Four new species of the genus Luzonomyza Malloch (Diptera, Lauxaniidae) from China

Four species of the genus Luzonomyza Malloch, 1929 from southwest China are described as new to science: Luzonomyza vittifacies Li & Yang, sp. nov., L. serrata Li & Yang, sp. nov., L. honghensis Li & Yang, sp. nov., and L. brevis Li & Yang, sp. nov. A key to Luzonomyza species is also presented.


Introduction
The genus Luzonomyza Malloch, 1929 was erected as a subgenus of Trigonometopus Macquart 1835 on the basis of a single species from the Philippines, Trigonometopus bakeri Bezzi, 1913. From the 20 th to the 21 st century, considerable contributions were made to the genus by several taxonomists. In his key, Stuckenberg (1971) first recognized Luzonomyza (= Luzonomyia) as a valid subgenus. Shatalkin (1997) described a new species Trigonometopus (Tetroxyrhina) nigripalpis from Thailand (at that time, Tetroxyrhina Hendel, 1938 was also considered a subgenus of Trigonometopus), and

Morphological descriptions
General terminology follows Cumming and Wood (2009) and Gaimari and Silva (2010). Genitalia preparations were made by removing and macerating the apical portion of the abdomen in cold saturated NaOH for 6 h, after which they were rinsed and neutralized for dissection and study. After examination in glycerin, they were transferred to fresh glycerin and stored in a microvial pinned below the specimen or moved to ethanol in a tube together with the wet specimens.

Taxonomy
Key to the known species of the genus Luzonomyza Malloch Wing hyaline, very faintly yellow-tinged along anterior margin; haltere yellow with faintly brown-tinged knob; male epandrium without dorsoapical processes; postgonites simple and long . Diagnosis. Frons with 3 brown longitudinal stripes, median longitudinal stripe wide, extending from anterior margin to ocellar triangle, lateral longitudinal stripes narrow; face with a diamond-shaped brown marking in the middle, four angles of marking extending to facial margins. Mesonotum with 4 brown stripes. Epandrium with paired dorsoapical processes; phallapodeme claviform, shorter than phallus.
Description. Male. Body length 4.8 mm, wing length 4.3 mm. Head yellow. Face with an angular hump on middle of basal half, lateral margin brown on apical half, with a diamond-shaped brown marking in the middle, 4 angles of marking extending to facial margins; parafacial with sparse short hairs, with a black spot between eye and antennal bases, and with 5 long setae extending to gena. Frons ~1.2× longer than wide and parallel-sided, with 3 brown longitudinal stripes, a broader brown median longitudinal stripe extending from anterior margin to ocellar triangle, 2 lateral longitudinal stripes narrower and pale brown, anterior half with short setulae; ocellar triangle grayish black, ocellar setae very small, hair-like, anterior fronto-orbital seta reclinate, shorter than the posterior one. Gena with broad brown stripe, ~1/3 height of eye. Antenna yellow, rounded apically, ~1.2× longer than high; arista brown except for yellow base, pubescent. Proboscis yellow with white and black setulae, and with a pair of irregular blackish-brown lateral spots apically; palpus yellow with black setulae. Thorax (Fig. 3) brownish yellow, with grayish-white pruinescence. Mesonotum with 4 brown stripes extending to tip of scutellum, occupying most of scutellum. 0+3 dorsocentral setae, anteriormost dorsocentral seta away from scutal suture; acrostichal setulae in 4 rows; a pair of prescutellar setae, shorter than anteriormost dorsocentral seta. Dorsal and posterior margin of anepisternum and dorsal margin of katepisternum pale yellow. One anepisternal seta, 1 katepisternal seta. Legs mostly yellow; fore tar- someres 2-5 pale brown, mid-legs differently colored: only right mid femur blackish brown but brownish yellow at base. Fore femur with 7 posterodorsal setae and 6 posteroventral setae, fore tibia with a long dorsal preapical seta and a short apicoventral seta. Mid tibia with a strong dorsal preapical seta and an apicoventral seta. Hind femur with a weak preapical anterodorsal seta; hind tibia with a long dorsal preapical seta and a short apicoventral seta. Wing pale brown along costal margin, extending to M 1 , a brown spot on each of the crossveins r-m and dm-cu; subcostal cell brown; costa with 2 nd (between R 1 and R 2+3 ), 3 rd (between R 2+3 and R 4+5 ) and 4 th (between R 4+5 and M 1 ) sections in ratios of 9.7: 1.5: 1.4; r-m on middle of discal cell; ultimate and penultimate sections of M 1 in ratios of 6.6: 3.5; ultimate section of CuA 1 ~1/5 of penultimate. Haltere pale yellow.
Abdomen (Fig. 4) yellow, tergites 2-6 blackish brown on posterior margin. Male genitalia : syntergosternite confluent with epandrium, near triangular. Epandrium with a pair of long conical dorsoapical processes in lateral view, a pair of lateral processes broad apically and narrow basally on anterior margin. Surstylus situated in ventral angle and small; hypandrium V-shaped, with 2 pairs of inner apical processes. Gonopod absent, hypandrium confluent with phallus. Phallus with a pair of lateral preapical acute processes in ventral view; dorsal process broader in lateral view, vertical to phallus, anterior apical angle acute. Phallus deeply concave apically, phallapodeme claviform, shorter than phallus.
Remarks. This new species is very similar to Luzonomyza sasakawai from Thailand and Vietnam by the body markings and wing type, but it can be separated from the latter by the 3 narrow brown stripes on the frons; by the brown fore tarsomeres 2-5; by the epandrium with dorsoapical processes. In Luzonomyza sasakawai, the frons has a narrow brown stripe; the fore tarsomeres 3-5 are black; the epandrium is without dorsoapical process.
Distribution. China (Yunnan). Diagnosis. Frons with a brown median stripe extending from anterior margin to ocellar triangle; gena with broad brown stripe. Acrostichal setulae in 4 rows. Epandrium with a pair of dorsoapical processes in lateral view and a pair of lateral processes on anterior margin; hypandrium, gonopod, and phallus confluent together. Phallus with 2 pairs of lateral processes and a pair of median processes apically. Phallapodeme longer than phallus.

Luzonomyza honghensis
Description. Male. Body length 3.7 mm. Head (Fig. 9) yellow. Face with an angular hump on middle of basal half; parafacial with sparse short hairs, with a black spot between eye and antennal bases, and with 5 long setae extending to gena. Frons ~1.3× longer than wide and parallel-sided, with a brown median stripe extending from anterior margin to ocellar triangle, and frons with short setulae on anterior half; ocellar triangle grayish black, ocellar setae very small, hair-like; fronto-orbital setae missing. Gena with broad brown stripe, ~1/2 height of eye. Antenna yellow, first flagellomere and arista missing. Proboscis yellow with white and black setulae, and with a pair of irregular lateral spots apically; palpus yellow with black setulae. Thorax (Fig. 11) brownish yellow, with grayish-white pruinescence. Mesonotum with 4 brown stripes extending to tip of scutellum. 0+3 dorsocentral setae, anteriormost dorsocentral seta away from scutal suture; acrostichal setulae in 4 rows; a pair of prescutellar setae, all setae on thorax missing. Dorsal margin of anepisternum and katepisternum pale yellow. One anepisternal seta, 1 katepisternal seta. Legs yellow, fore tarsomeres and hind legs missing, mid tarsomeres 4 and 5 brown. Fore femur with 7 posterodorsal setae and 7 posteroventral setae, fore tibia with a long dorsal preapical seta and a short apicoventral seta. Mid tibia with a strong dorsal preapical seta and an apicoventral seta. Hind femur with a weak preapical anterodorsal seta; hind tibia with a long dorsal preapical seta and a short apicoventral seta. Wing pale brown along anterior margin, a brown spot on each of the crossveins r-m and dm-cu; subcostal cell brown but pale brown apically. Haltere pale yellow. Abdomen (Fig. 12) yellow, tergites 2-6 blackish brown on posterior margin but yellow laterally. Male genitalia (Figs 13-16): syntergosternite confluent with epandrium, broad dorsally and narrow ventrally. Epandrium with a pair of long black conical dorsoapical processes in lateral view, with a pair of lateral processes on anterior margin. Surstylus situated in ventral angle and small, ventral margin with setae, hypandrium V-shaped, disconnected in the middle and with 2 pairs of inner processes apically. Gonopod short and thick, extending to both sides; hypandrium, gonopod and phallus confluent together. Phallus with 2 pairs of different lateral processes and a pair of median processes apically; median processes claviform in lateral view. Phallus deeply concave apically, phallapodeme claviform, longer than phallus.

Female. Unknown.
Remarks. This new species is very similar to Luzonomyza sinica from China (Hainan) and Thailand in the body markings, wing type, and surstylus, but it can be separated from the latter by the brown mid tarsomeres 4 and 5 and the 2 pairs of apical processes of the phallus. In Luzonomyza sinica, the mid tarsi are yellow and the phallus is not bifurcated apically.
Distribution. China (Yunnan). Diagnosis. Face with 2 brown longitudinal stripes, gena with apical half of inner margin and ventral margin brown. Proboscis apically with a pair of Y-shaped brown spots. Mesonotum with 4 brown stripes extending to tip of scutellum. Legs pale yellow, fore femur with 7 posteroventral setae. Gonopod indistinct; both sides of phallus serrated. Phallus indistinct concave apically.

Luzonomyza serrata
Description. Male. Body length 3.4-4.0 mm, wing length 3.5-3.8 mm. Head (Fig. 17) yellow. Face with an angular hump on middle of basal half and 2 brown longitudinal stripes; parafacial with sparse short hairs and with 4 long setae extending to gena, with a black spot between eye and antennal bases, gena with apical half of inner margin and ventral margin brown. Frons ~1.4× longer than wide and parallel-sided, with a brown median stripe extending from anterior margin to ocellar triangle and with short setulae on anterior half; ocellar triangle grayish black, ocellar setae very small, hair-like; anterior fronto-orbital seta reclinate, shorter than the posterior one. Gena ~half height of eye and with broad brown stripe. Antenna yellow, first flagellomere and arista missing. Proboscis yellow with white and black setulae, and apically with a pair of Y-shaped brown spots; palpus yellow with black setulae.
Thorax (Fig. 20) brownish yellow, with grayish-white pruinescence. Mesonotum with 4 brown stripes extending to tip of scutellum, occupying most of scutellum. 0+3 dorsocentral setae, anteriormost dorsocentral seta away from scutal suture; acrostichal setulae in 4 rows; a pair of prescutellar setae, all setae on thorax missing. Dorsal margin of anepisternum and katepisternum yellow. One anepisternal seta, 1 katepisternal seta. Legs pale yellow, fore femur and basal half of tibia brown, tarsomeres 4 and 5 pale brown, mid and hind femora and tibiae yellow but pale yellow apically. Fore femur with 7 posterodorsal setae and 7 posteroventral setae, fore tibia with a long dorsal preapical seta and a short apicoventral seta. Mid tibia with a strong dorsal preapical seta and an apicoventral seta. Hind femur with a weak preapical anterodorsal seta; hind tibia with a long dorsal preapical seta and a short apicoventral seta. Wing brown along costal margin, extending to M 1 , a brown spot on each of the crossveins r-m and dm-cu; subcostal cell brown; costa with 2 nd (between R 1 and R 2+3 ), 3 rd (between R 2+3 and R 4+5 ),  and 4 th (between R 4+5 and M 1 ) sections in ratios of 9.0: 1.6: 1.2; r-m beyond middle of discal cell; ultimate and penultimate sections of M 1 in ratios of 5.9: 3.0; ultimate section of CuA 1 ~1/5 of penultimate. Haltere pale yellow. Abdomen (Fig. 21) yellow, tergites 2-6 blackish brown on posterior margin. Male genitalia : syntergosternite confluent with epandrium, broad dorsally and narrow ventrally. Epandrium with a pair of long black conical dorsoapical processes in lateral view, with a pair of lateral processes on anterior margin. Surstylus absent, ventral margin with setae, hypandrium V-shaped, with a pair of lateral acute processes. Gonopod indistinct; hypandrium, gonopod and phallus confluent together. Both sides of phallus serrated, with a dorsal process apically in lateral view. Phallus indistinct concave apically. Phallapodeme claviform, shorter than phallus.

Remarks.
This new species is very similar to Luzonomyza pseudoforficula from Thailand in the body markings, wing type, and leg color, but it can be separated from the latter by the yellow antenna and the phallus being serrated on both sides. In Luzonomyza pseudoforficula, the antenna is black, and the phallus is not serrated in ventral view.
Distribution. China (Yunnan). Diagnosis. Head yellow; face with a pair of brown stripes extending from antennal base and confluent on ventral margin. Thorax brownish yellow with grayish-white pruinescence; legs yellow, fore tarsomeres 4 and 5 brown. Abdomen yellow, tergites 2-6 black on posterior margin but tergite 6 yellow posteromedially. Male genitalia: hypandrium broad, membranous; pregonite confluent with hypandrium; phallus with a pair of lateral acute processes near base in ventral view, apical concave V-shaped, with a dorsal acute subapical process in lateral view, apex acute and curved dorsally.

Luzonomyza vittifacies
Description. Male. Body length 3.2 mm, wing length 3.4 mm. Head (Fig. 26) yellow. Face brownish yellow, with a pair of brown longitudinal stripes extending from antennal bases and confluent on ventral margin, face with an angular hump on middle of basal half; inner margin of parafacial with a brown stripe, broadening towards gena, with a black round spot between eye and antennal bases, parafacial with sparse short setulae, and 6 short black setae extending from parafacial ventral corner to gena. Frons as long as wide and parallel-sided, with a blackishbrown median line extending from anterior margin to ocellar triangle, and with short setulae on anterior half, denser on anterior margin; ocellar triangle grayish black; ocellar setae very small, hair-like, anterior fronto-orbital seta (situated at middle of fronto-orbital plate) reclinate, shorter than the posterior one. Gena ~1/3 height of eye and with broad brown stripe. Antenna yellow, first flagellomere brownish yellow and rounded apically, ~1.5× longer than high; arista brown, pubescent. Proboscis mostly yellow except blackish brown at tip, with white and black setulae; palpus yellow with black setulae. Thorax (Fig. 29) brownish yellow, with grayish-white pruinescence. Mesonotum with 4 broad brown stripes, 2 brown median stripes extending to tip of scutellum; 0+3 dorsocentral setae, anteriormost dorsocentral seta away from scutal suture; acrostichal setulae in 4 rows; a pair of prescutellar setae, missing. One anepisternal seta, 1 katepisternal seta. Legs mostly yellow, fore tarsomeres 4 and 5 brown. Fore femur with 8 posterodorsal setae and 6 posteroventral setae, fore tibia with a long dorsal preapical seta and a short apicoventral seta. Mid tibia with a strong dorsal preapical seta and an apicoventral seta. Hind tibia with a long dorsal preapical seta and a short apicoventral seta. Wing brown along costal margin extending to M 1 and with hyaline spots, a brown spot on each of the crossveins r-m and dm-cu; subcostal cell brown; costa with 2 nd (between R 1 and R 2+3 ), 3 rd (between R 2+3 and R 4+5 ) and 4 th (between R 4+5 and M 1 ) sections in ratios of 7.1: 1.4: 1.2; r-m beyond middle of discal cell; ultimate and penultimate sections of M 1 in ratios of 4.9: 2.5; ultimate section of CuA 1 ~1/5 of penultimate. Haltere yellow.
Abdomen (Fig. 30) yellow, tergites 2-6 black on posterior margin, but tergite 6 yellow posteromedially. Male genitalia (Figs 31-34): syntergosternite confluent with epandrium. Epandrium with a pair of black long conical dorsoapical processes in lateral view. Surstylus broken, hypandrium broad and membranous. Gonopod confluent with hypandrium, phallus consisting of a pair of sclerites in ventral view and a pair of lateral acute processes near base, with V-shaped apical concavity, broad basally and narrow apically in lateral view, with a dorsal acute process subapically, apex acute and curved dorsally. Phallapodeme claviform in ventral view. Ejaculatory apodeme bent.
Remarks. This new species is very similar to Luzonomyza gaimarii from China (Yunnan) in the wing spots and the thoracic and abdominal spots, but it can be separated from the latter by the pair of brown stripes on the face that extend down from antennal base and are confluent on ventral margin; by the 4 rows of acrostichal setulae; by r-m extending beyond middle of discal cell; by the absence of a lateral concavity in the hypandrium; and by the phallus being acute and curved dorsally in lateral view. In Luzonomyza gaimarii, the face has no spot; the acrostichal setulae are arranged in 2 rows; crossvein r-m is in the middle of the discal cell; the hypandrium has a lateral concavity; and the phallus is not curved dorsally in lateral view.

Discussion
This study increases the number of known Luzonomyza species in the world to 13. Seven species occur in China, accounting for more than half of the total species worldwide. Except for L. sinica in Hainan Province, the other six species are all found in Yunnan Province. There may be several reasons for the high number of species in Yunnan. One reason may be the location in the southwest of China, which has diverse climate types and a unique geographical location with suitable climate conditions. It has been considered to be a hotspot of global biodiversity for many years, and its fauna has attracted much attention. Another important reason may be that the seemingly more limited distribution of this genus may be the result of insufficient sampling outside Yunnan. There are still many areas in China with rich biological biodiversity that remain poorly investigated. We believe that the species diversity of the genus Luzonomyza in China may be underestimated, and there may be new species in other areas, so further investigations are needed.