterior stpl; meron with hairs nearby the posterior spiracle; both post pronotal lobe and halter tawny; leg entirely yellow except black-brown tarsi; fore tibia without median p; hind tibia without pd; thorax with thick grey-brown pruinosity.....................................................................D. keiseri Emden 1965

- Lower stpl equidistant from anterior and posterior ones; meron without hairs; post pronotal lobe yellow; halter brown; at least basal part of femur dark; tibia and tarsi yellow; fore tibia with one median p; hind tibia with 1–3 pd; thorax with thin greyish-brown pruinosity......................................................................................................D. pallitarsis (Stein,1909)

5. Tergites 4 and 5 dark brown, slightly darker than the ones before; tergite 5 with thin pruinosity ....................................................................................... D. quadrata (Wiedemann, 1824)

- Tergite 5 and posterior part of tergite 4 black, shining, and without pruinosity....................

............................................................................................................. D. monticola Emden, 1965

6. Postpedicel about 8 times as long as pedicel, exceeding upper half of eyes; light yellow, exceeding lower margin of eyes; legs yellow except tarsi brown.................................................

............................................................................................................... D. antennata (Stein, 1918)

- Postpedicel almost 5 times as long as pedicel, not exceeding lower margin of eyes .....................7

7. Scutellum with lower margin laterally with flat or curved black hairs, ventrally with upright cilia ...................................................................................................................................8

- Scutellum with its lower margin bare ....................................................................................12

8. Scutellum ventrally with yellow upright hairs distally; its lower margin laterally with pale thin hairs (sometimes only a few) ......................................................................................9

- Scutellum without upright hairs distally; its lower margin laterally with many flat or curved, black hairs .....................................................................................................................10

9. Body dark black; abdomen always olive, with metallic luster; more yellowish in the lower areas, sometimes with femur yellow; palpus dark brown; end of M1 upcurved distinctly; coxae brown; hind tibia with two strong ad ..................... D. bibax (Wiedemann, 1830)

- Body brownish yellow mostly; abdomen reddish brown or orange; middle part of scutum dark; palpus yellow; end of M1 straight; coxae greyish white; hind tibia only with one ad ..........................................................................................................D. flavipalpis (Stein, 1915)

10. Katepimeron with hairs; frons as wide as anterior ocellus; hind femur pv longer than the maximum breadth of the femur; tergites 4 and 5 black, but tergite 5 with orange margin ....................................................................................................D. aureomarginata Emden, 1965

- Katepimeron bare.....................................................................................................................11

11. Frons narrow, only 0.5 as wide as antenna at the most; hind femur pv equal to the longest diameter of femur; abdomen entirely yellowish brown ..............................................

.......................................................................................................D. luteiventris (Rondani, 1873)

-Frons broad, about 2 times as wide as antenna; hind femur pv less than half as broad as femur; syntergite 1 and 2 brownish yellow; tergite 3 dark brown; tergites 4 and 5 black .............

.....................................................................................................D. latiorbitalis Xue and Wei, 1998

12. Eyes with long, dense hairs; antenna dark brown; postgena with a few pale hairs; anatergite bare......................................................................... D. dasiomma Xue and Kano, 1994

- Eyes bare or with few short and scattered hairs..................................................................13

13. Palpus orange or yellow at least at apex ...........................................................................14

- Palpus entirely dark.................................................................................................................26

14. Palpus yellow at apex...........................................................................................................15

- Palpus entirely orange or yellow to light yellow.................................................................18

15. Antenna dark brown; postalar wall bare or with fine hairs; lower occiput hairs entirely black; mid femur basal 3/5 with dense pv; longest shorter than segment width; subapical ad usually 1; hind tibia without pd…......................…D. fulvoapicata Emden, 1965

- Antenna yellow; postalar wall with hairs…………......................................................……16

16. Lower occiput hairs black; abdomen yellow; tergites 3, 4, and 5 with long triangular median vittae; tergites 3 and 4 with semicircular lateral spots........................................................

.......................................................................................................................D. maculiventra sp. n.

- Lower occiput hairs yellow; abdomen mostly dark brown with yellow base………...17

17. Katepimeron with hairs; scutum with two black vittae (inner ones inconspicuous); median vitta with brown pruinosity; the part under marginal scutellar setae with a row of small hairs; hind tibia with two avs…............................................D. declivityata Xue and Lin, 1996

- Katepimeron bare; scutum with four black vittae; median vitta dark brown; the part under marginal scutellar setae bare; hind tibia with three avs…..........D. albiceps (Van der Wulp, 1881)

18. Fore femur anteroventrally with a row of pectinate setae……....................................19

- Fore femur anteroventrally without pectinate setae……….........................….....…..........23

19. Mid femur anteroventrally with a row of pectinate setae; anterior margin of wing with costal spine; most of abdomen blackish except apices of tergite 4 orange....................

..............................................................................................................D. setifemur Malloch, 1928

- Mid femur anteroventrally without pectinate setae……............................…….................20

20. Postalar wall bare; costa ventral surface bare; abdomen except tergites 3, 4, and 5 brownish-black, rest orange-yellow translucent........................D. palpiaurantia Feng, 1999

- Postalar wall with hairs…...……….....................................................…................................21

21. Hind tibia with one small pd………................................................D. latistriata Malloch.1924

- Hind tibia without pd……………………………………….…...........……..……..................22

22. Lower occiput hairs yellow; anatergite with hairs; costa ventral surface bare; thorax with four distinct black vittae; tarsi black……………..........……. D. pahangensis Malloch, 1925

- Lower occiput hairs black; anatergite bare; hind femur mostly brown, and tarsi dark brown; abdomen mostly pitch black…………………...................D. nigricauda Emden, 1965

23. Antenna entirely yellow; thorax dark brown; scutum with four brown stripes; scutellum brownish-yellow, with anterior and posterior spiracles yellow……………...........................

......................................................................................................D. corrugicerca Xue and Liu, 1996

- Postpedicel entirely or mostly brown…........................................………………................24

24. Anatergite bare; ommatidia on anterior upper part of eyes distinctly enlarged; postalar wall with a few pale hairs; thorax with vittae only up to scutoscutellar suture; abdomen shiny, with thin pruinosity……………………..........……...…… D. heteromma Emden, 1965

- Anatergite with hairs................................................................................…............................25

25. Antenna dark brown; thorax yellow except first half of scutum, katepisternum and meron black; postalar wall with hairs………..........………..........……… D. sinica Feng, 2003

- Antenna mostly dark brown; base yellow; thorax mostly black; postalar wall bare…......

................................................................……….........................................…. D. bimaculata sp. n.

26. Fore femur anteroventrally with a row of pectinate setae……......…..........................27

- Fore femur anteroventrally without pectinate setae…….................................……….......30

27. Mid femur anteroventrally with a row of pectinate setae; each tergite with brown posterior margin; posterior part of tergite 5 with two yellow spots; all tibiae yellow; rest of legs dark brown.................................................................D. biangulata Xue, 1996

- Mid femur anteroventrally without pectinate setae…….....…............................…………28

28. Hind tibia without pd; thorax brownish yellow; scutum dark brown, with four dark vittae; postpronotal lobe and scutellum yellow; metepisternum bare; radial node and ventral face of basal R4+5 with short setula; sternite 5 slender; legs yellow..................................

............................................................................................D. jianfenglingensis Xue and Liu, 2011

- Hind tibia with pd ....................................................................................................................29

29. Hind femur with three pds; legs yellow except tarsi black; postpronotal lobe and scutum not yellow.............................................................................................. D. femorata (Stein, 1915)

- Hind femur with one pd; legs yellow except hind tibia dark; postpronotal lobe and scutum yellow............................................................................................ D. pectinipes (Stein, 1909)

30. Dorsal surface of abdomen densely and evenly pruinose, nearer to hair roots pale, with distinct fish-like scales; ommatidia not enlarged; palpus dark brown; vittae of thorax approaching scutoscutellar suture; postalar wall bare.....D. scabipollinosa Xue, 1996

- Dorsal surface of abdomen without or with uneven pruinosity, without any distinct fish-like scales...............................................................................................................................31

31. Postpedicel entirely or mostly brown……………………….............................................32

- Antenna entirely pale yellow, yellow, or yellowish-brown………………............………35

32. Postalar wall with hairs; costa ventral surface posterior margin with a few fine pale hairs (different from usual short pubescence); thorax mainly orange, without distinct stripes; hind tibia with small pd; tarsi brown…………....................D. apicallis (Stein, 1904)

- Postalar wall bare………….....................………….................................................…………33

33. Tegula blackish brown; thorax brown to dark brown; abdomen without distinct pruinosity, slightly shining; tergites 4 and 5 entirely black............ D. yunnanensis Xue and Liu, 2011

- Tegula yellow………………........................................................................…………………34

34. Thorax with dense greyish-yellow pruinosity; coxa, trochanter, and base of femur brown; tibia, tarsi, and most of femur brownish-yellow; abdomen cordiform in dorsal view, with dense brownish-grey pruinosity, not shining ........................................................

.................................................................................................D. wuzhishanensis Xue and Liu, 2011

- Thorax with thin pale grey pruinosity, slightly shining; legs brownish-yellow except coxa dark brown; abdomen rounded in dorsal view, with thin pale grey pruinosity, shining................................................................................................ D. hainanensis Xue and Liu, 2011

35. At least basal part of midsurface and hind femur dark ..................................................36

- At least middle and hind femur yellow.................................................................................37

36. Scutellum mostly yellow, only postpronotal lobe on scutum yellow; fore femur brown; tibiae yellow................................................................................ D. alterna (Stein, 1915)

- Scutellum black; fore femur black; only fore tibia dark brown ............................................

.........................................................................................................D. flavocaudata Malloch, 1925

37. Mid femur anteroventrally with a row of pectinate setae; hind tibia with one small pd; abdomen tergites middle section with a complete broad median vittae and large transverse spots on posterior margin; the spots more or less fused with the median stripe………........................................................................................D. varicauda, Emden, 1965

- Mid femur anteroventrally without pectinate setae; hind tibia without pd......................38

38. Anterior margin of wing with costal spine; thorax brown to dark brown, with grey pruinosity; calypter brown; halter with its apex brown ..........D. nigrifolia Xue and Liu, 2011

- Anterior margin of wing without costal spine; most of thorax yellow with thin pruinosity, slightly shining; calypter pale yellow; halter with apex yellow.......................................

............................................................................................................... D. pallicornis (Stein, 1915)

4. Discussion

The taxonomic study of this genus remains challenging, as only a subset of species from the Ethiopian Region have been categorized into two subgenera based on their distinct diagnostic characteristics [20,21,22,23]. However, most species within this genus, including those distributed in China, have not yet been classified at the subgeneric level and remain unassigned to any subgenus. Future investigations should employ integrated morphological and molecular analyses to elucidate phylogenetic relationships within the genus, which would establish a more substantiated framework for subgeneric delineation.

This taxonomic ambiguity likely reflects both the genus’ remarkable morphological diversity and the limitations of current classification systems in establishing clear subgeneric boundaries. Although research on this genus in China remains relatively limited, the country’s complex topography and climatic conditions suggest that further systematic investigations are likely to reveal the existence of additional new species. This study describes three new species and reports two new records of the genus from China. An updated identification key to all known Chinese species in the genus and additional distribution information are provided. The discovery and description of these new species will not only enrich the taxonomic framework of the genus but also provide critical research materials for exploring its phylogenetic relationships, biogeographic distribution, and adaptive evolution.